The long-range collective flow of particles produced in oxygen-oxygen (OO) and neon-neon (NeNe) collisions is measured with the CMS detector at the CERN LHC. The data samples were collected at a center-of-mass energy per nucleon pair of 5.36 TeV, with integrated luminosities of 7 nb$^{-1}$ and 0.8 nb$^{-1}$ for OO and NeNe collisions, respectively. Two- and four-particle azimuthal correlations are measured over nearly five units of pseudorapidity. Significant elliptic ($v_2$) and triangular ($v_3$) flow harmonics are observed in both systems. The ratios of $v_n$ coefficients between NeNe and OO collisions reveal sensitivity to quadrupole correlations in the nuclear wave functions. Hydrodynamic models with $\textit{ab initio}$ nuclear structure inputs qualitatively reproduce the collision-overlap dependence of both the $v_n$ values and the NeNe to OO ratios. These measurements provide new constraints on hydrodynamic models for small collision systems and offer valuable input on the nuclear structure of $^{16}$O and $^{20}$Ne.
The $v_{2}\{2,\lvert\Delta\eta\rvert>2\}$, $v_{3}\{2,\lvert\Delta\eta\rvert>2\}$ and $v_{2}\{4\}$ values for charged particles as functions of centrality in OO collisions at 5.36 TeV.
The $v_{2}\{2,\lvert\Delta\eta\rvert>2\}$, $v_{3}\{2,\lvert\Delta\eta\rvert>2\}$ and $v_{2}\{4\}$ values for charged particles as functions of centrality in NeNe collisions at 5.36 TeV.
The $v_{2}\{2,\lvert\Delta\eta\rvert>2\}$ and $v_{2}\{4\}$ ratios for charged particles as functions of centrality in NeNe to OO collisions at 5.36 TeV.
A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H $\to$$\mathrm{c\bar{c}}$, produced in association with a top quark-antiquark pair ($\mathrm{t\bar{t}}$H) is presented. The search is performed with data from proton-proton collisions at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. Advanced machine learning techniques are employed for jet flavor identification and event classification. The Higgs boson decay to a bottom quark-antiquark pair is measured simultaneously and the observed $\mathrm{t\bar{t}}$H (H $\to$$\mathrm{b\bar{b}}$) event rate relative to the standard model expectation is 0.91 $^{+0.26}_{-0.22}$. The observed (expected) upper limit on the product of production cross section and branching fraction $σ$($\mathrm{t\bar{t}}$H) $\mathcal{B}$(H $\to$$\mathrm{c\bar{c}}$) is 0.11 (0.13) pb at 95% confidence level, corresponding to 7.8 (8.7) times the standard model prediction. When combined with the previous search for H $\to$ $\mathrm{c\bar{c}}$ via associated production with a W or Z boson, the observed (expected) 95% confidence interval on the Higgs-charm Yukawa coupling modifier, $κ_\mathrm{c}$, is $\lvert{κ_\mathrm{c}}\rvert$ $\lt$ 3.5 (2.7), the most stringent constraint to date.
Upper limits on the signal strength for $\text{H}\to\text{c}\overline{\text{c}}$ decays with respect to the standard model expectation of unity.
Upper limits on the signal strength for $\text{t}\overline{\text{t}}\text{H}(\text{H}\to\text{c}\overline{\text{c}})$ decays with respect to the standard model expectation of unity.
Signal strength and significance for $\text{t}\overline{\text{t}}\text{H}(\text{H}\to\text{b}\overline{\text{b}})$ decays with respect to the standard model expectation of unity.
The $pp \to W^{\pm} (\to μ^{\pm} ν_μ) X$ cross-sections are measured at a proton-proton centre-of-mass energy $\sqrt{s} = 5.02$ TeV using a dataset corresponding to an integrated luminosity of 100 pb$^{-1}$ recorded by the LHCb experiment. Considering muons in the pseudorapidity range $2.2 < η< 4.4$, the cross-sections are measured differentially in twelve intervals of muon transverse momentum between $28 < p_\mathrm{T} < 52$ GeV. Integrated over $p_\mathrm{T}$, the measured cross-sections are \begin{align*} σ_{W^+ \to μ^+ ν_μ} &= 300.9 \pm 2.4 \pm 3.8 \pm 6.0~\text{pb}, \\ σ_{W^- \to μ^- \barν_μ} &= 236.9 \pm 2.1 \pm 2.7 \pm 4.7~\text{pb}, \end{align*} where the first uncertainties are statistical, the second are systematic, and the third are associated with the luminosity calibration. These integrated results are consistent with theoretical predictions. This analysis introduces a new method to determine the $W$-boson mass using the measured differential cross-sections corrected for detector effects. The measurement is performed on this statistically limited dataset as a proof of principle and yields \begin{align*} m_W = 80369 \pm 130 \pm 33~\text{MeV}, \end{align*} where the first uncertainty is experimental and the second is theoretical.
The measured differential cross sections ($d\sigma/dp_T$) for $W^+$. The first systematic uncertainty is statistical and the second is systematic.
The measured differential cross sections ($d\sigma/dp_T$) for $W^-$. The first systematic uncertainty is statistical and the second is systematic.
The correlation matrix corresponding to the statistical uncertainties on the differential cross-section ($d\sigma/dp_T$) fit results for $W^+$. To combine with $W^-$, use the rows and columns ordered as $W^+$ and then $W^-$. Assume no correlation in the statistical uncertainties between $W^+$ and $W^-$ (zero entries in the off-diagonal blocks).
This paper presents a search for new physics through the process where a new massive particle, X, decays into a Higgs boson and a second particle, Y. The Higgs boson subsequently decays into a bottom quark-antiquark pair, reconstructed as a single large-radius jet. The decay products of Y are also assumed to produce a single large-radius jet. The identification of the Y particle is enhanced by computing the anomaly score of its candidate jet using an autoencoder, which measures deviations from typical QCD multijet jets. This allows a simultaneous search for multiple Y decay scenarios within a single analysis. In the main benchmark process, Y is a scalar particle that decays into W$^+$W$^-$. Two other benchmark processes are also considered, where Y is a scalar particle decaying into a light quark-antiquark pair, or into a top quark-antiquark pair. The last benchmark considers Y as a hadronically decaying top quark, arising from the decay of a vector-like quark into a top quark and a Higgs boson. Data recorded by the CMS experiment at a center-of-mass energy of 13 TeV in 2016$-$2018, and corresponding to an integrated luminosity of 138 fb$^{-1}$, are analyzed. No significant excess is observed, and upper limits on the benchmark signal cross section for various masses of X and Y, at 95% confidence level, are placed.
The $m_{jj}$ and $m_{J}$ projections for the number of observed events (black markers) compared with the backgrounds estimated in the fit to the data (filled histograms) in the CR. Pass and Fail categories are shown. The high level of agreement between the model and the data in the Fail region is due to the nature of the background estimate. The lower panels show the ``Pull'' defined as $(\text{observed events}{-}\text{expected events})/\sqrt{\smash[b]{\sigma_\text{obs}^{2} + \sigma_\text{exp}^{2}}}$, where $\sigma_\text{obs}$ and $\sigma_\text{exp}$ are the total uncertainties in the observation and the background estimation, respectively.
The $m_{jj}$ and $m_{J}$ projections for the number of observed events (black markers) compared with the backgrounds estimated in the fit to the data (filled histograms) in the CR. Pass and Fail categories are shown. The high level of agreement between the model and the data in the Fail region is due to the nature of the background estimate. The lower panels show the ``Pull'' defined as $(\text{observed events}{-}\text{expected events})/\sqrt{\smash[b]{\sigma_\text{obs}^{2} + \sigma_\text{exp}^{2}}}$, where $\sigma_\text{obs}$ and $\sigma_\text{exp}$ are the total uncertainties in the observation and the background estimation, respectively.
The $m_{jj}$ and $m_{J}$ projections for the number of observed events (black markers) compared with the backgrounds estimated in the fit to the data (filled histograms) in the CR. Pass and Fail categories are shown. The high level of agreement between the model and the data in the Fail region is due to the nature of the background estimate. The lower panels show the ``Pull'' defined as $(\text{observed events}{-}\text{expected events})/\sqrt{\smash[b]{\sigma_\text{obs}^{2} + \sigma_\text{exp}^{2}}}$, where $\sigma_\text{obs}$ and $\sigma_\text{exp}$ are the total uncertainties in the observation and the background estimation, respectively.
At hadron colliders, the net transverse momentum of particles that do not interact with the detector (missing transverse momentum, $\vec{p}_\mathrm{T}^\text{miss}$) is a crucial observable in many analyses. In the standard model, $\vec{p}_\mathrm{T}^\text{miss}$ originates from neutrinos. Many beyond-the-standard-model particles, such as dark matter candidates, are also expected to leave the experimental apparatus undetected. This paper presents a novel $\vec{p}_\mathrm{T}^\text{miss}$ estimator, DeepMET, which is based on deep neural networks that were developed by the CMS Collaboration at the LHC. The DeepMET algorithm produces a weight for each reconstructed particle based on its properties. The estimator is based on the negative vector sum of the weighted transverse momenta of all reconstructed particles in an event. Compared with other estimators currently employed by CMS, DeepMET improves the $\vec{p}_\mathrm{T}^\text{miss}$ resolution by 10$-$30%, shows improvement for a wide range of final states, is easier to train, and is more resilient against the effects of additional proton-proton interactions accompanying the collision of interest.
Recoil responses of different $\vec{p}^\mathrm{miss}_\mathrm{T}$ estimators in data and MC simulations after the $Z\to\mu\mu$ selections, as a function of $q_T$.
Response-corrected resolutions of $u_{\parallel}$ vs $q_T$ of different $\vec{p_{T}^{miss}}$ estimators in data after the $Z\to\mu\mu$ selections, as a function of $q_T$.
Response-corrected resolutions of $u_{\perp}$ vs $q_T$ of different $\vec{p_{T}^{miss}}$ estimators in data after the $Z\to\mu\mu$ selections, as a function of $q_T$.
A model-independent measurement of the differential production cross section of the Higgs boson decaying into a pair of W bosons, with a final state including two jets produced in association, is presented. In the analysis, events are selected in which the decay products of the two W bosons consist of an electron, a muon, and missing transverse momentum. The model independence of the measurement is maximized by making use of a discriminating variable that is agnostic to the signal hypothesis developed through machine learning. The analysis is based on proton-proton collision data at $\sqrt{s}$ = 13 TeV collected with the CMS detector from 2012$-$2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The production cross section is measured as a function of the difference in azimuthal angle between the two jets. The differential cross section measurements are used to constrain Higgs boson couplings within the standard model effective field theory framework.
Measured fiducial cross section summing VBF and ggF production modes.
Measured fiducial cross section of VBF and ggF production modes.
Measured fiducial cross section of VBF and ggF production modes.
This paper presents a search for a Higgs boson produced in association with a charm quark (cH) which allows to probe the Higgs-charm Yukawa coupling strength modifier $κ_\mathrm{c}$. Higgs boson decays to a pair of W bosons are considered, where one W boson decays to an electron and a neutrino, and the other \PW boson decays to a muon and a neutrino. The data, corresponding to an integrated luminosity of 138 fb$^{-1}$, were collected between 2016 and 2018 with the CMS detector at the LHC at a center-of-mass energy of $\sqrt{s}$ = 13 TeV. Upper limits at the 95% confidence level (CL) are set on the ratio of the measured yield to the standard model expectation for cH production. The observed (expected) upper limit is 1065 (506). When combined with the previous search for cH in the diphoton decay channel of the Higgs boson, the limits are interpreted as observed (expected) constraints at 95% CL on the value of $κ_\mathrm{c}$, $\lvertκ_\mathrm{c}\rvert$ $\lt$ 47 (51).
Upper limits of $\mu_{cH}$ at 95%CL for each data-taking period.
Two-dimensional likelihood contour of $\mu_{bkg-H+c}$ and $\mu_{cH}$.
Upper limits of $\mu_{cH}$ at 95% CL of the combined analysis
Using proton-proton collision data collected by the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016$-$2018, corresponding to an integrated luminosity of 140 fb$^{-1}$, the first full reconstruction of the three vector B meson states, B$^{*+}$, B$^{*0}$, and B$^{*0}_\text{s}$, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be $m(\text{B}^{*+}) - m(\text{B}^+)$ = 45.277 $\pm$ 0.039 $\pm$ 0.027 MeV, $m(\text{B}^{*0}) - m(\text{B}^0)$ = 45.471 $\pm$ 0.056 $\pm$ 0.028 MeV, and $m(\text{B}^{*0}_\text{s}) - m(\text{B}_\text{s})$ = 49.407 $\pm$ 0.132 $\pm$ 0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude.
The measured mass differences between vector and ground B meson states.
Extracted masses of $\mathrm{B}^{*+}$, $\mathrm{B}^{*0}$, and $\mathrm{B}^{*0}_{\mathrm{s}}$ mesons. The values are obtained using the measurements in Table 1 and the ground state masses from PDG 2024 (S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)), which are the source of the last uncertainties.
Extracted mass differences between vector B meson states of different flavour. The values are obtained using the measurements in Table 4 and the ground state mass differences from PDG 2024 (S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)), which are the source of the last uncertainties.
The STAR experiment reports new, high-precision measurements of the transverse single-spin asymmetries for $π^{\pm}$ within jets, namely the Collins asymmetries, from transversely polarized ${p^{\uparrow}p}$ collisions at $\sqrt{s}$ = 510 GeV. The energy-scaled distribution of jet transverse momentum, $x_{\mathrm{T}} = 2p_{\mathrm{T,jet}}/\sqrt s$, shows a remarkable consistency for Collins asymmetries of $π^{\pm}$ in jets between $\sqrt{s}$ = 200 GeV and 510 GeV. This indicates that the Collins asymmetries are nearly energy independent with, at most, a very weak scale dependence in $p^{\uparrow}p$ collisions. These results extend to high-momentum scales ($Q^2 \leq 3400$ GeV$^2$) and enable unique tests of evolution and universality in the transverse-momentum-dependent formalism, thus providing important constraints for the Collins fragmentation functions.
Collins asymmetries, $A_{\mathrm{UT}}^{\sin(\phi_S - \phi_H)}$, as a function of jet $x_{\mathrm{T}}$ ($\equiv \frac{2p_{\mathrm{T,jet}}}{\sqrt{s}}$) for $\pi^{+}$ in $p^{\uparrow}p$ collisions at $\sqrt{s} = 510$ GeV. Vertical bars show the statistical uncertainties; boxes show the systematic uncertainties in $x_{\mathrm{T}}$ and $A_{\mathrm{UT}}$
Collins asymmetries, $A_{\mathrm{UT}}^{\sin(\phi_S - \phi_H)}$, as a function of jet $x_{\mathrm{T}}$ ($\equiv \frac{2p_{\mathrm{T,jet}}}{\sqrt{s}}$) for $\pi^{-}$ in $p^{\uparrow}p$ collisions at $\sqrt{s} = 510$ GeV. Vertical bars show the statistical uncertainties; boxes show the systematic uncertainties in $x_{\mathrm{T}}$ and $A_{\mathrm{UT}}
Collins asymmetries, $A_{\mathrm{UT}}^{\sin(\phi_S - \phi_H)}$, as a function of $\pi^{+}$ momentum fraction longitudinal momentum fraction $z$ in $p^{\uparrow}p$ collisions at $\sqrt{s} = 510$ GeV. Vertical bars show the statistical uncertainties; boxes show the systematic uncertainties.
We present the first measurements of the forward and midrapidity $η$-meson cross sections from $p$$+$$p$ collisions at $\sqrt{s}=500$ and $510$~GeV, respectively. We also report the midrapidity $η/π^0$ ratio at 510 GeV. The forward cross section is measured differentially in $η$-meson transverse momentum ($p_T$) from 1.0 to 6.5~GeV/$c$ for pseudorapidity $3.0<|η|<3.8$. The midrapidity cross section is measured from 3.5 to 44 GeV/$c$ for pseudorapidity $|η|<0.35$. Both cross sections serve as critical inputs to an updated global analysis of the $η$-meson fragmentation functions.
The invariant differential cross section of $\eta$ mesons at forward rapidity in pp collisions at center-of-mass energy 500 GeV.
The invariant differential cross section of $\eta$ mesons at central rapidity in pp collisions at center-of-mass energy 510 GeV.
The ratio of $\eta$ to $\pi^0$ cross sections at central rapidity in pp collisions at center-of-mass energy 510 GeV.
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