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Measurement of the Higgs boson production via vector boson fusion and its decay into bottom quarks in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A measurement of the Higgs boson (H) production via vector boson fusion (VBF) and its decay into a bottom quark-antiquark pair (b (b) over bar) is presented using proton-proton collision data recorded by the CMS experiment at root s = 13TeV and corresponding to an integrated luminosity of 90.8 fb(-1). Treating the gluon-gluon fusion process as a background and constraining its rate to the value expected in the standard model (SM) within uncertainties, the signal strength of the VBF process, defined as the ratio of the observed signal rate to that predicted by the SM, is measured to be mu(qqH)(Hb (b) over bar) = 1.01(-0.46)(+0.55). The VBF signal is observed with a significance of 2.4 standard deviations relative to the background prediction, while the expected significance is 2.7 standard deviations. Considering inclusive Higgs boson production and decay into bottom quarks, the signal strength is measured to be mu(incl.)(Hb (b) over bar) = 0.99(-0.41)(+0.48), corresponding to an observed (expected) significance of 2.6 (2.9) standard deviations.
Higher-order moments of the elliptic flow distribution in PbPb collisions at √sNN=5.02 TeV
(Springer, 2024) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Özdemir, Kadri
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 root s(NN) = 5.02TeV. 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} greater than or similar to v(2){6} greater than or similar to v(2){8} greater than or similar to 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.
Study of charm hadronization with prompt Λc+ baryons in proton-proton and lead-lead collisions at √sNN=5.02 TeV
(Springer, 2024) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Özdemir, Kadri
The production of prompt Lambda(+)(c) baryons is measured via the exclusive decay channel Lambda(+)(c) -> pK(-) pi(+) at a center-of-mass energy per nucleon pair of 5.02TeV, using proton-proton (pp) and lead-lead (PbPb) collision data collected by the CMS experiment at the CERN LHC. The pp and PbPb data were obtained in 2017 and 2018 with integrated luminosities of 252 and 0.607 nb(-1), respectively. The measurements are performed within the Lambda(+)(c) rapidity interval vertical bar y vertical bar < 1 with transverse momentum (p(T)) ranges of 3-30 and 6-40 GeV/c for pp and PbPb collisions, respectively. Compared to the yields in pp collisions scaled by the expected number of nucleon-nucleon interactions, the observed yields of Lambda(+)(c) with p(T) > 10 GeV/c are strongly suppressed in PbPb collisions. The level of suppression depends significantly on the collision centrality. The Lambda(+)(c)/D-0 production ratio is similar in PbPb and pp collisions at p(T) > 10 GeV/c, suggesting that the coalescence process does not play a dominant role in prompt Lambda(+)(c) baryon production at higher p(T).
Measurement of the τ lepton polarization in Z boson decays in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
The polarization of tau leptons is measured using leptonic and hadronic tau lepton decays in Z -> tau(+)tau(-) events in proton-proton collisions at root s = 13 TeV recorded by CMS at the CERN LHC with an integrated luminosity of 36.3 fb(-1). The measured tau(-) lepton polarization at the Z boson mass pole is P-tau(Z) = -0.144 +/- 0.006 (stat) +/- 0.014 (syst) = -0.144 +/- 0.015, in good agreement with the measurement of the tau lepton asymmetry parameter of A(tau) = 0.1439 +/- 0.0043 = -P-tau(Z) at LEP. The tau lepton 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(eff)(W), independently of the Z boson production mechanism. The obtained value sin(2)theta(eff)(W) = 0.2319 +/- 0.0008(stat) +/- 0.0018(syst) = 0.2319 +/- 0.0019 is in good agreement with measurements at e(+)e(-) colliders.
Search for long-lived heavy neutral leptons with lepton flavour conserving or violating decays to a jet and a charged lepton
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
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-lN to each lepton generation l 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 |V-mu N(2)| > 5 (4) x 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.
Search for long-lived particles decaying to final states with a pair of muons in proton-proton collisions at √s=13.6 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
An inclusive search for long-lived exotic particles (LLPs) decaying to final states with a pair of muons is presented. The search uses data corresponding to an integrated luminosity of 36.6 fb(-1) collected by the CMS experiment from the proton-proton collisions at root s - 13.6TeV in 2022, the first year of Run 3 of the CERN LHC. The experimental signature is a pair of oppositely charged muons originating from a secondary vertex spatially separated from the proton-proton interaction point by distances ranging from several hundred mu m to several meters. The sensitivity of the search benefits from new triggers for displaced dimuons developed for Run 3. The results are interpreted in the framework of the hidden Abelian Higgs model, in which the Higgs boson decays to a pair of long-lived dark photons, and of an R-parity violating supersymmetry model, in which long-lived neutralinos decay to a pair of muons and a neutrino. The limits set on these models are the most stringent to date in wide regions of lifetimes for LLPs with masses larger than 10 GeV.
Search for dark matter particles in W+W- events with transverse momentum imbalance in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
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 (l = electrons or muons). The analysis is based on proton-proton collision data collected at a center-of-mass energy of 13TeV 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 l nu qq and 2l2 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.
Search for a third-generation leptoquark coupled to a τ lepton and a b quark through single, pair, and nonresonant production in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search is presented for a third-generation leptoquark (LQ) coupled exclusively to a tau lepton and a b quark. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV recorded with the CMS detector, corresponding to an integrated luminosity of 138 fb(-1). Events with tau leptons and a varying number of jets originating from b quarks are considered, targeting the single and pair production of LQs, as well as nonresonant t-channel LQ exchange. An excess is observed in the data with respect to the background expectation in the combined analysis of all search regions. For a benchmark LQ mass of 2 TeV and an LQ-b-tau coupling strength of 2.5, the excess reaches a local significance of up to 2.8 standard deviations. Upper limits at the 95% confidence level are placed on the LQ production cross section in the LQ mass range 0.5-2.3 TeV, and up to 3 TeV for t-channel LQ exchange. Leptoquarks are excluded below masses of 1.22-1.88 TeV for different LQ models and varying coupling strengths up to 2.5. The study of nonresonant tau tau production through t-channel LQ exchange allows lower limits on the LQ mass of up to 2.3 TeV to be obtained.
Inclusive and diferential cross section measurements of t(t)over-barb(b)over-bar production in the lepton plus jets channel at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
Measurements of inclusive and normalized differential cross sections of the associated production of top quark-antiquark and bottom quark-antiquark pairs, t (t) over barb (b) over bar, are presented. The results are based on data from proton-proton collisions collected by the CMS detector at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 138 fb(-1). The cross sections are measured in the lepton+jets decay channel of the top quark pair, using events containing exactly one isolated electron or muon and at least five jets. Measurements are made in four fiducial phase space regions, targeting different aspects of the t (t) over barb (b) over bar process. Distributions are unfolded to the particle level through maximum likelihood fits, and compared with predictions from several event generators. The inclusive cross section measurements of this process in the fiducial phase space regions are the most precise to date. In most cases, the measured inclusive cross sections exceed the predictions with the chosen generator settings. The only exception is when using a particular choice of dynamic renormalization scale, mu(R) = 1/2 Pi(i=t), (t) over bar ,b (b) over bar m(T, i)(,)(1/4) where m(T), (2)(i) = m(i)(2) + p(T,i)(2) are the transverse masses of top and bottom quarks. The differential cross sections show varying degrees of compatibility with the theoretical predictions, and none of the tested generators with the chosen settings simultaneously describe all the measured distributions.
Search for a new resonance decaying into two spin-0 bosons in a final state with two photons and two bottom quarks in proton-proton collisions at √s=13 TeV
(Springer, 2024) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Özdemir, Kadri
A search for a new boson X is presented using CERN LHC proton-proton collision data collected by the CMS experiment at root s = 13 TeV in 2016-2018, and corresponding to an integrated luminosity of 138 fb(-1). The resonance X decays into either a pair of Higgs bosons HH of mass 125 GeV or an H and a new spin-0 boson Y. One H subsequently decays to a pair of photons, and the second H or Y, to a pair of bottom quarks. The explored mass ranges of X are 260-1000 GeV and 300-1000 GeV, for decays to HH and to HY, respectively, with the Y mass range being 90-800 GeV. For a spin-0 X hypothesis, the 95% confidence level upper limit on the product of its production cross section and decay branching fraction is observed to be within 0.90-0.04 fb, depending on the masses of X and Y. The largest deviation from the background-only hypothesis with a local (global) significance of 3.8 (below 2.8) standard deviations is observed for X and Y masses of 650 and 90 GeV, respectively. The limits are interpreted using several models of new physics.
Search for heavy neutral leptons in final states with electrons, muons, and hadronically decaying tau leptons in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search for heavy neutral leptons (HNLs) of Majorana or Dirac type using proton-proton collision data at root s = 13TeV= 13 TeV is presented. The data were collected by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 138 fb(-1). Events with three charged leptons (electrons, muons, and hadronically decaying tau leptons) are selected, corresponding to HNL production in association with a charged lepton and decay of the HNL to two charged leptons and a standard model (SM) neutrino. The search is performed for HNL masses between 10 GeV and 1.5 TeV. No evidence for an HNL signal is observed in data. Upper limits at 95% confidence level are found for the squared coupling strength of the HNL to SM neutrinos, considering exclusive coupling of the HNL to a single SM neutrino generation, for both Majorana and Dirac HNLs. The limits exceed previously achieved experimental constraints for a wide range of HNL masses, and the limits on tau neutrino coupling scenarios with HNL masses above the W boson mass are presented for the first time.
Measurement of the primary Lund jet plane density in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A measurement is presented of the primary Lund jet plane (LJP) density in inclusive jet production in proton-proton collisions. The analysis uses 138 fb(-1) of data collected by the CMS experiment at root s = 13TeV. The LJP, a representation of the phase space of emissions inside jets, is constructed using iterative jet declustering. The transverse momentum kT and the splitting angle Delta R of an emission relative to its emitter are measured at each step of the jet declustering process. The average density of emissions as function of ln( k(T)/GeV) and ln( R/Delta R) is measured for jets with distance parameters R = 0.4 or 0.8, transverse momentum p(T) > 700 GeV, and rapidity |y| < 1.7. The jet substructure is measured using the charged-particle tracks of the jet. The measured distributions, unfolded to the level of stable charged particles, are compared with theoretical predictions from simulations and with perturbative quantum chromodynamics calculations. Due to the ability of the LJP to factorize physical effects, these measurements can be used to improve different aspects of the physics modeling in event generators.
Search for W' bosons decaying to a top and a bottom quark in leptonic final states in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search for W' bosons decaying to a top and a bottom quark in final states including an electron or a muon is performed with the CMS detector at the LHC. The analyzed data correspond to an integrated luminosity of 138 fb(-1) of proton-proton collisions at a center-of-mass energy of 13TeV. Good agreement with the standard model expectation is observed and no evidence for the existence of the W' boson is found over the mass range examined. The largest observed deviation from the standard model expectation is found for a W' boson mass (m(W)') hypothesis of 3.8TeV with a relative decay width of 1%, with a local (global) significance of 2.6 (2.0) standard deviations. Upper limits on the production cross sections of W' bosons decaying to a top and a bottom quark are set. Left- and right-handed W' bosons with m(W)' below 3.9 and 4.3TeV, respectively, are excluded at the 95% confidence level, under the assumption that the new particle has a narrow decay width. Limits are also set for relative decay widths up to 30%.
Search for Higgs boson pair production in the b(b)over-bar W+W- decay mode in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search for Higgs boson pair (HH) production with one Higgs boson decaying to two bottom quarks and the other to two W bosons are presented. The search is done using proton-proton collisions data at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 138 fb(-1) recorded by the CMS detector at the LHC from 2016 to 2018. The final states considered include at least one leptonically decaying W boson. No evidence for the presence of a signal is observed and corresponding upper limits on the HH production cross section are derived. The limit on the inclusive cross section of the nonresonant HH production, assuming that the distributions of kinematic observables are as expected in the standard model (SM), is observed (expected) to be 14 (18) times the value predicted by the SM, at 95% confidence level. The limits on the cross section are also presented as functions of various Higgs boson coupling modifiers, and anomalous Higgs boson coupling scenarios. In addition, limits are set on the resonant HH production via spin-0 and spin-2 resonances within the mass range 250-900 GeV.
Search for long-lived heavy neutrinos in the decays of B mesons produced in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search for long-lived heavy neutrinos (N) in the decays of B mesons produced in proton-proton collisions at root s = 13 TeV is presented. The data sample corresponds to an integrated luminosity of 41.6 fb(-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 < m(N) < 3 GeV and decay lengths in the range 10(-2) < c tau(N) < 10(4) mm, where tau(N) is the N proper mean lifetime. Signal events are defined by the signature B -> l(B)NX; N -> l(+/-)pi(-/+), where the leptons l(B) and l 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 l(+/-)pi(-/+) invariant mass distributions. Limits at 95% confidence level on the sum of the squares of the mixing amplitudes between heavy and light neutrinos, vertical bar V-N vertical bar(2), and on c tau(N) are obtained in different mixing scenarios for both Majorana and Dirac-like N particles. The most stringent upper limit vertical bar V-N vertical bar(2) < 2.0 x 10(-5) is obtained at m(N) = 1.95 GeV for the Majorana case where N mixes exclusively with muon neutrinos. The limits on vertical bar V-N vertical bar(2) for masses 1 < m(N) < 1.7 GeV are the most stringent from a collider experiment to date.
Multiplicity and transverse momentum dependence of charge-balance functions in pPb and PbPb collisions at LHC energies
(Springer, 2024) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Özdemir, Kadri
Measurements of the charge-dependent two-particle angular correlation function in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of root s(NN) = 8.16 TeV and lead-lead (PbPb) collisions at root s(NN) = 5.02 TeV are reported. The pPb and PbPb data sets correspond to integrated luminosities of 186 nb(-1) and 0.607 nb(-1), respectively, and were collected using the CMS detector at the CERN LHC. The charge-dependent correlations are characterized by balance functions of same- and opposite-sign particle pairs. The balance functions, which contain information about the creation time of charged particle pairs and the development of collectivity, are studied as functions of relative pseudorapidity (Delta eta) and relative azimuthal angle (Delta phi), for various multiplicity and transverse momentum (p(T)) intervals. A multiplicity dependence of the balance function is observed in Delta eta and Delta phi for both systems. The width of the balance functions decreases towards high-multiplicity collisions in the momentum region < 2 GeV, for pPb and PbPb results. Integrals of the balance functions are presented in both systems, and a mild dependence of the charge-balancing fractions on multiplicity is observed. No multiplicity dependence is observed at higher transverse momentum. The data are compared with HYDJET, HIJING, and AMPT generator predictions, none of which capture completely the multiplicity dependence seen in the data. The comparison of results with different center-of-mass energies suggests that the balance functions become narrower at higher energies, which is consistent with the idea of delayed hadronization and the effect of radial flow.
Search for dark QCD with emerging jets in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search for emerging jets produced in proton-proton collisions at a center-of-mass energy of 13 TeV is performed using data collected by the CMS experiment corresponding to an integrated luminosity of 138 fb(-1). This search examines a hypothetical dark quantum chromodynamics (QCD) sector that couples to the standard model (SM) through a scalar mediator. The scalar mediator decays into an SM quark and a dark sector quark. As the dark sector quark showers and hadronizes, it produces long-lived dark mesons that subsequently decay into SM particles, resulting in a jet, known as an emerging jet, with multiple displaced vertices. This search looks for pair production of the scalar mediator at the LHC, which yields events with two SM jets and two emerging jets at leading order. The results are interpreted using two dark sector models with different flavor structures, and exclude mediator masses up to 1950 (1950) GeV for an unflavored (flavor-aligned) dark QCD model. The unflavored results surpass a previous search for emerging jets by setting the most stringent mediator mass exclusion limits to date, while the flavor-aligned results provide the first direct mediator mass exclusion limits to date.
Search for central exclusive production of top quark pairs in proton-proton collisions at √s=13 TeV with tagged protons
(Springer, 2024) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Özdemir, Kadri
A search for the central exclusive production of top quark-antiquark pairs (t (t) over bar) is performed for the first time using proton-tagged events in proton-proton collisions at the LHC at a centre-of-mass energy of 13TeV. The data correspond to an integrated luminosity of 29.4 fb(-1). The t (t) over bar decay products are reconstructed using the central CMS detector, while forward protons are measured in the CMS-TOTEM precision proton spectrometer. An observed (expected) upper bound on the production cross section of 0.59 (1.14) pb is set at 95% confidence level, for collisions of protons with fractional momentum losses between 2 and 20%.
Search for Higgs boson pair production with one associated vector boson in proton-proton collisions at √s=13 TeV
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search for Higgs boson pair (HH) production in association with a vector boson V (W or Z boson) is presented. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb(-1). Both hadronic and leptonic decays of V bosons are used. The leptons considered are electrons, muons, and neutrinos. The HH production is searched for in the b (b) over barb (b) over bar decay channel. An observed (expected) upper limit at 95% confidence level of VHH production cross section is set at 294 (124) times the standard model prediction. Constraints are also set on the modifiers of the Higgs boson trilinear self-coupling, k(lambda), assuming k(2V) = 1, and vice versa on the coupling of two Higgs bosons with two vector bosons, k(2V). The observed (expected) 95% confidence intervals of these coupling modifiers are -37.7 < k(lambda) < 37.2 (-30.1 < k(lambda) < 28.9) and -12.2 < k(2V) < 13.5 (-7.2 < k(2V) < 8.9), respectively.
Search for a resonance decaying to a W boson and a photon in proton-proton collisions at √s=13 TeV using leptonic W boson decays
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Özdemir, Kadri
A search for a new charged particle X with mass between 0.3 and 2.0TeV decaying to a W boson and a photon is presented, using proton-proton collision data at a center-of-mass energy of 13TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb(-1). Particle X has electric charge +/- 1 and is assumed to have spin 0. The search is performed using the electron and muon decays of the W boson. No significant excess above the predicted background is observed. The upper limit at 95% confidence level on the product of the production cross section of the X and its branching fraction to a W boson and a photon is found to be 94 (137) fb for a 0.3TeV resonance and 0.75 (0.81) fb for a 2.0TeV resonance, for an X width-to-mass ratio of 0.01% (5%). This search presents the most stringent constraints to date on the existence of such resonances across the probed mass range. A statistical combination with an earlier study based on the hadronic decay mode of the W boson is also performed, and the upper limit at 95% confidence level for a 2.0TeV resonance is reduced to 0.50 (0.63) fb for an X width-to-mass ratio of 0.01% (5%).