Schwarzschild black hole as particle accelerator of spinning particles

TL;DR

This paper demonstrates that spinning particles near a Schwarzschild black hole can collide with unbounded energy in the center of mass frame, extending the Bañados-Silk-West effect to spinning particles and highlighting the role of near-critical trajectories.

Contribution

It shows the existence of a BSW-like effect for spinning particles in Schwarzschild spacetime, including conditions for unbounded collision energy and the impact of multiple scattering.

Findings

Unbounded center-of-mass energy possible for spinning particles near Schwarzschild black holes.

Near-critical trajectories are crucial for high-energy collisions.

Multiple scattering allows high-energy collisions even when initial energy-to-mass ratio is above a certain threshold.

Abstract

It is shown that in the Schwarzschild background there exists direct counterpart of the Ba\~{n}ados-Silk-West effect for spinning particles. This means that if two particles collide near the black hole horizon, their energy in the centre of mass frame can grow unbounded. In doing so, the crucial role is played by so-called near-critical trajectories when particle's parameters are almost fine-tuned. Direct scenario of the collision under discussion is possible with restriction on the energy-to-mass ratio \thinspace $E/m<\frac{1}{2\sqrt{3}}$ only. However, if one takes into account multiple scattering, this becomes possible for $E\geq m$ as well.