학술논문
Measurement of $J/\psi$ and $\psi\left(2S\right)$ production in $p+p$ and $p+d$ interactions at 120 GeV
Document Type
Working Paper
Author
Leung, C. H.; Nagai, K.; Nakano, K.; Nawarathne, D.; Dove, J.; Prasad, S.; Wuerfel, N.; Aidala, C. A.; Arrington, J.; Ayuso, C.; Barker, C. L.; Brown, C. N.; Chang, W. C.; Chen, A.; Christian, D. C.; Dannowitz, B. P.; Daugherity, M.; Fassi, L. El; Geesaman, D. F.; Gilman, R.; Goto, Y.; Guo, R.; Hague, T. J.; Holt, R. J.; Hossain, M. F.; Isenhower, D.; Kinney, E.; Klein, A.; Kleinjan, D. W.; Kudo, Y.; Lin, P. -J.; Liu, K.; Liu, M. X.; Lorenzon, W.; McClellan, R. E.; McGaughey, P. L.; Medeiros, M. M.; Miyachi, Y.; Miyasaka, S.; Morton, D. H.; Nakahara, K.; Nara, S.; Pate, S. F.; Peng, J. C.; Pun, A.; Ramson, B. J.; Reimer, P. E.; Rubin, J. G.; Sanftl, F.; Sawada, S.; Sawada, T.; Scott, M. B. C.; Shibata, T. -A.; Tadepalli, A. S.; Teo, M.; Towell, R. S.; Uemura, S.; Wang, S. G.; Wickes, A. B.; Wu, J.; Ye, Z. H.
Source
Subject
Language
Abstract
We report the $p+p$ and $p+d$ differential cross sections measured in the SeaQuest experiment for $J/\psi$ and $\psi\left(2S\right)$ production at 120 GeV beam energy covering the forward $x$-Feynman ($x_F$) range of $0.5 < x_F <0.9$. The measured cross sections are in good agreement with theoretical calculations based on the nonrelativistic QCD (NRQCD) using the long-distance matrix elements deduced from a recent global analysis of proton- and pion-induced charmonium production data. The $\sigma_{\psi\left(2S\right)} / \sigma_{J/\psi}$ cross section ratios are found to increase as $x_F$ increases, indicating that the $q \bar{q}$ annihilation process has larger contributions in the $\psi\left(2S\right)$ production than the $J/\psi$ production. The $\sigma_{pd}/2\sigma_{pp}$ cross section ratios are observed to be significantly different for the Drell-Yan process and $J/\psi$ production, reflecting their different production mechanisms. We find that the $\sigma_{pd}/2\sigma_{pp}$ ratios for $J/\psi$ production at the forward $x_F$ region are sensitive to the $\bar{d}/ \bar{u}$ flavor asymmetry of the proton sea, analogous to the Drell-Yan process. The transverse momentum ($p_T$) distributions for $J/\psi$ and $\psi\left(2S\right)$ production are also presented and compared with data collected at higher center-of-mass energies.
Comment: 8 pages, 7 figures
Comment: 8 pages, 7 figures