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# Transport Meeting

Venue: Physics Building, Max-von-Laue-Str. 1, PHYS 02.116
Time: Thursday, January 23, 2:15pm (s.t.)
Contact: hees@itp.uni-frankfurt.de

# Untangling the evolution of heavy ion collisions using direct photon interferometry

## Oscar Garcia-Montero

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 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. We study also the feasibility of measuring a direct photon HBT signal in the upcoming high-luminosity LHC runs. Considering only statistical uncertainties, we find that with the projected $\sim 10^{10}$ heavy ion events a measurement of the HBT correlations for $k_{\perp}<1 \; \text{GeV}$ is statistically significant.

The talk will be live-streamed (but not recorded) via Vidyo under
https://vc.uni-frankfurt.de/join/idcqq8I3y2FCW6p8DTQF9CTQJc

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