Regge trajectory relation for the universal description of the heavy-heavy systems: diquarks, mesons, baryons and tetraquarks

Abstract

By employing the nonlinear Regge trajectory relation M=mR+βx(x+c0x)2/3(x=l,nr), we investigate the heavy-heavy systems, such as the doubly heavy diquarks, the doubly heavy mesons, the heavy-heavy baryons, and the heavy-heavy tetraquarks. The fitted Regge trajectories illustrate that these heavy-heavy systems satisfy the above formula and show the existence of an universal description of the heavy-heavy systems. The universality embodies not only the universal behavior M∼x2/3 but also the universal parameters. The values of cfnr and cfl vary with different heavy-heavy systems, but they are close to one. There is an inequality βnr>βl, and it holds for all the discussed heavy-heavy systems. Moreover, the expression of βx [Eq. (11)] explains its variation with the change of the constituents' masses.