2017/05/29 by Z. Sun, Sun, Zhan, Xiong Deng +3
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.1705.10230
openalex publication_date 2017/05/29 · openalex created_date 2024/04/11 · openalex updated_date 2026/07/28
Within the framework of the non-relativistic QCD (NRQCD), we make a systematical study of the yields and polarizations of J/ψ and Υ via γγ→ J/ψ(Υ)+γ+X in photon-photon collisions at the Circular Electron Positron Collider (CEPC), up to \mathcal O(α3αs). We find that this process at CEPC is quite "clean", namely the direct photoproduction absolutely dominate over the single- and double- resolved processes, at least 2 orders of magnitude larger. It is found that the next-to-leading order (NLO) QCD corrections will significantly reduce the results due to that the virtual corrections to 3S11 is large and negative. For J/ψ, as pt increases, the color octet (CO) processes will provide increasingly important contributions to the total NLO results. Moreover the inclusion of CO contributions will dramatically change the polarizations of J/ψ from toally transverse to longitudinal, which can be regarded as a distinct signal for the CO mechanism. However, for the case of Υ, the effects of the CO processes are negligible, both for yields and polarizations. For J/ψ, the dependence of the yields on the value of the renormalization scale μr is moderate, while significant for the polarization. The impact of the variation of μλ is found to be relatively slight. As for the case of Υ, the uncertainties of μr and μλ just bring about negligible effects. The future measurements on this semi-inclusive photoproductions of J/ψ(Υ)+γ+X, especially on the polarization parameters of J/ψ, will be a good laboratory for the study of heavy quarkonium production mechanism and helpful to clarify the problems of the J/ψ polarization puzzle.