The major problem in the cosmological nucleosynthesis is the evaluation of
the reaction rate. The present scenario is that the standard thermonuclear
function in the Maxwell-Boltzmann form is evaluated by using various
techniques. The Maxwell-Boltzmannian approach to nuclear reaction rate theory
is extended to cover Tsallis statistics (Tsallis, 1988) and more general cases
of distribution functions. The main purpose of this paper is to investigate in
some more detail the extended reaction probability integral in the equilibrium
thermodynamic argument and in the cut-off case. The extended reaction
probability integrals will be evaluated in closed form for all convenient
values of the parameter by means of residue calculus. A comparison of the
standard reaction probability integrals with the extended reaction probability
integrals is also done.Comment: 21 pages, LaTe