32 Search Results

A measurement is presented of electroweak (EW) production of a $$\mathrm{W} $$ boson in association with two jets in proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\text {V} $$. The data sample was recorded by the CMS Collaboration at the LHC and corresponds to an integrated luminosity of 35.9$$\,\text {fb}^{-1}$$. The measurement is performed for the $$\ell \nu $$jj final state (with $$\ell \nu $$ indicating a lepton–neutrino pair, and j representing the quarks produced in the hard interaction) in a kinematic region defined by invariant mass $$m_\mathrm {jj} >120\,\text {Ge}\text {V} $$ and transverse momenta $$p_\mathrm {T j} > 25\,\text {Ge}\text {V}more » $$. The cross section of the process is measured in the electron and muon channels yielding $$\sigma _\mathrm {EW}(\mathrm{W} \mathrm {jj})= 6.23 \pm 0.12 \,\text {(stat)} \pm 0.61 \,\text {(syst)} \,\text {pb} $$ per channel, in agreement with leading-order standard model predictions. The additional hadronic activity of events in a signal-enriched region is studied, and the measurements are compared with predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. Limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are $$-2.3< c_{{\mathrm{W} \mathrm{W} \mathrm{W}}}/\varLambda ^2 < 2.5\,\text {Te}\text {V} ^{-2}$$, $$-8.8< c_{\mathrm{W}}/\varLambda ^2 < 16\,\text {Te}\text {V} ^{-2}$$, and $$-45< c_{\mathrm{B}}/\varLambda ^2 < 46\,\text {Te}\text {V} ^{-2}$$. These results are combined with the CMS EW $$\mathrm{Zjj} $$ analysis, yielding the constraint on the $$c_{{\mathrm{W} \mathrm{W} \mathrm{W}}}$$ coupling: $$-1.8< c_{{\mathrm{W} \mathrm{W} \mathrm{W}}}/\varLambda ^2 < 2.0\,\text {Te}\text {V} ^{-2}$$.« less

New sets of CMS underlying-event parameters ("tunes") are presented for the PYTHIA8 event generator. These tunes use the NNPDF3.1 parton distribution functions (PDFs) at leading (LO), next-to-leading (NLO), or next-to-next-to-leading (NNLO) orders in perturbative quantum chromodynamics, and the strong coupling evolution at LO or NLO. Measurements of charged-particle multiplicity and transverse momentum densities at various hadron collision energies are fit simultaneously to determine the parameters of the tunes. Comparisons of the predictions of the new tunes are provided for observables sensitive to the event shapes at LEP, global underlying event, soft multiparton interactions, and double-parton scattering contributions. In addition, comparisonsmore » are made for observables measured in various specific processes, such as multijet, Drell-Yan, and top quark-antiquark pair production including jet substructure observables. The simulation of the underlying event provided by the new tunes is interfaced to a higher-order matrix-element calculation. For the first time, predictions from PYTHIA8 obtained with tunes based on NLO or NNLO PDFs are shown to reliably describe minimum-bias and underlying-event data with a similar level of agreement to predictions from tunes using LO PDF sets.« less

Measurements are presented of the triple-differential cross section for inclusive isolated-photon+jet events in pp collisions at $$\sqrt{s} =$$ 8 TeV as a function of photon transverse momentum ($$p_\mathrm{T}^\gamma$$), photon pseudorapidity ($$\eta^\gamma$$), and jet pseudorapidity ($$\eta^\text{jet}$$). The data correspond to an integrated luminosity of 19.7 fb$$^{-1}$$ that probe a broad range of the available phase space, for $$|\eta^\gamma|<1.44$$ and 1.57$$<|\eta^\gamma|<$$2.50, $$|\eta^\text{jet}|<$$2.5, 40$$< p_\mathrm{T}^\gamma<$$ 1000 GeV, and jet transverse momentum, $$p_\mathrm{T}^\text{jet}$$, $$>$$25 GeV. The measurements are compared to next-to-leading order perturbative quantum chromodynamics calculations, which reproduce the data within uncertainties.

A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, $$\Delta\phi_{12}$$ , 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 13 TeV and corresponding to an integrated luminosity of 35.9 fb$$^{-1}$$ 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 partonmore » 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 177$$^\circ < \Delta\phi_{12} <$$ 180$$^\circ$$. The 2- and 3-jet measurements are not simultaneously described by any of models.« less

Exclusive $$\rho^0$$(770) photoproduction is measured for the first time in ultraperipheral pPb collisions at $$\sqrt{s_\mathrm{NN}} =$$ 5.02 TeV with the CMS detector. The cross section $$\sigma (\gamma$$p $$\to$$ $$\rho^0$$(770)p) is 11.2 $$\pm$$ 1.4 (stat) $$\pm$$ 1.0 (syst) $$\mu$$b at $$\langle W_{\gamma\mathrm{p}}\rangle =$$ 92.6 GeV for photon-proton centre-of-mass energies $$W_{\gamma\mathrm{p}}$$ between 29 and 213 GeV. The differential cross section d$$\sigma/$$d$$|t|$ is measured in the interval 0.025$ < |t| < 1$ GeV$$^{2}$$ as a function of $$W_{\gamma\mathrm{p}}$$, where $$t$$ is the squared four-momentum transfer at the proton vertex. The results are compared with previous measurements and theoretical predictions. The measured cross sectionmore » $$\sigma (\gamma$$ p$$ \to \rho^0$$(770)p) has a power-law dependence on the photon-proton centre-of-mass, consistent with electron-proton collision measurements performed at HERA. The $$W_{\gamma\mathrm{p}}$$ dependence of the exponential slope of the differential cross section d$$\sigma/$$d$$|t|$ is also measured and is consistent with the previous measurements.« less

The performance of missing transverse momentum (p^→_T^miss) reconstruction algorithms for the CMS experiment is presented, using proton-proton collisions at a center-of-mass energy of 13 TeV, collected at the CERN LHC in 2016. The data sample corresponds to an integrated luminosity of 35.9 fb^-1. The results include measurements of the scale and resolution of p^→_T^miss, and detailed studies of events identified with anomalous p^→_T^miss. The performance is presented of a p^→_T^miss reconstruction algorithm that mitigates the effects of multiple proton-proton interactions, using the "pileup per particle identification" method. The performance is shown of an algorithm used to estimate the compatibility ofmore » the reconstructed p^→_T^miss with the hypothesis that it originates from resolution effects.« less

A search is presented for a heavy pseudoscalar boson $$\text {A}$$ decaying to a Z  boson and a Higgs boson with mass of 125 $$\,\text {GeV}$$ . 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 $$\,\text {fb}^{-1}$$ collected in 2016 by the CMS experiment at the LHC from proton–proton collisions at a center-of-mass energy of 13 $$\,\text {Te}\text {V}$$ . The data are foundmore » to be consistent with the background expectations. Exclusion limits are set in the context of two-Higgs-doublet models in the $$\text {A}$$ boson mass range between 225 and 1000 $$\,\text {GeV}$$ .« less

An embedding technique is presented to estimate standard model $$\tau\tau$$ backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed $$\mu\mu$$ events and replaced with simulated tau leptons with the same kinematic properties. In this way a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed.more » The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at $$\sqrt{s}=$$ 13 TeV corresponding to an integrated luminosity of 41.5 fb$$^{-1}$$.« less

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 TeV. The data correspond to an integrated luminosity of 35.9 fb$$^{-1}$$ 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 b-tagged jets, and the missing transverse momentum. No significant excess of events is observed with respect to the expectations from standard model processes. Limits aremore » 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 GeV and the production of top squarks with masses as large as 1230 GeV are excluded at 95% confidence level.« less

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 $$\sqrt{s} =$$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$$^{-1}$$. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quark-antiquark pair) and the following decay modes: H $$\to$$ $$\gamma\gamma$$, ZZ, WW, $$\tau\tau$$, bb, and $$\mu\mu$$.more » 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 $$\mu$$ $$=$$ 1.17 $$\pm$$ 0.10, assuming a Higgs boson mass of 125.09 GeV. Additional results are given for parametrizations with varying assumptions on the scaling behavior of the different production and decay modes, including generic ones based on ratios of cross sections and branching fractions or coupling modifiers. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.« less