The standard model (SM) production of four top quarks (
) in proton-proton collisions is studied by the CMS Collaboration. The data sample, collected during the 2016-2018 data taking of the LHC, ...corresponds to an integrated luminosity of 137
at a center-of-mass energy of 13
. The events are required to contain two same-sign charged leptons (electrons or muons) or at least three leptons, and jets. The observed and expected significances for the
signal are respectively 2.6 and 2.7 standard deviations, and the
cross section is measured to be
. The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson,
, yielding a limit of
at
confidence level, where
is the SM value of
. They are also used to constrain the oblique parameter of the Higgs boson in an effective field theory framework,
. Limits are set on the production of a heavy scalar or pseudoscalar boson in Type-II two-Higgs-doublet and simplified dark matter models, with exclusion limits reaching 350-470
and 350-550
for scalar and pseudoscalar bosons, respectively. Upper bounds are also set on couplings of the top quark to new light particles.
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Two related searches for phenomena beyond the standard model (BSM) are performed using events with hadronic jets and significant transverse momentum imbalance. The results are based on a sample of ...proton-proton collisions at a center-of-mass energy of
, collected by the CMS experiment at the LHC in 2016-2018 and corresponding to an integrated luminosity of 137
. The first search is inclusive, based on signal regions defined by the hadronic energy in the event, the jet multiplicity, the number of jets identified as originating from bottom quarks, and the value of the kinematic variable
for events with at least two jets. For events with exactly one jet, the transverse momentum of the jet is used instead. The second search looks in addition for disappearing tracks produced by BSM long-lived charged particles that decay within the volume of the tracking detector. No excess event yield is observed above the predicted standard model background. This is used to constrain a range of BSM models that predict the following: the pair production of gluinos and squarks in the context of supersymmetry models conserving
-parity, with or without intermediate long-lived charginos produced in the decay chain; the resonant production of a colored scalar state decaying to a massive Dirac fermion and a quark; or the pair production of scalar and vector leptoquarks each decaying to a neutrino and a top, bottom, or light-flavor quark. In most of the cases, the results obtained are the most stringent constraints to date.
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Measurements are presented of the triple-differential cross section for inclusive isolated-photon+jet events in Formula omitted collisions at Formula omitted TeV as a function of photon transverse ...momentum ( Formula omitted), photon pseudorapidity ( Formula omitted), and jet pseudorapidity ( Formula omitted). The data correspond to an integrated luminosity of Formula omitted that probe a broad range of the available phase space, for Formula omitted and Formula omitted, Formula omitted, Formula omitted Formula omitted, and jet transverse momentum, Formula omitted, > 25 Formula omitted. The measurements are compared to next-to-leading order perturbative quantum chromodynamics calculations, which reproduce the data within uncertainties.
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The average total energy as well as its hadronic and electromagnetic components are measured with the CMS detector at pseudorapidities Formula omitted in proton-proton collisions at a centre-of-mass ...energy Formula omitted. The results are presented as a function of the charged particle multiplicity in the region Formula omitted. This measurement is sensitive to correlations induced by the underlying event structure over a very wide pseudorapidity region. The predictions of Monte Carlo event generators commonly used in collider experiments and ultra-high energy cosmic ray physics are compared to the data. All generators considered overestimate the fraction of energy going into hadrons.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for new physics in top quark production is performed in proton-proton collisions at Formula omitted. The data set corresponds to an integrated luminosity of Formula omitted collected in 2016 ...with the CMS detector. Events with two opposite-sign isolated leptons (electrons or muons), and Formula omitted quark jets in the final state are selected. The search is sensitive to new physics in top quark pair production and in single top quark production in association with a Formula omitted boson. No significant deviation from the standard model expectation is observed. Results are interpreted in the framework of effective field theory and constraints on the relevant effective couplings are set, one at a time, using a dedicated multivariate analysis. This analysis differs from previous searches for new physics in the top quark sector by explicitly separating Formula omitted from Formula omitted events and exploiting the specific sensitivity of the Formula omitted process to new physics.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, Formula omitted, is presented. The measurement considers events ...where the two leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of Formula omitted and corresponding to an integrated luminosity of Formula omitted are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region Formula omitted. The 2- and 3-jet measurements are not simultaneously described by any of models.
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Exclusive \{{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\ photoproduction is measured for the first time in ultraperipheral pPb collisions at \\sqrt{\smash b{s_{_{\mathrm {NN}}} = ...5.02\,\text {Te}\text {V} \ with the CMS detector. The cross section \\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p})\ is \11.0 \pm 1.4\,\text {(stat)} \pm 1.0\,\text {(syst)} \\\mu \b at \\langle W_{{\upgamma _{}^{}} \mathrm{p}}\rangle = 92.6\,\text {Ge}\text {V} \ for photon–proton centre-of-mass energies \W_{{\upgamma _{}^{}} \mathrm{p}}\ between 29 and \213\,\text {Ge}\text {V} \. The differential cross section \\mathrm {d}\sigma /\mathrm {d}|t |\ is measured in the interval \0.025< |t | < 1\,\text {Ge}\text {V} ^{2}\ as a function of \W_{{\upgamma _{}^{}} \mathrm{p}}\, where t is the squared four-momentum transfer at the proton vertex. The results are compared with previous measurements and theoretical predictions. The measured cross section \\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p})\ has a power-law dependence on the photon–proton centre-of-mass, consistent with electron–proton collision measurements performed at HERA. The \W_{{\upgamma _{}^{}} \mathrm{p}}\ dependence of the exponential slope of the differential cross section \\mathrm {d}\sigma /\mathrm {d}|t |\ is also measured.
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A search is presented for a heavy pseudoscalar boson Formula omitted decaying to a Z boson and a Higgs boson with mass of 125 Formula omitted. In the final state considered, the Higgs boson decays to ...a bottom quark and antiquark, and the Z boson decays either into a pair of electrons, muons, or neutrinos. The analysis is performed using a data sample corresponding to an integrated luminosity of 35.9 Formula omitted collected in 2016 by the CMS experiment at the LHC from proton-proton collisions at a center-of-mass energy of 13 Formula omitted. The data are found to be consistent with the background expectations. Exclusion limits are set in the context of two-Higgs-doublet models in the Formula omitted boson mass range between 225 and 1000 Formula omitted.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for supersymmetry is presented based on events with at least one photon, jets, and large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of 13 ...Formula omitted. The data correspond to an integrated luminosity of 35.9 Formula omitted and were recorded at the LHC with the CMS detector in 2016. The analysis characterizes signal-like events by categorizing the data into various signal regions based on the number of jets, the number of Formula omitted-tagged jets, and the missing transverse momentum. No significant excess of events is observed with respect to the expectations from standard model processes. Limits are placed on the gluino and top squark pair production cross sections using several simplified models of supersymmetric particle production with gauge-mediated supersymmetry breaking. Depending on the model and the mass of the next-to-lightest supersymmetric particle, the production of gluinos with masses as large as 2120 Formula omitted and the production of top squarks with masses as large as 1230 Formula omitted are excluded at 95% confidence level.
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Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton-proton collision ...data set recorded with the CMS detector in 2016 at Formula omitted, corresponding to an integrated luminosity of 35.9 Formula omitted. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a Formula omitted or Formula omitted boson, or a top quark-antiquark pair) and the following decay modes: Formula omitted, Formula omitted, Formula omitted, Formula omitted, Formula omitted, and Formula omitted. Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be Formula omitted, assuming a Higgs boson mass of Formula omitted. Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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