Spin-orbit inversion of excited heavy quark mesons

Abstract

The mesonic heavy quark spin multiplets with s{sub scr(l)}{sup {pi}{sub scr(l)}}= (1) /(2) {sup +} and (3) /(2) {sup +} are expected to be the lowest-lying excitations above the pseudoscalar and vector ground states with s{sub scr(l)}{sup {pi}{sub scr(l)}}= (1) /(2) {sup {minus}}. I show that for charm and bottom these multiplets are probably inverted, with the 2{sup +} and 1{sup +} states with s{sub scr(l)}{sup {pi}{sub scr(l)}}= (3) /(2) {sup +} about 150MeV {ital below} the 1{sup +} and 0{sup +} states with s{sub scr(l)}{sup {pi}{sub scr(l)}}= (1) /(2) {sup +}. If verified, such an inversion would both support the expectation that confinement has no dynamical spin-dependence and indicate that heavy- and light-quark systems may be characterized by the same effective low-energy degrees of freedom. As an important by-product, this work establishes the dynamics of the strange quark as a critical link between heavy- and light-quark hadrons, justifying efforts toward a much more complete experimental and theoretical understanding of strange mesons and baryons and of strange quarkonia. {copyright} {ital 1998} {ital The American Physical Society}