Diquarks and the Semi-Leptonic Decay of ${\Lambda }_b$ in the Hybrid Scheme

Abstract

In this work we use the heavy-quark-light-diquark picture to study the semileptonic decay ${\Lambda }_b\to {\Lambda }_c+l+{\bar{\nu }}_l$ in the so-called hybrid scheme. Namely, we apply the heavy quark effective theory (HQET) for larger $q^2$ (corresponding to small recoil), which is the invariant mass square of $l+\bar{\nu }$, whereas the perturbative QCD approach for smaller $q^2$ to calculate the form factors. The turning point where we require the form factors derived in the two approaches to be connected, is chosen near ${\rho }_{cut}=1.1$. It is noted that the kinematic parameter $\rho$ which is usually adopted in the perturbative QCD approach, is in fact exactly the same as the recoil factor $\omega =v\cdot v^{\prime }$ used in HQET where $v$, $v^{\prime }$ are the four velocities of ${\Lambda }_b$ and ${\Lambda }_c$ respectively. We find that the final result is not much sensitive to the choice, so that it is relatively reliable. Moreover, we apply a proper numerical program within a small range around ${\rho }_{cut}$ to make the connection sufficiently smooth and we parameterize the form factor by fitting the curve gained in the hybrid scheme. The expression and involved parameters can be compared with the ones gained by fitting the experimental data. In this scheme the end-point singularities do not appear at all. The calculated value is satisfactorily consistent with the data which is recently measured by the DELPHI collaboration within two standard deviations.

arXiv comment16 pages, including 4 figures, revtex4

References in corpus (21)

• Penguin Enhancement and $B\to K\pi$ decays in perturbative QCD
• Fat penguins and imaginary penguins in perturbative QCD
• Branching Ratio and CP Violation of B to pi pi Decays in Perturbative QCD Approach
• Covariant Light-Front Approach for s-wave and p-wave Mesons: Its Application to Decay Constants and Form Factors
• Infrared factorization in inclusive B meson decays
• Second Order Power Corrections in the Heavy Quark Effective Theory II. Baryon Form Factors
• Applicability of Perturbative QCD to $B\to D$ Decays
• QCD Sum Rule Analysis for the Λ_b to Λ_c Semileptonic Decay
• 1/m Corrections to Heavy Baryon Masses in the Heavy Quark Effective Theory Sum Rules
• Isgur-Wise Function for ${\Lambda }_b\to {\Lambda }_c$ in B-S Approach
• Octet-Baryon Form Factors in the Diquark Model
• Λ_b \to ΛJ/ψdecay in perturbative QCD
• Bethe-Salpeter Equation for Heavy Baryons ω_{Q}^{(*)} in the Diquark Picture
• Comparison of 1/mQ^2 Corrections in Mesons and Baryons
• Applicability of perturbative QCD to ${\Lambda }_b\to {\Lambda }_c$ decays
• Measurement of the Lambda_b^0 Decay Form Factor
• Note on the Slope Parameter of the Baryonic Λ_b to Λ_c Isgur-Wise Function
• The ${\Lambda }_b\to pl\bar{\nu }$ decay in perturbative QCD
• Analysis of Lambda_b to Lambda_c Weak Decays in Heavy Quark Effective Theory
• PQCD analysis of inclusive semileptonic decays of B mesons
• 1/N_c Expansion of the Heavy Baryon Isgur-Wise Functions

Cited by in corpus (23)

• Next-to-leading-order corrections to $B\to \pi$ form factors in $k_T$ factorization
• Weak Decays of Heavy Baryons in Light-Front Approach
• Perturbative Corrections to ${\Lambda }_b\to \Lambda$ Form Factors from QCD Light-Cone Sum Rules
• Anatomy of the pQCD Approach to the Baryonic Decays ${\Lambda }_b\to p\pi ,pK$
• Diquarks and Λ_{b}\toΛ_c weak decays
• Evaluating decay Rates and Asymmetries of ${\Lambda }_b$ into Light Baryons in LFQM
• ${\Lambda }_b\to p,\Lambda$ transition form factors from QCD light-cone sum rules
• ${\Sigma }_b\to {\Sigma }_c$ and ${\Omega }_b\to {\Omega }_c$ weak decays in the light-front quark model
• Revisiting ${\Lambda }_b\to {\Lambda }_c$ and ${\Sigma }_b\to {\Sigma }_c$ weak decays in the light-front quark model
• The semi-leptonic form factors of ${\Lambda }_b\to {\Lambda }_c$ and ${\Xi }_b\to {\Xi }_c$ in QCD sum rules
• Revisiting semileptonic decays of ${\Lambda }_{b(c)}$ supported by baryon spectroscopy
• ${\Lambda }_b\to p$ transition form factors in perturbative QCD
• First Measurement of the Ratio of Branching Fractions B(Lambda_b to Lambda_c mu nu)/B(Lambda_b to Lambda_c pi)
• A global analysis of charmless two body hadronic decays for anti-triplet charmed baryons
• Charm Physics - A Field Full with Challenges and Opportunities
• ${\Lambda }_b\to {\Lambda }_c$ Form Factors from QCD Light-Cone Sum Rules
• Restudy of the color-allowed two-body nonleptonic decay of bottom baryons ${\Xi }_b$ and ${\Omega }_b$ supported by hadron spectroscopy
• ${\Omega }_b$ semi-leptonic weak decays
• Transition form factors and angular distributions of the ${\mathbf{\Lambda }}_{\mathbf{b}}\to \mathbf{\Lambda }(1520)(\to \mathbf{N}\bar{\mathbf{K}}){\mathbf{\ell }}^{+}{\mathbf{\ell }}^{-}$ decay supported by baryon spectroscopy
• Light-Cone Sum Rules Analysis of ${\Xi }_{Q{Q}^{\prime }q}\to {\Sigma }_{Q^{\prime }}^{\ast }$ Weak Decays
• b-baryon semi-tauonic decays in the Standard Model
• The study of weak decays induced by ${\frac{1}{2}}^{+}\to {\frac{3}{2}}^{-}$ transition in light-cone sum rules
• Searching for New Physics in Semi-Leptonic Baryon Decays