Production of Low Mass Electron Pairs Due to the Photon-Photon Mechanism in Central Collisions

TL;DR

This paper calculates the gamma-gamma mechanism's contribution to low mass electron pairs in heavy ion collisions, finding it negligible in CERES but potentially significant at small invariant masses and certain rapidities, with implications for RHIC.

Contribution

It provides a detailed calculation of dilepton production via photon-photon interactions, highlighting its limited role in current experiments and offering formulas for future scenarios.

Findings

Mechanism negligible in CERES data

Potentially large at small invariant masses

Applicability of equivalent photon approximation

Abstract

We calculate the probability for dilepton production in central relativistic heavy ion collisions due to the gamma-gamma mechanism. This is a potential background to more interesting mechanisms. We find that this mechanism is negligible in the CERES experiments. Generally, the contribution due to this mechanism is small in the central region, while it can be large for small invariant masses and forward or backward rapidities. A simple formula based on the equivalent photon approximation and applications to a possible scenario at RHIC are also given.