HYPERFINE MIXING IN b → c SEMILEPTONIC AND ELECTROMAGNETIC DECAYS OF DOUBLY HEAVY bc BARYONS

C Albertus,J Nieves,E Hernández

doi:10.1142/s2010194514601070

Abstract

We show that semileptonic and electromagnetic decays involving spin-1/2 doubly heavy bc baryons are very sensitive to hyperfine mixing in their wave functions. We further show how heavy quark spin symmetry relations, obtained in the infinite heavy quark mass limit and near zero recoil, could be used to extract the admixtures in a model independent way from semileptonic decay data. On the other hand the infinite heavy quark mass limit gives wrong predictions in the electromagnetic case.

Highlights

For baryons with two heavy quarks, heavy quark spin symmetry (HQSS) tell us that, in the infinite heavy quark mass limit, the total spin of the two heavy quark subsystem Sh can be chosen to be well defined, either Sh = 0 or Sh = 1.1 This isC
We show that semileptonic and electromagnetic decays involving spin-1/2 doubly heavy bc baryons are very sensitive to hyperfine mixing in their wave functions
We further show how heavy quark spin symmetry relations, obtained in the infinite heavy quark mass limit and near zero recoil, could be used to extract the admixtures in a model independent way from semileptonic decay data

Summary

Quark content Shπ

Because the actual heavy quark masses are finite, the hyperfine interaction between the light quark and any of the heavy quarks can admix both Sh = 0 and Sh = 1 components into the wave function This is known as hyperfine mixing and it is only relevant for total spin-1/2 states. The first calculation to use mixed states was presented in Ref. 4 and there the authors showed the tremendous impact configuration mixing had on b → c semileptonic transitions involving spin-1/2 bc baryons. In this contribution we present our results in Ref. 2 for b → c semileptonic decay widths, that qualitatively confirm the findings in Ref. 4, and the results for electromagnetic decays that we obtained in Ref. 5. All parameters in the potential (including quark masses) were adjusted to describe the light and heavy-light meson spectrum

For its use in baryons we take the usual prescription

This work