A search for the non-resonant production of Higgs boson pairs in the $HH\rightarrow b\bar{b}\tau^+\tau^-$ channel is performed using 140 fb$^{-1}$ of proton-proton collisions at a centre-of-mass energy of $13$ TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. The analysis strategy is optimised to probe anomalous values of the Higgs boson self-coupling modifier $\kappa_\lambda$ and of the quartic $HHVV$ ($V = W,Z$) coupling modifier $\kappa_{2V}$. No significant excess above the expected background from Standard Model processes is observed. An observed (expected) upper limit $\mu_{HH}<5.9$$(3.3)$ is set at 95% confidence-level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The coupling modifiers are constrained to an observed (expected) 95% confidence interval of $-3.1 < \kappa_\lambda < 9.0$ ($-2.5 < \kappa_\lambda < 9.3$) and $-0.5 < \kappa_{2V} < 2.7$ ($-0.2 < \kappa_{2V} < 2.4$), assuming all other Higgs boson couplings are fixed to the Standard Model prediction. The results are also interpreted in the context of effective field theories via constraints on anomalous Higgs boson couplings and Higgs boson pair production cross-sections assuming different kinematic benchmark scenarios.
Observed (filled circles) and expected (open circles) 95% CL upper limits on $\mu_{HH}$ from the fit of each individual channel and the combined fit in the background-only ($\mu_{HH} = 0$) hypothesis. The dashed lines indicate the expected 95% CL upper limits on $\mu_{HH}$ in the SM hypothesis ($\mu_{HH} = 1$). The inner and outer bands indicate the $\pm 1\sigma$ and $\pm 2\sigma$ variations, respectively, on the expected limit with respect to the background-only hypothesis due to statistical and systematic uncertainties.
Observed and expected 95% CL upper limits on $\mu_{HH}$, $\mu_{ggF}$ and $\mu_{VBF}$ from the individual SR likelihood fits as well as the combined results. The $\mu_{ggF}$ and $\mu_{VBF}$ limits are quoted both from the results of the simultaneous fit of both signal strengths (central column), and from independent fits for the individual production modes, assuming the other to be as predicted by the SM. The uncertainties quoted on the combined expected upper limits correspond to the 1σ uncertainty band.
Observed (solid line) value of $-2\ln\Lambda$ as a function of $\kappa_{\lambda}$ for the combined fit, when all other coupling modifiers are fixed to their SM predictions.
A search for new physics in final states consisting of at least one photon, multiple jets, and large missing transverse momentum is presented, using proton-proton collision events at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 137 fb$^{-1}$, recorded by the CMS experiment at the CERN LHC from 2016 to 2018. The events are divided into mutually exclusive bins characterized by the missing transverse momentum, the number of jets, the number of b-tagged jets, and jets consistent with the presence of hadronically decaying W, Z, or Higgs bosons. The observed data are found to be consistent with the prediction from standard model processes. The results are interpreted in the context of simplified models of pair production of supersymmetric particles via strong and electroweak interactions. Depending on the details of the signal models, gluinos and squarks of masses up to 2.35 and 1.43 TeV, respectively, and electroweakinos of masses up to 1.23 TeV are excluded at 95% confidence level.
SM background predictions, data observations and signal yields in the signal region.
The 95% CL observed upper limits on the production cross sections for $m_{\tilde{g}}$ in T5bbbbZg.
Gluino - neutralino mass points lying on the observed exclusion contour of T5bbbbZg model.
A search for supersymmetry involving the pair production of gluinos decaying via off-shell third-generation squarks into the lightest neutralino ($\tilde\chi^0_1$) is reported. It exploits LHC proton$-$proton collision data at a centre-of-mass energy $\sqrt{s} = 13$ TeV with an integrated luminosity of 139 fb$^{-1}$ collected with the ATLAS detector from 2015 to 2018. The search uses events containing large missing transverse momentum, up to one electron or muon, and several energetic jets, at least three of which must be identified as containing $b$-hadrons. Both a simple kinematic event selection and an event selection based upon a deep neural-network are used. No significant excess above the predicted background is found. In simplified models involving the pair production of gluinos that decay via off-shell top (bottom) squarks, gluino masses less than 2.44 TeV (2.35 TeV) are excluded at 95% CL for a massless $\tilde\chi^0_1$. Limits are also set on the gluino mass in models with variable branching ratios for gluino decays to $b\bar{b}\tilde\chi^0_1$, $t\bar{t}\tilde\chi^0_1$ and $t\bar{b}\tilde\chi^-_1$ / $\bar{t}b\tilde\chi^+_1$.
A summary of the uncertainties in the background estimates for SR-Gtt-0L-B. The individual experimental and theoretical uncertainties are assumed to be uncorrelated and are combined by adding in quadrature.
A summary of the uncertainties in the background estimates for SR-Gtt-0L-M1. The individual experimental and theoretical uncertainties are assumed to be uncorrelated and are combined by adding in quadrature.
A summary of the uncertainties in the background estimates for SR-Gtt-0L-M2. The individual experimental and theoretical uncertainties are assumed to be uncorrelated and are combined by adding in quadrature.
Measurements of the total and differential fiducial cross sections for the Z boson decaying into two neutrinos are presented at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were collected by the CMS detector in 2016 and correspond to an integrated luminosity of 35.9 fb$^{-1}$. In these measurements, events are selected containing an imbalance in transverse momentum and one or more energetic jets. The fiducial differential cross section is measured as a function of the Z boson transverse momentum. The results are combined with a previous measurement of charged-lepton decays of the Z boson.
The measured and predicted inclusive fiducial cross sections in fb. The experimental measurement includes both statistical and systematics uncertainties. The theoretical prediction includes both the QCD scale and PDF uncertainties.
Experimental uncertainties affecting transfer factors in the analysis that is used to estimate the W background in the signal region (SR). The number of W boson events are denoted as $W_{SR}$ for the SR and in analogy as $W_{\mu\nu}$ ($W_{e\nu}$) for the single-muon (single-electron) control region (CR).
Uncertainties assigned to the simulation based processes in SR and CRs.
Differential Higgs boson (H) production cross sections are sensitive probes for physics beyond the standard model. New physics may contribute in the gluon-gluon fusion loop, the dominant Higgs boson production mechanism at the LHC, and manifest itself through deviations from the distributions predicted by the standard model. Combined spectra for the H $\to$ $\gamma\gamma$, H $\to$ ZZ, and H $\to$ $\mathrm{b\overline{b}}$ decay channels and the inclusive Higgs boson production cross section are presented, based on proton-proton collision data recorded with the CMS detector at $\sqrt{s} =$ 13 TeV corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The transverse momentum spectrum is used to place limits on the Higgs boson couplings to the top, bottom, and charm quarks, as well as its direct coupling to the gluon field. No significant deviations from the standard model are observed in any differential distribution. The measured total cross section is 61.1 $\pm$ 6.0 (stat) $\pm$ 3.7 (syst) pb, and the precision of the measurement of the differential cross section of the Higgs boson transverse momentum is improved by about 15% with respect to the H $\to$ $\gamma\gamma$ channel alone.
Combined Higgs boson transverse momentum spectrum
Higgs boson transverse momentum spectrum, $H\rightarrow\gamma\gamma$
Higgs boson transverse momentum spectrum, $H\rightarrow ZZ$
A search is presented for decays of Z and Higgs bosons to a J$/\psi$ meson and a photon, with the subsequent decay of the J$/\psi$ to $\mu^+\mu^-$. The analysis uses data from proton-proton collisions with an integrated luminosity of 35.9 fb$^{-1}$ at $\sqrt{s} =$ 13 TeV collected with the CMS detector at the LHC. The observed limit on the Z $\to$ J$/\psi \gamma$ decay branching fraction, assuming that the J$/\psi$ meson is produced unpolarized, is 1.4 $\times$ 10$^{-6}$ at 95% confidence level, which corresponds to a rate higher than expected in the standard model by a factor of 15. For extreme-polarization scenarios, the observed limit changes from -13.6 to +8.6% with respect to the unpolarized scenario. The observed upper limit on the branching fraction for H $\to$ J$/\psi \gamma$ where the J$/\psi$ meson is assumed to be transversely polarized is 7.6 $\times$ 10$^{-4}$, a factor of 260 larger than the standard model prediction. The results for the Higgs boson are combined with previous data from proton-proton collisions at $\sqrt{s} =$ 8 TeV to produce an observed upper limit on the branching fraction for H $\to$ J$/\psi \gamma$ that is a factor of 220 larger than the standard model value.
Upper observed and expected limits on branching fraction of $Z (H)\rightarrow J/\psi\gamma$ decay of the $Z (H)$ boson.
Searches for non-resonant and resonant Higgs boson pair production are performed in the $\gamma\gamma WW^{*}$ channel with the final state of $\gamma\gamma\ell\nu jj$ using 36.1 fb$^{-1}$ of proton-proton collision data recorded at a centre-of-mass energy of $\sqrt{s} = 13$ TeV by the ATLAS detector at the Large Hadron Collider. No significant deviation from the Standard Model prediction is observed. A 95% confidence-level observed upper limit of 7.7 pb is set on the cross section for non-resonant production, while the expected limit is 5.4 pb. A search for a narrow-width resonance $X$ decaying to a pair of Standard Model Higgs bosons $HH$ is performed with the same set of data, and the observed upper limits on $\sigma(pp \rightarrow X) \times B(X \rightarrow HH)$ range between 40.0 pb and 6.1 pb for masses of the resonance between 260 GeV and 500 GeV, while the expected limits range between 17.6 pb and 4.4 pb. When deriving the limits above, the Standard Model branching ratios of the $H \rightarrow \gamma\gamma$ and $H \rightarrow WW^{*}$ are assumed.
Number of data events without pTyy selection for $m_X$ = 260 GeV.
Number of data events witht pTyy selection for non-resonant.
Observed and expected 95% CL upper limits on the cross-section of gluon-fusion initialted resonant production of the mass of the resonance times the branch ratio (BR) of X to HH with assuming the BR of H to gammagamma and H to WW.
A search is performed for resonant and non-resonant Higgs boson pair production in the $\gamma\gamma b\bar{b}$ final state. The data set used corresponds to an integrated luminosity of 36.1 fb$^{-1}$ of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No significant excess relative to the Standard Model expectation is observed. The observed limit on the non-resonant Higgs boson pair cross-section is 0.73 pb at 95% confidence level. This observed limit is equivalent to 22 times the predicted Standard Model cross-section. The Higgs boson self-coupling ($\kappa_\lambda = \lambda_{HHH} / \lambda_{HHH}^{\rm SM}$) is constrained at 95% confidence level to $-8.2 < \kappa_\lambda < 13.2$. For resonant Higgs boson pair production through X $\rightarrow$ HH $\rightarrow$ $\gamma\gamma b\bar{b}$, the limit is presented, using the narrow-width approximation, as a function of $m_X$ in the range 260 GeV $< m_X <$ 1000 GeV. The observed limits range from 1.1 pb to 0.12 pb over this mass range.
Number of expected and observed events in the 1- and 2-tag categories in the resonant analysis. The loose and tight selections are not orthogonal.
The 95% CL observed and expected limits on the Higgs boson pair cross-section in picobarn and as a multiple of the SM production cross-section. The expected 1 sigma CLs bands are also indicated.
Number of data events for the 1-tag category with the loose selection in bins of diphoton mass.
A search for a Higgs boson decaying into a pair of electrons or muons and a photon is described. Higgs boson decays to a Z boson and a photon (H $\to$ Z$\gamma\to\ell\ell\gamma$, $\ell =$ e or $\mu$), or to two photons, one of which has an internal conversion into a muon pair (H $\to\gamma^{*}\gamma\to\mu\mu\gamma$) were considered. The analysis is performed using a data set recorded by the CMS experiment at the LHC from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. No significant excess above the background prediction has been found. Limits are set on the cross section for a standard model Higgs boson decaying to opposite-sign electron or muon pairs and a photon. The observed limits on cross section times the corresponding branching fractions vary between 1.4 and 4.0 (6.1 and 11.4) times the standard model cross section for H $\to\gamma^{*}\gamma\to\mu\mu\gamma$ (H $\to$ Z$\gamma\to\ell\ell\gamma$) in the 120-130 GeV mass range of the $\ell\ell\gamma$ system. The H $\to\gamma^*\gamma\to\mu\mu\gamma$ and H $\to$ Z$\gamma\to\ell\ell\gamma$ analyses are combined for $m_\mathrm{H} =$ 125 GeV, obtaining an observed (expected) 95% confidence level upper limit of 3.9 (2.0) times the standard model cross section.
Exclusion limit, at 95% CL, on the cross section of the $H \rightarrow \gamma^{*}\gamma \rightarrow \mu\mu\gamma$ process relative to the SM prediction, as a function of the Higgs boson mass.
Exclusion limit, at 95% CL, on the cross section of the $H \rightarrow Z\gamma \rightarrow ll\gamma$ process relative to the SM prediction, as a function of the Higgs boson mass.
Exclusion limit, at 95% CL, on the cross section of the $H \rightarrow ll\gamma$ relative to the SM prediction, for an SM Higgs boson of $m_{H} = 125$ GeV. The upper limits of each analysis category, as well as their combinations, are shown.
Measurements of prompt $\psi$(2S) meson production cross sections in proton-lead (pPb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{_\mathrm{NN}}}=$ 5.02 TeV are reported. The results are based on pPb and pp data collected by the CMS experiment at the LHC, corresponding to integrated luminosities of 34.6 nb$^{-1}$ and 28.0 pb$^{-1}$, respectively. The nuclear modification factor $R_\mathrm{pPb}$ is measured for prompt $\psi$(2S) in the transverse momentum range 4 $<$ p$_\mathrm{T}$ $<$ 30 GeV$/c$ and the center-of-mass rapidity range $-$2.4 $< y_\mathrm{cm} <$ 1.93. The results on $\psi$(2S) $R_\mathrm{pPb}$ are compared to the corresponding modification factor for prompt J$/\psi$ mesons and are found to be more suppressed than the J$/\psi$ states over the entire kinematic range studied.
Differential cross section (multiplied by the dimuon branching fraction) of prompt $\psi$(2S) mesons in pPb collisions at $\sqrt(s_{\textrm{NN}})=5.02 $ TeV, as a function of $p_{\textrm{T}}$, for four backward $y_{\mathrm{CM}}$ regions. The fully correlated luminosity uncertainty of 3.5% is not inlcuded in the point-by-point uncertainty.
Differential cross section (multiplied by the dimuon branching fraction) of prompt $\psi$(2S) mesons in pPb collisions at $\sqrt(s_{\textrm{NN}})=5.02 $ TeV, as a function of $p_{\textrm{T}}$, for four backward $y_{\mathrm{CM}}$ regions. The fully correlated luminosity uncertainty of 3.5% is not included in the point-by-point uncertainty. NOTE- The cross section unit is nb (nano barn); the y-axes of the figures in the publication show pb (pico barn) by mistake.
Differential cross section (multiplied by the dimuon branching fraction) of prompt $\psi$(2S) mesons in pPb collisions at $\sqrt(s_{\textrm{NN}})=5.02 $ TeV, as a function of $p_{\textrm{T}}$, for three forward $y_{\mathrm{CM}}$ regions. The fully correlated luminosity uncertainty of 3.5% is not inlcuded in the point-by-point uncertainty.
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