The photon production and collective flows from magnetic induced gluon fusion and splitting in early stage of high energy nuclear collision

Abstract

We present an event-by-event study of photon production in early stage of high energy nuclear collisions, where the system is dominant by highly occupied of gluons and initialized by McLerran-Venugopalan model. The photons are produced through the gluon fusion and splitting processes when strong magnetic field is included. We study the spectra and collective flows of the photons and show their dependence on transverse momentum $q_{T}$. It is found that in our approach the photons from boost invariant evolving glasma provide visible enhancement on spectrum and obvious contribution on $v_{2}$ of the total direct photons. The results, by weighting on top of parton-hadron-string dynamics (PHSD) model, agree even better with experiment measurements in Au-Au 20\%-40\% centrality collisions at $\sqrt{s_{NN}}=200$GeV.