No Arabic abstract
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.
Production cross-sections of prompt charm mesons are measured with the first data from $pp$ collisions at the LHC at a centre-of-mass energy of $13,mathrm{TeV}$. The data sample corresponds to an integrated luminosity of $4.98 pm 0.19,mathrm{pb}^{-1}$ 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, $p_{mathrm{T}}$, and rapidity, $y$, and cover the range $0 < p_{mathrm{T}} < 15,mathrm{GeV}/c$ and $2.0 < y < 4.5$. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of $1 < p_{mathrm{T}} < 8,mathrm{GeV}/c$ are found to be begin{equation} sigma(pp to D^{0} X) = 2072 pm 2 pm 124,mumathrm{b} sigma(pp to D^{+} X) = 834 pm 2 pm phantom{1}78,mumathrm{b} sigma(pp to D_{s}^{+} X) = 353 pm 9 pm phantom{1}76,mumathrm{b} sigma(pp to D^{*+} X) = 784 pm 4 pm phantom{1}87,mumathrm{b} end{equation} where the uncertainties are due to statistical and systematic uncertainties, respectively.
Charm production at the LHC in pp collisions at sqrt(s)=7 TeV is studied with the LHCb detector. The decays D0 -> K- pi+, D+ -> K- pi+ pi+, D*+ -> D0(K- pi+) pi+, D_s+ -> phi(K- K+) pi+, Lambda_c+ -> p K- pi+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb^{-1}. Differential cross-sections dsigma/dp_T are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0 < p_T < 8 GeV/c and 2.0 < y < 4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above p_T-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives sigma(cbar{c})_{p_T < 8 GeV/c, 2.0 < y < 4.5} = 1419 +/- 12 (stat) +/- 116 (syst) +/- 65 (frag) microbarn, where the uncertainties are statistical, systematic, and due to the fragmentation functions.
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 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 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.