Polarization observables for millicharged particles in photon collisions

TL;DR

This paper calculates polarization observables for producing millicharged particles of various spins in polarized photon collisions, providing a model-independent method to identify their spin and aiding experimental searches.

Contribution

It offers a systematic, model-independent calculation of polarization observables for millicharged particles of different spins in photon collisions, aiding experimental discrimination.

Findings

Photon polarization asymmetries can distinguish particle spins.

Calculations are based on electromagnetic gauge invariance and unitarity.

Results are applicable to photon-photon collision experiments.

Abstract

Particles in a hidden sector can potentially acquire a small electric charge through their interaction with the Standard Model and can consequently be observed as millicharged particles. We systematically compute the production of millicharged scalar, fermion and vector boson particles in collisions of polarized photons. The presented calculation is model independent and is based purely on the assumptions of electromagnetic gauge invariance and unitarity. Polarization observables are evaluated and analyzed for each spin case. We show that the photon polarization asymmetries are a useful tool for discriminating between the spins of the produced millicharged particles. Phenomenological implications for searches of millicharged particles in dedicated photon-photon collision experiments are also discussed.