[Show abstract][Hide abstract] ABSTRACT: Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top quark (the top squark) and the Higgs boson (Higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 fb-1 of proton-proton collision data at s=8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the top squark mass below 360 to 410 GeV, depending on the Higgsino mass.
[Show abstract][Hide abstract] ABSTRACT: We present a measurement of the W boson production charge asymmetry in pp¯→W+X→eν+X events at a center of mass energy of 1.96 TeV, using 9.7 fb-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The neutrino longitudinal momentum is determined by using a neutrino weighting method, and the asymmetry is measured as a function of the W boson rapidity. The measurement extends over wider electron pseudorapidity region than previous results and is the most precise to date, allowing for precise determination of proton parton distribution functions in global fits.
[Show abstract][Hide abstract] ABSTRACT: We present a measurement of the direct CP-violating charge asymmetry in Ds+→ϕπ± decays where the ϕ meson decays to K+K-, using the full Run II data set with an integrated luminosity of 10.4 fb-1 of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. The normalized difference ACP in the yield of Ds+ and Ds- mesons in these decays is measured by fitting the difference between their reconstructed invariant mass distributions. This results in an asymmetry of ACP=[-0.38±0.27]%, which is the most precise measurement of this quantity to date. The result is consistent with the standard model prediction of zero CP asymmetry in this decay.
[Show abstract][Hide abstract] ABSTRACT: Results are presented from a search for the production of a heavy gauge boson
W' decaying into a top and a bottom quark, using a data set collected by the
CMS experiment at sqrt(s)=8 TeV and corresponding to an integrated luminosity
of 19.5 inverse femtobarns. Various models of W'-boson production are studied
by allowing for an arbitrary combination of left- and right-handed couplings.
The analysis is based on the detection of events with a lepton (e, mu), jets,
and missing transverse energy in the final state. No evidence for W'-boson
production is found and 95% confidence level upper limits on the production
cross section times branching fraction are obtained. For W' bosons with purely
right-handed couplings, and for those with left-handed couplings assuming no
interference effects, the observed 95% confidence level limit is M(W')>2.05
TeV. For W' bosons with purely left-handed couplings, including interference
effects, the observed 95% confidence level limit is M(W')>1.84 TeV. The results
presented in this paper are the most stringent limits published to date.
[Show abstract][Hide abstract] ABSTRACT: A measurement of total and fiducial inclusive W and Z boson production cross
sections in pp collisions at sqrt(s)=8 TeV is presented. Electron and muon
final states are analyzed in a data sample collected with the CMS detector
corresponding to an integrated luminosity of 18.2 +/- 0.5 inverse picobarns.
The measured total inclusive cross sections times branching fractions are
sigma(pp to W X) B(W to l nu ) = 12.21 +/- 0.03 (stat.) +/- 0.24 (syst.) +/-
0.32 (lum.) nb and sigma(pp to Z X) B(Z to l+ l-) = 1.15 +/- 0.01 (stat.) +/-
0.02 (syst.) +/- 0.03 (lum.) nb for the dilepton mass in the range of 60 to 120
GeV. The measured values agree with next-to-next-to-leading-order QCD cross
section calculations. Ratios of cross sections are reported with a precision of
2%. This is the first measurement of inclusive W and Z boson production in
proton-proton collisions at sqrt(s)=8 TeV.
[Show abstract][Hide abstract] ABSTRACT: We present the first measurements of the ratios of cross sections σ(pp¯→Z+c jet)/σ(pp¯→Z+jet) and σ(pp¯→Z+c jet)/σ(pp¯→Z+b jet) for the associated production of a Z boson with at least one charm or bottom quark jet. Jets have transverse momentum pTjet >20 GeV and pseudorapidity | ηjet |<2.5. These cross section ratios are measured differentially as a function of jet and Z boson transverse momenta, based on 9.7 fb-1 of pp¯ collisions collected with the D0 detector at the Fermilab Tevatron Collider at s=1.96 TeV. The measurements show significant deviations from perturbative QCD calculations and predictions from various event generators.
[Show abstract][Hide abstract] ABSTRACT: The first observation of the associated production of a single top quark and
a W boson is presented. The analysis is based on a data set corresponding to an
integrated luminosity of 12.2 inverse femtobarns of proton-proton collisions at
sqrt(s) = 8 TeV recorded by the CMS experiment at the LHC. Events with two
leptons and a jet originating from a b quark are selected. A multivariate
analysis based on kinematic and topological properties is used to separate the
signal from the dominant t t-bar background. An excess consistent with the
signal hypothesis is observed, with a significance which corresponds to 6.1
standard deviations above a background-only hypothesis. The measured production
cross section is 23.4 +/- 5.4 pb, in agreement with the standard model