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

We report on the inclusive production cross sections of J/$psi$, $psi$(2S), $Upsilon$(1S), $Upsilon$(2S) and $Upsilon$(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 $0u003cp_{rm T}u003c20$ GeV/$c$ for J/$psi$, $0u003cp_{rm T}u003c12$ GeV/$c$ for all other resonances, and for $2.5u003cyu003c4$. The cross sections, integrated over $p_{rm T}$ and $y$, and assuming unpolarized quarkonia, are $sigma_{{rm J}/psi} = 8.63pm0.04pm0.79$ $mu$b, $sigma_{psi{rm (2S)}} = 1.18pm0.08pm0.21$ $mu$b, $sigma_{Upsilon{rm(1S)}} = 68pm6pm7$ nb, $sigma_{Upsilon{rm(2S)}} = 25pm5pm4$ nb and $sigma_{Upsilon{rm(3S)}} = 9pm4pm1$ nb, where the first uncertainty is statistical and the second one is systematic. These values agree, within at most $1.2sigma$, with measurements performed by the LHCb collaboration in the same rapidity range.