Measurement of the Lambda_b^0 Decay Form Factor

Abstract

The form factor of Lambda_b^0 baryons is estimated using 3.46 10^6 hadronic Z decays collected by the DELPHI experiment between 1992 and 1995. Charmed Lambda_c^+ baryons fully reconstructed in the pK-pi+, pK0_S, and Lambda pi+pi+pi- modes, are associated to a lepton with opposite charge in order to select Lambda_b^0 -> Lambda_c^+ l^- anti-nu_l decays. From a combined likelihood and event rate fit to the distribution of the Isgur-Wise variable w, and using the Heavy Quark Effective Theory (HQET), the slope of the b-baryon form factor is measured to be: rho-hat^2 = 2.03 +/- 0.46 (stat) ^{+0.72}_{-1.00} (syst). The exclusive semileptonic branching fraction Br(Lambda_b^0 -> Lambda_c^+ l^- anti-nu_l) can be derived from rho-hat^2 and is found to be (5.0^{+1.1}_{-0.8} (stat) ^{+1.6}_{-1.2} (syst))%. Limits on other branching fractions are also obtained.

24 pages, 7 figures

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• Evaluating decay Rates and Asymmetries of ${\Lambda }_b$ into Light Baryons in LFQM
• PQCD Calculation for ${\Lambda }_b\to \Lambda \gamma$ in the Standard Model
• Combined nonrelativistic constituent quark model and heavy quark effective theory study of semileptonic decays of Λ_b and Ξ_b baryons
• Measurement of the shape of the ${\Lambda }_b^0\to {\Lambda }_c^{+}{\mu }^{-}\overline{\nu }$ differential decay rate
• Revisiting semileptonic decays of ${\Lambda }_{b(c)}$ supported by baryon spectroscopy
• Global fit to $b\to c\tau \nu$ anomalies as of Spring 2024
• Note on the Slope Parameter of the Baryonic Λ_b to Λ_c Isgur-Wise Function
• Semileptonic Decays of Heavy Omega Baryons in a Quark Model
• Diquarks and the Semi-Leptonic Decay of ${\Lambda }_b$ in the Hybrid Scheme
• Nonleptonic two-body weak decays of ${\Lambda }_b$ in modified MIT bag model
• First Measurement of the Ratio of Branching Fractions B(Lambda_b to Lambda_c mu nu)/B(Lambda_b to Lambda_c pi)
• Fragmentation fractions of two-body b-baryon decays
• Prospects for improved ${\Lambda }_c$ branching fractions
• Calculation of BR(${\bar{B}}^0\to {\Lambda }_c^{+}+\bar{p})$ in the PQCD Approach
• Light-cone Sum Rule Analysis of Semileptonic Decays ${\Lambda }_b^0\to {\Lambda }_c^{+}{\ell }^{-}{\overline{\nu }}_{\ell }$
• The Average Kinetic Energy of the Heavy Quark in ${\Lambda }_b$ in the Bethe-Salpeter Equation Approach
• Interpreting LHCb's ${\Lambda }_b\to {\Lambda }_c\tau \bar{\nu }$ measurement and puzzles in semileptonic ${\Lambda }_b$ decays
• Production of charged $\rho$ meson in bottom hadron charmed decays and the effect of the finite width correction of the $\rho$ meson
• Baryons and baryoniums in the perspective of QCD sum rules
• Heavy Quark Spin Symmetry and Heavy Baryons: Electroweak Decays