Manipulating strong electromagnetic fields with the average transverse momentum of relativistic nuclear collisions

TL;DR

This paper proposes using the mean transverse momentum of charged hadrons as an event-shape engineering tool to better estimate the magnetic field strength in high-energy heavy-ion collisions, aiding the search for the chiral magnetic effect.

Contribution

It introduces a novel method based on average transverse momentum for selecting events with stronger magnetic fields in heavy-ion collisions, improving upon traditional ellipticity-based methods.

Findings

Event-shape selection based on $[p_t]$ correlates well with magnetic field strength.

This method offers a more effective way to identify conditions favorable for the chiral magnetic effect.

The approach enhances experimental capabilities in studying electromagnetic phenomena in nuclear collisions.

Abstract

We show that an event-shape engineering based on the mean transverse momentum of charged hadrons, $[p_t]$, provides an optimal handle on the strength of the magnetic field created in central heavy-ion collisions at high energy. This is established through quantitative evaluations of the correlation existing between the event-by-event magnetic field produced by the spectator protons in 5.02 TeV Pb+Pb collisions and the event-by-event $[p_t]$ at a given collision centrality. We argue that the event selection based on $[p_t]$ provides a better handle on the magnetic field than the more traditional selection based on the event ellipticities. Advantages brought by this new method for the experimental search of the chiral magnetic effect are discussed.