Low-mass dilepton production through transport process in quark-gluon plasma

TL;DR

This paper investigates low-mass dielectron enhancement in heavy ion collisions by modeling transport processes in quark-gluon plasma using relativistic hydrodynamics, identifying key transport coefficients needed to match experimental data.

Contribution

It introduces a parameterization of the spectral function with transport coefficients D and τ_J within a relativistic hydrodynamics framework to explain dielectron spectra.

Findings

Diffusion coefficient D must be at least 2/T to match data.

Dielectrons mainly originate from high-temperature QGP phase.

Transport process significantly contributes to low-mass dielectron production.

Abstract

We attempt to understand the low-mass dielectron enhancement observed by PHENIX Collaboration at Relativistic Heavy Ion Collider (RHIC) by transport peak in the spectral function. On the basis of the second-order formalism of relativistic dissipative hydrodynamics, we parameterize the spectral function in low-frequency and long-wavelength region by two transport coefficients, electric diffusion coefficient $D$ and relaxation time $\tau_{\rm J}$, and compared our theoretical dielectron spectra with the experimental data. We study spectrum of dielectrons produced in relativistic heavy ion collisions by using the profile of matter evolution under full (3+1)-dimensional hydrodynamics. We find that the experimental data require the diffusion coefficient to be $D\geq 2/T$, with $T$ being temperature. Our analysis shows that dielectrons emitted through transport process mainly come from high-temperature QGP phase.