Minicharged Particles from the Sun: A Cutting-Edge Bound

Abstract

We study the impact on the Sun of an exotic energy-loss channel caused by plasmon decay into fermionic minicharged particles with charge $\epsilon e$ and mass $m_f$. We compare solar models with this extra emission to helioseismological and neutrino data, obtaining a bound $\epsilon <2.2\times 10^{-14}\ ({\rm 95\%\, CL})$ for $m_f\lesssim 25 \, \text{eV}$. Our result is comparable to previous limits from the cooling of globular cluster stars, while at the same time it is better understood and takes theoretical and observational errors into account.