Axion-like particles (ALPs) coupled to nucleons can be efficiently produced in core-collapse supernovae (SNe) and then, if they couple to photons, convert into gamma rays in cosmic magnetic fields, generating short gamma-ray bursts. Though ALPs from a Galactic SN would induce an intense and easily detectable gamma-ray signal, such events are exceedingly rare. In contrast, a few SNe per year...
The study of semileptonic $B$ decays into charmed mesons $D^{(*)}$ plays a crucial role in the determination of CKM matrix element $V_{cb}$, improving and studying the nonperturbative dynamics of QCD, in testing heavy-quark symmetry. Indeed, these processes are described by matrix elements between hadronic states, which are nonperturbative. They can be expressed in terms of functions of $q^2$...
