The prompt production of the charmonium $\chi_{c1}$ and $\chi_{c2}$ mesons has been studied in proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=7$ TeV. The $\chi_c$ mesons are identified through their decays $\chi_c\to J/\psi\,\gamma$ with $J/\psi \to \mu^+ \mu^-$ using 36 $\mathrm{pb^{-1}}$ of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for the two $\chi_c$ spin states, $\sigma(\chi_{c2})/\sigma(\chi_{c1})$, has been determined as a function of the $J/\psi$ transverse momentum, $p_{\mathrm{T}}^{J/\psi}$, in the range from 2 to 15 GeV/$c$. The results are in agreement with the next-to-leading order non-relativistic QCD model at high $p_{\mathrm{T}}^{J/\psi}$ and lie consistently above the pure leading-order colour singlet prediction.
Ratio of cross sections for $\chi_{c2}$ to $\chi_{c1}$ production in bins of $J/\psi$ transverse momentum over the $J/\psi$ rapidity range 2.0 to 4.5. The second systematic error represents the uncertainty in the $\chi_c \to J/\psi \gamma$ branching fractions with the maximum uncertainties from the unknown $\chi_c$ polarizations shown separately.
A measurement of the cross section for the inclusive production of isolated prompt photons in pp collisions at a centre-of-mass energy sqrt(s) = 7TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<|eta|<1.81 in the transverse energy range 15 < E_T <100 GeV. The results are based on an integrated luminosity of 880 nb-1, collected with the ATLAS detector at the Large Hadron Collider. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data based on the observed distribution of the transverse isolation energy in a narrow cone around the photon candidate. The results are compared to predictions from next-to-leading order perturbative QCD calculations.
The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range < 0.6.
The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range 0.6 to 1.37.
The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range 1.52 to 1.81.
The production of K_short mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements of the beam currents, sizes and positions, and is found to be 6.8 +/- 1.0 microbarn^-1. The differential prompt K_short production cross-section is measured as a function of the K_short transverse momentum and rapidity in the region 0 < pT < 1.6 GeV/c and 2.5 < y < 4.0. The data are found to be in reasonable agreement with previous measurements and generator expectations.
The measured cross sections as a function of transverse momentum for prompt K0S production in three rapidity regions. The first systematic error is the uncorrelated systemtatic error and the second is the systematic error correlated across bins.
The double differential prompt K0S production cross section in three rapidity bands.
The double differential prompt K0S production cross section in the rapidity band 2.5 to 4.0.
We report final results on prompt electron production in hadronic events from e+e− annihilations at √s =29 GeV, obtained with the DELCO detector at the SLAC storage ring PEP. We find the semielectronic branching ratios of charm and bottom quarks to be B(c→se+νe)=(11.6−0.9 +1.1)% and B(b→ce−ν¯e)=(14.9−1.9 +2.2)% respectively. These results, from the complete data set, are consistent with an earlier analysis of partial data and indicate hard fragmentation functions for both c and b quarks, with mean values 〈zc〉=0.59±0.04 and 〈zb〉=0.72±0.05. The errors indicated here are a combination of statistical and systematic uncertainties.
Axis error includes +- 0.0/0.0 contribution (NOT GIVEN).
Axis error includes +- 0.0/0.0 contribution (NOT GIVEN).
Axis error includes +- 0.0/0.0 contribution (NOT GIVEN).
We have studied the production of prompt muons in hadronic events from e+e− annihilation at a center-of-mass energy of 29 GeV with the PEP4-TPC (Time Projection Chamber) detector. The muon p and pt distributions are well described by a combination of bottom- and charm-quark decays, with fitted semimuonic branching fractions of (15.2±1.9±1.2)% and (6.9±1.1±1.1)%, respectively. The muon spectra imply hard fragmentation functions for both b and c quarks, with 〈z(b quark)〉=0.80±0.05±0.05 and 〈z(c quark)〉=0.60±0.06±0.04. We derive neutral-current axial-vector couplings of a(b quark)=-0.9±1.1±0.3 and a(c quark)=1.5±1.5±0.5 from the forward-backward asymmetries.
PT is the transverse momentum of the muon relative to the event thrust axis.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT < 1 GeV/c.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT > 1 GeV/c.
We have measured the inclusive prompt electron cross section over a wide momentum range (P>0.5 GeV/c) with the PEP-4 TPC detector. The semielectronic branching fractions of thec andb quarks are (9.1±0.9 (stat.)±1.3 (syst.))% and (11.0±1.8±1.0)%, respectively. Theb quark fragmentation function peaks at highz with 〈zb〉=0.74±0.05±0.03. The axial couplings to the neutral current areac=2.3±1.4±1.0 for thec quark andab=−2.0±1.9±0.5 for theb quark.
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