Inclusive quarkonium production at forward rapidity in pp collisions at $\sqrt{s}=8$ TeV

Abstract

We report on the inclusive production cross sections of J/$ψ$, $ψ$(2S), $Υ$(1S), $Υ$(2S) and $Υ$(3S), measured at forward rapidity with the ALICE detector in pp collisions at a center-of-mass energy $\sqrt{s}=8$ TeV. The analysis is based on data collected at the LHC and corresponds to an integrated luminosity of 1.28 pb$^{-1}$. Quarkonia are reconstructed in the dimuon-decay channel. The differential production cross sections are measured as a function of the transverse momentum $p_{\rm T}$ and rapidity $y$, over the $p_{\rm T}$ ranges $0<p_{\rm T}<20$ GeV/$c$ for J/$ψ$, $0<p_{\rm T}<12$ GeV/$c$ for all other resonances, and for $2.5<y<4$. The cross sections, integrated over $p_{\rm T}$ and $y$, and assuming unpolarized quarkonia, are $σ_{{\rm J}/ψ} = 8.98\pm0.04\pm0.82$ $μ$b, $σ_{ψ{\rm (2S)}} = 1.23\pm0.08\pm0.22$ $μ$b, $σ_{Υ{\rm(1S)}} = 71\pm6\pm7$ nb, $σ_{Υ{\rm(2S)}} = 26\pm5\pm4$ nb and $σ_{Υ{\rm(3S)}} = 9\pm4\pm1$ nb, where the first uncertainty is statistical and the second one is systematic. These values agree, within at most $1.4σ$, with measurements performed by the LHCb collaboration in the same rapidity range.