The dynamics of the approach to equilibrium of the hydrogen atom is investigated numerically through a Monte Carlo procedure. We show that, before approaching ionization, the hydrogen atom may live in a quasi-equilibrium state, characterized by aging, whose duration increases exponentially as...

A special quantum-group oscillator presents an upper bound in its energy spectrum, which is preceded by an accumulation of infinite levels. The standard Boltzmann–Gibbs (BG) statistical-mechanics formalism is inadequate for dealing with such systems, since the partition function diverges for...