Semileptonic $Λ_{b,c}$ to Nucleon Transitions in Full QCD at Light Cone

Abstract

The tree level semileptonic Λ b → plν and Λc → nlν transitions are investigated using the light cone QCD sum rules approach in full theory. The spin-1/2, ΛQ baryon with Q = b or c, is considered by the most general form of its interpolating current. The time ordering product of the initial and transition currents is expanded in terms of the nucleon distribution amplitudes with different twists. Considering two sets of independent input parameters entering to the nucleon wave functions, namely, QCD sum rules and Lattice QCD parameters, the related form factors and their heavy quark effective theory limits are calculated and compared with the existing predictions of other approaches. It is shown that our results satisfy the heavy quark symmetry relations for lattice input parameters and b case exactly and the maximum violation is for charm case and QCD sum rules input parameters. The obtained form factors are used to compute the transition rates both in full theory and heavy quark effective theory. A comparison of the results on decay rate of Λ b → plν with those predicted by other phenomenological methods or the same method in heavy quark effective theory with different interpolating current and distribution amplitudes of the Λ b is also presented.

Charmed Baryon Physics Circa 2021

“…These form factors have been evaluated using the non-relativistic quark model (NRQM) [227][228][229][230], MIT bag model [227], relativistic quark model (RQM) [231][232][233][234] light-front quark model (LFQM) [222,[235][236][237], QCD sum rules (QSR) [238][239][240][241][242], lattice QCD [243][244][245] and SU(3) flavor symmetry [246].…”

Charmed baryons circa 2015

“…Dipole q 2 dependence for form factors is assumed whenever the form factor momentum dependence is not available in the model. Four different sets of predictions for Λ + c → ne + ν e not listed in Table XIII were presented in the sum rule calculations of [121]. The semileptonic decays of Ω c have been treated in [122] within the framework of a constituent quark model.…”

$Λ_b \to p l^- \barν$ form factors from lattice QCD with static b quarks

“…Calculations of Λ b → p form factors have been performed using QCD sum rules [14,15] and light-cone sum rules [16][17][18][19]. Light-cone sum rules are most reliable at low q 2 (corresponding to large proton momentum in the Λ b rest frame), and even there the uncertainty of the best available calculations is of order 20% [19].…”