The polarizations of the Y(1S), Y(2S), and Y(3S) mesons are measured as a function of the charged particle multiplicity in proton-proton collisions at sqrt(s) = 7 TeV. The measurements are performed with a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The results are extracted from the dimuon decay angular distributions, in two ranges of Y(nS) transverse momentum (10-15 and 15-35 GeV), and in the rapidity interval abs(y) < 1.2. The results do not show significant changes from low- to high-multiplicity pp collisions, although large uncertainties preclude definite statements in the Y(2S) and Y(3S) cases.
$\Upsilon$(nS) polarization parameter $\lambda_\vartheta$ in the HX frame for $p_T$ of 10 to 15 GeV. The global uncertainties, independent of state and $N_{ch}$ bin, are also indicated.
$\Upsilon$(nS) polarization parameter $\lambda_\varphi$ in the HX frame for $p_T$ of 10 to 15 GeV. The global uncertainties, independent of state and $N_{ch}$ bin, are also indicated.
$\Upsilon$(nS) polarization parameter $\lambda_{\vartheta\varphi}$ in the HX frame for $p_T$ of 10 to 15 GeV. The global uncertainties, independent of state and $N_{ch}$ bin, are also indicated.
The angular distributions and the differential branching fraction of the decay B0 to K*0(892) mu mu are studied using data corresponding to an integrated luminosity of 20.5 inverse femtobarns collected with the CMS detector at the LHC in pp collisions at sqrt(s) = 8 TeV. From 1430 signal decays, the forward-backward asymmetry of the muons, the K*0(892) longitudinal polarization fraction, and the differential branching fraction are determined as a function of the dimuon invariant mass squared. The measurements are among the most precise to date and are in good agreement with standard model predictions.
The measured values of signal yield, FL, AFB, and differential branching fraction in bins of the dimuon invariant mass squared. The (FL,AFB) correlation factors are also shown.
The measured values of FL, AFB, and differential branching fraction in bins of the dimuon invariant mass squared, combining the 7 TeV and 8 TeV results.
Measurements of the five most significant angular coefficients, A[0] through A[4], for Z bosons produced in pp collisions at $\sqrt{s}$ = 8 TeV and decaying to $\mu^+ \mu^-$ are presented as a function of the transverse momentum and rapidity of Z boson. The integrated luminosity of the dataset collected with the CMS detector at the LHC corresponds to 19.7 inverse femtobarns. These measurements provide comprehensive information about Z boson production mechanisms, and are compared to QCD predictions at leading order, next-to-leading order, and next-to-next-to-leading order in perturbation theory.
The five angular coefficients A0 to A4 and A0-A2 in bins of qT for |y| < 1.
The five angular coefficients A0 to A4 and A0-A2 in bins of qT for 1 < |y| < 2.1.
The transverse polarization of $\Lambda$ and $\bar\Lambda$ hyperons produced in proton-proton collisions at a center-of-mass energy of 7 TeV is measured. The analysis uses 760 $\mu$b$^{-1}$ of minimum bias data collected by the ATLAS detector at the LHC in the year 2010. The measured transverse polarization averaged over Feynman $x_{\rm F}$ from $5\times 10^{-5}$ to 0.01 and transverse momentum $p_{\rm T}$ from 0.8 to 15 GeV is $-0.010 \pm 0.005({\rm stat}) \pm 0.004({\rm syst})$ for $\Lambda$ and $0.002 \pm 0.006({\rm stat}) \pm 0.004({\rm syst})$ for $\bar\Lambda$. It is also measured as a function of $x_{\rm F}$ and $p_{\rm T}$, but no significant dependence on these variables is observed. Prior to this measurement, the polarization was measured at fixed-target experiments with center-of-mass energies up to about 40 GeV. The ATLAS results are compatible with the extrapolation of a fit from previous measurements to the $x_{\rm F}$ range covered by this mesurement.
Transverse polarization POL of LAMBDA and LAMBDABAR hyperons averaged over PT and XF.
Transverse polarization POL of LAMBDA and LAMBDABAR hyperons as a function of XF.
Transverse polarization POL of LAMBDA and LAMBDABAR hyperons as a function of PT.
The polarizations of prompt J/psi and psi(2S) mesons are measured in proton-proton collisions at sqrt(s) = 7 TeV, using a dimuon data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The prompt J/psi and psi(2S) polarization parameters lambda[theta], lambda[phi], and lambda[theta,phi], as well as the frame-invariant quantity lambda(tilde), are measured from the dimuon decay angular distributions in three different polarization frames. The J/psi results are obtained in the transverse momentum range 14 < pt < 70 GeV, in the rapidity intervals abs(y) < 0.6 and 0.6 < abs(y) < 1.2. The corresponding psi(2S) results cover 14 < pt < 50 GeV and include a third rapidity bin, 1.2 < abs(y) < 1.5. No evidence of large transverse or longitudinal polarizations is seen in these kinematic regions, which extend much beyond those previously explored.
Lambda-Theta in the CS frame for the J/psi as a function of pT for 0.0 < |y| < 0.6.
Lambda-Theta in the CS frame for the J/psi as a function of pT for 0.6 < |y| < 1.2.
Lambda-Phi in the CS frame for the J/psi as a function of pT for 0.0 < |y| < 0.6.
The polarizations of the Y(1S), Y(2S), and Y(3S) mesons are measured in proton-proton collisions at sqrt(s) = 7 TeV, using a data sample of Y(nS) to oppositely charged muon pair decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters lambda[theta], lambda[phi], and lambda[theta,phi], as well as the frame-invariant quantity lambda-tilde, are presented as a function of the Y(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges abs(y) < 0.6 and 0.6 < abs(y) < 1.2. No evidence of large transverse or longitudinal polarizations has been seen in the explored kinematic region.
Distribution of Lambda-Theta in the CS frame for Y(1S) production in the |y| range 0.0-0.6.
Distribution of Lambda-Theta in the CS frame for Y(1S) production in the |y| range 0.6-1.2.
Distribution of Lambda-Phi in the CS frame for Y(1S) production in the |y| range 0.0-0.6.
Results onK0 and Λ production ine+e− annihilation at c.m. energies of 14, 22 and 34 GeV are presented. The shape of theK0 and Λ differential cross sections are very similar to each other and to those of π±,K± and\(p(\bar p)\). Scaling violations are observed forK0 production. We obtain a value for the probability to produce strange quark-antiquark pairs relative to that to produce up or down quark-antiquark pairs of 0.35±0.02±0.05. The value ofRh=σ(e+e-→hX)/σµµ is shown to rise steadily with c.m. energy for all particle species. At 34 GeV we find 1.48±0.05K0 and 0.31±0.03 Λ per event. We have searched for possible Λ polarization. The production ofK0's and Λ's in jets is examined as a function ofpT2 and rapidity and compared to that of all charged particles; the yields in two and three jets are also investigated. Results are presented from events with two baryons\((\Lambda ,\bar \Lambda ,por\bar p)\) observed.
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