Jet quenching in mini-quark-gluon plasma: Medium modification factor $I_{pA}$ for photon-tagged jets

Abstract: We calculate the medium modification factor $I_{pA}$ for the photon-tagged jet fragmentation functions for scenario with the quark-gluon plasma formation in $pA$ and $pp$ collisions. We perform calculations of radiative and collisional parton energy loss in the quark-gluon plasma with running $\alpha_s$ which has a plateau around $Q\sim \kappa T$ with $\kappa$ fitted to the LHC data on the heavy ion $R_{AA}$. We find that the theoretical prediction for $I_{pA}$ in $5.02$ TeV $p$+Pb collisions are within errors consistent with the data from ALICE [1]. However, a definite conclusion about the presence or absence of jet quenching in $pA$ collisions cannot be drawn due to large experimental errors of the ALICE data [1]. Our calculations show that this requires a significantly more accurate measurement of $I_{pA}$.