清涼飮料税論

The production of J/\).psi\) and $\psi(2S)$ was measured with the ALICE detector in Pb-Pb collisions at the LHC. The measurement was performed at forward rapidity 2.5 < y < 4 \() down to zero transverse momentum \(p_{\rm T} in the dimuon decay channel. Inclusive J/\).psi\) yields were extracted in different centrality classes and the centrality dependence of the average $p_{\rm T}$ is presented. The J/\).psi\) suppression, quantified with the nuclear modification factor $R_{\rm AA}$ , was studied as a function of centrality, transverse momentum and rapidity. Comparisons with similar measurements at lower collision energy and theoretical models indicate that the J/\).psi\) production is the result of an interplay between color screening and recombination mechanisms in a deconfined partonic medium, or at its hadronization. Results on the $\psi(2S)$ suppression are provided via the ratio of $\psi(2S)$ over J/\).psi\) measured in pp and Pb-Pb collisions

Inclusive quarkonium production at forward rapidity in pp collisions at root s=8 TeV

We report on the inclusive production cross sections of J/psi, psi(2S), gamma(1S), gamma(2S) and gamma(3S), measured at forward rapidity with the ALICE detector in pp collisions at a center-of-mass energy root s = 8 TeV. The analysis is based on data collected at the LHC and corresponds to an integrated luminosity of 1.23 pb(-1). Quarkonia are reconstructed in the dimuon-decay channel. The differential production cross sections are measured as a function of the transverse momentum p(T) and rapidity y, over the p(T) ranges 0 < p(T) < 20 GeV/c for J/psi, 0 < p(T) < 12 GeV/c for all other resonances, and for 2.5 < y < 4. The cross sections, integrated over p(T) and y, and assuming unpolarized quarkonia, are sigma(J/psi) = 8.98 +/- 0.04 +/- 0.82 mu b, sigma(psi(2S)) = 1.23 +/- 0.08 +/- 0.22 mu b, sigma(gamma(1S)) = 71 +/- 6 +/- 7 nb, sigma(gamma(2S)) = 26 +/- 5 +/- 4 nb and sigma(gamma(3S)) = 9 +/- 4 +/- 1 nb, where the first uncertainty is statistical and the second one is systematic. These values agree, within at most 1.4 sigma, with measurements performed by the LHCb collaboration in the same rapidity range