Combined nonrelativistic constituent quark model and heavy quark effective theory study of semileptonic decays of {lambda}{sub b} and {xi}{sub b} baryons
- Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain)
- Grupo de Fisica Nuclear, Facultad de Ciencias, E-37008 Salamanca (Spain)
We present the results of a nonrelativistic constituent quark model study of the semileptonic decays {lambda}{sub b}{sup 0}{yields}{lambda}{sub c}{sup +}l{sup -}{nu}{sub l} and {xi}{sub b}{sup 0}{yields}{xi}{sub c}{sup +}l{sup -}{nu}{sub l} (l=e,{mu}). We work on coordinate space, with baryon wave functions recently obtained from a variational approach based on heavy quark symmetry. We develop a novel expansion of the electroweak current operator, which supplemented with heavy quark effective theory constraints, allows us to predict the baryon form factors and the decay distributions for all q{sup 2} (or equivalently w) values accessible in the physical decays. Our results for the partially integrated longitudinal and transverse decay widths, in the vicinity of the w=1 point, are in excellent agreement with lattice calculations. Comparison of our integrated {lambda}{sub b}-decay width to experiment allows us to extract the V{sub cb} Cabbibo-Kobayashi-Maskawa matrix element for which we obtain a value of |V{sub cb}|=0.040{+-}0.005(stat){sub -0.002}{sup +0.001}(theory) also in excellent agreement with a recent determination by the DELPHI Collaboration from the exclusive B{sub d}{sup 0}{yields}D*{sup +}l{sup -}{nu}{sub l} decay. Besides for the {lambda}{sub b}({xi}{sub b})-decay, the longitudinal and transverse asymmetries and the longitudinal to transverse decay ratio are <a{sub L}>=-0.954{+-}0.001(-0.945{+-}0.002), <a{sub T}>=-0.665{+-}0.002(-0.628{+-}0.004), and R{sub L/T}=1.63{+-}0.02(1.53{+-}0.04), respectively.
- OSTI ID:
- 20705709
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 71, Issue 1; Other Information: DOI: 10.1103/PhysRevD.71.014012; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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