Bound on the curvature of the Isgur-Wise function of the baryon semileptonic decay {lambda}{sub b}{yields}{lambda}{sub c}l{nu}{sub l}
- Laboratoire de Physique Theorique, Universite de Paris XI, Batiment 210, 91405 Orsay Cedex (France)
In the heavy quark limit of QCD, using the operator product expansion, the formalism of Falk for hadrons of arbitrary spin, and the nonforward amplitude, as proposed by Uraltsev, we formulate sum rules involving the Isgur-Wise function {xi}{sub {lambda}}(w) of the baryon transition {lambda}{sub b}{yields}{lambda}{sub c}l{nu}{sub l}, where the light cloud has j{sup P}=0{sup +} for both initial and final baryons. We recover the lower bound for the slope {rho}{sub {lambda}}{sup 2}=-{xi}{sub {lambda}}{sup '}(1){>=}0 obtained by Isgur et al., and we generalize it by demonstrating that the Isgur-Wise function {xi}{sub {lambda}}(w) is an alternate series in powers of (w-1), i.e. (-1){sup n}{xi}{sub {lambda}}{sup (n)}(1){>=}0. Moreover, exploiting systematically the sum rules, we get an improved lower bound for the curvature in terms of the slope, {sigma}{sub {lambda}}{sup 2}={xi}{sub {lambda}}{sup ''}(1){>=}(3/5)[{rho}{sub {lambda}}{sup 2}+({rho}{sub {lambda}}{sup 2}){sup 2}]. This bound constrains the shape of the Isgur-Wise function and it will be compelling in the analysis of future precise data on the differential rate of the baryon semileptonic decay {lambda}{sub b}{yields}{lambda}{sub c}l{nu}{sub l}, that has a large measured branching ratio, of about 5%.
- OSTI ID:
- 21254706
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 79, Issue 1; Other Information: DOI: 10.1103/PhysRevD.79.014023; (c) 2009 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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