Abstract

We make an analysis of three -loop effects of the strong coupling constant in the study of masses and decay constants of the heavy-flavour pseudo-scalar mesons (PSM) D, D_s , B, B_s,B_c, eta _c and eta _b in a non-relativistic QCD potential model using Dalgarno’s perturbation theory (DPT). The first order mesonic wavefunction is obtained using Dalgarno’s perturbation theory. The three-loop effects of strong coupling constant are included in the wave function in co-ordinate space and then used to examine the static and dynamic properties of the heavy-flavour mesons for 2S and 3S higher states. The results are compared with the other models available and are found to be compatible with available experimental values. In V-scheme, the three-loop effects on masses and decay constants of heavy-flavour mesons show a significant result.

Highlights

  • The non-relativistic predictions of Potential Models with a non-relativistic Hamiltonian for the heavy-light and heavyheavy mesons are found to be in fair agreement with the updated experimental data, theoretical results like QCD sum rule [1,2], Lattice results [3] and relativistic harmonic confinement model (RHCM) [53]

  • V-scheme is a standard way of taking into account the higher order effects of QCD, which are expressed as power series in the running strong coupling constant αM S in M S-scheme

  • The mass and the decay constant of heavy-flavour pseudoscalar meson including only spin–spin interaction are given in [26,27] as: MP = m1 + m2 + En,l + Hss where, m1 and m2 are the masses of quark–antiquark and αs is the strong coupling constant identified as αV in the present work, En,l is the non-relativistic binding energy between the quark–antiquark composition and the van Royen–Weisskopf formula [54] for the decay of pseudo-scalar meson is, fP =

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Summary

Introduction

The non-relativistic predictions of Potential Models with a non-relativistic Hamiltonian for the heavy-light and heavyheavy mesons are found to be in fair agreement with the updated experimental data, theoretical results like QCD sum rule [1,2], Lattice results [3] and relativistic harmonic confinement model (RHCM) [53]. We have obtained a total first order corrected wavefunction for 2S and 3S states using Dalgarno’s method of perturbation [30] with linear part of the Cornell potential [19,31] as perturbation in co-ordinate space. This wavefunction is used to estimate the masses and decay constants of heavy-light and heavy-heavy pseudo-scalar mesons in this improved QCD Potential model approach. The rest of the paper is organised as follows: Sect. 2 contains formalism, Sect. 3 contains results while Sect. 4 includes the conclusion

V-scheme: three-loop effects
Dalgarno’s perturbation theory
The expression of mass and decay constant of pseudo-scalar meson
Input parameters used in the calculation
Calculation of effective strong coupling constant
Calculation of different parameters used in the expression of mass MP
Sources of uncertainties and possible future improvements
Conclusion
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