Electromagnetic tomography of radial flow in the quark-gluon plasma

TL;DR

This paper introduces a new multimessenger method combining photon and dilepton spectra to measure the radial flow of the quark-gluon plasma, enabling electromagnetic tomography of early-time QGP dynamics.

Contribution

It develops a calibrated model framework that correlates dilepton-inferred temperature with an experimentally accessible radial flow measure, $v_r^ ext{eff}$, avoiding unmeasurable references.

Findings

Establishes a stable linear correlation between $v_r^ ext{eff}$ and dilepton-inferred temperature.

Provides a concrete experimental precision target for future measurements at RHIC and LHC.

Creates a framework for electromagnetic tomography of the QGP's early-time dynamics.

Abstract

We present a novel multimessenger approach to extract the effective radial flow of the quark-gluon plasma (QGP) by jointly analyzing thermal photon and dilepton spectra in heavy-ion collisions. A key feature of this method is that it circumvents the need for a directly unmeasurable reference -- the photon temperature in the absence of flow -- by establishing, within a calibrated model framework, a stable, approximately linear correlation with the dilepton-inferred temperature. This construction defines an experimentally constructible quantity, $v_r^\mathrm{eff}$, which reflects early-time collectivity and exhibits a strong correlation with the spacetime-averaged radial velocity of the QGP. Together with previous results linking dilepton slopes to the initial QGP temperature, our work establishes a consistent framework for electromagnetic tomography of the QGP. Our framework quantifies the experimental precision target, thereby providing a concrete roadmap for future measurements at RHIC and the LHC and opening a new avenue to probe the early-time dynamics of hot QCD matter.