No Arabic abstract
The production cross-sections of $J/psi$ mesons in proton-proton collisions at a centre-of-mass energy of $sqrt{s}=5$ TeV are measured using a data sample corresponding to an integrated luminosity of $9.13pm0.18~text{pb}^{-1}$, collected by the LHCb experiment. The cross-sections are measured differentially as a function of transverse momentum, $p_{text{T}}$, and rapidity, $y$, and separately for $J/psi$ mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised $J/psi$ mesons, the production cross-sections integrated over the kinematic range $0<p_{text{T}}<20~text{GeV}/c$ and $2.0<y<4.5$ are $8.154pm0.010pm0.283~mutext{b}$ for prompt $J/psi$ mesons and $0.820pm0.003pm0.034~mutext{b}$ for nonprompt $J/psi$ mesons, where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at $sqrt{s}=8$ TeV and $13$ TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for $J/psi$ mesons at a centre-of-mass energy per nucleon pair of $sqrt{s_{text{NN}}}=5$ TeV. The results are compared with theoretical predictions.
The production of J/psi mesons in proton-proton collisions at sqrt(s)=7 TeV is studied with the LHCb detector at the LHC. The differential cross-section for prompt J/psi production is measured as a function of the J/psi transverse momentum pT and rapidity y in the fiducial region 0<pT<14 GeV/c and 2.0<y<4.5. The differential cross-section and fraction of J/psi from b-hadron decays are also measured in the same pT and y ranges. The analysis is based on a data sample corresponding to an integrated luminosity of 5.2pb-1. The measured cross-sections integrated over the fiducial region are 10.52 +/- 0.04 +/- 1.40 +1.64/-2.20 mub for prompt J/psi production and 1.14 +/- 0.01 +/- 0.16 mub for J/psi from b-hadron decays, where the first uncertainty is statistical and the second systematic. The prompt J/psi production cross-section is obtained assuming no J/psi polarisation and the third error indicates the acceptance uncertainty due to this assumption.
The production of J/psi mesons is studied with the LHCb detector using data from pp collisions at sqrt(s)=2.76 TeV corresponding to an integrated luminosity of 71 nb^-1. The differential cross-section for inclusive J/psi production is measured as a function of its transverse momentum pT. The cross-section in the fiducial region 0<pT<12 GeV/c and rapidity 2.0<y<4.5 is measured to be 5.6 +/- 0.1(stat) +/- 0.4 (syst) mub, with the assumption of unpolarised J/psi production. The fraction of J/psi production from b-hadron decays is measured to be (7.1 +/- 0.6 (stat) +/- 0.7 (syst)) %.
The differential cross-section as a function of rapidity has been measured for the exclusive production of $J/psi$ and $psi(2S)$ mesons in proton-proton collisions at $sqrt{s}=7$ TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pb$^{-1}$. The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to be $$begin{array}{rl} sigma_{pprightarrow J/psirightarrow{mu^+}{mu^-}}(2.0<eta_{mu^pm }<4.5)=&291pm 7pm19 {rm pb}, sigma_{pprightarrowpsi(2S)rightarrow{mu^+}{mu^-}}(2.0<eta_{mu^pm}<4.5)=&6.5pm 0.9pm 0.4 {rm pb},end{array}$$ where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects.
Production cross-sections of prompt charm mesons are measured using data from $pp$ collisions at the LHC at a centre-of-mass energy of $5,$TeV. The data sample corresponds to an integrated luminosity of $8.60pm0.33,$pb$^{-1}$ collected by the LHCb experiment. The production cross-sections of $D^0$, $D^+$, $D_s^+$, and $D^{*+}$ mesons are measured in bins of charm meson transverse momentum, $p_{text{T}}$, and rapidity, $y$. They cover the rapidity range $2.0<y<4.5$ and transverse momentum ranges $0 < p_{text{T}} < 10, text{GeV}/c$ for $D^0$ and $D^+$ and $1 < p_{text{T}} < 10, text{GeV}/c$ for $D_s^+$ and $D^{*+}$ mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of $1 < p_{text{T}} < 8, text{GeV}/c$ are determined to be sigma(pprightarrow D^0 X) = 1004 pm 3 pm 54,mutext{b} sigma(pprightarrow D^+ X) = 402 pm 2 pm 30,mutext{b} sigma(pprightarrow D_s^+ X) = 170 pm 4 pm 16,mutext{b} sigma(pprightarrow D^{*+} X)= 421 pm 5 pm 36,mutext{b} where the uncertainties are statistical and systematic, respectively.
The ALICE Collaboration has measured inclusive J/psi production in pp collisions at a center of mass energy sqrt(s)=2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges |y|<0.9 and 2.5<y<4 and have been obtained by measuring the electron and muon pair decay channels, respectively. The integrated luminosities for the two channels are L^e_int=1.1 nb^-1 and L^mu_int=19.9 nb^-1, and the corresponding signal statistics are N_J/psi^e+e-=59 +/- 14 and N_J/psi^mu+mu-=1364 +/- 53. We present dsigma_J/psi/dy for the two rapidity regions under study and, for the forward-y range, d^2sigma_J/psi/dydp_t in the transverse momentum domain 0<p_t<8 GeV/c. The results are compared with previously published results at sqrt(s)=7 TeV and with theoretical calculations.