Measurement of flavor asymmetry of the light-quark sea in the proton with Drell-Yan dimuon production in p+p and p+d collisions at 120 GeV
- Dove, J;
- Kerns, B;
- Leung, C;
- McClellan, RE;
- Miyasaka, S;
- Morton, DH;
- Nagai, K;
- Prasad, S;
- Sanftl, F;
- Scott, MBC;
- Tadepalli, AS;
- Aidala, CA;
- Arrington, J;
- Ayuso, C;
- Barker, CT;
- Brown, CN;
- Chang, TH;
- Chang, WC;
- Chen, A;
- Christian, DC;
- Dannowitz, BP;
- Daugherity, M;
- Diefenthaler, M;
- Fassi, L El;
- Geesaman, DF;
- Gilman, R;
- Goto, Y;
- Guo, L;
- Guo, R;
- Hague, TJ;
- Holt, RJ;
- Isenhower, D;
- Kinney, ER;
- Kitts, ND;
- Klein, A;
- Kleinjan, DW;
- Kudo, Y;
- Lin, P-J;
- Liu, K;
- Liu, MX;
- Lorenzon, W;
- Makins, NCR;
- de Medeiros, M Mesquita;
- McGaughey, PL;
- Miyachi, Y;
- Mooney, I;
- Nakahara, K;
- Nakano, K;
- Nara, S;
- Peng, JC;
- Puckett, AJ;
- Ramson, BJ;
- Reimer, PE;
- Rubin, JG;
- Sawada, S;
- Sawada, T;
- Shibata, T-A;
- Shiu, SH;
- Su, D;
- Teo, M;
- Tice, BG;
- Towell, RS;
- Uemura, S;
- Watson, TS;
- Wang, SG;
- Wickes, AB;
- Wu, J;
- Xi, Z;
- Ye, Z
- et al.
Abstract
Evidence for a flavor asymmetry between the ū and d¯ quark distributions in the proton has been found in deep-inelastic scattering and Drell-Yan experiments. The pronounced dependence of this flavor asymmetry on x (fraction of nucleon momentum carried by partons) observed in the Fermilab E866 Drell-Yan experiment suggested a drop of the d¯(x)/ū(x) ratio in the x>0.15 region. We report results from the SeaQuest Fermilab E906 experiment with improved statistical precision for d¯(x)/ū(x) in the large x region up to x=0.45 using the 120 GeV proton beam. Two different methods for extracting the Drell-Yan cross section ratios, σpd/2σpp, from the SeaQuest data give consistent results. The d¯(x)/ū(x) ratios and the d¯(x)-ū(x) differences are deduced from these cross section ratios for 0.13