Inclusive cross section and double-helicity asymmetry for $$\pi^{0}$$ production at midrapidity in $$p$$$+$$$p$$ collisions at $$\sqrt{s}=510$$ GeV
- Univ. of Colorado, Boulder, CO (United States); et al.
PHENIX measurements are presented for the cross section and double-helicity asymmetry (ALL) in inclusive π⁰ production at midrapidity from p+p collisions at √s = 510 GeV from data taken in 2012 and 2013 at the Relativistic Heavy Ion Collider. The next-to-leading-order perturbativequantum- 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 π⁰ALL results follow an increasingly positive asymmetry trend with pT and √s with respect to the predictions and are in excellent agreement with the latest global analysis results. This analysis incorporated earlier results on π0 and jet ALL, and suggested a positive contribution of gluon polarization to the spin of the proton ΔG for the gluon momentum fraction range x > 0.05. The data presented here extend to a currently unexplored region, down to x 0.01, and thus provide additional constraints on the value of ΔG.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States). Relativistic Heavy Ion Collider
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
- Contributing Organization:
- PHENIX Collaboration
- OSTI ID:
- 1254805
- Report Number(s):
- BNL--111967-2016-JA; KB01-01-021
- Journal Information:
- Physical Review D, Journal Name: Physical Review D Vol. 93; ISSN 2470-0010
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English