Estimates of Riesz Constants for the Dirac System with an Integrable Potential

We consider the Dirac operator on the interval [0, pi] with an integrable potential P = (p(ij) (x))(i,j-1)(2) and strongly regular boundary conditions U. It is well known that for any integrable potential P the system {y(n) }(n subset of Z) of root functions of the strongly regular operator L-P,L-U is a Riesz basis in the space H = L-2[0, pi] x L-2[0, pi]. We obtain estimates, uniform on every compact set of potentials, of the Riesz constants parallel to T parallel to parallel to T (1)parallel to, where T is the operator of transition to an orthonormal basis.