Searches for resonances decaying into pairs of jets are performed using proton-proton collision data collected at √ s = 13 TeV corresponding to an integrated luminosity of up to 36 fb −1 . A low-mass search, for resonances with masses between 0.6 and 1.6 TeV, is performed based on events with dijets reconstructed at the trigger level from calorimeter information. A high-mass search, for resonances with masses above 1.6 TeV, is performed using dijets reconstructed offline with a particle-flow algorithm. The dijet mass spectrum is well described by a smooth parameterization and no evidence for the production of new particles is observed. Upper limits at 95% confidence level are reported on the production cross section for narrow resonances with masses above 0.6 TeV. In the context of specific models, the limits exclude string resonances with masses below 7.7 TeV, scalar diquarks below 7.2 TeV, axigluons and colorons below 6.1 TeV, excited quarks below 6.0 TeV, color-octet scalars below 3.4 TeV, W bosons below 3.3 TeV, Z bosons below 2.7 TeV, Randall-Sundrum gravitons below 1.8 TeV and in the range 1.9 to 2.5 TeV, and dark matter mediators below 2.6 TeV. The limits on both vector and axial-vector mediators, in a simplified model of interactions between quarks and dark matter particles, are presented as functions of dark matter particle mass and coupling to quarks. Searches are also presented for broad resonances, including for the first time spin-1 resonances with intrinsic widths as large as 30% of the resonance mass. The broad resonance search improves and extends the exclusions of a dark matter mediator to larger values of its mass and coupling to quarks. IntroductionModels of physics that extend the standard model (SM) often require new particles that couple to quarks (q) and/or gluons (g) and decay to dijets. The natural width of resonances in the dijet mass (m jj ) spectrum increases with the coupling, and may vary from narrow to broad compared to the experimental resolution. For example, in a model in which dark matter (DM) particles couple to quarks through a DM mediator, the mediator can decay to either a pair of DM particles or a pair of jets and therefore can be observed as a dijet resonance [1, 2] that is either narrow or broad, depending on the strength of the coupling. When the resonance is broad, its observed line-shape depends significantly on the resonance spin. Here we report a search for narrow dijet resonances and a complementary search for broad resonances that considers multiple values of the resonance spin and widths as large as 30% of the resonance mass. Both approaches are sensitive to resonances with intrinsic widths that are small compared to the experimental resolution, but the broad resonance search is also sensitive to resonances with larger intrinsic widths. We explore the implications for multiple specific models of dijet resonances and for a range of quark coupling strength for a DM mediator.We present model independent results for s-channel dijet resonances and apply the results to...

A search is presented for new physics in events with two low-momentum, oppositely charged leptons (electrons or muons) and missing transverse momentum in protonproton collisions at a centre-of-mass energy of 13 TeV. The data collected using the CMS detector at the LHC correspond to an integrated luminosity of 35.9 fb −1 . The observed event yields are consistent with the expectations from the standard model. The results are interpreted in terms of pair production of charginos and neutralinos ( χ ± 1 and χ 0 2 ) with nearly degenerate masses, as expected in natural supersymmetry models with light higgsinos, as well as in terms of the pair production of top squarks ( t), when the lightest neutralino and the top squark have similar masses. At 95% confidence level, wino-like χ ± 1 / χ 0 2 masses are excluded up to 230 GeV for a mass difference of 20 GeV relative to the lightest neutralino. In the higgsino-like model, masses are excluded up to 168 GeV for the same mass difference. For t pair production, top squark masses up to 450 GeV are excluded for a mass difference of 40 GeV relative to the lightest neutralino. Data and simulated samplesThe data used in this search correspond to an integrated luminosity of 35.9 fb −1 of protonproton (pp) collisions at a centre-of-mass energy of 13 TeV, recorded in 2016 using the CMS detector. The data are selected using two triggers: an inclusive p miss T trigger, which is used for signal regions (SRs) with an offline p miss T cut > 200 GeV and an additional trigger which requires two muons to lower the offline p miss T cut to 125 GeV. Both the muon p T and the muon pair p T have a trigger online cut of p T > 3 GeV. The inclusive p miss T triggers correspond to an integrated luminosity of 35.9 fb −1 , whereas the events recorded with the dimuon+p miss T trigger correspond to 33.2 fb −1 .Simulated signal and major background processes, such as tt, W+jets, and Z+jets are generated with the MADGRAPH5 aMC@NLO 2.2.2 [32, 33] event generator at leading order (LO) precision in perturbative QCD using the MLM merging scheme [34]. Additional partons are modelled A The CMS Collaboration

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 19.4 fb −1 of proton-proton collisions at √ s = 8 TeV collected with the CMS detector at the CERN LHC in 2012. The analysis focuses on searches for a kinematic edge in the invariant mass distribution of the oppositesign same-flavor lepton pair and for final states with an on-shell Z boson. The observations are consistent with expectations from standard model processes and are interpreted in terms of upper limits on the production of supersymmetric particles. The CMS collaboration 23 IntroductionThis paper presents a search for physics beyond the standard model (SM) in events containing a pair of opposite-sign same-flavor (SF) electrons or muons, jets, and an imbalance in transverse momentum. The analysis is based on a sample of proton-proton (pp) collisions collected at a center-of-mass energy of 8 TeV with the CMS detector [1] at the CERN LHC in 2012 and corresponds to an integrated luminosity of 19.4 fb −1 .The invariant mass distribution of the two-lepton system can exhibit an excess that increases with the dilepton mass, followed by a sharp decrease and thus an "edge", if the two leptons originate from the decay of an on-shell heavy neutral particle. This kind of signature is fairly generic for models of physics beyond the SM (BSM), assumes an isotropic decay, and is purely kinematic in origin. In models of supersymmetry (SUSY) [2], an edge with a triangular shape is expected in the cascade process χ 0 2 → → χ 0 1 + − [3], where χ 0 2 and χ 0 1 are respectively the next-to-lightest and lightest neutralino, with a selectron or smuon, the SUSY partners of an electron or muon. Alternatively, the χ 0 2 can undergo a three-body decay to χ 0 1 + − through a virtual Z * boson, also yielding an edge in the dilepton -1 - JHEP04(2015)124mass spectrum but with a more rounded shape. Another possibility is the decay of a χ 0 2 to an on-shell Z boson, χ 0 2 → χ 0 1 Z. This latter process does not produce an edge but rather a dilepton mass peak near 91 GeV. These processes arise as a consequence of the gaugecoupling structure of SUSY and are a characteristic feature of SUSY decay chains. Their relative importance depends on the SUSY mass hierarchy and is thus model dependent.This search is therefore motivated by the possible existence of the fairly generic signal shape of an edge, or of a peak at the Z boson mass, that would be visible in the invariant mass distribution of the two leptons. The position of the edge would give an indication of the unknown BSM mass hierarchy. The dilepton invariant mass provides a search variable that is unaffected by uncertainties in the jet energy scale and resolution, and the search for an edge is therefore complementary to searches based solely on hadronic quantities.The CMS Collaboration previously presented two searches for BSM physics based on events with an opp...

A search for physics beyond the standard model is performed using a sample of highmass diphoton events produced in proton-proton collisions at √ s = 13 TeV. The data sample was collected in 2016 with the CMS detector at the LHC and corresponds to an integrated luminosity of 35.9 fb −1 . The search is performed for both resonant and nonresonant new physics signatures. At 95% confidence level, lower limits on the mass of the first Kaluza-Klein excitation of the graviton in the Randall-Sundrum warped extra-dimensional model are determined to be in the range of 2.3 to 4.6 TeV, for values of the associated coupling parameter between 0.01 and 0.2. Lower limits on the production of scalar resonances and model-independent cross section upper limits are also provided. For the large extra-dimensional model of Arkani-Hamed, Dimopoulos, and Dvali, lower limits are set on the string mass scale M S ranging from 5.6 to 9.7 TeV, depending on the model parameters. The first exclusion limits are set in the two-dimensional parameter space of a continuum clockwork model. Published in Physical Review D asThe CMS detector is a multi-purpose collider detector at the LHC. The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter (HCAL), each composed of a barrel and two endcap sections. Forward calorimeters extend the pseudorapidity (η) coverage provided by the barrel and endcap detectors. Muons are detected

A search is presented for single production of a vector-like quark (T) decaying to a Z boson and a top quark, with the Z boson decaying leptonically and the top quark decaying hadronically. The search uses data collected by the CMS experiment in protonproton collisions at a center-of-mass energy of 13 TeV in 2016, corresponding to an integrated luminosity of 35.9 fb −1 . The presence of forward jets is a particular characteristic of single production of vector-like quarks that is used in the analysis. For the first time, different T quark width hypotheses are studied, from negligibly small to 30% of the new particle mass. At the 95% confidence level, the product of cross section and branching fraction is excluded above values in the range 0.26-0.04 pb for T quark masses in the range 0.7-1.7 TeV, assuming a negligible width. A similar sensitivity is observed for widths of up to 30% of the T quark mass. The production of a heavy Z boson decaying to Tt, with T → tZ, is also searched for, and limits on the product of cross section and branching fractions for this process are set between 0.13 and 0.06 pb for Z boson masses in the range from 1.5 to 2.5 TeV.