Constraining Heavy Axionlike Particles by Energy Deposition in Globular Cluster Stars

Heavy axionlike particles (ALPs) with masses up to a few 100 keV and coupled with photons can be efficiently produced in stellar plasmas. We present a new "ballistic" recipe that covers both the energy-loss and energy-transfer regimes, and we perform the first dedicated simulation of Globular Cluster stars including the ALP energy transfer. This argument allows us to constrain ALPs with m_a≲0.4 MeV and g_{a γ}≃10^-5 GeV^-1 , probing a section of the ALP parameter space informally known as the "cosmological triangle". This region is particularly interesting since it has been excluded only using standard cosmological arguments that can be evaded in nonstandard scenarios.