Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Benato, L.; Bergauer, T.; Dragicevic, M.; Giordano, C.; Hussain, P.S.

A search for long-lived particles originating from the decay of b hadrons produced in proton-proton collisions with a center-of-mass energy of 13 TeV at the LHC is presented. The analysis is performed on a dataset recorded in 2018, corresponding to an integrated luminosity of 41.6 fb-1. Interactions of the long-lived particles in the CMS endcap muon system would create hadronic or electromagnetic showers, producing clusters of detector hits. Selected events contain at least one such high-multiplicity cluster in the muon endcaps and require the presence of a displaced muon. The most stringent upper limits to date on the branching fraction B(B - ΚΦ), where the long-lived particle Φ decays to a pair of hadrons, are obtained for Φ masses of 0.3-3.0 GeV and Φ mean proper decay lengths in the range of 1-500 cm.

Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Benato, L.; Bergauer, T.; Dragicevic, M.; Giordano, C.; Hussain, P.S.

A search for flavor violating decays of the Z boson to charged leptons is performed using data from proton-proton collisions at [Formula Presented] TeVcollected with the CMS detector at the LHC,corresponding to an integrated luminosity of 138 fb−1. Each of the decays [Formula Presented] isconsidered. The data are consistent with the backgrounds expected from standard model processes. For the [Formula Presented] channel the observed (expected) 95% confidence level upper limit on the branching fraction is [Formula Presented], which is the most stringent direct limit to date on this process; the corresponding limits for the [Formula Presented] channels are [Formula Presented], respectively. Additionally, the eμ final state is used to search for lepton flavor violating decays of Z' resonances in the mass range from 110 to 500 GeV. No significant excess is observed above the predicted background levels.

Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Escalante Del Valle, A.; Hussain, P.S.

A search is performed for charged-lepton flavor violating processes in top quark ((Formula presented)) production and decay. The data were collected by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of (Formula presented). The selected events are required to contain one opposite-sign electron-muon pair, a third charged lepton (electron or muon), and at least one jet of which no more than one is associated with a bottom quark. Boosted decision trees are used to distinguish signal from background, exploiting differences in the kinematics of the final states particles. The data are consistent with the standard model expectation. Upper limits at 95% confidence level are placed in the context of effective field theory on the Wilson coefficients, which range between (Formula presented) depending on the flavor of the associated light quark and the Lorentz structure of the interaction. These limits are converted to upper limits on branching fractions involving up (charm) quarks, (Formula presented) ((Formula presented)), of (Formula presented), (Formula presented), and (Formula presented) for tensorlike, vectorlike, and scalarlike interactions, respectively.

Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Hussain, P.S.; Jeitler, M.

A measurement of the ratio of branching fractions (Formula presented) in the (Formula presented), (Formula presented) decay channel is presented. This measurement uses a sample of proton-proton collision data collected at a center-of-mass energy of (Formula presented) by the CMS experiment in 2018, corresponding to an integrated luminosity of (Formula presented). The measured ratio, (Formula presented), agrees with the value of (Formula presented) predicted by the standard model, which assumes lepton flavor universality. By testing lepton flavor universality, this measurement is a probe of new physics using (Formula presented) mesons, which are currently only produced at the LHC.

Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Benato, L.; Bergauer, T.; Damanakis, K.; Dragicevic, M.

A general search is presented for supersymmetric particles (sparticles) in scenarios featuring compressed mass spectra using proton-proton collisions at a center-of-mass energy of 13 TeV, recorded with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of 138 fb−1. Awide range of potential sparticle signatures are targeted, including pair production of electroweakinos, sleptons, and top squarks. The search focuses on events with a high transverse momentum system from initial-stateradiation jets recoiling against a potential sparticle system with significant missing transverse momentum. Events are categorized based on their lepton multiplicity, jet multiplicity, number of b-tagged jets, and kinematic variables sensitive to the sparticle masses and mass splittings. The sensitivity extends to higher parent sparticle masses than previously probed at the LHC for production of pairs of electroweakinos, sleptons, and top squarks with mass spectra featuring small mass splittings (compressed mass spectra). The observed results demonstrate agreement with the predictions of the background-only model. Lower mass limits are set at 95% confidence level on production of pairs of electroweakinos, sleptons, and top squarks that extend to 325, 275, and 780 GeV, respectively, for the most favorable compressed mass regime cases.

Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Benato, L.; Bergauer, T.; Chatterjee, S.; Damanakis, K.

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 μb−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 are 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.

Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Hussain, P.S.; Jeitler, M.

An analysis is presented based on models of the intrinsic transverse momentum (intrinsic (Formula presented)) of partons in nucleons by studying the dilepton transverse momentum in Drell-Yan events. Using parameter tuning in event generators and existing data from fixed-target experiments and from hadron colliders, our investigation spans 3 orders of magnitude in center-of-mass energy and 2 orders of magnitude in dilepton invariant mass. The results show an energy-scaling behavior of the intrinsic (Formula presented) parameters, independent of the dilepton invariant mass at a given center-of-mass energy.

Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Hussain, P.S.; Jeitler, M.

A measurement of the Higgs boson mass and width via its decay to two (Formula presented) bosons is presented. Proton-proton collision data collected by the CMS experiment, corresponding to an integrated luminosity of (Formula presented) at a center-of-mass energy of 13 TeV, is used. The invariant mass distribution of four leptons in the on-shell Higgs boson decay is used to measure its mass and constrain its width. This yields the most precise single measurement of the Higgs boson mass to date, (Formula presented), and an upper limit on the width (Formula presented) at 95% confidence level. A combination of the on- and off-shell Higgs boson production decaying to four leptons is used to determine the Higgs boson width, assuming that no new virtual particles affect the production, a premise that is tested by adding new heavy particles in the gluon fusion loop model. This result is combined with a previous CMS analysis of the off-shell Higgs boson production with decay to two leptons and two neutrinos, giving a measured Higgs boson width of (Formula presented), in agreement with the standard model prediction of 4.1 MeV. The strength of the off-shell Higgs boson production is also reported. The scenario of no off-shell Higgs boson production is excluded at a confidence level corresponding to 3.8 standard deviations.

Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Hussain, P.S.; Jeitler, M.

A search for flavor-changing neutral current interactions of the top quark (t) and the Higgs boson (H)is presented. The search is based on proton-proton collision data collected in 2016–2018 at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, and corresponding to an integrated luminosity of 138 fb−1. Events containing a pair of leptons with the same-sign electric charge and at least one jet are considered. The results are used to constrain the branching fraction (B) of the top quark decaying to a Higgs boson and an up (u) or charm (c) quark. No significant excess above the estimated background was found. The observed (expected) upper limits at a 95% confidence level are found to be 0.072% (0.059%) for B(t → Hu) and 0.043% (0.062%) for B(t → Hc). These results are combined with two other searches performed by the CMS Collaboration for flavor-changing neutral current interactions of top quarks and Higgs bosons in final states where the Higgs boson decays to either a pair of photons or a pair of bottom quarks. The resulting observed (expected) upper limits at the 95% confidence level are 0.019% (0.027%) for B(t → Hu) and 0.037% (0.035%) for B(t → Hc).

Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Benato, L.; Bergauer, T.; Chatterjee, S.; Damanakis, K.

A measurement of the WZγ 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 ps ¼ 13 TeV recorded with the ffiffi 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, l±νlþl−, where l ¼ e or μ, accompanied by an additional photon. The observed (expected) significance of the WZγ signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region, where events with an l originating from a tau lepton decay are excluded, to be 5.48 ± 1.11 fb, which is compatible with the prediction of 3.69 ± 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 axionlike particles.