Mikhail Stephanov

We compute photon emission rate enhancement near the QCD critical point using an effective theory of dynamic critical phenomena and derive a universal photon spectrum. The emission rate scales similar to conductivity, increasing with the correlation length ( ξ ), diverging at the critical point. The spectrum exhibits ω d N γ / d 3 k ∝ ω − 1 / 2 in the scaling regime, with the transition occurring at a frequency comparable to shear damping rate ω ∼ γ η / ξ 2 , reflecting the nonequilibrium properties of the near-critical liquid.

We review recent theoretical developments relevant to heavy-ion experiments carried out within the Beam Energy Scan program at the Relativistic Heavy Ion Collider. Our main focus is on the description of the dynamics of systems created in heavy-ion collisions and establishing the necessary connection between the experimental observables and the QCD phase diagram.