Semirelativistic stability of boson stars and tightened bounds on their critical mass

We study a system of self-gravitating identical bosons by means of a semirelativistic Hamiltonian comprising the relativistic kinetic energies of the involved particles and added (instantaneous) Newtonian gravitational pair interaction potentials. With the help of an improved lower bound to the bottom of the spectrum of this Hamiltonian, we are able to enlarge the known region for relativistic stability of boson stars against gravitational collapse and to sharpen the predictions for their maximum stable mass.