Solutions of a Dirac hydrogenlike mesons and scalar confinement in low orbital angular momentum states

Wavefunctions of a relativistic heavy quark-light quark $(Q,q)$ system described by a Dirac hamiltonian are analyzed. By assuming that the confinement potential is a Lorentz scalar (S), the slope of the Isgur-Wise function is calculated at zero recoil point. The result obtained is $\xi^\prime(1)=-0.93\pm 0.05.$ This means that the solutions are perfectly consistent. If relativistic corrections in the light quark wave functions are included the result is $\xi^\prime(1)=-1.01\pm 0.04.$ From heavy-light data this suggest that if relativistic effects are considered, scalar confinement is reliable in low orbital angular momentum states.