Inclusive cross section and double-helicity asymmetry for ${\pi }^0$ production at midrapidity in $p$$+$$p$ collisions at $\sqrt{s}=510$ GeV

Abstract

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 $x\sim 0.01$, 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.

arXiv comment413 authors, 8 pages, 4 figures. v2 is version accepted as PRD Rapid Communication. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.html

References in corpus (20)

• Parton distributions for the LHC
• Extraction of Spin-Dependent Parton Densities and Their Uncertainties
• Evidence for polarization of gluons in the proton
• Global Analysis of Helicity Parton Densities and Their Uncertainties
• Mid-Rapidity Neutral Pion Production in Proton-Proto Collisions at sqrt(s_NN) = 200 GeV
• Prospects for Spin Physics at RHIC
• Global Analysis of Fragmentation Functions for Protons and Charged Hadrons
• Parton-to-Pion Fragmentation Reloaded
• Inclusive cross section and double helicity asymmetry for π^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton
• Determination of Polarized PDFs from a QCD Analysis of Inclusive and Semi-inclusive Deep Inelastic Scattering Data
• Longitudinal double-spin asymmetry and cross section for inclusive jet production in polarized proton collisions at sqrt(s) = 200 GeV
• QCD Analysis of the Polarized World Data
• QCD Analysis of Polarized Deep Inelastic Scattering Data
• Precision Measurement of the Longitudinal Double-spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at $\sqrt{s}=200$ GeV
• Inclusive cross section and double helicity asymmetry for pi^0 production in p+p collisions at sqrt(s) = 62.4 GeV
• The gluon spin contribution to the proton spin from the double helicity asymmetry in inclusive pi^0 production in polarized p+p collisions at sqrt(s)=200 GeV
• Inclusive double-helicity asymmetries in neutral pion and eta meson production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=200$ GeV
• Neutral pion cross section and spin asymmetries at intermediate pseudorapidity in polarized proton collisions at sqrt{s} = 200 GeV
• Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV
• Improved Measurement of Double Helicity Asymmetry in Inclusive Midrapidity pi^0 Production for Polarized p+p Collisions at sqrt(s)=200 GeV

Cited by in corpus (37)

• Parton Fragmentation Functions
• The ALICE experiment: a journey through QCD
• Iterative Monte Carlo analysis of spin-dependent parton distributions
• Gluon orbital angular momentum at small-$x$
• Small-$x$ asymptotics of the quark helicity distribution
• Small-$x$ Asymptotics of the Gluon Helicity Distribution
• ${\pi }^0$ and $\eta$ meson production in proton-proton collisions at $\sqrt{s}=8$ TeV
• Isovector parton distribution functions of the proton on a superfine lattice
• Systematic Analysis of the Non-extensive Statistical Approach in High Energy Particle Collisions - Experiment vs. Theory
• Longitudinal double-spin asymmetry for inclusive jet and dijet production in $pp$ collisions at $\sqrt{s}=510$ GeV
• Next-to-next-to-leading order QCD analysis of spin-dependent parton distribution functions and their uncertainties: Jacobi polynomials approach
• Helicity at Small $x$: Oscillations Generated by Bringing Back the Quarks
• Using the Tsallis distribution for hadron spectra in $pp$ collisions: Pions and quarkonia at $\sqrt{s}$ = 5--13000 GeV
• Nucleon spin structure functions at NNLO in the presence of target mass corrections and higher twist effects
• Pion Fragmentation Functions at High Energy Colliders
• Transverse spin-dependent azimuthal correlations of charged pion pairs measured in p${}^{\uparrow }$+p collisions at $\sqrt{s}$ = 500 GeV
• Analytical approaches to the determination of spin-dependent parton distribution functions at NNLO approximation
• Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at $\sqrt{s}=200$ GeV
• Cross section and longitudinal single-spin asymmetry $A_L$ for forward $W^{\pm }\to {\mu }^{\pm }\nu$ production in polarized $p$$+$$p$ collisions at $\sqrt{s}=510$ GeV
• Single-spin asymmetry of $J/\psi$ production in $p$$+$$p$, $p$$+$Al, and $p$$+$Au collisions with transversely polarized proton beams at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Strong Interaction Physics at the Luminosity Frontier with 22 GeV Electrons at Jefferson Lab
• Neural Network QCD analysis of charged hadron Fragmentation Functions in the presence of SIDIS data
• Measurement of charged pion double spin asymmetries at midrapidity in longitudinally polarized $p$$+$$p$ collisions at $\sqrt{s}=510$ GeV
• Neutral-Current Weak Interactions at an EIC
• Longitudinal Double-Spin Asymmetries for ${\pi }^0$s in the Forward Direction for 510 GeV Polarized $pp$ Collisions
• Nonperturbative-transverse-momentum effects and evolution in dihadron and direct photon-hadron angular correlations in $p$$+$$p$ collisions at $\sqrt{s}$=510 GeV
• $J/\psi$ and $\psi (2S)$ production at forward rapidity in $p$+$p$ collisions at $\sqrt{s}=510$ GeV
• Measurements of double-helicity asymmetries in inclusive $J/\psi$ production in longitudinally polarized $p+p$ collisions at $\sqrt{s}=510$ GeV
• Production of ${\pi }^0$ and $\eta$ mesons in U$+$U collisions at $\sqrt{s_{{}_{NN}}}=192$ GeV
• Global analysis of fragmentation functions to light neutral hadrons
• Accessing gluon polarization with high-$P_T$ hadrons in SIDIS
• Double longitudinal-spin asymmetries in $J/\psi$ production at RHIC
• Precision measurement of the longitudinal double-spin asymmetry for dijet production at intermediate pseudorapidity in polarized $pp$ collisions at $\sqrt{s}$ = 200 GeV
• QCD and High Energy Interactions: Moriond 2016 Theory Summary
• Gauge Invariant Noether's Theorem and The Proton Spin Crisis
• Measurement of $\varphi$-meson production at forward rapidity in $p$$+$$p$ collisions at $\sqrt{s}$=510 GeV and energy dependence of ${\sigma }_{\varphi }$ from $\sqrt{s}$=200 GeV to 7 TeV
• Recent results on cold-QCD from RHIC