Search for exotic decays of the Higgs boson to a pair of pseudoscalars in the $\mu\mu$bb and $\tau\tau$bb final states

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 84 (2024) 493, 2024.
Inspire Record 2760544 DOI 10.17182/hepdata.145999

A search for exotic decays of the Higgs boson (H) with a mass of 125 GeV to a pair of light pseudoscalars $\mathrm{a}_1$ is performed in final states where one pseudoscalar decays to two b quarks and the other to a pair of muons or $\tau$ leptons. A data sample of proton-proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 138 fb$^{-1}$ recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (CL) on the Higgs boson branching fraction to $\mu\mu$bb and to $\tau\tau$bb, via a pair of $\mathrm{a}_1$s. The limits depend on the pseudoscalar mass $m_{\mathrm{a}_1}$ and are observed to be in the range (0.17-3.3) $\times$ 10$^{-4}$ and (1.7-7.7) $\times$ 10$^{-2}$ in the $\mu\mu$bb and $\tau\tau$bb final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine model-independent upper limits on the branching fraction $\mathcal{B}$(H $\to$ $\mathrm{a}_1\mathrm{a}_1$ $\to$ $\ell\ell$bb) at 95% CL, with $\ell$ being a muon or a $\tau$ lepton. For different types of 2HDM+S, upper bounds on the branching fraction $\mathcal{B}$(H $\to$ $\mathrm{a}_1\mathrm{a}_1$) are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, $\mathcal{B}($H $\to$ $\mathrm{a}_1\mathrm{a}_1$) values above 0.23 are excluded at 95% CL for $m_{\mathrm{a}_1}$ values between 15 and 60 GeV.

4 data tables

Observed and expected upper limits at 95% CL on B($\text{H} \rightarrow \text{a}_{1}\text{a}_{1} \rightarrow \mu\mu$bb) as functions of $m_{\text{a}_{1}}$. The inner and outer bands indicate the regions containing the distribution of limits located within 68 and 95% confidence intervals, respectively, of the expectation under the background-only hypothesis.

Observed and expected upper limits at 95% CL on B($\text{H} \rightarrow \text{a}_{1}\text{a}_{1} \rightarrow \tau\tau$bb) in percent as functions of $m_{\text{a}_{1}}$, for the combination of the $\mu\tau_{\text{h}}$, $e\tau_{\text{h}}$, and $e\mu$ channels. The inner and outer bands indicate the regions containing the distribution of limits located within 68 and 95% confidence intervals, respectively, of the expectation under the background-only hypothesis.

Observed and expected upper limits at 95% CL on B($\text{H} \rightarrow \text{a}_{1}\text{a}_{1} \rightarrow ll$bb) in percent, where $l$ stands for muons or $\tau$ leptons, obtained from the combination of the $\mu\mu$bb and $\tau\tau$bb channels. The results are obtained as functions $m_{\text{a}_{1}}$ for 2HDM+S models, independent of the type and tan $\beta$ parameter. The inner and outer bands indicate the regions containing the distribution of limits located within 68 and 95% confidence intervals, respectively, of the expectation under the background-only hypothesis.

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Search for long-lived heavy neutral leptons with lepton flavour conserving or violating decays to a jet and a charged lepton

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 03 (2024) 105, 2024.
Inspire Record 2735808 DOI 10.17182/hepdata.145688

A search for long-lived heavy neutral leptons (HNLs) is presented, which considers the hadronic final state and coupling scenarios involving all three lepton generations in the 2-20 GeV HNL mass range for the first time. Events comprising two leptons (electrons or muons) and jets are analyzed in a data sample of proton-proton collisions, recorded with the CMS experiment at the CERN LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. A novel jet tagger, based on a deep neural network, has been developed to identify jets from an HNL decay using various features of the jet and its constituent particles. The network output can be used as a powerful discriminating tool to probe a broad range of HNL lifetimes and masses. Contributions from background processes are determined from data. No excess of events in data over the expected background is observed. Upper limits on the HNL production cross section are derived as functions of the HNL mass and the three coupling strengths $V_{\ell\mathrm{N}}$ to each lepton generation $\ell$ and presented as exclusion limits in the coupling-mass plane, as lower limits on the HNL lifetime, and on the HNL mass. In this search, the most stringent limit on the coupling strength is obtained for pure muon coupling scenarios; values of $\lvert V_{\mu\mathrm{N}}\rvert^{2}$$\gt $ 5 (4) $\times$ 10$^{-7}$ are excluded for Dirac (Majorana) HNLs with a mass of 10 GeV at a confidence level of 95% that correspond to proper decay lengths of 17 (10) mm.

24 data tables

Observed number of events and predicted number of background events per category for resolved categories

Observed number of events and predicted number of background events per category for boosted categories

Two-dimensional exclusion limits for Majorana HNL pure electron coupling scenario

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Higher-order moments of the elliptic flow distribution in PbPb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

The CMS collaboration Tumasyan, Armen ; Adam, Wolfgang ; Andrejkovic, Janik Walter ; et al.
JHEP 2024 (2024) 106, 2024.
Inspire Record 2724506 DOI 10.17182/hepdata.132638

The hydrodynamic flow-like behavior of charged hadrons in high-energy lead-lead collisions is studied through multiparticle correlations. The elliptic anisotropy values based on different orders of multiparticle cumulants, $v_{2}\{2k\}$, are measured up to the tenth order ($k$ = 5) as functions of the collision centrality at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. The data were recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 0.607 nb$^{-1}$. A hierarchy is observed between the coefficients, with $v_{2}\{2\} > v_{2}\{4\} \gtrsim v_{2}\{6\} \gtrsim v_{2}\{8\} \gtrsim v_{2}\{10\}$. Based on these results, centrality-dependent moments for the fluctuation-driven event-by-event $v_{2}$ distribution are determined, including the skewness, kurtosis and, for the first time, superskewness. Assuming a hydrodynamic expansion of the produced medium, these moments directly probe the initial-state geometry in high-energy nucleus-nucleus collisions.

8 data tables

The $v_2\{2k\}$ ($k = 1, ..., 5$) values as functions of centrality in PbPb collisions at $\sqrt{s_{NN}}=5.02~\textrm{Te}\textrm{V}$. The measurement is performed with charged particles within the acceptance region.

The relative differences $(v_2\{2k\}-v_2\{10\})/v_2\{10\}$ ($k = 1, ..., 4$) as functions of centrality in PbPb collisions at $\sqrt{s_{NN}}=5.02~\textrm{Te}\textrm{V}$. The measurement is performed with charged particles within the acceptance region.

The $h_1$ and the $h_2$ hydrodynamic probes as functions of centrality in PbPb collisions at $\sqrt{s_{NN}}=5.02~\textrm{Te}\textrm{V}$. The measurement is performed with charged particles within the acceptance region.

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Search for dark matter particles in W$^+$W$^-$ events with transverse momentum imbalance in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 03 (2024) 134, 2024.
Inspire Record 2712865 DOI 10.17182/hepdata.139719

A search for dark matter particles is performed using events with a pair of W bosons and large missing transverse momentum. Candidate events are selected by requiring one or two leptons ($\ell =$ electrons or muons). The analysis is based on proton-proton collision data collected at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC and corresponding to an integrated luminosity of 138 fb$^{-1}$. No significant excess over the expected standard model background is observed in the $\ell\nu$qq and 2$\ell$2$\nu$ final states of the W$^+$W$^-$ boson pair. Limits are set on dark matter production in the context of a simplified dark Higgs model, with a dark Higgs boson mass above the W$^+$W$^-$ mass threshold. The dark matter phase space is probed in the mass range 100-300 GeV, extending the scope of previous searches. Current exclusion limits are improved in the range of dark Higgs masses from 160 to 250 GeV, for a dark matter mass of 200 GeV.

61 data tables

Leading lepton $p_T$ pre-fit distribution for selected events in SR1 of the di-leptonic channel for the full dataset. The error bars on the data points represent the statistical uncertainty of the data, and the error bars on the predicted yields represent the combined systematic and statistical uncertainty in each bin. The signal prediction represents the mass point: $m_s = 160 GeV, m_{\chi} = 100 GeV, m_{Z'} = 500 GeV$. The last bin includes the overflow.

Trailing lepton $p_T$ pre-fit distribution for selected events in SR1 of the di-leptonic channel for the full dataset. The error bars on the data points represent the statistical uncertainty of the data, and the error bars on the predicted yields represent the combined systematic and statistical uncertainty in each bin. The signal prediction represents the mass point: $m_s = 160 GeV, m_{\chi} = 100 GeV, m_{Z'} = 500 GeV$. The last bin includes the overflow.

Missing $p_T$ pre-fit distribution for selected events in SR2 of the di-leptonic channel for the full dataset. The error bars on the data points represent the statistical uncertainty of the data, and the error bars on the predicted yields represent the combined systematic and statistical uncertainty in each bin. The signal prediction represents the mass point: $m_s = 160 GeV, m_{\chi} = 100 GeV, m_{Z'} = 500 GeV$. The last bin includes the overflow.

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Determination of $|V_{cb}|$ using $\overline{B}^0\to D^{*+}\ell^-\bar\nu_\ell$ decays with Belle II

The Belle-II collaboration Adachi, I. ; Adamczyk, K. ; Aggarwal, L. ; et al.
Phys.Rev.D 108 (2023) 092013, 2023.
Inspire Record 2705370 DOI 10.17182/hepdata.145129

We determine the CKM matrix-element magnitude $|V_{cb}|$ using $\overline{B}^0\to D^{*+}\ell^-\bar\nu_\ell$ decays reconstructed in $189 \, \mathrm{fb}^{-1}$ of collision data collected by the Belle II experiment, located at the SuperKEKB $e^+e^-$ collider. Partial decay rates are reported as functions of the recoil parameter $w$ and three decay angles separately for electron and muon final states. We obtain $|V_{cb}|$ using the Boyd-Grinstein-Lebed and Caprini-Lellouch-Neubert parametrizations, and find $|V_{cb}|_\mathrm{BGL}=(40.57\pm 0.31 \pm 0.95\pm 0.58)\times 10^{-3}$ and $|V_{cb}|_\mathrm{CLN}=(40.13 \pm 0.27 \pm 0.93\pm 0.58 )\times 10^{-3}$ with the uncertainties denoting statistical components, systematic components, and components from the lattice QCD input, respectively. The branching fraction is measured to be ${\cal B}(\overline{B}^0\to D^{*+}\ell^-\bar\nu_\ell)=(4.922 \pm 0.023 \pm 0.220)\%$. The ratio of branching fractions for electron and muon final states is found to be $0.998 \pm 0.009 \pm 0.020$. In addition, we determine the forward-backward angular asymmetry and the $D^{*+}$ longitudinal polarization fractions. All results are compatible with lepton-flavor universality in the Standard Model.

8 data tables

Measured partial decay rates $\Delta\Gamma$ (in units of $10^{-15}$ GeV)

Average of normalized decay rates over $\overline{B}^0\to D^{*+} e^- \bar\nu_e$ and $\overline{B}^0\to D^{*+} \mu^- \bar\nu_\mu$ decays

Full experimental (statistical and systematic) correlations (in \%) of the partial decay rates for the $\overline{B}^0\to D^{*+} e^- \bar\nu_e$ and $\overline{B}^0\to D^{*+} \mu^- \bar\nu_\mu$ decays.

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Search for direct production of GeV-scale resonances decaying to a pair of muons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 12 (2023) 070, 2023.
Inspire Record 2704121 DOI 10.17182/hepdata.140424

A search for direct production of low-mass dimuon resonances is performed using $\sqrt{s}$ = 13 TeV proton-proton collision data collected by the CMS experiment during the 2017-2018 operation of the CERN LHC with an integrated luminosity of 96.6 fb$^{-1}$. The search exploits a dedicated high-rate trigger stream that records events with two muons with transverse momenta as low as 3 GeV but does not include the full event information. The search is performed by looking for narrow peaks in the dimuon mass spectrum in the ranges of 1.1-2.6 GeV and 4.2-7.9 GeV. No significant excess of events above the expectation from the standard model background is observed. Model-independent limits on production rates of dimuon resonances within the experimental fiducial acceptance are set. Competitive or world's best limits are set at 90% confidence level for a minimal dark photon model and for a scenario with two Higgs doublets and an extra complex scalar singlet (2HDM+S). Values of the squared kinetic mixing coefficient $\varepsilon^2$ in the dark photon model above 10$^{-6}$ are excluded over most of the mass range of the search. In the 2HDM+S, values of the mixing angle $\sin(\theta_\text{H})$ above 0.08 are excluded over most of the mass range of the search with a fixed ratio of the Higgs doublets vacuum expectation $\tan\beta$ = 0.5.

7 data tables

The signal acceptance and reconstruction efficiency are extracted from DY and pseudoscalar simulations. The acceptance of DY simulation is the fraction of signal events where a muon pair is present, and each muon has ${p}_{\mathrm{T}} >4$ GeV and $|\eta|<1.9$. The acceptance of pseudoscalar simulation is the fraction of signal events where a muon pair is present, each muon has ${p}_{\mathrm{T}} >5$ GeV and $|\eta|<1.9$, and the muon pair have ${p}_{\mathrm{T}}>20~(35)$ GeV for $m_{\mu\mu}>4.2$ GeV ($<2.6$ GeV). The reconstruction efficiency is the efficiency of signal events satisfying the trigger requirements, the muon identification, and vertex selection.

Expected and observed model independent upper limits at 95% CL on the product of the signal cross section, the branching fraction to a pair of muons for the inclusive dimuon selection, and fiducial acceptance.

Expected and observed model independent upper limits at 95% CL on the product of the signal cross section, the branching fraction to a pair of muons for the boosted dimuon selection, and fiducial acceptance.

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Measurement of the $\tau$ lepton polarization in Z boson decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 01 (2024) 101, 2024.
Inspire Record 2702153 DOI 10.17182/hepdata.144221

The polarization of $\tau$ leptons is measured using leptonic and hadronic $\tau$ lepton decays in Z $\to$$\tau^+\tau^-$ events in proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded by CMS at the CERN LHC with an integrated luminosity of 36.3 fb$^{-1}$. The measured $\tau^-$ polarization at the Z boson mass pole is $\mathcal{P}_{\tau}$(Z) = $-$0.144 $\pm$ 0.006 (stat) $\pm$ 0.014 (syst) = $-$0.144 $\pm$ 0.015, in good agreement with the measurement of the $\tau$ lepton asymmetry parameter of $A_{\tau}$ = 0.1439 $\pm$ 0.0043 = $-\mathcal{P}_{\tau}$(Z) at LEP. The $\tau$ polarization depends on the ratio of the vector to axial-vector couplings of the $\tau$ leptons in the neutral current expression, and thus on the effective weak mixing angle $\sin^{2}\theta_\mathrm{W}^{\text{eff}}$, independently of the Z boson production mechanism. The obtained value $\sin^{2}\theta_\mathrm{W}^{\text{eff}}$ = 0.2319 $\pm$ 0.0008 (stat) $\pm$ 0.0018 (syst) = 0.2319 $\pm$ 0.0019 is in good agreement with measurements at e$^+$e$^-$ colliders.

3 data tables

Fit results for the average $\tau^{-}$ lepton polarization for the 11 event categories and the combined fit as the lowest point in the figure

Fit results for the average $\tau^{-}$ lepton polarization for categories grouped into 4 channels.

A comparison of the $\tau$ lepton asymmetry, $A_{\tau}$ measured from the tau lepton polarization in this paper and other measurements.


Evidence for the Higgs boson decay to a $Z$ boson and a photon at the LHC

The ATLAS & CMS collaborations Aad, Georges ; Abbott, Braden Keim ; Abeling, Kira ; et al.
Phys.Rev.Lett. 132 (2024) 021803, 2024.
Inspire Record 2666787 DOI 10.17182/hepdata.142406

The first evidence for the Higgs boson decay to a $Z$ boson and a photon is presented, with a statistical significance of 3.4 standard deviations. The result is derived from a combined analysis of the searches performed by the ATLAS and CMS Collaborations with proton-proton collision data sets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around 140 fb$^{-1}$ for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is $2.2\pm0.7$ times the Standard Model prediction, and agrees with the theoretical expectation within 1.9 standard deviations.

1 data table

The negative profile log-likelihood test statistic, where $\Lambda$ represents the likelihood ratio, as a function of the signal strength $\mu$ derived from the ATLAS data, the CMS data, and the combined result.


Measurement of the production cross section for a W boson in association with a charm quark in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Tumasyan, Armen ; Adam, Wolfgang ; Andrejkovic, Janik Walter ; et al.
Eur.Phys.J.C 84 (2024) 27, 2024.
Inspire Record 2685711 DOI 10.17182/hepdata.141611

The strange quark content of the proton is probed through the measurement of the production cross section for a W boson and a charm (c) quark in proton-proton collisions at a center-of-mass energy of 13 TeV. The analysis uses a data sample corresponding to a total integrated luminosity of 138 fb$^{-1}$ collected with the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm jets are tagged using the presence of a muon or a secondary vertex inside the jet. The W+c production cross section and the cross section ratio $R^\pm_\text{c}$ = $\sigma$(W$^+$+$\bar{\text{c}}$) / $\sigma$(W$^-$+$\text{c}$) are measured inclusively and differentially as functions of the transverse momentum and the pseudorapidity of the lepton originating from the W boson decay. The precision of the measurements is improved with respect to previous studies, reaching 1% in $R^\pm_\text{c}$. The precision of the measurements is improved with respect to previous studies, reaching 1% in $R^\pm_\text{c}$ = 0.950 $\pm$ 0.005 (stat) $\pm$ 0.010 (syst). The measurements are compared with theoretical predictions up to next-to-next-to-leading order in perturbative quantum chromodynamics.

13 data tables

Particle level efficiency*acceptance correction factors and cross section measurements for the four channels (W decay to muon or electron and charm identification via muon or secondary vertex inside a jet). The combined measurement is shown in the last row.

Parton level efficiency*acceptance correction factors and cross section measurements for the four channels (W decay to muon or electron and charm identification via muon or secondary vertex inside a jet). The combined measurement is shown in the last row.

Inclusive cross section predictions at QCD NLO accuracy from MCFM using different PDF sets

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Tests of light-lepton universality in angular asymmetries of $B^0 \to D^{*-} \ell \nu$ decays

The Belle-II collaboration Adachi, I. ; Adamczyk, K. ; Aggarwal, L. ; et al.
Phys.Rev.Lett. 131 (2023) 181801, 2023.
Inspire Record 2685572 DOI 10.17182/hepdata.144759

We present the first comprehensive tests of light-lepton universality in the angular distributions of semileptonic $B^0$-meson decays to charged spin-1 charmed mesons. We measure five angular-asymmetry observables as functions of the decay recoil that are sensitive to lepton-universality-violating contributions. We use events where one neutral $B$ is fully reconstructed in $\Upsilon\left(4S\right)\to{}B \overline{B}$ decays in data corresponding to $189~\mathrm{fb}^{-1}$ integrated luminosity from electron-positron collisions collected with the Belle II detector. We find no significant deviation from the standard model expectations.

2 data tables

Observed values of all angular asymmetry variables.

Full experimental covariance matrix of all angular asymmetry variables.