Neutral pion cross section and spin asymmetries at intermediate pseudorapidity in polarized proton collisions at s = 200 GeV

Journal Article

The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8<η<2.0 in polarized proton-proton collisions at s=200 GeV are presented. Neutral pions were detected using the end cap electromagnetic calorimeter in the STAR detector at RHIC. The cross section was measured over a transverse momentum range of 5<16 GeV/c and is found to agree with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry ALL is measured in the same pseudorapidity range and spans a range of Bjorken-x down to x≈0.01. The measured ALL is consistent with model predictions for varying degrees of gluon polarization. The parity-violating asymmetry AL is also measured and found to be consistent with zero. The transverse single-spin asymmetry AN is measured over a previously unexplored kinematic range in Feynman-x and pT. Such measurements may aid our understanding of the onset and kinematic dependence of the large asymmetries observed at more forward pseudorapidity (η≈3) and their underlying mechanisms. The AN results presented are consistent with a twist-3 model prediction of a small asymmetry over the present kinematic range. © 2014 American Physical Society.

Full Text

Duke Authors

Cited Authors

  • Adamczyk, L; Adkins, JK; Agakishiev, G; Aggarwal, MM; Ahammed, Z; Alekseev, I; Alford, J; Anson, CD; Aparin, A; Arkhipkin, D; Aschenauer, EC; Averichev, GS; Balewski, J; Banerjee, A; Barber, B; Barnovska, Z; Beavis, DR; Bellwied, R; Betancourt, MJ; Bhasin, A; Bhati, AK; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, LC; Bordyuzhin, IG; Borowski, W; Bouchet, J; Brandin, AV; Bridgeman, A; Brovko, SG; Bültmann, S; Bunzarov, I; Burton, TP; Butterworth, J; Caines, H; Calderón De La Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, MC; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, HF; Chen, JH; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, MJM; Corliss, R; Cramer, JG; Crawford, HJ; Cui, X; Das, S; Davila Leyva, A; De Silva, LC; Debbe, RR; Dedovich, TG; Deng, J; Derevschikov, AA; Derradi De Souza, R; Dhamija, S; Di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Dion, A; Djawotho, P; Dong, X; Drachenberg, JL; Draper, JE; Du, CM; Dunkelberger, LE; Dunlop, JC; Efimov, LG; Engelage, J; Engle, KS; Eppley, G; Eun, L; Evdokimov, O; Fatemi, R; Fazio, S; Fedorisin, J; Fersch, RG; Filip, P; Finch, E; Fisyak, Y; Flores, CE; Gagliardi, CA; Gangadharan, DR; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Grosnick, D

Published Date

  • January 15, 2014

Published In

Volume / Issue

  • 89 / 1

Electronic International Standard Serial Number (EISSN)

  • 1550-2368

International Standard Serial Number (ISSN)

  • 1550-7998

Digital Object Identifier (DOI)

  • 10.1103/PhysRevD.89.012001

Citation Source

  • Scopus