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 $0 < p_{\rm T} < 20$ GeV/$c$ for J/$\psi$, $0 < p_{\rm T} < 12$ 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 $\sigma_{\rm J/\psi} = 8.63\pm 0.04\pm 0.79$ mb, $\sigma_{\psi(2S)}= 1.18\pm 0.08\pm 0.21$ mb, $\sigma_{\Upsilon(1S)} = 68\pm 6\pm 7$ nb, $\sigma_{\Upsilon(2S)} = 25\pm 5\pm 4$ nb and $\sigma_{\Upsilon(3S)} = 9\pm 4\pm 1$ nb, where the first uncertainty is statistical and the second one is systematic. These values agree, within at most 1.2$\sigma$, with measurements performed by the LHCb collaboration in the same rapidity range.