  The scattering of two charged strongly interacting particles is described on
the basis of the P-matrix approach. In the P matrix, it is proposed to isolate
explicitly the background term corresponding to purely Coulomb interaction,
whereby it becomes possible to improve convergence of the expansions used and
to obtain a correct asymptotic behavior of observables at high energies. The
expressions for the purely Coulomb background P matrix, its poles and residues,
and purely Coulomb eigenfunctions of the P-matrix approach are obtained. The
nuclear-Coulomb low-energy scattering parameters of two charged hadrons are
investigated on the basis of this approach combined with the method of
isolating the background P matrix. Simple explicit expressions for the
nuclear-Coulomb scattering length and effective range in terms of the residual
P matrix are derived. These expressions give a general form of the
nuclear-Coulomb low-energy scattering parameters for models of finite-range
strong interaction. Specific applications of the general expressions derived in
this study are exemplified by considering some exactly solvable models of
strong interaction containing hard core repulsion, and, for these models, the
nuclear-Coulomb low-energy scattering parameters for arbitrary values of the
orbital angular momentum are found explicitly. In particular, the
nuclear-Coulomb scattering length and effective range are obtained explicitly
for the boundary-condition model, the model of a hard-core delta-shell
potential, the Margenau model, and the model of hard-core square-well
potential.
