Toward the discovery of novel <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>B</mml:mi><mml:mi>c</mml:mi></mml:msub></mml:math> states: Radiative and hadronic transitions
B. Martín-González, Pablo G. Ortega, D. R. Entem, F. Fernández, Jorge Segovia
Abstract
The properties of the ${B}_{c}$-meson family ($c\overline{b}$) are still not well determined experimentally because the specific mechanisms of formation and decay remain poorly understood. Unlike heavy quarkonia, i.e., the hidden heavy quark-antiquark sectors of charmonium ($c\overline{c}$) and bottomonium ($b\overline{b}$), the ${B}_{c}$ mesons cannot annihilate into gluons and they are, consequently, more stable. The excited ${B}_{c}$ states, lying below the lowest strong-decay $BD$ threshold, can only undergo radiative decays and hadronic transitions to the ${B}_{c}$ ground state, which then decays weakly. As a result of this, a rich spectrum of narrow excited states below the $BD$ threshold appear, whose total widths are 2 orders of magnitude smaller than those of the excited levels of charmonium and bottomonium. In a different article, we determined bottom-charmed meson masses using a nonrelativistic constituent quark model which has been applied to a wide range of hadron physical observables, and thus the model parameters are completely constrained. Herein, continuing to our study of the ${B}_{c}$ sector, we calculate the relevant radiative decay widths and hadronic transition rates between $c\overline{b}$ states which are below the $BD$ threshold. This shall provide the most promising signals for discovering excited ${B}_{c}$ states that are below the lowest strong-decay $BD$ threshold. Finally, our results are compared with other models to measure the reliability of the predictions and point out differences.