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Comparison of transverse single-spin asymmetries for forward π0 production in polarized pp, pAl and pAu collisions at nucleon pair c.m. energy sNN =200 GeV

  • Author(s): Adam, J;
  • Adamczyk, L;
  • Adams, JR;
  • Adkins, JK;
  • Agakishiev, G;
  • Aggarwal, MM;
  • Ahammed, Z;
  • Alekseev, I;
  • Anderson, DM;
  • Aparin, A;
  • Aschenauer, EC;
  • Ashraf, MU;
  • Atetalla, FG;
  • Attri, A;
  • Averichev, GS;
  • Bairathi, V;
  • Barish, K;
  • Behera, A;
  • Bellwied, R;
  • Bhasin, A;
  • Bielcik, J;
  • Bielcikova, J;
  • Bland, LC;
  • Bordyuzhin, IG;
  • Brandenburg, JD;
  • Brandin, AV;
  • Butterworth, J;
  • Caines, H;
  • Calderón De La Barca Sánchez, M;
  • Cebra, D;
  • Chakaberia, I;
  • Chaloupka, P;
  • Chan, BK;
  • Chang, FH;
  • Chang, Z;
  • Chankova-Bunzarova, N;
  • Chatterjee, A;
  • Chen, D;
  • Chen, J;
  • Chen, JH;
  • Chen, X;
  • Chen, Z;
  • Cheng, J;
  • Cherney, M;
  • Chevalier, M;
  • Choudhury, S;
  • Christie, W;
  • Chu, X;
  • Crawford, HJ;
  • Csanád, M;
  • Daugherity, M;
  • Dedovich, TG;
  • Deppner, IM;
  • Derevschikov, AA;
  • Didenko, L;
  • Dilks, C;
  • Dong, X;
  • Drachenberg, JL;
  • Dunlop, JC;
  • Edmonds, T;
  • Elsey, N;
  • Engelage, J;
  • Eppley, G;
  • Esumi, S;
  • Evdokimov, O;
  • Ewigleben, A;
  • Eyser, O;
  • Fatemi, R;
  • Fazio, S;
  • Federic, P;
  • Fedorisin, J;
  • Feng, CJ;
  • Feng, Y;
  • Filip, P;
  • Finch, E;
  • Fisyak, Y;
  • Francisco, A;
  • Fulek, L;
  • Gagliardi, CA;
  • Galatyuk, T;
  • Geurts, F;
  • Gibson, A;
  • Gopal, K;
  • Gou, X;
  • Grosnick, D;
  • Guryn, W;
  • Hamad, AI;
  • Hamed, A;
  • Harabasz, S;
  • Harris, JW;
  • He, S;
  • He, W;
  • He, XH;
  • He, Y;
  • Heppelmann, S;
  • Heppelmann, S;
  • Herrmann, N;
  • Hoffman, E;
  • Holub, L;
  • Hong, Y
  • et al.
Abstract

The STAR collaboration reports a measurement of the transverse single-spin asymmetries, AN, for neutral pions produced in polarized proton collisions with protons (pp), with aluminum nuclei (pAl) and with gold nuclei (pAu) at a nucleon-nucleon center-of-mass energy of 200 GeV. Neutral pions are observed in the forward direction relative to the transversely polarized proton beam, in the pseudorapidity region 2.7<η<3.8. Results are presented for π0s observed in the STAR forward meson spectrometer electromagnetic calorimeter in narrow Feynman x (xF) and transverse momentum (pT) bins, spanning the range 0.172.5 GeV/c. It is further observed that the value of AN is significantly larger for events with a large-pT isolated π0 than for events with a nonisolated π0 accompanied by additional jetlike fragments. The nuclear dependence r(A) is similar for isolated and nonisolated π0 events.

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