Kerr-Sen Black Hole as Accelerator for Spinning Particles

TL;DR

This paper investigates whether Kerr-Sen black holes can accelerate spinning particles to arbitrarily high energies, extending previous work on geodesic particles by including spin effects through the Mathisson-Papapetrou-Dixon equations.

Contribution

It introduces the analysis of spinning particles in Kerr-Sen black holes and demonstrates conditions for infinite collision energy involving spin and angular momentum.

Findings

Divergence of collision energy occurs under critical relations of energy and angular momentum.

Spinning particles can reach arbitrarily high energies near Kerr-Sen black holes.

The study extends BSW mechanism to include particle spin effects.

Abstract

It has been proved that arbitrarily high-energy collision between two particles can occur near the horizon of an extremal Kerr black hole as long as the energy $E$ and angular momentum $L$ of one particle satisfies a critical relation, which is called the BSW mechanism. Previous researchers mainly concentrate on geodesic motion of particles. In this paper, we will take spinning particle which won't move along a timelike geodesic into our consideration, hence, another parameter $s$ describing the particle's spin angular momentum was introduced. By employing the Mathisson-Papapetrou-Dixon equation describing the movement of spinning particle, we will explore whether a Kerr-Sen black hole which is slightly different from Kerr black hole can be used to accelerate a spinning particle to arbitrarily high energy. We found that when one of the two colliding particles satisfies a critical relation between the energy $E$ and the total angular momentum $J$, or has a critical spinning angular momentum $s_c$, a divergence of the center-of-mass energy $E_{cm}$ will be obtained.