Inclusive J/$\psi$ production is studied in minimum-bias proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 5.02 TeV by ALICE at the CERN LHC. The measurement is performed at mid-rapidity ($|y| < 0.9$) in the dielectron decay channel down to zero transverse momentum $p_{\rm T}$, using a data sample corresponding to an integrated luminosity of $L_{\rm int} = 19.4 \pm$ 0.4 nb$^{-1}$. The measured $p_{\rm T}$-integrated inclusive J/$\psi$ production cross section is d$\sigma$/d$y$ = 5.64 $\pm$ 0.22 (stat.) $\pm 0.33$ (syst.) $\pm 0.12$ (lumi.) $\mu$b. The $p_{\rm T}$-differential cross section d$^{2} \sigma$/d$p_{\rm T}$d$y$ is measured in the $p_{\rm T}$ range 0$-$10 GeV/$c$ and compared with state-of-the-art perturbative QCD calculations. The J/$\psi$ $\langle p_{\rm T} \rangle$ and $\langle p_{\rm T}^{2} \rangle$ are extracted and compared with results obtained at other collision energies.
We report on the inclusive J/$\psi$ production cross section measured at the CERN Large Hadron Collider in proton-proton collisions at a centre-of-mass energy $\sqrt{s}~=~13$ TeV. The J/$\psi$ mesons are reconstructed in the $\rm e^{+} e^{-}$ decay channel and the measurements are performed at midrapidity ($|y|<0.9$) in the transverse-momentum interval $0< p_{\rm T} <40$ GeV/$c$, using a minimum bias data sample corresponding to an integrated luminosity $L_{\text{int}} = 32.2~\text{nb}^{-1}$ and an Electromagnetic Calorimeter triggered data sample with $L_{\text{int}} = 8.3~\mathrm{pb}^{-1}$. The $p_{\rm T}$-integrated J/$\psi$ production cross section at midrapidity, computed using the minimum bias data sample, is $\text{d}\sigma/\text{d}y|_{y=0} = 8.97\pm0.24~(\text{stat})\pm0.48~(\text{syst})\pm0.15~(\text{lumi})~\mu\text{b}$. An approximate logarithmic dependence with the collision energy is suggested by these results and available world data, in agreement with model predictions. The integrated and $p_{\rm T}$-differential measurements are compared with measurements in pp collisions at lower energies and with several recent phenomenological calculations based on the non-relativistic QCD and Color Evaporation models.
Inclusive J/$\psi$ production is studied in Xe-Xe interactions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\rm NN}}= 5.44$ TeV, using the ALICE detector at the CERN LHC. The J/$\psi$ meson is reconstructed via its decay into a muon pair, in the centre-of-mass rapidity interval $2.5<y<4$ and down to zero transverse momentum. In this Letter, the nuclear modification factors $R_{\rm AA}$ for inclusive J/$\psi$, measured in the centrality range 0-90% as well as in the centrality intervals 0-20% and 20-90% are presented. The $R_{\rm AA}$ values are compared to previously published results for Pb-Pb collisions at $\sqrt{s_{\rm NN}}= 5.02$ TeV and to the calculation of a transport model. A good agreement is found between Xe-Xe and Pb-Pb results as well as between data and the model.
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.
Inclusive jet production (e+e- -> e+e- +jet+X) is studied in collisions of quasi-real photons radiated by the LEP beams at e+e- centre-of-mass energies sqrt see from 189 to 209 GeV. Jets are reconstructed using the kp jet algorithm. The inclusive differential cross-section is measured as a function of the jet transverse momentum, ptjet, in the range 5 <ptjet < 40 GeV for pseudo-rapidities, etaj, in the range -1.5 < etaj < 1.5. The results are compared to predictions of perturbative QCD in next-to-leading order in the strong coupling constant.
The reactions e^+e^- -> e^+e^- Lambda X and e^+e^- -> e^+e^- Lambda X are studied using data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 209 GeV. Inclusive differential cross sections are measured as a function of the lambda transverse momentum, p_t, and pseudo-rapidity, eta, in the ranges 0.4 GeV < p_t < 2.5 GeV and |\eta| < 1.2. The data are compared to Monte Carlo predictions. The differential cross section as a function of p_t is well described by an exponential of the form A exp (- p_t / <p_t>)$.
The HELIOS experiment has measured inclusivep⊥ spectra of negative particles in the rapidity region 1.0<y<1.9. The general shape of thep⊥ spectra in p +W, O+W and S+W is similar, but cannot be described by a single exponential. Compared to p+p collisions, an excess is observed for low and highp⊥. This effect increases with the projectile mass. Except for very lowE⊥, the average transverse momentum <p⊥> is found to be approximately constant up to the highest accessible values ofE⊥.
We have measured the single-particle inclusive cross sections for p+p→π±+X, K±+X, p+X, p¯+X in the low-p⊥ region (≲ 1.5 GeV/c) as a function of the radial scaling variable XR in p−p collisions at 100, 200, and 400 GeV at Fermilab. The measured π+π− and K+K− ratios are shown to be remarkably similar to the same ratios which have recently been measured at large p⊥ at 90° in the center-of-mass system.
The authors have measured the inclusive production of direct photons in the transverse momentum (pT) range 2.1-5.0 GeV/c in 200-GeV/c collisions of protons and π+ mesons on a carbon target. A significant yield of direct photons was observed for pT>2.5 GeV/c. The invariant cross section for direct-photon production, when compared with measurements from the CERN intersecting storage rings, can be expressed in terms of pT and xT=2pTs as (42±14)(1−xT)8.1±1.0pT−6.6±0.3 μb/GeV2 for the c.m. energy range from s=19.4 to 63 GeV, and for the xT range from 0.2 to 0.5.
Measurements of the differential cross section for the inclusive production of high-energy π0's are reported for the reactions π±p→π0X at a laboratory momentum of 14 GeV/c. The kinematic range covered, in terms of the Feynman scaling variable x and the transverse momentum P⊥, is 0.25≤x≤1.0 and 0≤P⊥≤0.7 GeV/c. Two spectrometers, both employing large NaI(Tl) crystals, are used to detect the π0's and to identify them with a mass resolution of 17 MeV (full width at half maximum). The results are in accord with the hypothesis of limiting fragmentation, which regards the measured reactions, in the kinematic range covered, as examples of disfavored fragmentation.
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