Hyperfine mixing in semileptonic decay of doubly heavy baryons

Abstract

We qualitatively corroborate the results of W. Roberts and M. Pervin in Int. J. Mod. Phys. A 24, 2401 according to which hyperfine mixing greatly affects the decay widths of b → c semileptonic decays involving doubly heavy bc baryons. However, our predictions for the decay widths of the unmixed states differ from those reported in the work of Roberts and Pervin by a factor of 2, and this discrepancy translates to the mixed case. We further show that the predictions of heavy quark spin symmetry, might be used in the future to experimentally extract information on the admixtures in the actual physical bc baryons, in a model independent manner.

The role of hyperfine mixing in b→c semileptonic decays of doubly-heavy baryons

“…[3] and [4]. Our study on the semileptonic decay widths of bc baryons qualitatively corroborate the findings of Roberts and Pervin.…”

“…Mixed bc states are obtained by diagonalizing the corresponding mass matrices. In our calculation, the mixed states and masses are given by [3] …”

Exclusivec→s,dsemileptonic decays of ground-state spin-1/2and spin-Albertus1, Hernández2, Nieves3 2012Phys. Rev. DSelf Cite

“…[3] in the framework of the potential approach and QCD sum rules 1 . Since the modulus of the Cabbibo-Kobayashi-Maskawa (CKM) matrix elements |V cs |, |V cd | are much larger than |V cb |, one would expect the decay widths for c → s, d semileptonic decay of cb baryons to be much larger than the corresponding b → c driven decays which have been more extensively studied in the literature [1,[4][5][6][7][8]. However, this is corrected by a smaller available phase space, and the decay widths for c → s transitions turn out to be larger but of the same order of magnitude as the b → c decay widths, while widths for c → d transitions are much smaller.…”

“…The quark model masses in Table I have been taken from our previous works in Refs. [8,15], where they were obtained using the AL1 potential of Refs. [16,17].…”

“…For doubly heavy cb baryons baryons there is no experimental information on their masses and we shall use our own predictions in Ref. [8].…”