Quantum Cherenkov radiation by spinless and spin-1/2 particles

TL;DR

This paper explores quantum corrections to Cherenkov radiation for spinless and spin-1/2 particles using Quantum Field Theory, revealing that quantum effects depend on the medium and that spin flips are negligible for spin-1/2 particles.

Contribution

It provides a quantum Field Theory analysis of Cherenkov radiation for both spinless and spin-1/2 particles, including spin flip considerations and polarization properties.

Findings

Quantum corrections depend on the refractive index for absolute values.

Relative quantum corrections are medium-independent for ultrarelativistic particles.

Spin flip is practically negligible for spin-1/2 particles in this process.

Abstract

In this paper, the Cherenkov radiation process is investigated in the frame of the Quantum Field Theory, both for the spinless and spin-1/2 charged particles. In the latter case, the polarization density matrix technique was used to account for the spin flip. If compared with the Classical Electrodynamics results, in both cases several quantum corrections arise, coinciding up to the photon's energy linear term. It is shown that, while the absolute value of these corrections significantly relies on the refractive index, the relative quantum correction stays independent of the medium in the case of the ultrarelativistic particles. It the case of the spin-1/2 particles it turns out that the spin flip practically never occurs in this process. For both cases, spinless and spin-1/2, the outgoing photon polarization vector lies always in the plane formed by the initial particle's momentum vector and the final photon's wave vector.