The results of a search for the production of two scalar bosons in final states with two photons and two tau leptons are presented. The search considers both nonresonant production of a Higgs boson pair, HH, and resonant production via a new boson X which decays either to HH or to H and a new scalar Y. The analysis uses up to 138 fb$^{-1}$ of proton-proton collision data, recorded between 2016 and 2018 by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV. No evidence for signal is found in the data. For the nonresonant production, the observed (expected) upper limit at 95% confidence level (CL) on the HH production cross section is set at 930 (740) fb, corresponding to 33 (26) times the standard model prediction. At 95% CL, HH production is observed (expected) to be excluded for values of $κ_λ$ outside the range between $-$12 ($-$9.4) and 17 (15). Observed (expected) upper limits at 95% CL for the XHH cross section are found to be within 160 to 2200 (200 to 1800) fb, depending on the mass of X. In the X $\to$ Y($γγ$)H($ττ$) search, the observed (expected) upper limits on the product of the production cross section and decay branching fractions vary between 0.059$-$1.2 fb (0.087$-$0.68 fb). For the X $\to$ Y($γγ$)H($ττ$) search the observed (expected) upper limits on the product of the production cross section and Y $to$ $γγ$ branching fraction vary between 0.69$-$15 fb (0.73$-$8.3 fb) in the low Y mass search, tightening constraints on the next-to-minimal supersymmetric standard model, and between 0.64$-$10 fb (0.70$-$7.6 fb) in the high Y mass search.
Observed and expected 95% CL upper limits on the nonresonant $\mathrm{HH}$ production cross section, $\sigma(\mathrm{pp} \to \mathrm{HH})$, as a function of the Higgs boson self-coupling strength modifier $\kappa_\lambda$. All Higgs boson couplings other than $\lambda$ are assumed to have the values predicted in the SM.
Observed and expected 95% CL upper limits on the nonresonant $\mathrm{HH}$ production cross section, $\sigma(\mathrm{pp} \to \mathrm{HH})$, for thirteen different BSM benchmark scenarios from [arXiv:1507.02245, arXiv:1806.05162] which consider different values of the couplings, $\kappa_\lambda$, $\kappa_t$, $c_{2g}$, $c_g$, and $c_2$ (defined in Table 1).
Observed and expected 95% CL upper limits on the cross section for the resonant production of a new spin-0 particle $\mathrm{X}^{(0)}$ which decays to Higgs boson pairs, $\sigma(\mathrm{pp} \to \mathrm{X}^{(0)} \to \mathrm{HH})$, given for different values of $m_\mathrm{X}$ in the range 260-1000 GeV.
A search for nonresonant new physics phenomena in high-mass dilepton events produced in association with b-tagged jets is performed using proton-proton collision data collected in 2016$-$2018 by the CMS experiment at the CERN LHC, at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis considers two effective field theory models with dimension-six operators; involving four-fermion contact interactions between two leptons ($\ell\ell$, electrons or muons) and b or s quarks (bb$\ell\ell$ and bs$\ell\ell$). Two lepton flavor combinations (ee and $μμ$) are required and events are classified as having 0, 1, and $\geq$2 b-tagged jets in the final state. No significant excess is observed over the standard model backgrounds. Upper limits are set on the production cross section of the new physics signals. These translate into lower limits on the energy scale $Λ$ of 6.9 to 9.0 TeV in the bb$\ell\ell$ model, depending on model parameters, and on the ratio of energy scale and effective coupling, $Λ/g_*$, of 2.0 to 2.6 TeV in the bs$\ell\ell$ model. The latter represent the most stringent limits on this model to date. Lepton flavor universality is also tested by comparing the dielectron and dimuon mass spectra for different b-tagged jet multiplicities. No significant deviation from the standard model expectation of unity is observed.
Signal efficiencies with Full Run 2 dimuon channel for different bbll signal scenarios
Signal efficiencies with Full Run 2 dimuon channel for different bbll (destructive interference) signal scenarios
Signal efficiencies with Full Run 2 dimuon channel in 1b final state for different bbll signal scenarios
The jet cross-section and jet-substructure observables in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-$k_{t}$ algorithm with a jet radius $R=0.3$ for jets with transverse momentum within $8.0
The jet differential cross section as a function of jet $p_T$. Statistical uncertainties are typically smaller than the data points while systematic uncertainties are shown with boxes. An overall normalization systematic of 7% is not included in the point-by-point systematic uncertainties.
Distribution of the SoftDrop groomed momentum fraction $z_g$ for different jet $p_T$ bins. Standard SoftDrop parameters were used ($z_{cut}<0.1$ and $\beta=0$).
$\xi$ distributions for different jet $p_T$ bins.
The traditional quark model accounts for the existence of baryons, such as protons and neutrons, which consist of three quarks, as well as mesons, composed of a quark-antiquark pair. Only recently has substantial evidence started to accumulate for exotic states composed of four or five quarks and antiquarks. The exact nature of their internal structure remains uncertain. This paper reports the first measurement of quantum numbers of the recently discovered family of three all-charm tetraquarks, using data collected by the CMS experiment at the Large Hadron Collider from 2016 to 2018. The angular analysis techniques developed for the discovery and characterization of the Higgs boson have been applied to the new exotic states. The quantum numbers for parity $P$ and charge conjugation $C$ symmetries are found to be +1. The spin $J$ of these exotic states is consistent with 2$\hbar$, while 0$\hbar$ and 1$\hbar$ are excluded at 95% and 99% confidence level, respectively. The $J^{PC}=2^{++}$ assignment implies particular configurations of constituent spins and orbital angular momenta, which constrain the possible internal structure of these tetraquarks.
Summary of statistical tests.
Results from hypothesis test for pairs of spin-parity models.
The $\mathrm{J}/\psi\mathrm{J}/\psi$ invariant mass distribution in data.
A search for the rare decay D$^0$$\to$$\mu^+\mu^-$ is reported using proton-proton collision events at $\sqrt{s}$ = 13.6 TeV collected by the CMS detector in 2022$-$2023, corresponding to an integrated luminosity of 64.5 fb$^{-1}$. This is the first analysis to use a newly developed inclusive dimuon trigger, expanding the scope of the CMS flavor physics program. The search uses D$^0$ mesons obtained from D$^{*+}$$\to$ D$^0\pi^+$ decays. No significant excess is observed. A limit on the branching fraction of $\mathcal{B}$(D$^0$$\to$$\mu^+\mu^-$) $\lt$ 2.4 $\times$ 10$^{-9}$ at 95% confidence level is set. This is the most stringent upper limit set on any flavor changing neutral current decay in the charm sector.
Summary of branching fraction.
Summary of systematic uncertainties for the D->mumu branching fraction measurement with their corresponding contributions in the signal channel.
The distributions of the dipion invariant mass $m_{\pi\pi}$ for the normalization channel in data.
While dual-phase xenon time projection chambers (TPCs) have driven the sensitivity towards weakly interacting massive particles (WIMPs) at the GeV/c^2 to TeV/c^2 mass scale, the scope for sub-GeV/c^2 dark matter particles is hindered by a limited nuclear recoil energy detection threshold. One approach to probe for lighter candidates is to consider cases where they have been boosted by collisions with cosmic rays in the Milky Way, such that the additional kinetic energy lifts their induced signatures above the nominal threshold. In this Letter, we report first results of a search for cosmic ray-boosted dark matter (CRDM) with a combined 4.2 tonne-year exposure from the LUX-ZEPLIN (LZ) experiment. We observe no excess above the expected backgrounds and establish world-leading constraints on the spin-independent CRDM-nucleon cross section as small as 3.9 * 10^{-33} cm^2 at 90% confidence level for sub-GeV/c^2 masses.
90% CL CRDM-nucleon cross sections
A search for the violation of the charge-parity ($CP$) symmetry in the production of top quarks in association with Z bosons is presented, using events with at least three charged leptons and additional jets. The search is performed in a sample of proton-proton collision data collected by the CMS experiment at the CERN LHC in 2016-2018 at a center-of-mass energy of 13 TeV and in 2022 at 13.6 TeV, corresponding to a total integrated luminosity of 173 fb$^{-1}$. For the first time in this final state, observables that are odd under the $CP$ transformation are employed. Also for the first time, physics-informed machine-learning techniques are used to construct these observables. While for standard model (SM) processes the distributions of these observables are predicted to be symmetric around zero, $CP$-violating modifications of the SM would introduce asymmetries. Two $CP$-odd operators $\mathcal{O}_\text{tW}^\text{I}$ and $\mathcal{O}_\text{tZ}^\text{I}$ in the SM effective field theory are considered that may modify the interactions between top quarks and electroweak bosons. The obtained results are consistent with the SM prediction within two standard deviations, and exclusion limits on the associated Wilson coefficients of $-$2.7 $\lt$$c_\text{tW}^\text{I}$$\lt$ 2.5 and $-$0.2 $\lt$$c_\text{tZ}^\text{I}$$\lt$ 2.0 are set at 95% confidence level. The largest discrepancy is observed in $c_\text{tZ}^\text{I}$ where data is consistent with positive values, with an observed local significance with respect to the SM hypothesis of 2.5 standard deviations, when only linear terms are considered.
Distribution of the discretized $c_{\mathrm{tW}}^{\mathrm{I}}$ score for events in the $c_{\mathrm{tW}}^{\mathrm{I}}$-like category in tZq events. The contributions from the SM, linear, and quadratic terms when $c_{\mathrm{tW}}^{\mathrm{I}}$ is set to unity are plotted separately.
Distribution of the discretized $c_{\mathrm{tZ}}^{\mathrm{I}}$ score for events in the $c_{\mathrm{tZ}}^{\mathrm{I}}$-like category in $t\bar{t}Z$ events. The contributions from the SM, linear, and quadratic terms when $c_{\mathrm{tZ}}^{\mathrm{I}}$ is set to unity are plotted separately.
Distribution of the discretized $c_{\mathrm{tW}}^{\mathrm{I}}$ score for events in the $c_{\mathrm{tW}}^{\mathrm{I}}$-like category, compared with the predictions obtained when all fit parameters are set to their maximum likelihood value in the linear fit.
A measurement is presented of the cross section in proton-proton collisions for the production of two W bosons and one Z boson. It is based on data recorded by the CMS experiment at the CERN LHC at center-of-mass energies $\sqrt{s}$ = 13 and 13.6 TeV, corresponding to an integrated luminosity of 200 fb$^{-1}$. Events with four charged leptons (electrons or muons) in the final state are selected. Both nonresonant WWZ production and ZH production, with the Higgs boson decaying into two W bosons, are reported. For the first time, the two processes are measured separately in a simultaneous fit. Combining the two modes, signal strengths relative to the standard model (SM) predictions of 0.75$^{+0.34}_{-0.29}$ and 1.74$^{+0.71}_{-0.60}$ are measured for $\sqrt{s}$ = 13 and 13.6 TeV, respectively. The observed (expected) significance for the triboson signal is 3.8 (2.5) standard deviations for $\sqrt{s}$ = 13.6 TeV, thus providing the first evidence for triboson production at this center-of-mass energy. Combining the two modes and the two center-of-mass energies, the inclusive signal strength relative to the SM prediction is measured to be 1.03$^{+0.31}_{-0.28}$, with an observed (expected) significance of 4.5 (5.0) standard deviations.
Two-dimensional likelihood scan as a function of the individual WWZ and ZH signal strength parameters for the combined Run 2 and Run 3 datasets
One-dimensional likelihood scan as a function of the inclusive (WWZ + ZH) signal strength parameter for the combined Run 2 and Run 3 datasets
Comparison of the observed number of events to the SM-predicted number of events for each of the bins included in the fit for Run 2 (upper row) and Run 3 (lower row). The SM expectations are shown before performing the fit. The horizontal axis legend also indicates "WWZ-like" and "ZH-like" bins defined based on whether the WWZ BDT score is higher or lower than the ZH score.
A measurement of event-shape variables is presented, using a data sample produced in a special run with approximately one inelastic proton-proton collision per bunch crossing. The data were collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 64 $\mu$b$^{-1}$. A number of observables related to the overall distribution of charged particles in the collisions are corrected for detector effects and compared with simulations. Inclusive event-shape distributions, as well as differential distributions of event shapes as functions of charged-particle multiplicity, are studied. None of the models investigated is able to satisfactorily describe the data. Moreover, there are significant features common amongst all generator setups studied, particularly showing data being more isotropic than any of the simulations. Multidimensional unfolded distributions are provided, along with their correlations.
The unfolded charged particle multiplicity distribution of inelastic proton-proton collisions with at least three charged particles with transverse momentum higher than 0.5 GeV and pseudorapidity between -2.4 and 2.4. The total area of the histogram is normalised to 1.
The unfolded charged particle invariant mass distribution of inelastic proton-proton collisions with at least three charged particles with transverse momentum higher than 0.5 GeV and pseudorapidity between -2.4 and 2.4. The total area of the histogram is normalised to 1.
The unfolded charged particle sphericity distribution of inelastic proton-proton collisions with at least three charged particles with transverse momentum higher than 0.5 GeV and pseudorapidity between -2.4 and 2.4. The total area of the histogram is normalised to 1.
A search is performed for dark matter (DM) produced in association with a single top quark or a pair of top quarks using the data collected with the CMS detector at the LHC from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to 138 fb$^{-1}$ of integrated luminosity. An excess of events with a large imbalance of transverse momentum is searched for across 0, 1 and 2 lepton final states. Novel multivariate techniques are used to take advantage of the differences in kinematic properties between the two DM production mechanisms. No significant deviations with respect to the standard model predictions are observed. The results are interpreted considering a simplified model in which the mediator is either a scalar or pseudoscalar particle and couples to top quarks and to DM fermions. Axion-like particles that are coupled to top quarks and DM fermions are also considered. Expected exclusion limits of 410 and 380 GeV for scalar and pseudoscalar mediator masses, respectively, are set at the 95% confidence level. A DM particle mass of 1 GeV is assumed, with mediator couplings to fermions and DM particles set to unity. A small signal-like excess is observed in data, with the largest local significance observed to be 1.9 standard deviations for the 150 GeV pseudoscalar mediator hypothesis. Because of this excess, mediator masses are only excluded below 310 (320) GeV for the scalar (pseudoscalar) mediator. The results are also translated into model-independent 95% confidence level upper limits on the visible cross section of DM production in association with top quarks, ranging from 1 pb to 0.02 pb.
The post-fit $p_{\mathrm{T}}^{\text{miss}}$ distribution of the 1 b jet, 0 forward jet signal region in the all hadronic channel. A representative signal model distribution is shown for the scalar mediator interaction with $(m_{\chi},m_{\phi})=(1,100)$GeV and couplings set to unity. The grey dashed area in the upper panel represents the total uncertainty in all of the backgrounds and the chosen signal model, while in the lower panel it represents only the total uncertainty in the backgrounds.
The post-fit $p_{\mathrm{T}}^{\text{miss}}$ distribution of the 1 b jet, $\geq 1$ forward jet signal region in the all hadronic channel. A representative signal model distribution is shown for the scalar mediator interaction with $(m_{\chi},m_{\phi})=(1,100)$GeV and couplings set to unity. The grey dashed area in the upper panel represents the total uncertainty in all of the backgrounds and the chosen signal model, while in the lower panel it represents only the total uncertainty in the backgrounds.
The post-fit $p_{\mathrm{T}}^{\text{miss}}$ distribution of the $\geq 2$ b jet signal region in the all hadronic channel. A representative signal model distribution is shown for the scalar mediator interaction with $(m_{\chi},m_{\phi})=(1,100)$GeV and couplings set to unity. The grey dashed area in the upper panel represents the total uncertainty in all of the backgrounds and the chosen signal model, while in the lower panel it represents only the total uncertainty in the backgrounds.
Inclusive and differential cross sections for Higgs boson production in proton-proton collisions at a centre-of-mass energy of 13.6 TeV are measured using data collected with the CMS detector at the LHC in 2022, corresponding to an integrated luminosity of 34.7 fb$^{-1}$. Events with the diphoton final state are selected, and the measured inclusive fiducial cross section is $\sigma_\text{fid}$ = 74 $\pm$ 11 (stat) $^{+5}_{-4}$ (syst) fb, in agreement with the standard model prediction of 67.8 $\pm$ 3.8 fb. Differential cross sections are measured as functions of several observables: the Higgs boson transverse momentum and rapidity, the number of associated jets, and the transverse momentum of the leading jet in the event. Within the uncertainties, the differential cross sections agree with the standard model predictions.
Differential fiducial cross sections for pT of the Higgs boson
Example description
Differential fiducial cross sections for rapidity of the Higgs boson
Precision measurements of Higgs boson differential production cross sections are a key tool to probe the properties of the Higgs boson and test the standard model. New physics can affect both Higgs boson production and decay, leading to deviations from the distributions that are expected in the standard model. In this paper, combined measurements of differential spectra in a fiducial region matching the experimental selections are performed, based on analyses of four Higgs boson decay channels ($\gamma\gamma$, ZZ$^{(*)}$, WW$^{(*)}$, and $\tau\tau$) using proton-proton collision data recorded with the CMS detector at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The differential measurements are extrapolated to the full phase space and combined to provide the differential spectra. A measurement of the total Higgs boson production cross section is also performed using the $\gamma\gamma$ and ZZ decay channels, with a result of 53.4$^{+2.9}_{-2.9}$ (stat)$^{+1.9}_{-1.8}$ (syst) pb, consistent with the standard model prediction of 55.6 $\pm$ 2.5 pb. The fiducial measurements are used to compute limits on Higgs boson couplings using the $\kappa$-framework and the SM effective field theory.
Observed best fit differential cross section for the $p_{T}^{H}$ observable
Observed best fit differential cross section for the $N_{jets}$ observable
Observed best fit differential cross section for the $p_{T}^{j1}$ (GeV) observable
A search for charged-lepton flavour violation (CLFV) in top quark (t) production and decay is presented. The search uses proton-proton collision data corresponding to 138 fb$^{-1}$ collected with the CMS experiment at $\sqrt{s}$ = 13 TeV. The signal consists of the production of a single top quark via a CLFV interaction or top quark pair production followed by a CLFV decay. The analysis selects events containing a pair of oppositely charged muon and hadronically decaying $\tau$ lepton and at least three jets, where one has been identified to originate from the fragmentation of a bottom quark. Machine learning classification techniques are used to distinguish signal from standard model background events. The results of this search are consistent with the standard model expectations. The upper limits at 95% confidence level on the branching fraction $\mathcal{B}$ for CLFV top quark decays to a muon, a $\tau$ lepton, and an up or a charm quark are set at $\mathcal{B}$(t $\to \mu\tau$u) $\lt$ (0.040, 0.078, and 0.118) $\times$ 10$^{-6}$, and $\mathcal{B}$(t $\to\mu\tau$c) $\lt$ (0.810, 1.710, and 2.052) $\times$ 10$^{-6}$ for scalar, vector, and tensor-like operators, respectively.
The expected and observed upper limits on CLFV Wilson coefficients. The Limits on the Wilson coefficients are extracted from the upper limits on the cross sections.
The expected and observed upper limits on top quark CLFV branching fractions. The Limits on the top quark CLFV branching fractions are extracted from the upper limits on the Wilson coefficients.
The first measurement of the dijet transverse momentum balance $x_j$ in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}}$ = 8.16 TeV is presented. The $x_j$ observable, defined as the ratio of the subleading over leading jet transverse momentum in a dijet pair, is used to search for jet quenching effects. The data, corresponding to an integrated luminosity of 174.6 nb$^{-1}$, were collected with the CMS detector in 2016. The $x_j$ distributions and their average values are studied as functions of the charged-particle multiplicity of the events and for various dijet rapidity selections. The latter enables probing hard scattering of partons carrying distinct nucleon momentum fractions \x in the proton- and lead-going directions. The former, aided by the high-multiplicity triggers, allows probing for potential jet quenching effects in high-multiplicity events (with up to 400 charged particles), for which collective phenomena consistent with quark-gluon plasma (QGP) droplet formation were previously observed. The ratios of $x_j$ distributions for high- to low-multiplicity events are used to quantify the possible medium effects. These ratios are consistent with simulations of the hard-scattering process that do not include QGP production. These measurements set an upper limit on medium-induced energy loss of the subleading jet of 1.26% of its transverse momentum at the 90% confidence level in high multiplicity pPb events.
The unfolded dijet balance distribution, $(1/N_{dijet})(dN_{dijet}/dx_{j})$, as function of $x_{j}$ for the $10-60$, $60-120$, $120-185$, $185-250$ and $250-400$ multiplicity ranges with both jets at the midrapidity regions.
The unfolded dijet balance distribution, $(1/N_{dijet})(dN_{dijet}/dx_{j})$, as function of $x_{j}$ for the $10-60$, $60-120$, $120-185$, $185-250$ and $250-400$ multiplicity ranges with leading and subleading jets at midrapidity and forward regions, respectively.
The unfolded dijet balance distribution, $(1/N_{dijet})(dN_{dijet}/dx_{j})$, as function of $x_{j}$ for the $10-60$, $60-120$, $120-185$, $185-250$ and $250-400$ multiplicity ranges with leading and subleading jets at midrapidity and backward regions, respectively.
The first observation of coherent $\phi$(1020) meson photoproduction off heavy nuclei is presented using ultraperipheral lead-lead collisions at a center-of-mass energy per nucleon pair of 5.36 TeV. The data were collected by the CMS experiment and correspond to an integrated luminosity of 1.68 $\mu$b$^{-1}$. The $\phi$(1020) meson signals are reconstructed via the K$^+$K$^-$ decay channel. The production cross section is presented as a function of the $\phi$(1020) meson rapidity in the range 0.3 $\lt$$\lvert y\rvert$$\lt$ 1.0, probing gluons that carry a fraction of the nucleon momentum ($x$) around $10^{-4}$. The observed cross section exhibits little dependence on rapidity and is significantly suppressed, by a factor of ${\sim}$5, compared to a baseline model that treats a nucleus as a collection of free nucleons. Theoretical models that incorporate either nuclear shadowing or gluon saturation predict suppression of the $\phi$(1020) meson cross section with only a small dependence on rapidity, but the magnitude of the predicted suppression varies greatly. Models considering only nuclear shadowing effects result in the best agreement with the experimental data. This study establishes a powerful new tool for exploring nuclear effects and nuclear gluonic structure in the small-$x$ regime at a unique energy scale bridging the perturbative and nonperturbative quantum chromodynamics domains.
The differential coherent $\phi$ photoproduction cross section and the nuclear suppression factor as a function of rapidity.
A search for resonances in top quark pair ($\text{t}\bar{\text{t}}$) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC at $\sqrt{s}$ = 13 TeV, corresponding to 138 fb$^{-1}$. The analysis explores the invariant mass of the \ttbar system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematic $\text{t}\bar{\text{t}}$ threshold compared to the nonresonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar ($^1$S$^{[1]}_0$) quasi-bound toponium state, as predicted by nonrelativistic quantum chromodynamics. Using a simplified model for $^1$S$^{[1]}_0$ toponium, the cross section of the excess above the pQCD prediction is measured to be 8.8$^{+1.2}_{-1.4}$ pb.
Observed cross section of $\eta_t$
Observed values of twice the negative log-likelihood with respect to the best-fit point (2dNLL) as a function of the cross sections of $\eta_t$ and $\chi_t$.
A measurement of the WZ$\gamma$ triboson production cross section is presented. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis focuses on the final state with three charged leptons, $\ell^\pm\nu\ell^+\ell^-$, where $\ell$ = e or $\mu$, accompanied by an additional photon. The observed (expected) significance of the WZ$\gamma$ signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region to be 5.48 $\pm$ 1.11 fb, which is compatible with the prediction of 3.69 $\pm$ 0.24 fb at next-to-leading order in quantum chromodynamics. Exclusion limits are set on anomalous quartic gauge couplings and on the production cross sections of massive axion-like particles.
The distributions of the variables used in the simultaneous fit for the nonprompt $l$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the nonprompt $\gamma$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the ZZ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The production cross-section of high-mass $\tau$-lepton pairs is measured as a function of the dilepton visible invariant mass, using 140 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider. The measurement agrees with the predictions of the Standard Model. A fit to the invariant mass distribution is performed as a function of $b$-jet multiplicity, to constrain the non-resonant production of new particles described by an effective field theory or in models containing leptoquarks or $Z'$ bosons that couple preferentially to third-generation fermions. The constraints on new particles improve on previous results, and the constraints on effective operators include those affecting the anomalous magnetic moment of the $\tau$-lepton.
The measured unfolded differential cross sections.
The combined covariance matrix for the differential cross-section distribution.
Statistical covariance matrix for the differential cross-section distribution.
A search for $t$-channel exchange of leptoquarks (LQs) is performed in dimuon and dielectron spectra using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 138 fb$^{-1}$. Eight scenarios are considered, in which scalar or vector LQs couple up or down quarks to muons or electrons, for dilepton invariant masses above 500 GeV. The LQ masses are probed up to 5 TeV, beyond a regime probed by previous pair-production and single-production searches. The differential distributions of dilepton events are fit to templates that model the nonresonant LQ exchange and various standard model background processes. Limits are set on LQ-fermion coupling strengths for scalar and vector LQ masses in the 1-5 TeV range at 95% confidence level, establishing stringent limits on first- and second-generation LQs.
Observed and Expected UL exclusions on the $BR(H\to SUEP)$ of hadronic signals with $m_{A'} = 0.7\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.15$ and $BR(A' \rightarrow \pi\pi) = 0.7$.
The observed data in the dielectron channel and the fitted signal-plus-background templates, shown for the $S_{e u}$ scenario with a candidate LQ mass of 2.5 TeV. Distributions of events are binned in the reconstructed dilepton mass, rapidity, and cosine theta.
Observed and Expected UL exclusions on the $BR(H\to S)$ of leptonic signals with $m_{A'} = 0.5\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.2$ and $BR(A' \rightarrow \pi\pi) = 0.6$.
Energy-energy correlators are constructed by averaging the number of charged particle pairs within jets, weighted by the product of their transverse momenta, as a function of the angular separation of the particles within a pair. They are sensitive to a multitude of perturbative and nonperturbative quantum chromodynamics phenomena in high-energy particle collisions. Using lead-lead data recorded with the CMS detector, energy-energy correlators inside high transverse momentum jets are measured in heavy ion collisions for the first time. The data are obtained at a nucleon-nucleon center-of-mass energy of 5.02 TeV and correspond to an integrated luminosity of 1.70 nb$^{-1}$. A similar analysis is done for proton-proton collisions at the same center-of-mass energy to establish a reference. The ratio of lead-lead to proton-proton energy-energy correlators reveals significant jet substructure modifications in the quark-gluon plasma. The results are compared to different models that incorporate either color coherence or medium response effects, where the two effects predict similar substructure modifications.
The energy-energy correlator distributions constructed with charged particles with $p_{\mathrm{T}} > 1$ GeV for energy weight $n=1$ and jet $p_{\mathrm{T}}$ selection $120 < p_{\mathrm{T,jet}} < 140$ GeV. The results are shown for different centrality bins in PbPb collisions and for pp collisions.
The energy-energy correlator distributions constructed with charged particles with $p_{\mathrm{T}} > 1$ GeV for energy weight $n=1$ and jet $p_{\mathrm{T}}$ selection $120 < p_{\mathrm{T,jet}} < 140$ GeV. The results are shown for different centrality bins in PbPb collisions and for pp collisions.
The energy-energy correlator distributions constructed with charged particles with $p_{\mathrm{T}} > 1$ GeV for energy weight $n=1$ and jet $p_{\mathrm{T}}$ selection $140 < p_{\mathrm{T,jet}} < 160$ GeV. The results are shown for different centrality bins in PbPb collisions and for pp collisions.
A first search is presented for vector-like leptons (VLLs) decaying into a light long-lived pseudoscalar boson and a standard model $\tau$ lepton. The pseudoscalar boson is assumed to have a mass of 2 GeV and to decay exclusively into a pair of photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016-2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying $\tau$ lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.
The cluster reconstruction efficiency, including both DT and CSC clusters, as a function of the simulated r and |z| decay positions of the pseudoscalar into photons in events with MET > 200 GeV, for a VLL mass of 700 GeV and a pseudoscalar mass of 2 GeV, and a range of ctau values uniformly distributed between 0.01 and 0.1 m.
Distributions of the number of hits in the cluster (Nhits) for the DT category in the signal region (SR). The last histogram bin contains all overflow events.
Distributions of the number of hits in the cluster (Nhits) for the CSC category in the signal region (SR). The last histogram bin contains all overflow events.
A search for cascade decays of charged sleptons and sneutrinos using final states characterized by three leptons (electrons or muons) and missing transverse momentum is presented. The analysis is based on a dataset with 140 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of $\sqrt{s}$=13 TeV recorded by the ATLAS detector at the Large Hadron Collider. This paper focuses on a supersymmetric scenario that is motivated by the muon anomalous magnetic moment observation, dark mattter relic density abundance, and electroweak naturalness. A mass spectrum involving light higgsinos and heavier sleptons with a bino at intermediate mass is targeted. No significant deviation from the Standard Model expectation is observed. This search enables to place stringent constraints on this model, excluding at the 95% confidence level charged slepton and sneutrino masses up to 450 GeV when assuming a lightest neutralino mass of 100 GeV and mass-degenerate selectrons, smuons and sneutrinos.
Distribution of $m_{3\ell}$ in SROS-on-$eee$. The SR selections are applied for each distribution, except for the variable shown, for which the selection is indicated by a black arrow. The last bin includes the overflow. The `Others' category contains the production of Higgs boson, 3-top, 4-top, and single-top processes. Distributions for SBH signals are overlaid. The bottom panels show the ratio of the observed data to the predicted total background yields. The hatched band includes all statistical and systematic uncertainties.
Distribution of $m_{3\ell}$ in SROS-on-$e\mu\mu$. The SR selections are applied for each distribution, except for the variable shown, for which the selection is indicated by a black arrow. The last bin includes the overflow. The `Others' category contains the production of Higgs boson, 3-top, 4-top, and single-top processes. Distributions for SBH signals are overlaid. The bottom panels show the ratio of the observed data to the predicted total background yields. The hatched band includes all statistical and systematic uncertainties.
Distribution of $E_{\text{T}}^{\text{miss}}$ in SROS-on-b-$eee$. The SR selections are applied for each distribution, except for the variable shown, for which the selection is indicated by a black arrow. The last bin includes the overflow. The `Others' category contains the production of Higgs boson, 3-top, 4-top, and single-top processes. Distributions for SBH signals are overlaid. The bottom panels show the ratio of the observed data to the predicted total background yields. The hatched band includes all statistical and systematic uncertainties.
Measurements are presented of the W and Z boson production cross sections in proton-proton collisions at a center-of-mass energy of 13.6 TeV. Data collected in 2022 and corresponding to an integrated luminosity of 5.01 fb$^{-1}$ with one or two identified muons in the final state are analyzed. The results for the products of total inclusive cross sections and branching fractions for muonic decays of W and Z bosons are 11.93 $\pm$ 0.08 (syst) $\pm$ 0.17 (lumi) $^{+0.07}_{-0.07}$ (acc) nb for W$^+$ boson production, 8.86 $\pm$ 0.06 (syst) $\pm$ 0.12 (lumi) $^{+0.05}_{-0.06}$ (acc) nb for W$^-$ boson production, and 2.021 $\pm$ 0.009 (syst) $\pm$ 0.028 (lumi) $^{+0.011}_{-0.013}$ (acc) nb for the Z boson production in the dimuon mass range of 60-120 GeV, all with negligible statistical uncertainties. Furthermore, the corresponding fiducial cross sections, as well as cross section ratios for both fiducial and total phase space, are provided. The ratios include charge-separated results for W boson production (W$^+$ and W$^-$) and the sum of the two contributions (W$^\pm$), each relative to the measured Z boson production cross section. Additionally, the ratio of the measured cross sections for W$^+$ and W$^-$ boson production is reported. All measurements are in agreement with theoretical predictions, calculated at next-to-next-to-leading order accuracy in quantum chromodynamics.
Corrected normalized distribution of the transverse momentum of the leading muon in the Z boson signal region. Simulated contributions from Z boson, electroweak, and ttbar production, as well as their sum, and the data are shown.
Corrected normalized distribution of the transverse momentum of the trailing muon in the Z boson signal region. Simulated contributions from Z boson, electroweak, and ttbar production, as well as their sum, and the data are shown.
Corrected normalized distribution of the missing transverse momentum in the Z boson signal region. Simulated contributions from Z boson, electroweak, and ttbar production, as well as their sum, and the data are shown.
This paper presents the measurement of charged-hadron and identified-hadron ($K^\mathrm{0}_\mathrm{S}$, $Λ$, $Ξ^\mathrm{-}$) yields in photo-nuclear collisions using 1.7 $\mathrm{nb^{-1}}$ of $\sqrt{s_\mathrm{NN}} = 5.02$ TeV Pb+Pb data collected in 2018 with the ATLAS detector at the Large Hadron Collider. Candidate photo-nuclear events are selected using a combination of tracking and calorimeter information, including the zero-degree calorimeter. The yields as a function of transverse momentum and rapidity are measured in these photo-nuclear collisions as a function of charged-particle multiplicity. These photo-nuclear results are compared with 0.1 $\mathrm{nb^{-1}}$ of $\sqrt{s_\mathrm{NN}} = 5.02$ TeV $p$+Pb data collected in 2016 by ATLAS using similar charged-particle multiplicity selections. These photo-nuclear measurements shed light on potential quark-gluon plasma formation in photo-nuclear collisions via observables sensitive to radial flow, enhanced baryon-to-meson ratios, and strangeness enhancement. The results are also compared with the Monte Carlo DPMJET-III generator and hydrodynamic calculations to test whether such photo-nuclear collisions may produce small droplets of quark-gluon plasma that flow collectively.
The multiplicity distribution (#it{N}_{ch}^{rec}) from Pb+Pb photo-nuclear collisions.
The multiplicity distribution (#it{N}_{ch}^{rec}) from p+Pb collisions.
The Charged-hadron yields as a function of pT in different y selections in Pb+Pb photo-nuclear collisions.
Incoherent J/$\psi$ photoproduction in heavy ion ultraperipheral collisions (UPCs), in which the photon interacts with localized, fluctuating gluonic hotspots rather than the entire nucleus, provides a unique probe of those fluctuations. This study presents the first measurement of the dependence of this photoproduction yield on the photon-nucleon center-of-mass energy ($W_\gamma^\mathrm{N}$), using PbPb UPCs at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The data corresponds to an integrated luminosity of 1.52 nb$^{-1}$, recorded by the CMS experiment. The measurement covers a wide $W_\gamma^\mathrm{N}$ range of $\approx$40-400 GeV, probing gluons carrying a fraction of nucleon momentum $x$ in the range between 5.9 $\times$ 10$^{-3}$ and 6.5 $\times$ 10$^{-5}$. The measured incoherent J/$\psi$ photoproduction cross section is suppressed relative to theoretical predictions without nuclear effects. However, the ratio of incoherent to coherent photoproduction remains constant across the probed $W_\gamma^\mathrm{N}$ and $x$ range. Together, these results pose significant challenges to current theoretical models which include gluon saturation or nuclear shadowing effects.
The differential incoherent $\mathrm{J}/\psi$ photoproduction cross section as a function of $|y|$, in different neutron multiplicity classes.
The differential incoherent $\mathrm{J}/\psi$ photoproduction cross section as a function of $y$, in different neutron multiplicity classes.
The incoherent $\mathrm{J}/\psi$ photoproduction cross section as a function of photon-nuclear center-of-mass energy per nucleon $W_{\gamma \mathrm{N}}^{\mathrm{Pb}}$ or Bjorken $x$, measured in PbPb ultra-peripheral collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. The $W_{\gamma \mathrm{N}}^{\mathrm{Pb}}$ values used correspond to the center of each rapidity range. The theoretical uncertainties is due to the uncertainties in the photon flux.
Bound states of charm and anticharm quarks, known as charmonia, have a rich spectroscopic structure that can be used to probe the dynamics of hadron production in high-energy hadron collisions. Here, the cross section ratio of excited ($\psi$(2S)) and ground state (J/$\psi$) vector mesons is measured as a function of the charged-particle multiplicity in proton-lead (pPb) collisions at a center-of-mass (CM) energy per nucleon pair of 8.16 TeV. The data corresponding to an integrated luminosity of 175 nb$^{-1}$ were collected using the CMS detector. The ratio is measured separately for prompt and nonprompt charmonia in the transverse momentum range 6.5 $\lt$$p_\text{T}$$\lt$ 30 GeV and in four rapidity ranges spanning $-$2.865 $\lt$$y_\text{CM}$$\lt$ 1.935. For the first time, a statistically significant multiplicity dependence of the prompt cross section ratio is observed in proton-nucleus collisions. There is no clear rapidity dependence in the ratio. The prompt measurements are compared with a theoretical model which includes interactions with nearby particles during the evolution of the system. These results provide additional constraints on hadronization models of heavy quarks in nuclear collisions.
Normalized $\sigma_{\psi(2S)}/\sigma_{J/\psi}$ in $6.5<p_T<30.0\,GeV$ and $ -2.865 < y_{CM} < -2$ as functions of normalized $\text{N}^{{\text{corr.}}}_{\text{track}}$
Normalized $\sigma_{\psi(2S)}/\sigma_{J/\psi}$ in $6.5<p_T<30.0\,GeV$ and $ -2 < y_{CM} < -1$ as functions of normalized $\text{N}^{{\text{corr.}}}_{\text{track}}$
Normalized $\sigma_{\psi(2S)}/\sigma_{J/\psi}$ in $6.5<p_T<30.0\,GeV$ and $ -1 < y_{CM} < 1$ as functions of normalized $\text{N}^{{\text{corr.}}}_{\text{track}}$
This paper presents a first measurement of the cross-section for the charged-current Drell-Yan process $pp\rightarrow W^{\pm} \rightarrow \ell^{\pm} \nu$ above the resonance region, where $\ell$ is an electron or muon. The measurement is performed for transverse masses, $m_{\text{T}}^{\text{W}}$, between 200 GeV and 5000 GeV, using a sample of 140~fb$^{-1}$ of $pp$ collision data at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV collected by the ATLAS detector at the LHC during 2015-2018. The data are presented single differentially in transverse mass and double differentially in transverse mass and absolute lepton pseudorapidity. A test of lepton flavour universality shows no significant deviations from the Standard Model. The electron and muon channel measurements are combined to achieve a total experimental precision of 3% at low $m_{\text{T}}^{\text{W}}$. The single- and double differential $W$-boson charge asymmetries are evaluated from the measurements. A comparison to next-to-next-to-leading-order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading-order electroweak effects indicates the potential of the data to constrain parton distribution functions. The data are also used to constrain four fermion operators in the Standard Model Effective Field Theory formalism, in particular the lepton-quark operator Wilson coefficient $c_{\ell q}^{(3)}.$
The expected EFT limits at 95% CL, shown for the linear-only electron, muon, and combined fits.
The expected EFT limits at 95% CL, shown for the linear+quadratic electron, muon, and combined fits.
The observed EFT limits at 95% CL, shown for the linear-only electron, muon, and combined fits.
The mass of the top quark is measured using top-antitop-quark pair events with high transverse momentum top quarks. The dataset, collected with the ATLAS detector in proton--proton collisions at $\sqrt{s}=13$ TeV delivered by the Large Hadron Collider, corresponds to an integrated luminosity of 140 fb$^{-1}$. The analysis targets events in the lepton-plus-jets decay channel, with an electron or muon from a semi-leptonically decaying top quark and a hadronically decaying top quark that is sufficiently energetic to be reconstructed as a single large-radius jet. The mean of the invariant mass of the reconstructed large-radius jet provides the sensitivity to the top quark mass and is simultaneously fitted with two additional observables to reduce the impact of the systematic uncertainties. The top quark mass is measured to be $m_t = 172.95 \pm 0.53$ GeV, which is the most precise ATLAS measurement from a single channel.
Values and uncertainties for the parameters of interest in the profile likelihood fit to $\overline{m_J}$, $m_{jj}$, and $m_{tj}$ using data. The parameters of interest are the top quark mass, $m_t$, and the ratio of the measured cross-section to the Standard Model expectation of the $t\bar{t}$ cross-section, $\mu$.
Post-fit central values and uncertaintes for the nuisance parameters (including MC stat uncertainty terms) used in the profile likelihood fit to $\overline{m_J}$, $m_{jj}$, and $m_{tj}$ using data.
Covariance matrix for the profile likelihood fit to $\overline{m_J}$, $m_{jj}$, and $m_{tj}$ using data.
The jet axis decorrelation in inclusive jets is studied using lead-lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The jet axis decorrelation is defined as the angular difference between two definitions of the jet axis. It is obtained by applying two recombination schemes on all the constituents of a given jet reconstructed by the anti-$k_\mathrm{T}$ sequential algorithm with a distance parameter of $R$ = 0.4. The data set, corresponding to an integrated luminosity of 0.66 nb$^{-1}$, was collected in 2018 with the CMS detector at the CERN LHC. The jet axis decorrelations are examined across collision centrality selections and intervals of jet transverse momentum. A centrality dependent evolution of the measured distributions is observed, with a progressive narrowing seen in more central events. This narrowing could result from medium-induced modification of the internal jet structure or reflect color charge effects in energy loss. This new measurement probes jet substructure in previously unexplored kinematic domains and show great promise for providing new insights on the color charge dependence of energy loss to jet-quenching models.
The unfolded jet axis decorrelation distribution,$\frac{1}{N} \frac{dN}{d\Delta j}$, as a function of $\Delta j$ for the $0-10\%$, $10-30\%$, $30-50\%$, and $50-80\%$ centrality bins in the $120 < p_{\mathrm{T}} < 150$ GeV interval.
The unfolded jet axis decorrelation distribution,$\frac{1}{N} \frac{dN}{d\Delta j}$, as a function of $\Delta j$ for the $0-10\%$, $10-30\%$, $30-50\%$, and $50-80\%$ centrality bins in the $150 < p_{\mathrm{T}} < 190$ GeV interval.
The unfolded jet axis decorrelation distribution,$\frac{1}{N} \frac{dN}{d\Delta j}$, as a function of $\Delta j$ for the $0-10\%$, $10-30\%$, $30-50\%$, and $50-80\%$ centrality bins in the $190 < p_{\mathrm{T}} < 230$ GeV interval.
Charged hadron elliptic anisotropies ($v_2$) are presented over a wide transverse momentum ($p_\text{T}$) range for proton-lead (pPb) and lead-lead (PbPb) collisions at nucleon-nucleon center-of-mass energies of 8.16 and 5.02 TeV, respectively. The data were recorded by the CMS experiment and correspond to integrated luminosities of 186 nb$^{-1}$ and 0.607 nb$^{-1}$ for the pPb and PbPb systems, respectively. A four-particle cumulant analysis is performed using subevents separated in pseudorapidity to effectively suppress non-collective effects. At high $p_\text{T}$ ($p_\text{T}$$\gt$ 8 GeV), significant positive $v_2$ values are observed that are similar between pPb and PbPb collisions at comparable charged particle multiplicities. This observation suggests a common origin for the multi-particle collectivity for high-$p_\text{T}$ particles in the two systems.
The elliptic anisotropy $v_2\{4\}$ for charged hadron as a function of $p_T$ in pPb collisions at 8.16 TeV in $185 \le N_{trk}^{offline} <250$.
The elliptic anisotropy $v_2\{4\}$ for charged hadron as a function of $p_T$ in PbPb collisions at 5.02 TeV in $185 \le N_{trk}^{offline} <250$.
The elliptic anisotropy $v_2\{4\}$ as a function of $p_T$ with 4-subevent method compared between pPb collisions at 8.16 TeV and PbPb collisions at 5.02 TeV in $185 \le N_{trk}^{offline} <250$.
The polarization of the $\Lambda$ and $\overline{\Lambda}$ hyperons along the beam direction has been measured in proton-lead (pPb) collisions at a center-of-mass energy per nucleon pair of 8.16 TeV. The data were obtained with the CMS detector at the LHC and correspond to an integrated luminosity of 186.0 $\pm$ 6.5 nb$^{-1}$. A significant azimuthal dependence of the hyperon polarization, characterized by the second-order Fourier sine coefficient $P_{z,s2}$, is observed. The $P_{z,s2}$ values decrease as a function of charged particle multiplicity, but increase with transverse momentum. A hydrodynamic model that describes the observed $P_{z,s2}$ values in nucleus-nucleus collisions by introducing vorticity effects does not reproduce either the sign or the magnitude of the pPb results. These observations pose a challenge to the current theoretical implementation of spin polarization in heavy ion collisions and offer new insights into the origin of spin polarization in hadronic collisions at LHC energies.
The second-order Fourier sine coefficients of $\Lambda$, $\bar{\Lambda}$ and $\Lambda+\bar{\Lambda}$ polarizations along the beam direction as functions of $N_\mathrm{trk}^\mathrm{offline}$ in pPb collisions at 8.16 TeV.
The second-order Fourier sine coefficients of $\Lambda+\bar{\Lambda}$ polarization along the beam direction as functions of $p_{T}$ in pPb collisions at 8.16 TeV.
The second-order Fourier sine coefficients of $K_{S}^{0}$ polarization along the beam direction as functions of $N_\mathrm{trk}^\mathrm{offline}$ in pPb collisions at 8.16 TeV.
A search for beyond-the-standard-model neutral Higgs bosons decaying to a pair of bottom quarks, and produced in association with at least one additional bottom quark, is performed with the CMS detector. The data were recorded in proton-proton collisions at a centre-of-mass energy of 13 TeV at the CERN LHC, and correspond to an integrated luminosity of 36.7-126.9 fb$^{-1}$ depending on the probed mass range. No signal above the standard model background expectation is observed. Upper limits on the production cross section times branching fraction are set for Higgs bosons in the mass range of 125-1800 GeV. The results are interpreted in benchmark scenarios of the minimal supersymmetric standard model, as well as suitable classes of two-Higgs-doublet models.
Signal efficiency as a function of the mass $m_\phi$ after triple b tag selection for 2017 SL (squares), 2017 FH (triangles), and 2018 FH (circles) channels.
Expected and observed upper limits for the b-quark-associated Higgs boson production cross section times branching fraction of the decay into a b quark pair at 95% CL as functions of $m_\phi$ for the 2017 SL category. The vertical dashed lines indicate the boundaries of usage of the different fit ranges, as reflected in the rightmost column of Table 2.
Expected and observed upper limits for the b-quark-associated Higgs boson production cross section times branching fraction of the decay into a b quark pair at 95% CL as functions of $m_\phi$ for the 2017 FH category. The vertical dashed lines indicate the boundaries of usage of the different fit ranges, as reflected in the rightmost column of Table 2.
This paper presents a search for massive, charged, long-lived particles with the ATLAS detector at the Large Hadron Collider using an integrated luminosity of 140 $fb^{-1}$ of proton-proton collisions at $\sqrt{s}=13$ TeV. These particles are expected to move significantly slower than the speed of light. In this paper, two signal regions provide complementary sensitivity. In one region, events are selected with at least one charged-particle track with high transverse momentum, large specific ionisation measured in the pixel detector, and time of flight to the hadronic calorimeter inconsistent with the speed of light. In the other region, events are selected with at least two tracks of opposite charge which both have a high transverse momentum and an anomalously large specific ionisation. The search is sensitive to particles with lifetimes greater than about 3 ns with masses ranging from 200 GeV to 3 TeV. The results are interpreted to set constraints on the supersymmetric pair production of long-lived R-hadrons, charginos and staus, with mass limits extending beyond those from previous searches in broad ranges of lifetime.
The contour for the excluded mass--lifetime region for stau pair production obtained with the di-track search. All masses and lifetimes shown that are below the curve and above 200 GeV are excluded by the observed data (while the expected exclusion is between the upper curve down to 210 GeV for lifetimes above 3000 ns). The sensitivity extends indefinitely to longer lifetimes.
The contour for the excluded mass--lifetime region for stau pair production obtained with the di-track search. All masses and lifetimes shown that are below the curve and above 200 GeV are excluded by the observed data (while the expected exclusion is between the upper curve down to 210 GeV for lifetimes above 3000 ns). The sensitivity extends indefinitely to longer lifetimes.
The contour for the excluded mass--lifetime region for stau pair production obtained with the di-track search. All masses and lifetimes shown that are below the curve and above 200 GeV are excluded by the observed data (while the expected exclusion is between the upper curve down to 210 GeV for lifetimes above 3000 ns). The sensitivity extends indefinitely to longer lifetimes.
We present an inclusive search for anomalous production of single-photon events from neutrino interactions in the MicroBooNE experiment. The search and its signal definition are motivated by the previous observation of a low-energy excess of electromagnetic shower events from the MiniBooNE experiment. We use the Wire-Cell reconstruction framework to select a sample of inclusive single-photon final-state interactions with a final efficiency and purity of 7.0% and 40.2%, respectively. We leverage simultaneous measurements of sidebands of charged current $\nu_{\mu}$ interactions and neutral current interactions producing $\pi^{0}$ mesons to constrain signal and background predictions and reduce uncertainties. We perform a blind analysis using a dataset collected from February 2016 to July 2018, corresponding to an exposure of $6.34\times10^{20}$ protons on target from the Booster Neutrino Beam (BNB) at Fermilab. In the full signal region, we observe agreement between the data and the prediction, with a goodness-of-fit $p$-value of 0.11. We then isolate a sub-sample of these events containing no visible protons, and observe $93\pm22\text{(stat.)}\pm35\text{(syst.)}$ data events above prediction, corresponding to just above $2\sigma$ local significance, concentrated at shower energies below 600 MeV.
Fig. 2. The reconstructed shower energy. The individual signal and background event type categories added together form the unconstrained prediction.
Fig. 2. The constrained covariance matrix for the reconstructed shower energy. The matrix shows uncertainties and correlations between bins due to flux uncertainties, cross-section uncertainties, hadron reinteraction uncertainties, detector systematic uncertainties, Monte-Carlo statistical uncertainties, and dirt (outside cryostat) uncertainties. Data statistical uncertainties are not included. An example of how to add Pearson data statistical uncertainties can be found in the example code repository.
Fig. 2, Suppl. Fig. 5. The unconstrained covariance matrix for the reconstructed shower energy. The matrix shows uncertainties and correlations between bins due to flux uncertainties, cross-section uncertainties, hadron reinteraction uncertainties, detector systematic uncertainties, Monte-Carlo statistical uncertainties, and dirt (outside cryostat) uncertainties. Data statistical uncertainties are not included. An example of how to add Pearson data statistical uncertainties can be found in the example code repository.
A search for $\gamma$H production is performed with data from the CMS experiment at the LHC corresponding to an integrated luminosity of 138 fb$^{-1}$ at a proton-proton center-of-mass collision energy of 13 TeV. The analysis focuses on the topology of a boosted Higgs boson recoiling against a high-energy photon. The final states of H $\to$$\mathrm{b\bar{b}}$ and H $\to$ 4$\ell$ are analyzed. This study examines effective HZ$\gamma$ and H$\gamma\gamma$ anomalous couplings within the context of an effective field theory. In this approach, the production cross section is constrained to be $\sigma_{\gamma\text{H}}$$\lt$ 16.4 fb at 95% confidence level (CL). Simultaneous constraints on four anomalous couplings involving HZ$\gamma$ and H$\gamma\gamma$ are provided. Additionally, the production rate for H $\to$ 4$\ell$ is examined to assess potential enhancements in the Yukawa couplings between light quarks and the Higgs boson. Assuming the standard model values for the Yukawa couplings of the bottom and top quarks,the following simultaneous constraints are obtained: $\kappa_\text{u}$ = (0.0 $\pm$ 1.5) $\times$ 10$^{3}$, $\kappa_\text{d}$ = (0.0 $\pm$ 7.1) $\times$ 10$^{2}$, $\kappa_\text{s}$ = 0$^{+33}_{-34}$, and $\kappa_\text{c}$ = 0.0$^{+2.7}_{-3.0}$. This rules out the hypothesis that up- or down-type quarks in the first or second generation have the same Yukawa couplings as those in the third generation, with a CL greater than 95%.
Observed and expected constraints on the $\gamma H$ cross section $\sigma_{\gamma H}$ and on the $c_{\gamma\gamma}$, $c_{z\gamma}$, $\tilde{c}_{\gamma\gamma}$, $\tilde{c}_{z\gamma}$ couplings using the $ H\to b \bar b$ and $4\ell$ channels combined. The third and fourth rows show constraints on cross section multiplied by the branching fraction using the $H \rightarrow b \bar b $ and $H \rightarrow 4\ell$ channels only, respectively. The 68% (central value with uncertainties) and 95% (upper limit or allowed intervals) CL exclusion regions are shown.
Observed and expected constraints on the $\kappa_{u}$, $\kappa_{d}$, $\kappa_{s}$, and $\kappa_{c}$ couplings are shown using the $H \to 4\ell$ channel. In one scenario, all couplings except the one being shown are fixed at their SM values. In the other scenario, the Yukawa couplings for the three other light quarks are left unconstrained, and BSM contributions are allowed. The 68% (central value with error bars) and 95% (bracketed range or upper limit) CL exclusion regions are displayed.
Observed and expected constraints on the $\bar\kappa_{u}$, $\bar\kappa_{d}$, $\bar\kappa_{s}$, and $\bar\kappa_{c}$ defined as $\bar\kappa_{q}=y_{q}v/m_{b}$, following the same conventions as outlined in Table 3.
We report results from an updated search for neutral current (NC) resonant $\Delta$(1232) baryon production and subsequent $\Delta$ radiative decay (NC $\Delta\rightarrow N \gamma$). We consider events with and without final state protons; events with a proton can be compared with the kinematics of a $\Delta(1232)$ baryon decay, while events without a visible proton represent a more generic phase space. In order to maximize sensitivity to each topology, we simultaneously make use of two different reconstruction paradigms, Pandora and Wire-Cell, which have complementary strengths, and select mostly orthogonal sets of events. Considering an overall scaling of the NC $\Delta\rightarrow N \gamma$ rate as an explanation of the MiniBooNE anomaly, our data exclude this hypothesis at 94.4% CL. When we decouple the expected correlations between NC $\Delta\rightarrow N \gamma$ events with and without final state protons, and allow independent scaling of both types of events, our data exclude explanations in which excess events have associated protons, and do not exclude explanations in which excess events have no associated protons.
The four bins correspond to WC $1\gamma Np$, WC $1\gamma 0p$, Pandora $1\gamma 1p$, and Pandora $1\gamma 0p$ predictions. Systematic uncertainties on the predictions are illustrated, and a more detailed covariance matrix is included in the Constrained Signal Channels Covariance Matrix and Signal And Constraining Channels Covariance Matrix tabs. This corresponds to Fig. 1 and Table III of the paper.
Covariance matrix showing constrained uncertainties and correlations between bins due to flux uncertainties, cross-section uncertainties, hadron reinteraction uncertainties, detector systematic uncertainties, Monte-Carlo statistical uncertainties, and dirt (outside cryostat) uncertainties. Pearson data statistical uncertainties have been included, and include small correlations due to events which can be selected by both WC and Pandora. The four bins are the WC $1\gamma Np$, WC $1\gamma 0p$, Pandora $1\gamma 1p$, and Pandora $1\gamma 0p$ channels. This corresponds to Fig. 1 and Table II of the paper.
Four constraining channels. The four channels in order are NC $\pi^0 Np$, NC $\pi^0 0p$, $\nu_\mu$CC $Np$, and $\nu_\mu$CC $0p$. Each channel contains 15 bins from 0 to 1500 MeV of reconstructed neutrino energy, with an additional overflow bin. Unconstrained and constrained systematic uncertainties on the predictions are illustrated, and a more detailed covariance matrix is included in the Signal And Constraining Channels Covariance Matrix tab. This corresponds to Fig. 6 of the Supplemental Material.
The measurements of the Higgs boson (H) production cross sections performed by the CMS Collaboration in the four-lepton (4$\ell$, $\ell$ = e, $\mu$) final state at a center-of-mass energy $\sqrt{s}$ = 13.6 TeV are presented. These measurements are based on data collected with the CMS detector at the CERN LHC in 2022, corresponding to an integrated luminosity of 34.7 fb$^{-1}$. Cross sections are measured in a fiducial region closely matching the experimental acceptance, both inclusively and differentially, as a function of the transverse momentum and the absolute value of the rapidity of the four-lepton system. The H $\to$ ZZ $\to$ 4$\ell$ inclusive fiducial cross section is measured to be 2.89 $^{+0.53}_{-0.49}$ (stat) $^{+0.29}_{-0.21}$ (syst) fb, in agreement with the standard model expectation of 3.09 $^{+0.27}_{-0.24}$ fb.
Postfit reconstructed distribution of the 4-lepton invariant mass in the 70 < m4l < 350 GeV mass range.
Postfit reconstructed distribution of the 4-lepton invariant mass in the 105< m4l < 160 GeV mass range.
Measured inclusive fiducial H->ZZ->4l cross section in the various final states at 13.6 TeV.
A search for a heavy pseudoscalar Higgs boson, A, decaying to a 125 GeV Higgs boson h and a Z boson is presented. The h boson is identified via its decay to a pair of tau leptons, while the Z boson is identified via its decay to a pair of electrons or muons. The search targets the production of the A boson via the gluon-gluon fusion process, gg $\to$ A, and in association with bottom quarks, $\mathrm{b\bar{b}}$A. The analysis uses a data sample corresponding to an integrated luminosity of 138 fb$^{-1}$ collected with the CMS detector at the CERN LHC in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV. Constraints are set on the product of the cross sections of the A production mechanisms and the A $\to$ Zh decay branching fraction. The observed (expected) upper limit at 95% confidence level ranges from 0.049 (0.060) pb to 1.02 (0.79) pb for the gg $\to$ A process and from 0.053 (0.059) pb to 0.79 (0.61) pb for the $\text{b}\bar{\text{b}}$A process in the probed range of the A boson mass, $m_\text{A}$, from 225 GeV to 1 TeV. The results of the search are used to constrain parameters within the ${\text{M}_{\text{h,EFT}}^{\text{125}}}$ benchmark scenario of the minimal supersymmetric extension of the standard model. Values of $\tan\beta$ below 2.2 are excluded in this scenario at 95% confidence level for all $m_\text{A}$ values in the range from 225 to 350 GeV.
Exclusion limits on ggA production.
Exclusion limits on ggA production.
Example description
We measure for the first time the differential photoproduction cross section $d\sigma/dt$ of the $a_2(1320)$ meson at an average photon beam energy of 8.5~GeV, using data with an integrated luminosity of 104~pb$^{-1}$ collected by the GlueX experiment. We fully reconstruct the $\gamma p \to \eta\pi^0 p$ reaction and perform a partial-wave analysis in the $a_2(1320)$ mass region with amplitudes that incorporate the linear polarization of the beam. This allows us to separate for the first time the contributions of natural- and unnatural-parity exchanges. These measurements provide novel information about the photoproduction mechanism, which is critical for the search for spin-exotic states.
$a_2(1320)$ parity asymmetry, $P_{\sigma}$, in bins of four-momentum transfer. The first uncertainty is statistical, the second systematic.
$a_2(1320)$ differential cross section split into different reflectivity components, $\frac{d\sigma^+}{dt}$ and $\frac{d\sigma^-}{dt}$, in bins of four-momentum transfer. The first uncertainty is statistical, the second systematic.
$a_2(1320)$ differential cross section in the m=-1 projection split into different reflectivity components, $\frac{d\sigma^+_{-1}}{dt}$ and $\frac{d\sigma^-_{-1}}{dt}$, in bins of four-momentum transfer. The first uncertainty is statistical, the second systematic.
A pioneering machine-learning-based flavor-tagging algorithm combining same-side and opposite-side tagging is used to obtain the equivalent of 27$\,$000 tagged B$^0_\mathrm{s}$$\to$ J/$\psi\, \phi$(1020) decays from pp collisions at $\sqrt{s} =$ 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 96.5 fb$^{-1}$. A time- and flavor-dependent angular analysis of the $\mu^+\mu^-$K$^+$K$^-$ final state is used to measure parameters of the $\mathrm{B}^0_\mathrm{s}$-$\overline{\mathrm{B}}^0_\mathrm{s}$ system. The weak phase is measured to be $\phi_\mathrm{s}$ = $-$73 $\pm$ 23 (stat) $\pm$ 7 (syst) mrad, which, combined with a $\sqrt{s}$ = 8 TeV CMS result, gives $\phi_\mathrm{s}$ = $-$74 $\pm$ 23 mrad. This value differs from zero by 3.2 standard deviations, providing evidence for $CP$ violation in B$^0_\mathrm{s}$$\to$ J/$\psi\,\phi$(1020) decays. All measured physics parameters are found to agree with standard model predictions where available.
Measured values and uncertainties of the main parameters of interest, as obtained from the analysis to data at 13 TeV.
Values and uncertainties of the physics parameters obtained from the combination of the CMS 8 TeV and 13 TeV results using the BLUE method. The uncertainty includes both statistical and systematic sources.
Matrix of the correlations of the statistical uncertainties between pairs of physics parameters, as obtained from the analysis to data at 13 TeV.
The first search for a heavy neutral spin-1 gauge boson (Z') with nonuniversal fermion couplings produced via vector boson fusion processes and decaying to tau leptons or W bosons is presented. The analysis is performed using LHC data at $\sqrt{s}$ = 13 TeV, collected from 2016 to 2018 and corresponding to an integrated luminosity of 138 fb$^{-1}$. The data are consistent with the standard model predictions. Upper limits are set on the product of the cross section for production of the Z' boson and its branching fraction to $\tau\tau$ or WW. The presence of a Z' boson decaying to $\tau^+\tau^-$ (W$^+$W$^-$) is excluded for masses up to 2.45 (1.60) TeV, depending on the Z' boson coupling to SM weak bosons, and assuming a Z' $\to$$\tau^+\tau^-$ (W$^+$W$^-$) branching fraction of 50%.
Cutflow for VBF Z' to tautau in ditau 2016 channel for different signal scenarios
Cutflow for VBF Z' to tautau in ditau 2017 channel for different signal scenarios
Cutflow for VBF Z' to tautau in ditau 2018 channel for different signal scenarios
Charged Higgs bosons produced either in top-quark decays or in association with a top-quark, subsequently decaying via $H^{\pm} \to \tau^{\pm}\nu_{\tau}$, are searched for in 140 $\text{fb}^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV recorded with the ATLAS detector. Depending on whether the top-quark produced together with the $H^{\pm}$ decays hadronically or semi-leptonically, the search targets $\tau$+jets or $\tau$+lepton final states, in both cases with a $\tau$-lepton decaying into a neutrino and hadrons. No significant excess over the Standard Model background expectation is observed. For the mass range of $80 \leq m_{H^{\pm}} \leq 3000$ GeV, upper limits at 95% confidence level are set on the production cross-section of the charged Higgs boson times the branching fraction $\mathrm{\cal{B}}(H^{\pm} \to \tau^{\pm}\nu_{\tau})$ in the range 4.5 pb-0.4 fb. In the mass range 80-160 GeV, assuming the Standard Model cross-section for $t\bar{t}$ production, this corresponds to upper limits between 0.27% and 0.02% on $\mathrm{\cal{B}}(t\to bH^{\pm}) \times \mathrm{\cal{B}}(H^{\pm} \to \tau^{\pm}\nu_{\tau})$.
Observed and expected 95 % CL exclusion limits on $\sigma(pp\to tbH^+)\times \mathrm{\cal{B}}(H^+ \to \tau \nu)$ as a function of $m_{H^{\pm}}$, from a combined fit in the $\tau$+jets and $\tau$+lepton channels. The surrounding shaded bands correspond to the 1$\sigma$ and 2$\sigma$ confidence intervals around the expected limit.
Observed and expected 95 % CL exclusion limits on $\mathrm{\cal{B}}(t\to bH^+)\times \mathrm{\cal{B}}(H^+ \to \tau \nu)$ as a function of $m_{H^{\pm}}$, from a combined fit in the $\tau$+jets and $\tau$+lepton channels. The surrounding shaded bands correspond to the 1$\sigma$ and 2$\sigma$ confidence intervals around the expected limit.
Observed and expected 95 % CL exclusion limits on $\tan\beta$ as a function of $m_{H^{\pm}}$, shown in the context of the hMSSM scenario, for $m_{H^{\pm}}>150$ GeV and $(1 \leq \tan\beta \leq 60)$. The surrounding shaded bands correspond to the 1$\sigma$ and 2$\sigma$ confidence intervals around the expected limit.
Measurements of light-by-light scattering (LbL, $\gamma\gamma\to\gamma\gamma$) and the Breit--Wheeler process (BW, $\gamma\gamma$$\to$$\mathrm{e^+e^-}$) are reported in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV. The data sample, corresponding to an integrated luminosity of 1.7 nb$^{-1}$, was collected by the CMS experiment at the CERN LHC in 2018. Events with an exclusively produced $\gamma\gamma$ or $\mathrm{e^+e^-}$ pair with invariant masses $m^{\gamma\gamma,\mathrm{ee}}$$>$ 5 GeV, along with other fiducial criteria, are selected. The measured BW fiducial production cross section, $\sigma_\text{fid}$($\gamma\gamma$$\to$$\mathrm{e^+e^-}$) = 263.5 $\pm$ 1.8 (stat) $\pm$ 17.8 (syst) $\mu$b, as well as the differential distributions for various kinematic observables, are in agreement with leading-order quantum electrodynamics predictions complemented with final-state photon radiation. The measured differential BW cross sections allow discriminating between different theoretical descriptions of the photon flux of the lead ion. In the LbL final state, 26 exclusive diphoton candidate events are observed compared with 12.0 $\pm$ 2.9 expected for the background. Combined with previous results, the observed significance of the LbL signal with respect to the background-only hypothesis is above five standard deviations. The measured fiducial LbL scattering cross section, $\sigma_\text{fid} (\gamma\gamma\to\gamma\gamma)$ = 107 $\pm$ 24 (stat) $\pm$ 13 (syst) nb, is in agreement with next-to-leading-order predictions. Limits on the production of axion-like particles coupled to photons are set over the mass range 5-100 GeV, including the most stringent limits to date in the range of 5-10 GeV.
Probability for different neutron multiplicity classes (0n, 1n, and Xn with X $\ge$1) measured on each ZDC side for the exclusive $e^{+}e^{-}$ events passing the fiducial phase space of Table 1. The measured ratios are compared with SUPERCHIC 4.2, STARLIGHT 3.13, and gamma-UPC 1.6 predictions.
Differential cross sections for exclusive dielectron production, in the fiducial phase space of Table 1, as functions of the pair $p_T$. Data are compared with SUPERCHIC + FSR(PHOTOS++), STARLIGHT + FSR(PY8), and gamma-UPC + FSR(PY8) predictions.
Differential cross sections for exclusive dielectron production, in the fiducial phase space of Table 1, as functions of the pair rapidity. Data are compared with SUPERCHIC + FSR(PHOTOS++), STARLIGHT + FSR(PY8), and gamma-UPC + FSR(PY8) predictions.
This paper presents a new $\tau$-lepton reconstruction and identification procedure at the ATLAS detector at the Large Hadron Collider, which leads to significantly improved performance in the case of physics processes where a highly boosted pair of $\tau$-leptons is produced and one $\tau$-lepton decays into a muon and two neutrinos ($\tau_{\mu}$), and the other decays into hadrons and one neutrino ($\tau_{had}$). By removing the muon information from the signals used for reconstruction and identification of the $\tau_{had}$ candidate in the boosted pair, the efficiency is raised to the level expected for an isolated $\tau_{had}$. The new procedure is validated by selecting a sample of highly boosted $Z\rightarrow\tau_{\mu}\tau_{had}$ candidates from the data sample of $140$${fb}^{-1}$ of proton-proton collisions at $13$ TeV recorded with the ATLAS detector. Good agreement is found between data and simulation predictions in both the $Z\rightarrow\tau_{\mu}\tau_{had}$ signal region and in a background validation region. The results presented in this paper demonstrate the effectiveness of the $\tau_{had}$ reconstruction with muon removal in enhancing the signal sensitivity of the boosted $\tau_{\mu}\tau_{had}$ channel at the ATLAS detector.
The distribution of the TauID jet RNN score for $\tau_\mathrm{had}^{\mu\mkern-10mu\backslash}$ in the SR. `$Z(\rightarrow\tau\tau)$+jets' represents the contributions from the signal process. `Top' represents the predicted contributions from the $t\bar{t}$, single-top-quark, and $tW$ processes. `Diboson' indicates the contributions from $WW$, $WZ$, and $ZZ$ processes. `Other' includes the contributions from the $Z(\rightarrow\ell\ell)$+jets, $W$+jets, and Higgs boson processes. The uncertainties shown include both statistical and systematic sources.
The distribution of the TauID jet RNN score for $\tau_\mathrm{had}^{\mu\mkern-10mu\backslash}$ in the VR. `$Z(\rightarrow\tau\tau)$+jets' represents the contributions from the signal process. `Top' represents the predicted contributions from the $t\bar{t}$, single-top-quark, and $tW$ processes. `Diboson' indicates the contributions from $WW$, $WZ$, and $ZZ$ processes. `Other' includes the contributions from the $Z(\rightarrow\ell\ell)$+jets, $W$+jets, and Higgs boson processes. The uncertainties shown include both statistical and systematic sources.
The distribution of the $p_\mathrm{T}{}_{\mu\mathrm{-had}}^\mathrm{col}$ in the SR. `$Z(\rightarrow\tau\tau)+\text{jets}$' represents the contributions from the signal process. `Diboson' indicates the contributions from $WW$, $WZ$, and $ZZ$ processes. `Top' represents the predicted contributions from the $t\bar{t}$, single-top-quark, and $tW$ processes. `Other' includes the contributions from the $Z(\rightarrow\ell\ell)$+jets, $W$+jets, and Higgs boson processes. The uncertainties shown include both statistical and systematic sources.
In the standard model of particle physics, the masses of the carriers of the weak interaction, the W and Z bosons, are uniquely related. Physics beyond the standard model could change this relationship through the effects of quantum loops of virtual particles, thus making it of great importance to measure these masses with the highest possible precision. Although the mass of the Z boson is known to the remarkable precision of 22 parts per million (2.0 MeV), the W boson mass is known much less precisely, given the difficulty of the measurement. A global fit to electroweak data, used to predict the W boson mass in the standard model, yields an uncertainty of 6 MeV. Reaching a comparable experimental precision would be a sensitive and fundamental test of the standard model. Furthermore, a precision measurement of the W boson mass performed by the CDF Collaboration at the Fermilab Tevatron has challenged the standard model by significantly disagreeing with the prediction of the global electroweak fit and the average of other $m_\mathrm{W}$ measurements. We report the first W boson mass measurement by the CMS Collaboration at the CERN LHC, based on a data sample collected in 2016 at the proton-proton collision energy of 13 TeV. The W boson mass is measured using a large sample of W$\to\mu\nu$ events via a highly granular binned maximum likelihood fit to the kinematic properties of the muons produced in the W$^{+}$ and W$^{-}$ boson decays. The significant in situ constraints of theoretical inputs and their corresponding uncertainties, together with an accurate determination of the experimental effects, lead to a precise W boson mass measurement, $m_\mathrm{W} =$ 80$\,$360.2 $\pm$ 9.9 MeV, in agreement with the standard model prediction.
Postfit pulls, constraints, and impacts (both nominal and 'global') for all nuisance parameters in the W boson mass fit, sorted by the absolute value of the nominal impact.
Postfit pulls, constraints, and impacts (both nominal and 'global') for all nuisance parameters in the W boson mass fit (charge difference), sorted by the absolute value of the nominal impact.
Postfit pulls, constraints, and impacts (both nominal and 'global') for all nuisance parameters in the W-like Z boson mass fit, sorted by the absolute value of the nominal impact.
A search for exotic decays of the 125 GeV Higgs boson into a pair of new spin-0 particles, $H \to aa$, where one decays into a photon pair and the other into a $\tau$-lepton pair, is presented. Hadronic decays of the $\tau$-leptons are considered and reconstructed using a dedicated tagger for collimated $\tau$-lepton pairs. The search uses 140 fb$^{-1}$ of proton-proton collision data at a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider. The search is performed in the mass range of the $a$ boson between 10 GeV and 60 GeV. No significant excess of events is observed above the Standard Model background expectation. Model-independent upper limits at 95$\% $ confidence level are set on the branching ratio of the Higgs boson to the $\gamma\gamma\tau\tau$ final state, $\mathcal{B}(H\to aa\to \gamma\gamma\tau\tau)$, ranging from 0.2$\% $ to 2$\% $, depending on the $a$-boson mass hypothesis.
Distribution of the diphoton invariant mass for all events satisfying the analysis selections in the full Run 2 dataset.
Scan of the observed $p$-value as a function of $m_{a}$ for the background-only hypothesis.
The observed and expected ($\pm1\sigma$) upper limits at 95% CL on the branching ratio for $H\rightarrow aa\rightarrow \gamma\gamma\tau\tau$ as a function of the resonance mass hypothesis $m_{a}$.
A search for heavy neutral gauge bosons (Z') decaying into a pair of tau leptons is performed in proton-proton collisions at $\sqrt{s}$ = 13 TeV at the CERN LHC. The data were collected with the CMS detector and correspond to an integrated luminosity of 138 fb$^{-1}$. The observations are found to be in agreement with the expectation from standard model processes. Limits at 95% confidence level are set on the product of the Z' production cross section and its branching fraction to tau lepton pairs for a range of Z' boson masses. For a narrow resonance in the sequential standard model scenario, a Z' boson with a mass below 3.5 TeV is excluded. This is the most stringent limit to date from this type of search.
Cutflow for signal samples in the hadronic di-tau channel for 2016 signal samples. Each entry other than the total is the relative efficiency with respect to the previous selection.
Cutflow for signal samples in the hadronic di-tau channel for 2017 signal samples. Each entry other than the total is the relative efficiency with respect to the previous selection.
Cutflow for signal samples in the hadronic di-tau channel for 2018 signal samples. Each entry other than the total is the relative efficiency with respect to the previous selection.
This paper presents a model-agnostic search for narrow resonances in the dijet final state in the mass range 1.8-6 TeV. The signal is assumed to produce jets with substructure atypical of jets initiated by light quarks or gluons, with minimal additional assumptions. Search regions are obtained by utilizing multivariate machine-learning methods to select jets with anomalous substructure. A collection of complementary anomaly detection methods - based on unsupervised, weakly supervised, and semisupervised algorithms - are used in order to maximize the sensitivity to unknown new physics signatures. These algorithms are applied to data corresponding to an integrated luminosity of 138 fb$^{-1}$, recorded by the CMS experiment at the LHC, at a center-of-mass energy of 13 TeV. No significant excesses above background expectations are seen. Exclusion limits are derived on the production cross section of benchmark signal models varying in resonance mass, jet mass, and jet substructure. Many of these signatures have not been previously sought, making several of the limits reported on the corresponding benchmark models the first ever. When compared to benchmark inclusive and substructure-based search strategies, the anomaly detection methods are found to significantly enhance the sensitivity to a variety of models.
Exclusion limits on the production cross section of the Q* -> q Wprime model from the different anomaly detection methods
Exclusion limits on the production cross section of the X -> Y Yprime model from the different anomaly detection methods
Exclusion limits on the production cross section of the Wprime -> Bprime t model from the different anomaly detection methods
The inclusive WZ production cross section is measured in proton-proton collisions at a centre-of-mass energy of 13.6 TeV, using data collected during 2022 with the CMS detector, corresponding to an integrated luminosity of 34.7 fb$^{-1}$. The measurement uses multileptonic final states and a simultaneous likelihood fit to the number of events in four different lepton flavour categories: eee, ee$\mu$, $\mu\mu $e, and $\mu\mu\mu$. The selection is optimized to minimize the number of background events, and relies on an efficient prompt lepton discrimination strategy. The WZ production cross section is measured in a phase space defined within a 30 GeV window around the Z boson mass, as $\sigma_{\text{total}}$(pp $\to$ WZ) = 55.2 $\pm$ 1.2 (stat) $\pm$ 1.2 (syst) $\pm$ 0.8 (lumi) $\pm$ 0.3 (theo) pb. In addition, the cross section is measured in a fiducial phase space closer to the detector-level requirements. All the measurements presented in this paper are in agreement with standard model predictions.
Number of events for the different lepton flavour categories in the ZZ control region accounting for the fit to data. The hatched band includes all systematic uncertainties in the MC prediction. The vertical bars of the data account for the statistical uncertainty. The ratio panels show the ratio between data (black markers) with respect to the total prediction after the fit to data. Processes with a small contribution to this region are grouped in the ``Other" category
Number of events for the different lepton flavour categories in the ttZ control region accounting for the fit to data. The hatched band includes all systematic uncertainties in the MC prediction. The vertical bars of the data account for the statistical uncertainty. The ratio panels show the ratio between data (black markers) with respect to the total prediction after the fit to data. Processes with a small contribution to this region are grouped in the ``Other" category
Number of events for the different lepton flavour categories in the X+#gamma control region accounting for the fit to data. The hatched band includes all systematic uncertainties in the MC prediction. The vertical bars of the data account for the statistical uncertainty. The ratio panels show the ratio between data (black markers) with respect to the total prediction after the fit to data. Processes with a small contribution to this region are grouped in the ``Other" category
A measurement of off-shell Higgs boson production in the $H^*\to ZZ\to 4\ell$ decay channel is presented. The measurement uses 140 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the Large Hadron Collider and supersedes the previous result in this decay channel using the same dataset. The data analysis is performed using a neural simulation-based inference method, which builds per-event likelihood ratios using neural networks. The observed (expected) off-shell Higgs boson production signal strength in the $ZZ\to 4\ell$ decay channel at 68% CL is $0.87^{+0.75}_{-0.54}$ ($1.00^{+1.04}_{-0.95}$). The evidence for off-shell Higgs boson production using the $ZZ\to 4\ell$ decay channel has an observed (expected) significance of $2.5\sigma$ ($1.3\sigma$). The expected result represents a significant improvement relative to that of the previous analysis of the same dataset, which obtained an expected significance of $0.5\sigma$. When combined with the most recent ATLAS measurement in the $ZZ\to 2\ell 2\nu$ decay channel, the evidence for off-shell Higgs boson production has an observed (expected) significance of $3.7\sigma$ ($2.4\sigma$). The off-shell measurements are combined with the measurement of on-shell Higgs boson production to obtain constraints on the Higgs boson total width. The observed (expected) value of the Higgs boson width at 68% CL is $4.3^{+2.7}_{-1.9}$ ($4.1^{+3.5}_{-3.4}$) MeV.
Values of the test statistic $t_{\mu_{\mathrm{off-shell}}}$ assuming a single parameter of interest $\mu_{\mathrm{off-shell}}$ obtained with an Asimov dataset and with data in the $H^*\rightarrow ZZ\rightarrow 4\ell$ decay channel. The values from the histogram-based analysis (Phys. Lett. B 846 (2023) 138223) are added for comparison. The 68% and 95% confidence intervals obtained from the Neyman construction are also added.
Values of the test statistic $t_{\mu_{\mathrm{off-shell}}}$ assuming a single parameter of interest $\mu_{\mathrm{off-shell}}$ obtained with an Asimov dataset and with data in the $H^*\rightarrow ZZ\rightarrow 4\ell$ decay channel. The values with all nuisance parameters fixed at their best-fit values (stat-only) are added for comparison. The 68% and 95% confidence intervals obtained from the Neyman construction are also added.
Values of the test statistic $t_{\mu_{\mathrm{off-shell}}}$ assuming a single parameter of interest $\mu_{\mathrm{off-shell}}$ obtained with an Asimov dataset and with data when combining the $H^*\rightarrow ZZ\rightarrow 4\ell$ and $H^*\rightarrow ZZ\rightarrow 2\ell 2\nu$ decay channels. The values with all nuisance parameters fixed at their best-fit values (stat-only) are added for comparison. The 68% and 95% confidence intervals obtained from the Neyman construction are also added.
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