We have measured the cross section and single spin asymmetries from forward $W^{\pm}\rightarrow\mu^{\pm}\nu$ production in longitudinally polarized $p$$+$$p$ collisions at $\sqrt{s}=510$ GeV using the PHENIX detector at the Relativistic Heavy Ion Collider. The cross sections are consistent with previous measurements at this collision energy, while the most forward and backward longitudinal single spin asymmetries provide new insights into the sea quark helicities in the proton. The charge of the W bosons provides a natural flavor separation of the participating partons.
Single-spin asymmetries at forward $A^{FW}_L$ and backward $A^{BW}_L$ rapidities for $p$+$p$ collisions at $\sqrt{s}$ = 510 GeV for results in 2013 and 2012, plus combined results for both years.
The total $W$ boson production cross sections for $p$+$p$ collisions at $\sqrt{s}$ = 510 GeV for $\sigma$($W^+$ $\rightarrow$ $\mu^+$) and $\sigma$($W^-$ $\rightarrow$ $\mu^-$).
The cross section and transverse single-spin asymmetries of $\mu^{-}$ and $\mu^{+}$ from open heavy-flavor decays in polarized $p$+$p$ collisions at $\sqrt{s}=200$ GeV were measured by the PHENIX experiment during 2012 at the Relativistic Heavy Ion Collider. Because heavy-flavor production is dominated by gluon-gluon interactions at $\sqrt{s}=200$ GeV, these measurements offer a unique opportunity to obtain information on the trigluon correlation functions. The measurements are performed at forward and backward rapidity ($1.4<|y|<2.0$) over the transverse momentum range of $1.25<p_T<7$ GeV/$c$ for the cross section and $1.25<p_T<5$ GeV/$c$ for the asymmetry measurements. The obtained cross section is compared to a fixed-order-plus-next-to-leading-log perturbative-quantum-chromodynamics calculation. The asymmetry results are consistent with zero within uncertainties, and a model calculation based on twist-3 three-gluon correlations agrees with the data.
$A_N$ of negatively-charged muons from open heavy-flavor decays as a function of $p_T$ in the backward ($x_F$ < 0) and forward ($x_F$ > 0) regions.
$A_N$ of positively-charged muons from open heavy-flavor decays as a function of $p_T$ in the backward ($x_F$ < 0) and forward ($x_F$ > 0) regions.
$A_N$ of negatively-charged and positively-charged muons from open heavy-flavor decays as a function of $x_F$, where $x_F$ > 0 is along the direction of the polarized proton.
PHENIX measurements are presented for the cross section and double-helicity asymmetry ($A_{LL}$) in inclusive $\pi^0$ production at midrapidity from $p$$+$$p$ collisions at $\sqrt{s}=510$~GeV from data taken in 2012 and 2013 at the Relativistic Heavy Ion Collider. The next-to-leading-order perturbative-quantum-chromodynamics theory calculation is in excellent agreement with the presented cross section results. The calculation utilized parton-to-pion fragmentation functions from the recent DSS14 global analysis, which prefer a smaller gluon-to-pion fragmentation function. The $\pi^{0}A_{LL}$ results follow an increasingly positive asymmetry trend with $p_T$ and $\sqrt{s}$ with respect to the predictions and are in excellent agreement with the latest global analysis results. This analysis incorporated earlier results on $\pi^0$ and jet $A_{LL}$, and suggested a positive contribution of gluon polarization to the spin of the proton $\Delta G$ for the gluon momentum fraction range $x>0.05$. The data presented here extend to a currently unexplored region, down to $x\sim0.01$, and thus provide additional constraints on the value of $\Delta G$. The results confirm the evidence for nonzero $\Delta G$ using a different production channel in a complementary kinematic region.
The neutral pion production cross section at midrapidity in $p$ + $p$ collisions at $\sqrt{s}$ = 510 GeV as a function of $p_T$ and NLO pQCD calculations for theory scales $\mu = p_T/2$ (dotted line), $p_T$ (solid line) and 2$p_T$ (dashed line), with $\mu$ representing equal factorization, renormalization, and fragmentation scales.
$A_{LL}$ with point-to-point uncertainty $\delta A_{LL}$ vs $p_T$ for $\pi^0$ production at midrapidity in $p$ + $p$ collisions at $\sqrt{s}$ = 510 GeV. Not included in the figure/table are the correlated for all points scale systematic uncertainty of 6.5% (scales both the values and point-to-point uncertainties by the same factor). Correlated relative luminosity (shift) uncertainity of 3.6e-4 (shifts all points by the same value).
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