Direct Photons from Hot Quark Matter in Renormalized Finite-Time-Path QED

Ivan Dadić,Dubravko Klabučar,Domagoj Kuić

doi:10.3390/particles3040044

Ivan Dadić, Dubravko Klabučar + Show 1 more

Open Access

https://doi.org/10.3390/particles3040044

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Journal: Particles	Publication Date: Oct 20, 2020
Citations: 2	License type: CC BY 4.0

Affiliation: Rudjer Boskovic Institute, University of Zagreb

Abstract

Within the finite-time-path out-of-equilibrium quantum field theory (QFT), we calculate direct photon emission from early stages of heavy ion collisions, from a narrow window, in which uncertainty relations are still important and they provide a new mechanism for production of photons. The basic difference with respect to earlier calculations, leading to diverging results, is that we use renormalized QED of quarks and photons. Our result is a finite contribution that is consistent with uncertainty relations.

Highlights

Within the finite-time-path out-of-equilibrium quantum field theory (QFT), we calculate direct photon emission from early stages of heavy ion collisions, from a narrow window, in which uncertainty relations are still important and they provide a new mechanism for production of photons
Heavy ion collisions (HIC) result in many-particle final states that carry a lot of information, which is not easy to decode [1,2,3], including, for example, the recently emerged ‘direct photon puzzle’ [3]
We have calculated the production of photons from the early stage of quark gluon plasma, within the finite-time-path out-of-equilibrium QFT

Summary

Introduction

Heavy ion collisions (HIC) result in many-particle final states that carry a lot of information, which is not easy to decode [1,2,3], including, for example, the recently emerged ‘direct photon puzzle’ [3]. Pertinent calculations [17,18,19,20,21,22,23,24,25] of production of photons from the early stage of HIC, and the heated discussion afterwards [26], with the criticism on infinite energy that is released in photon yield, indicate that the subject is far from settled This calculation is performed in the finite-time-path (FTP) out-of-equilibrium QFT. The photons, which do not interact strongly with quarks and gluons, escape relatively carrying the valuable information on early stage of HIC. In this stage, the uncertainty relations allow large energy uncertainty producing fast oscillations.

Direct Photon Production

Energy Conserving Terms

Term Containing ReΠR

Cut Contributions

Comparison to the Wang-Boyanovsky Result

Conclusions