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A search is performed for long-lived massive neutral particles decaying to quark-antiquark pairs. The experimental signature is a distinctive topology of a pair of jets, originating at a secondary vertex. Events were collected with the CMS detector at the CERN LHC in proton-proton collisions at a center-of-mass energy of 8 TeV. The data analyzed correspond to an integrated luminosity of 18.5 fb −1 . No significant excess is observed above standard model expectations. Upper limits at 95% confidence level are set on the production cross section of a heavy neutral scalar particle, H, in the mass range of 200 to 1000 GeV, decaying promptly into a pair of long-lived neutral X particles in the mass range of 50 to 350 GeV, each in turn decaying into a quark-antiquark pair. For X with mean proper decay lengths of 0.4 to 200 cm, the upper limits are typically 0.5-200 fb. The results are also interpreted in the context of an R-parity-violating supersymmetric model with long-lived neutralinos decaying into a quark-antiquark pair and a muon. For pair production of squarks that promptly decay to neutralinos with mean proper decay lengths of 2-40 cm, the upper limits on the cross section are typically 0.5-3 fb. The above limits are the most stringent on these channels to date.

A study of vector boson scattering in pp collisions at a center-of-mass energy of 8 TeV is presented. The data sample corresponds to an integrated luminosity of 19.4 fb −1 collected with the CMS detector. Candidate events are selected with exactly two leptons of the same charge, two jets with large rapidity separation and high dijet mass, and moderate missing transverse energy. The signal region is expected to be dominated by electroweak same-sign W-boson pair production. The observation agrees with the standard model prediction. The observed significance is 2.0 standard deviations, where a significance of 3.1 standard deviations is expected based on the standard model. Cross section measurements for W AE W AE and WZ processes in the fiducial region are reported. Bounds on the structure of quartic vector-boson interactions are given in the framework of dimension-eight effective field theory operators, as well as limits on the production of doubly charged Higgs bosons.

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

Inclusive jet spectra from pp and PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV, collected with the CMS detector at the LHC, are presented. Jets are reconstructed with three different distance parameters (R = 0.2, 0.3 and 0.4) for transverse momentum (p T ) greater than 70 GeV/c and pseudorapidity |η| < 2. Next-toleading-order quantum chromodynamic calculations with non-perturbative corrections are found to over-predict jet production cross sections in pp for small distance parameters. The jet nuclear modification factors for PbPb compared to pp collisions, show a steady decrease from peripheral to central events, along with a weak dependence on the jet p T . They are found to be independent of the distance parameter in the measured kinematic range.