Astrophysical methods to constrain axions and other novel particle phenomena

Axion decay in a strong magnetic field

“…Therefore the axion [2], the pseudo-Goldstone boson associated with P Q-symmetry, is the subject of constant theoretical and experimental investigations (see, for example, [3,4]). The allowed range for the axion mass, and therefore for the P Q-symmetry breaking scale, f a : m a ≃ 6.3 10 6 GeV f a eV, (…”

“…is strongly constrained by astrophysical and cosmological considerations which leave a rather narrow window [3,4,5,6]:…”

“…It can be naturally explained by the fact that axions are very light, very weakly interacting (coupling constant ∼ f −1 a ) and very long living. The axion lifetime in vacuum is [3]:…”

Soft RPV through the baryon portal

“…A spontaneously broken R-symmetry gives rise to a massless R-axion that can accelerate supernova cooling and cause cosmological problems [28]. Conventionally, R-breaking arises only in the SUSY breaking sector and the BPR mechanism [29] generates an R-axion mass from a constant term in the superpotential introduced to cancel the cosmological constant.…”

Astrophysical Axion Bounds

“…Even when this particle flux cannot be directly measured, the properties of stars themselves would change if they lost too much energy into a new channel. This "energy-loss argument" has been widely used to constrain a long list of particle properties, see [1][2][3][4][5][6][7] for early examples and [8][9][10][11][12] for extensive reviews. We summarize here the main arguments that have been put forward, the observational evidence, and the resulting constraints for "invisible axions.…”