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

Journal Article · Wed Sep 06 00:00:00 EDT 2023 · Physical Review. C

DOI:https://doi.org/10.1103/PhysRevC.108.035202· OSTI ID:1998834

Dove, J.; Kerns, B.; Leung, C.; McClellan, R. E.; Miyasaka, S.; Morton, D. H.; Nagai, K.; Prasad, S.; Sanftl, F.; Scott, M. B. C.; Tadepalli, A. S.; Aidala, C. A.; Arrington, J.; Ayuso, C.; Barker, C. T.; Brown, C. N.; Chang, T. H.; Chang, W. C. ; Chen, A.; Christian, D. C. ; Dannowitz, B. P.; Daugherity, M.; Diefenthaler, M.; El Fassi, L.; Geesaman, D. F.; Gilman, R.; Goto, Y.; Guo, L.; Guo, R.; Hague, T. J.; Holt, R. J.; Isenhower, D.; Kinney, E. R.; Kitts, N. D.; Klein, A.; Kleinjan, D. W.; Kudo, Y.; Lin, P. -J.; Liu, K.; Liu, M. X.; Lorenzon, W.; Makins, N. C. R.; Mesquita de Medeiros, M.; McGaughey, P. L.; Miyachi, Y.; Mooney, I.; Nakahara, K.; Nakano, K. ; Nara, S.; Peng, J. C.; Puckett, A. J.; Ramson, B. J.; Reimer, P. E.; Rubin, J. G.; Sawada, S. ; Sawada, T. ; Shibata, T. -A. ; Shiu, S. H.; Su, D.; Teo, M.; Tice, B. G.; Towell, R. S.; Uemura, S.; Watson, T. S.; Wang, S. G.; Wickes, A. B.; Wu, J.; Xi, Z.; Ye, Z.

Evidence for a flavor asymmetry between the $$\bar{u}$$ and $$\bar{d}$$ quark distributions in the proton has been found in deep-inelastic scattering and DrellYan 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 $$\bar{d}$$(x)/$$\bar{u}$$(x) ratio in the x > 0.15 region. We report results from the SeaQuest Fermilab E906 experiment with improved statistical precision for $$\bar{d}$$(x)/$$\bar{u}$$(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, σ^pd/2σ^pp, from the SeaQuest data give consistent results. The $$\bar{d}$$(x)/$$\bar{u}$$(x) ratios and the $$\bar{d}$$(x)- $$\bar{u}$$(x) differences are deduced from these cross section ratios for 0.13 < x < 0.45. The SeaQuest and E866/NuSea $$\bar{d}$$(x)/$$\bar{u}$$(x) ratios are in good agreement for the x≲0.25 region. The new SeaQuest data, however, show that $$\bar{d}$$(x) continues to be greater than $$\bar{u}$$(x) up to the highest x value (x = 0.45). The new results on $$\bar{d}$$(x)/$$\bar{u}$$(x) and $$\bar{d}$$(x)-$$\bar{u}$$(x) are compared with various parton distribution functions and theoretical calculations.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP); USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); Mississippi State University
• Contributing Organization: FNAL E906/SeaQuest Collaboration
• Grant/Contract Number: AC02-06CH11357; AC02-07CH11359
• OSTI ID: 1998834
• Alternate ID(s): OSTI ID: 1915420; OSTI ID: 2228753
• Report Number(s): FERMILAB-PUB-22-921-ND-PPD; arXiv:2212.12160; PRVCAN; 035202
• Journal Information: Physical Review. C, Journal Name: Physical Review. C Vol. 108 Journal Issue: 3; ISSN 2469-9985
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
H &amp; He induced nuclear reactions
nucleon induced nuclear reactions
Parton distribution functions
light quarks
protons