Description of mass spectrum of Bc-meson family
DOI:
https://doi.org/10.24144/2415-8038.2019.46.107-117Keywords:
The calculated energy levels of the system ¯bc can be used for experimental search for Bc mesons.Abstract
Purpose. Calculation of the spectrum of masses of system ¯bc consisting of two heavy b and c quarks (Bc mesons family) within the potential models of heavy quarkonium. In particular, to calculate the spin-dependent splitting of the energy S and P levels of a given of heavy mesons family. Investigate the dependence of the energy splitting magnitude on the parameters of the interaction potential between the quarks.
Methods. The spin-dependent splittings of the S and P energy levels caused by spin-spin, spin-orbital and tensor interactions in the framework of the Breit-Fermi quasi-relativistic approximation with the screened quark interaction potential are calculated. Wave functions and matrix elements of spin-spin, spin-orbital and tensor interactions were calculated numerically.
Results. It is found that the energies of the S and P levels and the magnitude of the «fine» and «hyperfine» splitting depend essentially on the mixing constant λ of scalar and vector long-range screening potential and the constant of the strong interaction αs (whose value is almost unchanged within the Bc meson family). Increasing the contribution of the Lorentz vector potential to operators of spin-orbital, spin-spin and tensor interactions leads to increase of the magnitude of the corresponding splittings of energy levels. The obtained value of the mixing constant λ = 0.3 indicates that the confined screened potential has a predominantly scalar Lorentz nature (about 70 %), and the Coulomb-like potential of one-gluon exchange is purely a Lorentz vector.
Conclusions. The calculated energy levels of the system ¯bc can be used for experimental search for Bc mesons.
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