Probing the evolution of heavy-ion collisions using direct photon interferometry

Understand

We investigate the measurement of Hanbury Brown-Twiss (HBT) photon correlations as an experimental tool to discriminate different sources of photon enhancement, which are proposed to simultaneously reproduce the direct photon yield and the azimuthal anisotropy measured in nuclear collisions at RHIC and the LHC.

• To showcase this, we consider two different scenarios in which we enhance the yields from standard hydrodynamical simulations.
• In the first, additional photons are produced from the early pre-equilibrium stage computed from the \textit{bottom-up} thermalization scenario.
• In the second, the thermal rates are enhanced close to the pseudo-critical temperature $T_c\approx 155\,\text{MeV}$ using a phenomenological ansatz.