${\Lambda }_b\to {\Lambda }_c^{\ast }(2595,2625){\ell }^{-}\bar{\nu }$ form factors from lattice QCD

Abstract

We present the first lattice-QCD determination of the form factors describing the semileptonic decays ${\Lambda }_b\to {\Lambda }_c^{\ast }(2595){\ell }^{-}\bar{\nu }$ and ${\Lambda }_b\to {\Lambda }_c^{\ast }(2625){\ell }^{-}\bar{\nu }$, where the ${\Lambda }_c^{\ast }(2595)$ and ${\Lambda }_c^{\ast }(2625)$ are the lightest charm baryons with $J^P={\frac{1}{2}}^{-}$ and $J^P={\frac{3}{2}}^{-}$, respectively. These decay modes provide new opportunities to test lepton flavor universality and also play an important role in global analyses of the strong interactions in $b\to c$ semileptonic decays. We determine the full set of vector, axial vector, and tensor form factors for both decays, but only in a small kinematic region near the zero-recoil point. The lattice calculation uses three different ensembles of gauge-field configurations with $2+1$ flavors of domain-wall fermions, and we perform extrapolations of the form factors to the continuum limit and physical pion mass. We present Standard-Model predictions for the differential decay rates and angular observables. In the kinematic region considered, the differential decay rate for the ${\frac{1}{2}}^{-}$ final state is found to be approximately 2.5 times larger than the rate for the ${\frac{3}{2}}^{-}$ final state. We also test the compatibility of our form-factor results with zero-recoil sum rules.

30 pages, 9 figures

References in corpus (10)

• Charmed bottom baryon spectroscopy from lattice QCD
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• Precise predictions for ${\Lambda }_b\to {\Lambda }_c$ semileptonic decays
• ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay in scalar and vector leptoquark scenarios
• Investigation of Effects of New Physics in ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ Decay
• Probing new physics in semileptonic ${\Lambda }_b$ decays
• Precision Model-Independent Bounds from Global Analysis of $b\to c\ell \nu$ Form Factors
• Moving NRQCD for heavy-to-light form factors on the lattice
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Cited by in corpus (12)

• FLAG Review 2021
• FLAG Review 2024
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• First Observation of the Semileptonic Decay ${\Lambda }_c^{+}\to p{K}^{-}{e}^{+}{\nu }_e$
• Form Factor Counting and HQET Matching for New Physics in ${\Lambda }_b\to {\Lambda }_c^{\ast }l\nu$
• New physics effects on ${\Lambda }_b\to {\Lambda }_c^{\ast }\tau {\bar{\nu }}_{\tau }$ decays
• Investigating the transition form factors of ${\Lambda }_b\to {\Lambda }_c(2625)$ and ${\Xi }_b\to {\Xi }_c(2815)$ and the corresponding weak decays with support from baryon spectroscopy
• Is the ${\Lambda }_c(2625{)}^{+}$ the heavy quark spin symmetry partner of the ${\Lambda }_c(2595{)}^{+}$?
• The study of weak decays induced by ${\frac{1}{2}}^{+}\to {\frac{3}{2}}^{-}$ transition in light-cone sum rules
• Measurements of Born Cross Sections for $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c(2595{)}^{-}+c.c.$ and $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c(2625{)}^{-}+c.c.$ at $\sqrt{s}=$4918.0 and 4950.9 MeV
• Form factors of ${\Lambda }_b^0\to {\Lambda }_c(2595{)}^{+}$ within light-cone QCD sum rules