Аннотация:The
production
of
an
electron-positron
pair
by
two circularly polarized
photons
in
an
external
crossed
field is
investigated.
It is shown
that
in a
weak
field
the
total
cross section is
determined
not only
by
the perturbation-theory
series
but
also
by
the
oscillating
terms.
The
dependence
of the
cross section
on
the
photon
energy is found.
The
conditions under
which
the
effect
of
an
external
field
can
be
observed
are
indicated.