Sub-threshold / And ϒ Production in Collisions
Yoshitaka Hatta (Physics Department, Brookhaven National Laboratory, Upton, USA); Mark Strikman (Physics Department, Brookhaven National Laboratory, Upton, USA, Department of Physics, Pennsylvania State University, University Park, USA); Ji Xu (Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, USA, INPAC, SKLPPC, MOE KLPPC, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China); Feng Yuan (Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, USA)
We study sub-threshold heavy quarkonium ( and ϒ) photo-productions in γA collisions as an independent test of the universality of the nucleon-nucleon short range correlation (SRC) in nuclear scattering processes. Just below the γp threshold, the cross section is dominated by the mean field contribution of nucleons inside the nucleus. The SRC contributions start to dominate at lower photon energies, depending on the fraction of the SRC pairs in the target nucleus. We give an estimate of the cross sections in the sub-threshold region both for and ϒ. This may be helpful for future measurements at JLab as well as at the Electron-Ion Collider in the U.S., and especially in China.
