73 research outputs found

    Theoretical study of Axion-Like Particle (ALP) couplings to quarks and gluons, and experimental study of ALP resonances in dijet invariant mass spectrum using Monte Carlo data

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    In this report we will discuss study of theoretically well-motivated new particles called Axions. We will specifically calculate couplings of Axions to SM quarks and gluons. Furthermore, we will present experimental study of resonances of such new particles decaying into two jets by making their invariant mass distributions using simulated data generated by MadGraph5

    Measurement of inclusive and differential cross sections for W+^{+}W^{-} production in proton-proton collisions at s= \sqrt{s} = 13.6 TeV

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    Measurements at s= \sqrt{s}= 13.6 TeV of the opposite-sign W boson pair production cross section in proton-proton collisions are presented. The data used in this study were collected with the CMS detector at the CERN LHC in 2022, and correspond to an integrated luminosity of 34.8 fb1 ^{-1} . Events are selected by requiring one electron and one muon of opposite charge. A maximum likelihood fit is performed on signal- and background-enriched data categories defined by the flavour and charge of the leptons, the number of jets, and number of jets originating from b quarks. An inclusive W+^{+}W^{-} production cross section of 125.7 ± \pm 5.6 pb is measured, in agreement with standard model predictions. Cross sections are also reported in a fiducial region close to that of the detector acceptance, both inclusively and differentially, as a function of the jet multiplicity in the event. For first time in proton-proton collisions, WW events with at least two reconstructed jets are studied and compared with recent theoretical predictions.Measurements at s\sqrt{s} = 13.6 TeV of the opposite-sign W boson pair production cross section in proton-proton collisions are presented. The data used in this study were collected with the CMS detector at the CERN LHC in 2022, and correspond to an integrated luminosity of 34.8 fb1^{-1}. Events are selected by requiring one electron and one muon of opposite charge. A maximum likelihood fit is performed on signal- and background-enriched data categories defined by the flavour and charge of the leptons, the number of jets, and number of jets originating from b quarks. An inclusive W+^+W^- production cross section of 125.7 ±\pm 5.6 pb is measured, in agreement with standard model predictions. Cross sections are also reported in a fiducial region close to that of the detector acceptance, both inclusively and differentially, as a function of the jet multiplicity in the event. For first time in proton-proton collisions, WW events with at least two reconstructed jets are studied and compared with recent theoretical predictions

    Observation of the J/ψ\psi \to μ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe J/ψ\psi\toμ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb1{-1}. Normalizing to the J/ψ\psi\toμ+μ\mu^+\mu^- decay mode leads to a branching fraction [10.12.7+3.3^{+3.3}_{-2.7} (stat) ±\pm 0.4 (syst) ]×\times 107^{-7}, a value that is consistent with the standard model prediction

    Enriching the physics program of the CMS experiment via data scouting and data parking

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    International audienceSpecialized data-taking and data-processing techniques were introduced by the CMS experiment in Run 1 of the CERN LHC to enhance the sensitivity of searches for new physics and the precision of standard model measurements. These techniques, termed data scouting and data parking, extend the data-taking capabilities of CMS beyond the original design specifications. The novel data-scouting strategy trades complete event information for higher event rates, while keeping the data bandwidth within limits. Data parking involves storing a large amount of raw detector data collected by algorithms with low trigger thresholds to be processed when sufficient computational power is available to handle such data. The research program of the CMS Collaboration is greatly expanded with these techniques. The implementation, performance, and physics results obtained with data scouting and data parking in CMS over the last decade are discussed in this Report, along with new developments aimed at further improving low-mass physics sensitivity over the next years of data taking

    Observation of the J/ψ\psi\toμ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe J/ψ\psi\toμ+μμ+μ\mu^+\mu^-\mu^+\mu^- decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb1{-1}. Normalizing to the J/ψ\psi\toμ+μ\mu^+\mu^- decay mode leads to a branching fraction [10.12.7+3.3^{+3.3}_{-2.7} (stat) ±\pm 0.4 (syst) ]×\times 107^{-7}, a value that is consistent with the standard model prediction

    Review of searches for vector-like quarks, vector-like leptons, and heavy neutral leptons in proton-proton collisions at s\sqrt{s} = 13 TeV at the CMS experiment

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    International audienceThe LHC has provided an unprecedented amount of proton-proton collision data, bringing forth exciting opportunities to address fundamental open questions in particle physics. These questions can potentially be answered by performing searches for very rare processes predicted by models that attempt to extend the standard model of particle physics. The data collected by the CMS experiment in 2015-2018 at a center-of-mass energy of 13 TeV help to test the standard model at the highest precision ever and potentially discover new physics. An interesting opportunity is presented by the possibility of new fermions with masses ranging from the MeV to the TeV scale. Such new particles appear in many possible extensions of the standard model and are well motivated theoretically. They may explain the appearance of three generations of leptons and quarks, the mass hierarchy across the generations, and the nonzero neutrino masses. In this report, the status of searches targeting vector-like quarks, vector-like leptons, and heavy neutral leptons at the CMS experiment is discussed. A complete overview of final states is provided together with their complementarity and partial combination. The discovery potential for several of these searches at the High-Luminosity LHC is also discussed

    The CMS Statistical Analysis and Combination Tool: COMBINE

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    International audienceThis paper describes the COMBINE software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run COMBINE and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of COMBINE. However, the online documentation referenced within this paper provides an up-to-date and complete user guide

    Search for long-lived heavy neutrinos in the decays of B mesons produced in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search for long-lived heavy neutrinos (N) in the decays of \PB mesons produced in proton-proton collisions at s\sqrt{s} = 13 TeV is presented. The data sample corresponds to an integrated luminosity of 41.6 fb1^{-1} collected in 2018 by the CMS experiment at the CERN LHC, using a dedicated data stream that enhances the number of recorded events containing B mesons. The search probes heavy neutrinos with masses in the range 1 <\ltmNm_\mathrm{N}<\lt 3 GeV and decay lengths in the range 102^{-2}<\ltcτc\tau<\lt 104^{4} mm, where τN\tau_\mathrm{N} is the N proper mean lifetime. Signal events are defined by the signature B \toB\ell_\mathrm{B}NX; N \to±π\ell^{\pm} \pi^{\mp}, where the leptons B\ell_\mathrm{B} and \ell can be either a muon or an electron, provided that at least one of them is a muon. The hadronic recoil system, X, is treated inclusively and is not reconstructed. No significant excess of events over the standard model background is observed in any of the ±π\ell^{\pm}\pi^{\mp} invariant mass distributions. Limits at 95% confidence level on the sum of the squares of the mixing amplitudes between heavy and light neutrinos, VN2\vert V_\mathrm{N}\vert^2, and on cτc\tau are obtained in different mixing scenarios for both Majorana and Dirac-like N particles. The most stringent upper limit VN2\vert V_\mathrm{N}\vert^2 <\lt 2.0×\times105^{-5} is obtained at mNm_\mathrm{N} = 1.95 GeV for the Majorana case where N mixes exclusively with muon neutrinos. The limits on VN2\vert V_\mathrm{N}\vert^2 for masses 1 <\lt mNm_\mathrm{N} <\lt 1.7 GeV are the most stringent from a collider experiment to date
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