Relativistic effects in heavy mesons

TL;DR

The paper addresses the problem of accurately describing the spectra and radiative transitions of heavy mesons that contain at least one heavy quark. It introduces a relativistic potential model with a compact set of parameters and a variational treatment of L=0 and L=1 states, incorporating spin-dependent and Darwin-type corrections that align with Breit-like structures. The authors compute meson masses and the E1/M1 radiative widths, finding qualitative (and in many cases quantitative) agreement with experimental data across cc, bb, bc, cs, cu, and cd systems, and they emphasize the finite behavior as the light-quark mass vanishes. The work demonstrates the importance of relativistic effects in heavy-light mesons and offers predictions for radiative decays that can guide future experimental tests and provide a unified framework for heavy-meson spectroscopy. All results underscore the model's potential to resolve discrepancies that nonrelativistic approaches could not address.

Abstract

We discuss the application of a relativistic potential model to the description of the spectrum and radiative transitions in mesons containing at least one heavy quark (b or c). Although the model has a small number of parameters, it is possible to achieve qualitative agreement with all available experimental data, including those that could not be explained by all previous methods. This demonstrates the importance of taking relativistic effects into account. A remarkable property of the relativistic potential model is that the predictions for meson masses and partial widths of radiative transitions remain finite in the limit of zero light quark mass.