A first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 inverse-femtobarns. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. A differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution is used to extract a top quark spin asymmetry of 0.26 +/- 0.03 (stat) +/- 0.10 (syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.
The normalized differential cross section as a function of unfolded $\cos\theta_{\mu}^{*}$ for top quark.
The normalized differential cross section as a function of unfolded $\cos\theta_{\mu}^{*}$ for top antiquark.
The normalized differential cross section as a function of unfolded $\cos\theta_{\mu}^{*}$ for top quark and antiquark.
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.
This paper presents distributions of topological observables in inclusive three- and four-jet events produced in pp collisions at a centre-of-mass energy of 7 TeV with a data sample collected by the CMS experiment corresponding to a luminosity of 5.1 inverse femtobarns. The distributions are corrected for detector effects, and compared with several event generators based on two- and multi-parton matrix elements at leading order. Among the considered calculations, MADGRAPH interfaced with PYTHIA6 displays the best overall agreement with data.
CORRECTED NORMALIZED DISTRIBUTION OF THREE-JET MASS IN THE INCLUSIVE THREE-JET SAMPLE. THE PROVIDED UNCERTAINTY CORRESPONDS TO SYSTEMATIC UNCERTAINTY.
CORRECTED NORMALIZED DISTRIBUTION OF SCALED ENERGY OF THE LEADING-JET IN THE INCLUSIVE THREE-JET SAMPLE. THE PROVIDED UNCERTAINTY CORRESPONDS TO SYSTEMATIC UNCERTAINTY.
CORRECTED NORMALIZED DISTRIBUTION OF SCALED ENERGY OF THE SECOND-LEADING-JET IN THE INCLUSIVE THREE-JET SAMPLE. THE PROVIDED UNCERTAINTY CORRESPONDS TO SYSTEMATIC UNCERTAINTY.
A measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at sqrt(s) = 7 TeV is presented. The data sample corresponds to an integrated luminosity of 5.0 inverse femtobarns collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25 GeV respectively, in the pseudorapidity range abs(eta) < 2.5, abs(eta) not in [1.44,1.57] and with an angular separation Delta R > 0.45, is 17.2 +/- 0.2 (stat.) +/- 1.9 (syst.) +/- 0.4 (lum.) pb. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.
Values of D(SIG)/DM(GAMMA GAMMA) for the data. The error given on each value is the total uncertainty.
Values of D(SIG)/DPT(GAMMA GAMMA) for the data. The error given on each value is the total uncertainty.
Values of D(SIG)/DDELTA(PHI(GAMMA GAMMA)) (pb/rad) for the data. The error given on each value is the total uncertainty.
The integrated and differential cross sections for the production of pairs of isolated photons is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 36 inverse picobarns is analysed. A next-to-leading-order perturbative QCD calculation is compared to the measurements. A discrepancy is observed for regions of the phase space where the two photons have an azimuthal angle difference, $\Delta(\phi)$, less than approximately 2.8.
Integrated diphoton cross sections.
Measured diphoton differential cross sections as a function of the diphoton mass for the two pseusdorapidity ranges.
Measured diphoton differential cross sections as a function of the diphoton transverse momentum for the two pseusdorapidity ranges.
First measurements of charge-independent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) are presented for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and $|\eta| \leq 1.3$ from Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV. Strong charge-independent angular correlations are observed associated with jet-like structures and elliptic flow. The width of the jet-like peak on $\eta_1 - \eta_2$ increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of semi-hard scattered partons to a longitudinally-expanding medium. New methods of jet analysis introduced here provide evidence for nonperturbative QCD medium effects in heavy ion collisions.
Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for most-central collisions.
Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for mid-central collisions.
Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for mid-peripheral collisions.
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