Inclusive cross section and double-helicity asymmetry for π^0 production at midrapidity in p + p collisions at root s=510 GeV

Kód výsledku v IS VaVaI

RIV/68407700:21340/16:00235758 - isvavai.cz

Výsledek na webu

http://dx.doi.org/10.1103/PhysRevD.93.011501

DOI - Digital Object Identifier

10.1103/PhysRevD.93.011501

Jazyk výsledku

angličtina

Název v původním jazyce

Inclusive cross section and double-helicity asymmetry for π^0 production at midrapidity in p + p collisions at root s=510 GeV

Popis výsledku v původním jazyce

PHENIX measurements are presented for the cross section and double-helicity asymmetry (A_LL) in inclusive π^0 production at midrapidity from p + p collisions at root 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 π^0 A_LL results follow an increasingly positive asymmetry trend with p_T and root s with respect to the predictions and are in excellent agreement with the latest global analysis results. This analysis incorporated earlier results on π^0 and jet A_LL, 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 . The results confirm the evidence for nonzero ΔG using a different production channel in a complementary kinematic region.

Název v anglickém jazyce

Inclusive cross section and double-helicity asymmetry for π^0 production at midrapidity in p + p collisions at root s=510 GeV

Popis výsledku anglicky

PHENIX measurements are presented for the cross section and double-helicity asymmetry (A_LL) in inclusive π^0 production at midrapidity from p + p collisions at root 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 π^0 A_LL results follow an increasingly positive asymmetry trend with p_T and root s with respect to the predictions and are in excellent agreement with the latest global analysis results. This analysis incorporated earlier results on π^0 and jet A_LL, 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 . The results confirm the evidence for nonzero ΔG using a different production channel in a complementary kinematic region.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BF - Elementární částice a fyzika vysokých energií

OECD FORD obor

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Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
S - Specificky vyzkum na vysokych skolach
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physical Review D

ISSN

1550-7998

e-ISSN

—

Svazek periodika

93

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

8

Strana od-do

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Kód UT WoS článku

000367674200001

EID výsledku v databázi Scopus

2-s2.0-84955292171