Observation of a peaking structure in the J/ψφmass spectrum from B±→J/ψφK±decays

A peaking structure in the J/ψφmass spectrum near threshold is observed in B±→J/ψφK±decays, produced in pp collisions at √s=7TeVcollected with the CMS detector at the LHC. The data sample, selected on the basis of the dimuon decay mode of the J/ψ, corresponds to an integrated luminosity of 5.2fb−1. Fitting the structure to an S-wave relativistic Breit–Wigner lineshape above a three-body phase-space nonresonant component gives a signal statistical significance exceeding five standard deviations. The fitted mass and width values are m =4148.0 ±2.4 (stat.) ±6.3 (syst.) MeVand Γ=28+15−11(stat.) ±19 (syst.) MeV, respectively. Evidence for an additional peaking structure at higher J/ψφmass is also reported

Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs

Constraints are presented on the total width of the recently discovered Higgs boson, ΓH, using its relative on-shell and off-shell production and decay rates to a pair of Z bosons, where one Z boson decays to an electron or muon pair, and the other to an electron, muon, or neutrino pair. The analysis is based on the data collected by the CMS experiment at the LHC in 2011 and 2012, corresponding to integrated luminosities of 5.1fb−1at a center-of-mass energy √s=7TeVand 19.7fb−1at √s=8TeV. A simultaneous maximum likelihood fit to the measured kinematic distributions near the resonance peak and above the Z-boson pair production threshold leads to an upper limit on the Higgs boson width of ΓH\u3c22MeVat a 95% confidence level, which is 5.4 times the expected value in the standard model at the measured mass of mH=125.6GeV

Search for pair-produced resonances decaying to jet pairs in proton–proton collisions at √s=8TeV

Results are reported of a general search for pair production of heavy resonances decaying to pairs of hadronic jets in events with at least four jets. The study is based on up to 19.4fb−1of integrated luminosity from proton–proton collisions at a center-of-mass energy of 8TeV, recorded with the CMS detector at the LHC. Limits are determined on the production of scalar top quarks (top squarks) in the framework of R-parity violating supersymmetry and on the production of color-octet vector bosons (colorons). First limits at the LHC are placed on top squark production for two scenarios. The first assumes decay to a bottom quark and a light-flavor quark and is excluded for masses between 200 and 385GeV, and the second assumes decay to a pair of light-flavor quarks and is excluded for masses between 200 and 350GeV at 95% confidence level. Previous limits on colorons decaying to light-flavor quarks are extended to exclude masses from 200 to 835GeV

Long-range two-particle correlations of strange hadrons with charged particles in pPb and PbPb collisions at LHC energies

Measurements of two-particle angular correlations between an identified strange hadron (K0Sor Λ/Λ) and a charged particle, emitted in pPb collisions, are presented over a wide range in pseudorapidity and full azimuth. The data, corresponding to an integrated luminosity of approximately 35nb−1, were collected at a nucleon–nucleon center-of-mass energy (√sNN) of 5.02TeV with the CMS detector at the LHC. The results are compared to semi-peripheral PbPb collision data at √sNN=2.76TeV, covering similar charged-particle multiplicities in the events. The observed azimuthal correlations at large relative pseudorapidity are used to extract the second-order (v2) and third-order (v3) anisotropy harmonics of K0Sand Λ/Λparticles. These quantities are studied as a function of the charged-particle multiplicity in the event and the transverse momentum of the particles. For high-multiplicity pPb events, aclear particle species dependence of v2and v3is observed. For pT\u3c2GeV, the v2and v3values of K0Sparticles are larger than those of Λ/Λparticles at the same pT. This splitting effect between two particle species is found to be stronger in pPbthan in PbPbcollisions in the same multiplicity range. When divided by the number of constituent quarks and compared at the same transverse kinetic energy per quark, both v2and v3for K0Sparticles are observed to be consistent with those for Λ/Λparticles at the 10% level in pPbcollisions. This consistency extends over a wide range of particle transverse kinetic energy and event multiplicities

Search for new resonances decaying via WZ to leptons in proton–proton collisions at √s=8 TeV

A search is performed in proton–proton collisions at √s=8TeVfor exotic particles decaying via WZ to fully leptonic final states with electrons, muons, and neutrinos. The data set corresponds to an integrated luminosity of 19.5fb−1. No significant excess is observed above the expected standard model background. Upper bounds at 95% confidence level are set on the production cross section of a Wboson as predicted by an extended gauge model, and on the WW Zcoupling. The expected and observed mass limits for a Wboson, as predicted by this model, are 1.55 and 1.47TeV, respectively. Stringent limits are also set in the context of low-scale technicolor models under a range of assumptions for the model parameters

Search for stealth supersymmetry in events with jets, either photons or leptons, and low missing transverse momentum in pp collisions at 8TeV

The results of a search for new physics in final states with jets, either photons or leptons, and low missing transverse momentum are reported. The study is based on a sample of proton–proton collisions collected at a center-of-mass energy √s=8TeVwith the CMS detector in 2012. The integrated luminosity of the sample is 19.7fb−1. Many models of new physics predict the production of events with jets, electroweak gauge bosons, and little or no missing transverse momentum. Examples include stealth models of supersymmetry (SUSY), which predict a hidden sector at the electroweak energy scale in which SUSY is approximately conserved. The data are used to search for stealth SUSY signatures in final states with either two photons or an oppositely charged electron and muon. No excess is observed with respect to the standard model expectation, and the results are used to set limits on squark pair production in the stealth SUSY framework

Search for narrow high-mass resonances in proton–proton collisions at √s=8TeVdecaying to a Z and a Higgs boson

A search for a narrow, high-mass resonance decaying into Z and Higgs (H) bosons is presented. The final state studied consists of a merged jet pair and a τpair resulting from the decays of Z and Hbosons, respectively. The analysis is based on a data sample of proton–proton collisions at a center-of-mass energy of 8TeV, collected with the CMS experiment in 2012, and corresponding to an integrated luminosity of 19.7fb−1. In the resonance mass range of interest, which extends from 0.8 to 2.5TeV, the Z and H bosons are produced with large momenta, which implies that the final products of the two quarks or the two τleptons must be detected within a small angular interval. From a combination of all possible decay modes of the τleptons, production cross sections in a range between 0.9 and 27.8fb are excluded at 95% confidence level, depending on the resonance mass

Search for a pseudoscalar boson decaying into a Z boson and the 125 GeV Higgs boson in View the MathML sourceℓ+ℓ−bb‾ final states

Results are reported on a search for decays of a pseudoscalar A boson into a Z boson and a light scalar h boson, where the Z boson decays into a pair of oppositely-charged electrons or muons, and the h boson decays into bb. The search is based on data from proton–proton collisions at a center-of-mass energy √s=8TeVcollected with the CMS detector, corresponding to an integrated luminosity of 19.7fb−1. The h boson is assumed to be the standard model-like Higgs boson with a mass of 125GeV. With no evidence for signal, upper limits are obtained on the product of the production cross section and the branching fraction of the A boson in the Zh channel. Results are also interpreted in the context of two Higgs doublet models

Search for a standard model-like Higgs boson in the μ+μ−and e+e−decay channels at the LHC

A search is presented for a standard model-like Higgs boson decaying to the μ+μ−or e+e−final states based on proton–proton collisions recorded by the CMS experiment at the CERN LHC. The data correspond to integrated luminosities of 5.0fb−1at a centre-of-mass energy of 7TeV and 19.7fb−1at 8TeV for the μ+μ−search, and of 19.7fb−1at 8TeV for the e+e−search. Upper limits on the production cross section times branching fraction at the 95% confidence level are reported for Higgs boson masses in the range from 120 to 150GeV. For a Higgs boson with a mass of 125GeV decaying to μ+μ−, the observed (expected) upper limit on the production rate is found to be 7.4 (6.5+2.8−1.9) times the standard model value. This corresponds to an upper limit on the branching fraction of 0.0016. Similarly, for e+e−, an upper limit of 0.0019 is placed on the branching fraction, which is ≈3.7 ×105times the standard model value. These results, together with recent evidence of the 125GeV boson coupling to τ-leptons with a larger branching fraction consistent with the standard model, confirm that the leptonic couplings of the new boson are not flavour-universal

Measurement of the cross section ratio σttbb/σttjjin ppcollisions at√s=8TeV

The first measurement of the cross section ratio σttbb/σttjjis presented using a data sample corresponding to an integrated luminosity of 19.6fb−1collected in pp collisions at √s=8TeVwith the CMS detector at the LHC. Events with two leptons (eor μ) and four reconstructed jets, including two identified as b quark jets, in the final state are selected. The ratio is determined for a minimum jet transverse momentum pTof both 20 and 40GeV/c. The measured ratio is 0.022 ±0.003 (stat) ±0.005 (syst)for pT\u3e20GeV/c. The absolute cross sections σttbband σttjjare also measured. The measured ratio for pT\u3e40GeV/cis compatible with a theoretical quantum chromodynamics calculation at next-to-leading order