Cool WISPs for stellar cooling excesses

TL;DR

This paper investigates whether Weakly Interacting Slim Particles (WISPs) like axion-like particles and hidden photons can explain stellar cooling excesses observed in various stars, suggesting potential new physics detectable in upcoming experiments.

Contribution

It provides a comprehensive analysis of stellar cooling anomalies in terms of various WISPs, identifying ALPs and massless hidden photons as the most promising explanations.

Findings

ALPs and massless hidden photons can potentially explain the cooling excesses.

The ALP parameter space is testable by upcoming experiments like ALPS II and IAXO.

Massless hidden photons imply new physics at multi-TeV scales accessible at the LHC.

Abstract

Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a mild preference for a non-standard cooling mechanism when compared with theoretical models. This exotic cooling could be provided by Weakly Interacting Slim Particles (WISPs), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. Taken individually, these excesses do not show a strong statistical weight. However, if one mechanism could consistently explain several of them, the hint could be significant. We analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (ALPs). Among them, the ALP or a massless HP represent the best solution. Interestingly, the hinted ALP parameter space is accessible to the next generation proposed ALP searches, such as ALPS II and IAXO and the massless HP requires a multi TeV energy scale of new physics that might be accessible at the LHC.