Measurement of charged pion double spin asymmetries at midrapidity in longitudinally polarized p+pp+p collisions at s\sqrt {s} = 510 GeV

International audienceThe PHENIX experiment at the Relativistic Heavy Ion Collider has measured the longitudinal double spin asymmetries, ALL, for charged pions at midrapidity (|η|<0.35) in longitudinally polarized p+p collisions at s=510  GeV. These measurements are sensitive to the gluon spin contribution to the total spin of the proton in the parton momentum fraction x range between 0.04 and 0.09. One can infer the sign of the gluon polarization from the ordering of pion asymmetries with charge alone. The asymmetries are found to be consistent with global quantum-chromodynamics fits of deep-inelastic scattering and data at s=200  GeV, which show a nonzero positive contribution of gluon spin to the proton spin

J/ψJ/\psi and ψ(2S)\psi(2S) production at forward rapidity in pp+pp collisions at s=510\sqrt{s}=510 GeV

International audienceThe PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section, mean transverse momentum, mean transverse momentum squared of inclusive J/ψ, and cross section ratio of ψ(2S) to J/ψ at forward rapidity in p+p collisions at s=510  GeV via the dimuon decay channel. Comparison is made to inclusive J/ψ cross sections measured at s=200  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 (pT) and to next-to-leading order nonrelativistic QCD calculations for the rest of the pT range. These calculations overestimate the data at low pT. While consistent with the data within uncertainties above ≈3  GeV/c, the calculations are systematically below the data. The total cross section times the branching ratio is BR dσppJ/ψ/dy(1.2<|y|<2.2,0<pT<10  GeV/c)=54.3±0.5(stat)±5.5(syst)  nb

Measurement of ϕ\phi-meson production at forward rapidity in p+pp+p collisions at s=510 GeV\sqrt{s}=510\text{ }\text{ }\mathrm{GeV} and its energy dependence from s=200 GeV\sqrt{s}=200\text{ }\text{ }\mathrm{GeV} to 7 TeV

International audienceThe PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section of ϕ(1020)-meson production at forward rapidity in p+p collisions at s=510  GeV via the dimuon decay channel. The partial cross section in the rapidity and pT ranges 1.2<|y|<2.2 and 2<pT<7  GeV/c is σϕ=[2.28±0.09(stat)±0.14(syst)±0.27(norm)]×10-2  mb. The energy dependence of σϕ (1.2<|y|<2.2,2<pT<5  GeV/c) is studied using the PHENIX measurements at s=200 and 510 GeV and the Large Hadron Collider measurements at s=2.76 and 7 TeV. The experimental results are compared to various event generator predictions (pythia6, pythia8, phojet, ampt, epos3, and epos-lhc)

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at s=510\sqrt{s}=510 GeV in p⃗+p⃗\vec{p}+\vec{p} Collisions

We present the measurement of the cross section and double-helicity asymmetry $A_{LL}$ of direct-photon production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=510$ GeV. The measurement has been performed at midrapidity ($|\eta|<0.25$) with the PHENIX detector at the Relativistic Heavy Ion Collider. Direct photons are dominantly produced by the quark-gluon scattering at relativistic energies. Direct photons are produced from the initial partonic hard scattering and do not interact via the strong force. Therefore, this measurement provides a clean and direct access to the gluons in the polarized proton in the gluon-momentum-fraction range $0.02<x<0.08$

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at s=510\sqrt{s}=510 GeV in p⃗+p⃗\vec{p}+\vec{p} Collisions

We present the measurement of the cross section and double-helicity asymmetry $A_{LL}$ of direct-photon production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=510$ GeV. The measurement has been performed at midrapidity ($|\eta|<0.25$) with the PHENIX detector at the Relativistic Heavy Ion Collider. Direct photons are dominantly produced by the quark-gluon scattering at relativistic energies. Direct photons are produced from the initial partonic hard scattering and do not interact via the strong force. Therefore, this measurement provides a clean and direct access to the gluons in the polarized proton in the gluon-momentum-fraction range $0.02<x<0.08$