Second-order power corrections in the heavy-quark effective theory. II. Baryon form factors

Abstract

The analysis of 1/m 2 Q corrections of the previous paper is extended to the semileptonic decays of heavy baryons. We focus on the simplest case, the ground state Λ Q baryons, in which the light degrees of freedom are in a state of zero total angular momentum. The formalism, while identical in spirit, is considerably less cumbersome than for heavy mesons. The general results are applied to the semileptonic decay Λ b → Λ c ℓ ν. An estimate of the leading power corrections to the decay rate at zero recoil, which are of order 1/m 2 Q , is presented. It is pointed out that a measurement of certain asymmetry parameters would provide a direct measurement of 1/m 2 Q corrections. Finally, it is shown how the analysis could be extended to include excited heavy baryons such as the Σ Q and the Σ * Q .

Model-independent extraction of |Vcb| using dispersion relations

“…The normalization of the form factor g(ω = 1) has been estimated to be g(1) = 0.96 [17], g(1) = 0.89 [18], and g(1) = 0.93 [19]. We have included a QCD correction of 0.985, so to good approximation, this simply rescales the values of |V cb | in Table 1 by 0.985 g (1) .…”

Lectures on Heavy Quarks in Quantum Chromodynamics

“…In this aspect the derivation I present here goes beyond the more conventional analysis of Ref. [43,42]. The reader is nevertheless advised to consult the latter works to get a broader perspective of the heavy quark theory -the more approaches you master the better for you.…”

Semi-inclusive decaysΛb→Xc+(Ds,Ds*)atFischer1, Groote2, Körner3 et al. 2004Phys. Rev. D

“…An estimate of the spin-dependent parameter has been given in [16] with the result ǫ b = − K b [17] which puts the estimate of [16] at the upper bound of the constraint. We use the value of [16] keeping in mind that the numerical value of ǫ b could be reduced in more realistic calculations.…”