Photoproduction of $J/psi$ in p-p ultra-peripheral collisions at LHC energy

$J/psi$ production in p-p ultra-peripheral collisions through the elastic and inelastic photoproduction processes, where the virtual photons emitted from the projectile interact with the target, are studied. The comparisions between the exact treatment results and the ones of equivalent photon approximation are expressed as $Q^{2}$ (virtuality of photon), $z$ and $p_{T}$ distributions, and the total cross sections are also estimated. The method developed by Martin and Ryskin is employed to avoid double counting when the different production mechanism are considered simultaneously. The numerical results indicate that, the equivalent photon approximation can be only applied to the coherent or elastic electromagnetic process, the improper choice of $Q^{2}_{mathrm{max}}$ and $y_{mathrm{max}}$ will cause obvious errors. And the exact treatment is needed to deal accurately with the $J/psi$ photoproduction.

$sin (phi_Lambda-phi_S)$ azimuthal asymmetry in transversely polarized $Lambda$ production in SIDIS within TMD factorization at EIC

We investigate the $sin (phi_Lambda-phi_S)$ single-spin asymmetry in the transversely polarized $Lambda$ production in semi-inclusive deeply inelastic scattering process within the framework of the transverse momentum dependent~(TMD) factorization. The asymmetry is contributed by the convolution of the polarizing TMD fragmentation function $D_{1T}^perp$ of the $Lambda$ hyperon and the unpolarized TMD distribution function $f_1$ of the target nucleon. We apply two sets of $D_{1T}^{perp,Lambda^uparrow/q}$, the spectator diquark model result and available parametrization, to numerically estimate the $sin (phi_Lambda-phi_S)$ asymmetry at the kinematical region of electron ion collider (EIC). We take into account the TMD evolution effect in order to include the scale dependence of the TMD distribution functions and fragmentation functions. It is found that different sets of $D_{1T}^{perp,Lambda^uparrow/q}$ lead to different ${sin (phi_Lambda-phi_S)}$ asymmetry, particularly in sign. Future measurements on the $sin (phi_Lambda-phi_S)$ asymmetry with high precision at EIC can provide important cross check on the available $Lambda$ polarizing fragmentation functions as well as constrain them more stringently.

$cos 2 phi$ asymmetries in unpolarized semi-inclusive DIS

We use the Boer-Mulders functions parameterized from unpolarized $p+D$ Drell-Yan data by the FNAL E866/NuSea Collaboration combined with recently extracted Collins functions to calculate the $cos 2 phi$ asymmetries in unpolarized semi-inclusive deeply inelastic scattering (SIDIS) processes both for ZEUS at Hadron Electron Ring Accelerator (HERA) and Jefferson Lab experiments (JLab), and to compare our results with their data. We also give predictions for the $cos 2 phi$ asymmetries of SIDIS in the kinematical regime of HERMES Collaboration, and the forthcoming JLab experiments. We predict that the $cos 2 phi$ asymmetries of semi-inclusive $pi^-$ production are somewhat larger than that of $pi^+$ production. We suggest to measure these two processes separately, which will provide more detail information on the Boer-Mulders functions as well as on the Collins functions.