Longitudinal Spin Asymmetry and Cross Section of Inclusive {pi}0 Production in Polarized p + p Collisions at RHIC

Journal Article · Wed Jun 13 04:00:00 EDT 2007 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2750792· OSTI ID:21061910

Simon, Frank ^[1]

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1. Massachusetts Institute of Technology (United States)

We present the first measurement of the cross section and the double longitudinal spin asymmetry of inclusive {pi}0 production in polarized p+p collisions at {radical}(s) = 200 GeV at mid-rapidity with the STAR detector, using the barrel electromagnetic calorimeter. The measured cross section is compared to NLO pQCD calculations and can provide constraints on the pion fragmentation functions. Fragmentation is studied directly by measuring the momentum fraction of {pi}0 in jets, a quantity that is affected by the fragmentation process and jet reconstruction effects. The double longitudinal spin asymmetry is compared to NLO pQCD calculations based on different assumptions for the gluon polarization in the nucleon to provide constraints on {delta}g/g. At the present level of statistics the measured asymmetry disfavors a large positive gluon polarization, but can not yet distinguish between other scenarios.

• OSTI ID: 21061910
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 915; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ASYMMETRY
BROOKHAVEN RHIC
CROSS SECTIONS
GEV RANGE
GLUONS
INCLUSIVE INTERACTIONS
MULTIPARTICLE SPECTROMETERS
NUCLEONS
PARTICLE IDENTIFICATION
PARTICLE PRODUCTION
PARTICLE RAPIDITY
PARTICLE STRUCTURE
PIONS NEUTRAL
POLARIZATION
PROTON-PROTON INTERACTIONS
SPIN
STATISTICS