A search for Z bosons in the mu^+mu^- decay channel has been performed in PbPb collisions at a nucleon-nucleon centre of mass energy = 2.76 TeV with the CMS detector at the LHC, in a 7.2 inverse microbarn data sample. The number of opposite-sign muon pairs observed in the 60--120 GeV/c2 invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of (33.8 ± 5.5 (stat) ± 4.4 (syst)) 10^{-8}, in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.
The dimuon yield from Z0 decays per unit rapidity and per unit minumum bias event in the range |yrap| < 2.0.
The dimuon yield from Z0 decays per unit rapidity and per unit minumum bias event as a function of rapidity, and the nuclear modification factor RAA derived by using a POWHEG proton-proton reference.
The dimuon yield from Z0 decays per unit rapidity and per unit minumum bias event as a function of transverse momentum, and the nuclear modificationfactor RAA derived by using a POWHEG proton-proton reference.
The spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at centre-of-mass energies of 0.9 and 7 TeV. The K^0_s, Lambda, and Xi^- particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum. The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The transverse momentum distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.
The rapidity production spectra per NSD event spectra for KS mesons at 0.9 and 7 TeV.
The transverse momentum production spectra per NSD event spectra for KS mesons at 0.9 and 7 TeV.
The rapidity production spectra per NSD event spectra for LAMBDA mesons at 0.9 and 7 TeV.
A measurement of the inclusive bottom jet cross section is presented for events containing a $Z$ boson in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using the Collider Detector at Fermilab. $Z$ bosons are identified in their electron and muon decay modes, and $b$ jets with $E_T>20$ GeV and $|\eta|<1.5$ are identified by reconstructing a secondary decay vertex. The measurement is based on an integrated luminosity of about 330 ${\rm pb}^{-1}$. A cross section times branching ratio of $\sigma (Z+b {\rm jets}) \times {\cal B}(Z \to \ell^+ \ell^-)= 0.93 \pm 0.36$ pb is found, where ${\cal B}(Z\to \ell^+ \ell^-)$ is the branching ratio of the $Z$ boson or $\gamma^*$ into a single flavor dilepton pair ($e$ or $\mu$) in the mass range between 66 and 116 GeV$/c^2$. The ratio of $b$ jets to the total number of jets of any flavor in the $Z$ sample, within the same kinematic range as the $b$ jets, is $2.36 \pm 0.92%$. Here, the uncertainties are the quadratic sum of statistical and systematic uncertainties. Predictions made with NLO QCD agree, within experimental and theoretical uncertainties, with these measurements.
B-jet cross section for the di-letpon mass from 66 to 116 GeV.
Ratio of the b-jet cross section to the inclusive Z0 cross section.
Ratio of the b-jet cross section to the generic jet cross section.
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