Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CMS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Search for new physics in final states with two opposite-sign, same-flavor leptons, jets, and missing transverse momentum in pp collisions at sqrt(s) = 13 TeV

A search is presented for physics beyond the standard model in final states with two opposite-sign, same-flavor leptons, jets, and missing transverse momentum. The data sample corresponds to an integrated luminosity of 2.3 fb$^{−1}$ of proton-proton collisions at $ \sqrt{s}=13 $ TeV collected with the CMS detector at the LHC in 2015. The analysis uses the invariant mass of the lepton pair, searching for a kinematic edge or a resonant-like excess compatible with the Z boson mass. Both search modes use several event categories in order to increase the sensitivity to new physics. These categories are based on the rapidity of the leptons, the multiplicity of jets and b jets, the scalar sum of jet transverse momenta, and missing transverse momentum. The observations in all signal regions are consistent with the expectations from the standard model, and the results are interpreted in the context of simplified models of supersymmetry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Search for dark matter particles in proton-proton collisions at $\sqrt{s} = 8 $ TeV using razor variables

A search for dark matter particles directly produced in proton-proton collisions recorded by the CMS experiment at the LHC is presented. The data correspond to an integrated luminosity of 18.8 fb -1 at a center-of-mass energy of 8TeV. The event selection requires at least two jets and no isolated leptons. The razor variables are used to quantify the transverse momentum balance in the jet momenta. The study is performed separately for events with and without jets originating from b quarks. Furthermore, the observed yields are consistent with the expected backgrounds and, depending on the nature of the production mechanism, dark matter production at the LHC is excluded at 90% confidence level for a mediator mass scale Λ below 1 TeV. The use of razor variables yields results that complement those previously published.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the mass of the top quark in decays with a $J/\psi$ meson in pp collisions at 8 TeV

A first measurement of the top quark mass in the decay channel t → (W → ℓν) (b → J/ψ + X → μ$^{+}$ μ$^{−}$ + X) is presented. The analysis uses events selected from the proton-proton collisions recorded by the CMS detector at the LHC at a center-of-mass energy of 8 TeV. The data correspond to an integrated luminosity of 19.7 fb$^{−1}$, with 666 $ \mathrm{t}\overline{\mathrm{t}} $ and single top quark candidate events containing a reconstructed J/ψ candidate decaying into an oppositely-charged muon pair. The mass of the (J/ψ + ℓ) system, where ℓ is an electron or a muon from W boson decay, is used to extract a top quark mass of 173.5 ± 3.0 (stat) ± 0.9 (syst) GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Search for supersymmetry in events with at least one photon, missing transverse momentum, and large transverse event activity in proton-proton collisions at $ \sqrt{s}=13 $ TeV

A search for physics beyond the standard model in final states with at least one photon, large transverse momentum imbalance, and large total transverse event activity is presented. Such topologies can be produced in gauge-mediated supersymmetry models in which pair-produced gluinos or squarks decay to photons and gravitinos via short-lived neutralinos. The data sample corresponds to an integrated luminosity of 35.9 fb$^{−1}$ of proton-proton collisions at $ \sqrt{s}=13 $ TeV recorded by the CMS experiment at the LHC in 2016. No significant excess of events above the expected standard model background is observed. The data are interpreted in simplified models of gluino and squark pair production, in which gluinos or squarks decay via neutralinos to photons. Gluino masses of up to 1.50-2.00 TeV and squark masses up to 1.30-1.65 TeV are excluded at 95% confidence level, depending on the neutralino mass and branching fraction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Event shape variables measured using multijet final states in proton-proton collisions at $ \sqrt{s}=13 $ TeV

The study of global event shape variables can provide sensitive tests of predictions for multijet production in proton-proton collisions. This paper presents a study of several event shape variables calculated using jet four momenta in proton-proton collisions at a centre-of-mass energy of 13 TeV and uses data recorded with the CMS detector at the LHC corresponding to an integrated luminosity of 2.2 fb$^{-1}$. After correcting for detector effects, the resulting distributions are compared with several theoretical predictions. In conclusion, the agreement generally improves as the energy, represented by the average transverse momentum of the two leading jets, increases.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Measurement of the differential Drell-Yan cross section in proton-proton collisions at $\sqrt{\mathrm{s}} $ = 13 TeV

Measurements of the differential cross section for the Drell-Yan process, based on proton-proton collision data at a centre-of-mass energy of 13 TeV, collected by the CMS experiment, are presented. The data correspond to an integrated luminosity of 2.8 (2.3) fb$^{-1}$ in the dimuon (dielectron) channel. The total and fiducial cross section measurements are presented as a function of dilepton invariant mass in the range 15 to 3000 GeV, and compared with the perturbative predictions of the standard model. The measured differential cross sections are in good agreement with the theoretical calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Measurements of differential Z boson production cross sections in proton-proton collisions at $\sqrt{s}$ = 13 TeV

Measurements are presented of the differential cross sections for Z bosons produced in proton-proton collisions at $\sqrt{s} =$ 13 TeV and decaying to muons and electrons. The data analyzed were collected in 2016 with the CMS detector at the LHC and correspond to an integrated luminosity of 35.9 fb$^{-1}$. The measured fiducial inclusive product of cross section and branching fraction agrees with next-to-next-to-leading order quantum chromodynamics calculations. Differential cross sections of the transverse momentum $p_\mathrm{T}$, the optimized angular variable $\phi^*_\eta$, and the rapidity of lepton pairs are measured. The data are corrected for detector effects and compared to theoretical predictions using fixed order, resummed, and parton shower calculations. The uncertainties of the measured normalized cross sections are smaller than 0.5% for $\phi^*_\eta <$ 0.5 and for $p_\mathrm{T}^\mathrm{Z} <$ 50 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Search for anomalous triple gauge couplings in WW and WZ production in lepton + jet events in proton-proton collisions at $\sqrt{s} =$ 13 TeV

A search is presented for three additional operators that would lead to anomalous WWγ or WWZ couplings with respect to those in the standard model. They are constrained by studying events with two vector bosons, a W boson decaying to eν or μν, and a W or Z boson decaying hadronically, reconstructed as a single, massive, large- radius jet. The search uses a data set of proton-proton collisions at a centre-of-mass energy of 13 TeV, recorded by the CMS experiment at the CERN LHC in 2016, and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Using the reconstructed diboson invariant mass, 95% confidence intervals are obtained for the anomalous coupling parameters of -1.58 < $c_{WWW}$/Λ$^{2}$< 1.59 TeV$^{-2}$, -2.00 < c$_{W}$/Λ$^{2}$< 2.65 TeV$^{-2}$, and -8.78 < c$_{B}$/Λ$^{2}$< 8.54 TeV$^{-2}$, in agreement with standard model expectations of zero for each parameter. These are the strictest bounds on these parameters to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Measurement of prompt D 0 , D + , D *+ , and DS+$ {\mathrm{D}}_{\mathrm{S}}^{+} $ production in p–Pb collisions at sNN$ \sqrt{{\mathrm{s}}_{\mathrm{NN}}} $ = 5.02 TeV

The measurement of the production of prompt D 0 , D + , D *+, and $D_S^+$ mesons in proton–lead (p–Pb) collisions at the centre-of-mass energy per nucleon pair of \mathrm{\sqrt{s_{NN}}}$ = 5.02 TeV, with an integrated luminosity of 292 ± 11 μb -1 , are reported. Differential production cross sections are measured at mid-rapidity (-96 < y cms < 0.04) as a function of transverse momentum (p T ) in the intervals 0 < p T < 36 GeV/c for D 0 , 1 < p T < 36 GeV/c for D + and D *+ , and 2 < p T < 24 GeV/c for D + mesons. For each species, the nuclear modification factor R pPb is calculated as a function of p T using a proton-proton (pp) reference measured at the same collision energy. The results are compatible with unity in the whole p T range. The average of the non-strange D mesons R pPb is compared with theoretical model predictions that include initial-state effects and parton transport model predictions. The p T dependence of the D 0 , D + , and D *+ nuclear modification factors is also reported in the interval 1 < p T < 36 GeV/c as a function of the collision centrality, and the central-to-peripheral ratios are computed from the D-meson yields measured in different centrality classes. The results are further compared with charged-particle measurements and a similar trend is observed in all the centrality classes. The ratios of the p T -differential cross sections of D 0 , D + , D *+ , and $D_S^+$ mesons are also reported. The $D_S^+$ and D + yields are compared as a function of the charged-particle multiplicity for several p T intervals. No modification in the relative abundances of the four species is observed with respect to pp collisions within the statistical and systematic uncertainties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Study of the B + → J/Ψ$\bar{Λ}$p decay using proton-proton collisions at $\sqrt{s}$= 8TeV

A study of the B + → J/Ψ$\bar{Λ}$p decay using proton-proton collision data collected at $\sqrt{s}$= 8TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19:6 fb -1 , is presented. The ratio of branching fractions $\mathcal{B}$(B + → J/Ψ$\bar{Λ}$p) / $\mathcal{B}$(B + → j/Ψk* (892) + ) is measured to be (1.054 ±0.057(stat) ± 0.035(syst) ± 0.011($\mathcal{B}$))%, where the last uncertainty reflects the uncertainties in the world-average branching fractions of $\bar{Λ}$ and K* (892) + decays to reconstructed final states. The invariant mass distributions of the J/ψ$\bar{Λ}$, J/ψp, and $\bar{Λ}$p systems produced in the B + → J/Ψ$\bar{Λ}$p decay are investigated and found to be inconsistent with the pure phase space hypothesis. The analysis is extended by using a model-independent angular amplitude analysis, which shows that the observed invariant mass distributions are consistent with the contributions from excited kaons decaying to the $\bar{Λ}$p system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Dependence of inclusive jet production on the anti-k$_{T}$ distance parameter in pp collisions at $ \sqrt{\mathrm{s}} $ = 13 TeV

The dependence of inclusive jet production in proton-proton collisions with a center-of-mass energy of 13 TeV on the distance parameter R of the anti-k$_{T}$ algorithm is studied using data corresponding to integrated luminosities up to 35.9 fb$^{−1}$ collected by the CMS experiment in 2016. The ratios of the inclusive cross sections as functions of transverse momentum p$_{T}$ and rapidity y, for R in the range 0.1 to 1.2 to those using R = 0.4 are presented in the region 84 < p$_{T}$< 1588 GeV and |y|< 2.0. The results are compared to calculations at leading and next-to-leading order in the strong coupling constant using different parton shower models. The variation of the ratio of cross sections with R is well described by calculations including a parton shower model, but not by a leading-order quantum chromodynamics calculation including nonperturbative effects. The agreement between the data and the theoretical predictions for the ratios of cross sections is significantly improved when next-to-leading order calculations with nonperturbative effects are used.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Inclusive search for highly boosted Higgs bosons decaying to bottom quark-antiquark pairs in proton-proton collisions at $\sqrt{s} =$ 13 TeV

A search for standard model Higgs bosons (H) produced with transverse momentum (p$_{T}$) greater than 450 GeV and decaying to bottom quark-antiquark pairs ($ \mathrm{b}\overline{\mathrm{b}} $) is performed using proton-proton collision data collected by the CMS experiment at the LHC at $ \sqrt{s} $ = 13 TeV. The data sample corresponds to an integrated luminosity of 137 fb$^{−1}$. The search is inclusive in the Higgs boson production mode. Highly Lorentz-boosted Higgs bosons decaying to $ \mathrm{b}\overline{\mathrm{b}} $ are reconstructed as single large-radius jets, and are identified using jet substructure and a dedicated b tagging technique based on a deep neural network. The method is validated with Z →$ \mathrm{b}\overline{\mathrm{b}} $ decays. For a Higgs boson mass of 125 GeV, an excess of events above the background assuming no Higgs boson production is observed with a local significance of 2.5 standard deviations (σ), while the expectation is 0.7. The corresponding signal strength and local significance with respect to the standard model expectation are μ$_{H}$ = 3.7 ± 1.2(stat)$ {}_{-0.7}^{+0.8} $(syst)$ {}_{-0.5}^{+0.8} $(theo) and 1.9 σ. Additionally, an unfolded differential cross section as a function of Higgs boson p$_{T}$ for the gluon fusion production mode is presented, assuming the other production modes occur at the expected rates.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at $\sqrt{s}$ = 13 TeV

A search for new top quark interactions is performed within the framework of an effective field theory using the associated production of either one or two top quarks with a Z boson in multilepton final states. The data sample corresponds to an integrated luminosity of 138 fb -1 of proton-proton collisions at √s = 13 TeV collected by the CMS experiment at the LHC. Five dimension-six operators modifying the electroweak interactions of the top quark are considered. Novel machine-learning techniques are used to enhance the sensitivity to effects arising from these operators. Distributions used for the signal extraction are parameterized in terms of Wilson coefficients describing the interaction strengths of the operators. All five Wilson coefficients are simultaneously fit to data and 95% confidence level intervals are computed. All results are consistent with the SM expectations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Search for a heavy resonance decaying to a top quark and a W boson at $\sqrt{s}$ = 13 TeV in the fully hadronic final state

A search for a heavy resonance decaying to a top quark and a W boson in the fully hadronic final state is presented. The analysis is performed using data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb -1 recorded by the CMS experiment at the LHC. The search is focused on heavy resonances, where the decay products of each top quark or W boson are expected to be reconstructed as a single, large-radius jet with a distinct substructure. The production of an excited bottom quark, b*, is used as a benchmark when setting limits on the cross section for a heavy resonance decaying to a top quark and a W boson. The hypotheses of b* quarks with left-handed, right-handed, and vector-like chiralities are excluded at 95% confidence level for masses below 2.6, 2.8, and 3.1 TeV, respectively. These are the most stringent limits on the b* quark mass to date, extending the previous best limits by almost a factor of two.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of the top quark mass using events with a single reconstructed top quark in pp collisions at $$ \sqrt{s} $$ = 13 TeV

A measurement of the top quark mass is performed using a data sample enriched with single top quark events produced in the t channel. The study is based on proton- proton collision data, corresponding to an integrated luminosity of 35.9 fb -1 , recorded at √s = 13 TeV by the CMS experiment at the LHC in 2016. Candidate events are selected by requiring an isolated high-momentum lepton (muon or electron) and exactly two jets, of which one is identified as originating from a bottom quark. Multivariate discriminants are designed to separate the signal from the background. Optimized thresholds are placed on the discriminant outputs to obtain an event sample with high signal purity. The top quark mass is found to be $172.13^{+0.76}_{-0.77}$ GeV, where the uncertainty includes both the statistical and systematic components, reaching sub-GeV precision for the first time in this event topology. The masses of the top quark and antiquark are also determined separately using the lepton charge in the final state, from which the mass ratio and difference are determined to be $0.9952^{+0.0079}_{-0.0104}$ and $0.83^{+1.79}_{-1.35}$ GeV, respectively. The results are consistent with CPT invariance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of the inclusive and differential $t\overline{t}γ$ cross sections in the single-lepton channel and EFT interpretation at $\sqrt{s}$ = 13 TeV

The production cross section of a top quark pair in association with a photon is measured in proton-proton collisions at a center-of-mass energy of 13 TeV. The data set, corresponding to an integrated luminosity of 137 fb -1 , was recorded by the CMS experiment during the 2016–2018 data taking of the LHC. The measurements are performed in a fiducial volume defined at the particle level. Events with an isolated, highly energetic lepton, at least three jets from the hadronization of quarks, among which at least one is b tagged, and one isolated photon are selected. The inclusive fiducial $t\overline{t}γ$ cross section, for a photon with transverse momentum greater than 20 GeV and pseudorapidity |η| < 1.4442, is measured to be 798 ± 7(stat) ± 48(syst) fb, in good agreement with the prediction from the standard model at next-to-leading order in quantum chromodynamics. The differential cross sections are also measured as a function of several kinematic observables and interpreted in the framework of the standard model effective field theory (EFT), leading to the most stringent direct limits to date on anomalous electromagnetic dipole moment interactions of the top quark and the photon.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for physics beyond the standard model in top quark production with additional leptons in the context of effective field theory

A search for new physics in top quark production with additional final-state leptons is performed using data collected by the CMS experiment in proton-proton collisions at $ \sqrt{s} $ = 13 TeV at the LHC during 2016–2018. The data set corresponds to an integrated luminosity of 138 fb$^{−1}$. Using the framework of effective field theory (EFT), potential new physics effects are parametrized in terms of 26 dimension-six EFT operators. The impacts of EFT operators are incorporated through the event-level reweighting of Monte Carlo simulations, which allows for detector-level predictions. The events are divided into several categories based on lepton multiplicity, total lepton charge, jet multiplicity, and b-tagged jet multiplicity. Kinematic variables corresponding to the transverse momentum (p$_{T}$) of the leading pair of leptons and/or jets as well as the p$_{T}$ of on-shell Z bosons are used to extract the 95% confidence intervals of the 26 Wilson coefficients corresponding to these EFT operators. No significant deviation with respect to the standard model prediction is found.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

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

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 ε$^{2}$ 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(θ$_{H}$) 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 β = 0.5.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗