Hyperfine mixing in electromagnetic decay of doubly heavy bc baryons

C Albertus,E Hernández,J Nieves

doi:10.1016/j.physletb.2010.05.042

C Albertus, E Hernández + Show 1 more

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https://doi.org/10.1016/j.physletb.2010.05.042

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Abstract

We investigate the role of hyperfine mixing in the electromagnetic decay of ground state doubly heavy bc baryons. As in the case of a previous calculation on b→c semileptonic decays of doubly heavy baryons, we find large corrections to the electromagnetic decay widths due to this mixing. Contrary to the weak case just mentioned, we find here that one cannot use electromagnetic width relations obtained in the infinite heavy quark mass limit to experimentally extract information on the admixtures in a model independent way.

Highlights

In the infinite heavy quark mass limit, and according to heavy quark spin symmetry (HQSS) [1], one can select the heavy quark subsystem of a doubly heavy baryon to have a well defined total spin Sh = 0, 1
The calculation for b → c semileptonic decay of doubly heavy baryons was conducted by the same authors in Ref. [16], where they found that hyperfine mixing in the bc states had a tremendous impact on the decay widths
As a result of these considerations we included in Ref. [17] predictions for ratios that involved e.m. decay widths evaluated in the infinite heavy quark mass limit

Summary

INTRODUCTION

There, we showed how HQSS predictions for b → c semileptonic decay, could be used to experimentally obtain information on the admixtures of the bc baryons in a model independent manner Those ratios involved weak decays that have competing electromagnetic (e.m.) decays and they will be difficult to observe experimentally. [17] predictions for ratios that involved e.m. decay widths evaluated in the infinite heavy quark mass limit This limit implies that the spin of the heavy quark subsystem can not change in an e.m. transition. We are far from the infinite heavy quark mass limit according to which the spin of the heavy quark subsystem can not change in an e.m. transition Due to this fact the e.m. decay width ratios proposed in Ref. IV we present the results and the conclusions of our work

ELECTROMAGNETIC DECAY

Note the normalization of the baryon states should be such that

Nonrelativistic states

Matrix elements evaluation

RESULTS AND CONCLUSIONS