Spectroscopy and Regge trajectories of heavy quarkonia and B_c mesons

TL;DR

This paper calculates the mass spectra of heavy quarkonia and B_c mesons using a relativistic quark model, constructs Regge trajectories, and compares results with experimental data to interpret new charmonium-like states.

Contribution

It provides a fully relativistic calculation of heavy quarkonium spectra up to high excitations and analyzes the nonlinearity of Regge trajectories, including new insights into charmonium-like states.

Findings

Regge trajectories are nearly linear and parallel for daughter states.

Parent trajectories show nonlinearity, especially in bottomonia.

Results align with experimental data and suggest interpretations for new charmonium-like states.

Abstract

The mass spectra of charmonia, bottomonia and B_c mesons are calculated in the framework of the QCD-motivated relativistic quark model based on the quasipotential approach. The dynamics of heavy quarks and antiquarks is treated fully relativistically without application of the nonrelativistic v^2/c^2 expansion. The known one-loop radiative corrections to the heavy quark potential are taken into account perturbatively. The heavy quarkonium masses are calculated up to rather high orbital and radial excitations (L=5, n_r=5). On this basis the Regge trajectories are constructed both in the total angular momentum J and radial quantum number n_r. It is found that the daughter trajectories are almost linear and parallel, while parent trajectories exhibit some nonlinearity in the low mass region. Such nonlinearity is most pronounced for bottomonia and is only marginal for charmonia. The obtained results are compared with the available experimental data, and a possible interpretation of the new charmonium-like states above open charm production threshold is discussed.