Remark on Immirzi Parameter, Torsion, and Discrete Symmetries

TL;DR

This paper explores the symmetry properties of torsion interactions in quantum gravity, revealing that the new spin-torsion coupling is odd under charge conjugation and time reversal, affecting effective fermion interactions.

Contribution

It highlights the C and T odd nature of spin-torsion interactions, providing insight into their symmetry properties and implications for effective fermion interactions.

Findings

Spin-torsion interaction is odd under charge conjugation.

Interaction is also odd under time reversal.

Impacts the symmetry understanding of fermion interactions in quantum gravity.

Abstract

We point out that the new interaction of spinning particles with the torsion tensor, discussed recently, is odd under charge conjugation and time reversal. This explains rather unexpected symmetry properties of the induced effective 4-fermion interaction.