J/ψ and ψ(2S) production at forward rapidity in p+p collisions at s=510 GeV

Le résumé fourni par la source

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section, mean transverse momentum, mean transverse momentum squared of inclusive $J/\ensuremath{\psi}$, and cross section ratio of $\ensuremath{\psi}(2S)$ to $J/\ensuremath{\psi}$ at forward rapidity in $p+p$ collisions at $\sqrt{s}=510\text{ }\text{ }\mathrm{GeV}$ via the dimuon decay channel. Comparison is made to inclusive $J/\ensuremath{\psi}$ cross sections measured at $\sqrt{s}=200\text{ }\text{ }\mathrm{GeV}$ and 2.76--13 TeV. The result is also compared to leading-order nonrelativistic QCD calculations coupled to a color-glass-condensate description of the low-$x$ gluons in the proton at low transverse momentum (${p}_{T}$) and to next-to-leading order nonrelativistic QCD calculations for the rest of the ${p}_{T}$ range. These calculations overestimate the data at low ${p}_{T}$. While consistent with the data within uncertainties above $\ensuremath{\approx}3\text{ }\text{ }\mathrm{GeV}/c$, the calculations are systematically below the data. The total cross section times the branching ratio is BR $d{\ensuremath{\sigma}}_{pp}^{J/\ensuremath{\psi}}/dy(1.2<|y|<2.2,0<{p}_{T}<10\text{ }\text{ }\mathrm{GeV}/c)=54.3\ifmmode\pm\else\textpm\fi{}0.5(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}5.5(\mathrm{syst})\text{ }\text{ }\mathrm{nb}$.

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