157 research outputs found

    Measurement of the Higgs boson inclusive and differential fiducial production cross sections in the diphoton decay channel with pp collisions at s \sqrt{s} = 13 TeV

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    The measurements of the inclusive and differential fiducial cross sections of the Higgs boson decaying to a pair of photons are presented. The analysis is performed using proton-proton collisions data recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 137 fb−1^{−1}. The inclusive fiducial cross section is measured to be σfidσ_{fid}=73.4−5.3+5.4^{+5.4}_{−5.3}(stat)−2.2+2.4^{+2.4}_{−2.2}(syst) fb, in agreement with the standard model expectation of 75.4 ± 4.1 fb. The measurements are also performed in fiducial regions targeting different production modes and as function of several observables describing the diphoton system, the number of additional jets present in the event, and other kinematic observables. Two double differential measurements are performed. No significant deviations from the standard model expectations are observed

    Measurements of the Higgs boson production cross section and couplings in the W boson pair decay channel in proton-proton collisions at s=13 TeV\sqrt{s}=13\,\text {Te\hspace{-.08em}V}

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    Production cross sections of the standard model Higgs boson decaying to a pair of W bosons are measured in proton-proton collisions at a center-of-mass energy of 13Te\hspace{-.08em}V. The analysis targets Higgs bosons produced via gluon fusion, vector boson fusion, and in association with a W or Z boson. Candidate events are required to have at least two charged leptons and moderate missing transverse momentum, targeting events with at least one leptonically decaying W boson originating from the Higgs boson. Results are presented in the form of inclusive and differential cross sections in the simplified template cross section framework, as well as couplings of the Higgs boson to vector bosons and fermions. The data set collected by the CMS detector during 2016–2018 is used, corresponding to an integrated luminosity of 138fb−1. The signal strength modifier ÎŒ, defined as the ratio of the observed production rate in a given decay channel to the standard model expectation, is measured to be ÎŒ=0.95+0.10−0.09. All results are found to be compatible with the standard model within the uncertainties

    Measurement of the Higgs boson inclusive and differential fiducial production cross sections in the diphoton decay channel with pp collisions at s \sqrt{s} = 13 TeV

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    The measurements of the inclusive and differential fiducial cross sections of the Higgs boson decaying to a pair of photons are presented. The analysis is performed using proton-proton collisions data recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 137 fb−1^{−1}. The inclusive fiducial cross section is measured to be σfidσ_{fid}=73.4−5.3+5.4^{+5.4}_{−5.3}(stat)−2.2+2.4^{+2.4}_{−2.2}(syst) fb, in agreement with the standard model expectation of 75.4 ± 4.1 fb. The measurements are also performed in fiducial regions targeting different production modes and as function of several observables describing the diphoton system, the number of additional jets present in the event, and other kinematic observables. Two double differential measurements are performed. No significant deviations from the standard model expectations are observed

    Proton reconstruction with the CMS-TOTEM Precision Proton Spectrometer

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    The Precision Proton Spectrometer (PPS) of the CMS and TOTEM experiments collected 107.7 fb-1 in proton-proton (pp) collisions at the LHC at 13 TeV (Run 2). This paper describes the key features of the PPS alignment and optics calibrations, the proton reconstruction procedure, as well as the detector efficiency and the performance of the PPS simulation. The reconstruction and simulation are validated using a sample of (semi)exclusive dilepton events. The performance of PPS has proven the feasibility of continuously operating a near-beam proton spectrometer at a high luminosity hadron collider

    Search for Higgs Boson Decay to a Charm Quark-Antiquark Pair in Proton-Proton Collisions at √s = 13 TeV

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    A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H→cÂŻc, produced in association with a leptonically decaying V (W or Z) boson is presented. The search is performed with proton-proton collisions at √s=13  TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138  fb−1. Novel charm jet identification and analysis methods using machine learning techniques are employed. The analysis is validated by searching for Z→cÂŻc in VZ events, leading to its first observation at a hadron collider with a significance of 5.7 standard deviations. The observed (expected) upper limit on σ(VH)B(H→cÂŻc) is 0.94 (0.50+0.22−0.15)pb at 95% confidence level (C.L.), corresponding to 14 (7.6+3.4−2.3) times the standard model prediction. For the Higgs-charm Yukawa coupling modifier, Îșc, the observed (expected) 95% C.L. interval is 1.1<|Îșc|<5.5 (|Îșc|<3.4), the most stringent constraint to date

    Searches for additional Higgs bosons and for vector leptoquarks in ττ final states in proton-proton collisions at s \sqrt{s} = 13 TeV

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    Three searches are presented for signatures of physics beyond the standard model (SM) in ττ final states in proton-proton collisions at the LHC, using a data sample collected with the CMS detector at s=13TeV\sqrt{s} = 13 TeV, corresponding to an integrated luminosity of 138 fb−1^{−1}. Upper limits at 95% confidence level (CL) are set on the products of the branching fraction for the decay into ττ leptons and the cross sections for the production of a new boson ϕϕ, in addition to the H(125) boson, via gluon fusion (ggϕ)(ggϕ) or in association with b quarks, ranging from O(10pb)O(10 pb) for a mass of 60GeV60 GeV to 0.3 fb for a mass of 3.5TeV3.5 TeV each. The data reveal two excesses for ggϕggϕ production with local pp-values equivalent to about three standard deviations at mϕ=0.1mϕ = 0.1 and 1.2TeV1.2 TeV. In a search for tt-channel exchange of a vector leptoquark U1U_1, 95% CL upper limits are set on the dimensionless U1U_1 leptoquark coupling to quarks and ττ leptons ranging from 1 for a mass of 1TeV1 TeV to 6 for a mass of 5TeV5 TeV, depending on the scenario. In the interpretations of the Mh125M^{125}_h and Mh,EFT125M^{125}_{h,EFT} minimal supersymmetric SM benchmark scenarios, additional Higgs bosons with masses below 350GeV350 GeV are excluded at 95% CL

    Measurement of the Dependence of the Hadron Production Fraction Ratios fs/fuf_s / f_u and fd/fuf_d / f_u on BB Meson Kinematic Variables in Proton-Proton Collisions at s=13TeV\sqrt{s} = 13 TeV

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    The dependence of the ratio between the Bs0B^0_s and B+B^+ hadron production fractions, fs/fuf_s/f_u, on the transverse momentum (pT)(p_T) and rapidity of the BB mesons is studied using the decay channels Bs0→J/ψϕB^0_s→J/ψϕ and B+→J/ψK+B^+→J/ψK^+. The analysis uses a data 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 61.6  fb−161.6  fb^{−1}. The fs/fuf_s/f_u ratio is observed to depend on the BB pTp_T and to be consistent with becoming asymptotically constant at large pTp_T. No rapidity dependence is observed. The ratio of the B0B^0 to B+B^+ meson production fractions, fd/fuf_d/f_u, is also measured, for the first time in proton-proton collisions, using the B0→J/ψK∗0B^0→J/ψK^{*0} decay channel. The result is found to be within 1 standard deviation of unity and independent of pTpT and rapidity, as expected from isospin invariance

    Search for Exotic Higgs Boson Decays H → A A → 4 γ with Events Containing Two Merged Diphotons in Proton-Proton Collisions at √s = 13 TeV

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    We present the first direct search for exotic Higgs boson decays H→AA, A→γγ in events with two photonlike objects. The hypothetical particle A is a low-mass spin-0 particle decaying promptly to a merged diphoton reconstructed as a single photonlike object. We analyze the data collected by the CMS experiment at √s=13  TeV corresponding to an integrated luminosity of 136  fb−1. No excess above the estimated background is found. We set upper limits on the branching fraction B(H→AA→4γ) of (0.9–3.3)×10−3 at 95% confidence level for masses of A in the range 0.1–1.2 GeV

    Azimuthal anisotropy of dijet events in PbPb collisions at sNN \sqrt{s_{\textrm{NN}}} = 5.02 TeV

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    The path-length dependent parton energy loss within the dense partonic medium created in lead-lead collisions at a nucleon-nucleon center-of-mass energy of sNN−−−√ = 5.02 TeV is studied by determining the azimuthal anisotropies for dijets with high transverse momentum. The data were collected by the CMS experiment in 2018 and correspond to an integrated luminosity of 1.69 nb−1. For events containing back-to-back jets, correlations in relative azimuthal angle and pseudorapidity (η) between jets and hadrons, and between two hadrons, are constructed. The anisotropies are expressed as the Fourier expansion coefficients vn, n = 2–4 of these azimuthal distributions. The dijet vn values are extracted from long-range (1.5 < |∆η| < 2.5) components of these correlations, which suppresses the background contributions from jet fragmentation processes. Positive dijet v2 values are observed which increase from central to more peripheral events, while the v3 and v4 values are consistent with zero within experimental uncertainties

    Search for Nonresonant Pair Production of Highly Energetic Higgs Bosons Decaying to Bottom Quarks

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    A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the four-bottom-quark final state, using proton-proton collision data at 13 TeV corresponding to 138  fb−1 collected by the CMS experiment at the LHC. The analysis targets Lorentz-boosted H pairs identified using a graph neural network. It constrains the strengths relative to the standard model of the H self-coupling and the quartic VVHH couplings, Îș2V, excluding Îș2V=0 for the first time, with a significance of 6.3 standard deviations when other H couplings are fixed to their standard model values
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