Instituto de Fisica,

Universidad Nacional Autonoma de Mexico,

Apartado Postal 20-364,

01000 Mexico D.F.,

MEXICO

E-mail: moshi@fisica.unam.mx

**Transient phenomena in quantum bound states subjected
to a sudden perturbation**

**Abstract:**

Transient phenomena in quantum mechanics have been of interest to one
of the authors (MM) since long ago and, in this paper, we focus on the
problem of a potential $V_-$ which for negative times gives rise to bound
states and is suddenly changed at $t=0$ to a potential $V_+$ which includes
$V_-$ plus a perturbed term. An example will be the deuteron (where the
proton and neutron are assumed to interact through an oscillator potential)
submitted to a sudden electrostatic

field. The analysis for $t>0$ can be carried out with the help of appropriate
Feynmann propagators and we arrive at the result that the separation between
the nucleons has an amplitude that depends on the intensity of the electrostatic
field, but its period continues to be related with the inverse of the frequency
of the oscillator proposed for the interaction. A general approximate procedure
for arbitrary problems of this type is also presented at the end.

See contribution in PDF.