Particle production in strong electromagnetic fields in relativistic heavy-ion collisions

TL;DR

This paper reviews how strong electromagnetic fields generated in relativistic heavy-ion collisions influence quark-gluon plasma properties, particle production, and related phenomena, highlighting the importance of electromagnetic effects in understanding collision outcomes.

Contribution

It provides an analytical overview of electromagnetic field evolution, its impact on plasma anisotropy, and particle phenomena, emphasizing the need for experimental studies of these effects.

Findings

Electromagnetic fields reach up to 10 times the pion mass squared at LHC.

Magnetic fields induce azimuthal anisotropy in plasma flow.

Strong fields significantly affect particle production and energy loss mechanisms.

Abstract

I review the origin and properties of electromagnetic fields produced in heavy ion collisions. The field strength immediately after a collision is proportional to the collision energy and reaches eB\sim(m_\pi)^2 at RHIC and eB\sim10 (m_\pi)^2 at LHC. I demonstrate by explicit analytical calculation that after dropping by about one-two orders of magnitude during the first fm/c of plasma expansion, it freezes out and lasts for as long as quark-gluon plasma exists as a consequence of finite electrical conductivity of the plasma. Magnetic field breaks spherical symmetry in the direction perpendicular to the reaction plane and therefore all kinetic coefficients are anisotropic. I examine viscosity of QGP and show that magnetic field induces azimuthal anisotropy on plasma flow even in spherically symmetric geometry. Very strong electromagnetic field has an important impact on particle production. I discuss the problem of energy loss and polarization of fast fermions due to synchrotron radiation, consider photon decay induced by magnetic field, elucidate J/Psi dissociation via Lorentz ionization mechanism and examine electromagnetic radiation by plasma. I conclude that all processes in QGP are affected by strong electromagnetic field and call for experimental investigation.