Charm-baryon semileptonic decays and the strange ${\Lambda }^{\ast }$ resonances: New insights from lattice QCD

Abstract

Understanding the properties of the strange ${\Lambda }^{\ast }$ baryon resonances is a long-standing and fascinating problem. ${\Lambda }_c$ charm-baryon semileptonic weak decays to these resonances are highly sensitive to their internal structure and can be used to test theoretical models. We have performed the first lattice-QCD computation of the form factors governing ${\Lambda }_c$ semileptonic decays to a ${\Lambda }^{\ast }$ resonance: the ${\Lambda }^{\ast }(1520)$, which has negative parity and spin $3/2$. Here we present the resulting Standard-Model predictions of the ${\Lambda }_c\to {\Lambda }^{\ast }(1520){\ell }^{+}{\nu }_{\ell }$ differential and integrated decay rates as well as angular observables. Furthermore, by combining the recent BESIII measurement of the ${\Lambda }_c\to X{e}^{+}{\nu }_e$ inclusive semipositronic branching fraction [Phys. Rev. Lett. 121, 251801 (2018)] with lattice-QCD predictions of the ${\Lambda }_c\to \Lambda e^{+}{\nu }_e$, ${\Lambda }_c\to n{e}^{+}{\nu }_e$, and ${\Lambda }_c\to {\Lambda }^{\ast }(1520)e^{+}{\nu }_e$ decay rates, we obtain an upper limit on the sum of the branching fractions to all other semipositronic final states. In particular, this upper limit constrains the ${\Lambda }_c\to {\Lambda }^{\ast }(1405)e^{+}{\nu }_e$ branching fraction to be very small, which may be another hint for a molecular structure of the ${\Lambda }^{\ast }(1405)$.

6 pages, 1 figure

References in corpus (15)

• Lattice QCD Evidence that the Lambda(1405) Resonance is an Antikaon-Nucleon Molecule
• Multichannel one-to-two transition amplitudes in a finite volume
• The semileptonic decay Lambda_b -> Lambda_c + tau(-) + antinu_tau in the covariant confined quark model
• Two-pole structures in QCD: Facts, not fantasy!
• ${\Lambda }_c\to \Lambda {\ell }^{+}{\nu }_{\ell }$ form factors and decay rates from lattice QCD with physical quark masses
• Review of the $\mathbf{\Lambda }$(1405): A curious case of a strange-ness resonance
• QCD and the Strange Baryon Spectrum
• Structure of the $\mathbf{\Lambda }(1405)$ from Hamiltonian effective field theory
• Revisiting semileptonic decays of ${\Lambda }_{b(c)}$ supported by baryon spectroscopy
• ${\Lambda }_c\to {\Lambda }^{\ast }(1520)$ form factors from lattice QCD and improved analysis of the ${\Lambda }_b\to {\Lambda }^{\ast }(1520)$ and ${\Lambda }_b\to {\Lambda }_c^{\ast }(2595,2625)$ form factors
• ${\Lambda }_b\to {\Lambda }^{\ast }(1520){\ell }^{+}{\ell }^{-}$ form factors from lattice QCD
• Endpoint Relations for Baryons
• Flavor structure of $\Lambda$ baryons from lattice QCD: From strange to charm quarks
• ${\Lambda }_c$ Semileptonic Decays in a Quark Model
• The negative-parity spin-1/2 $\Lambda$ baryon spectrum from lattice QCD and effective theory

Cited by in corpus (8)

• Two-pole nature of the $\Lambda (1405)$ from lattice QCD
• Lattice QCD study of $\pi \Sigma -\bar{K}N$ scattering and the $\Lambda (1405)$ resonance
• ${\Lambda }_c\to {\Lambda }^{\ast }(1520)$ form factors from lattice QCD and improved analysis of the ${\Lambda }_b\to {\Lambda }^{\ast }(1520)$ and ${\Lambda }_b\to {\Lambda }_c^{\ast }(2595,2625)$ form factors
• Study of the Semileptonic Decay ${\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e$
• First Observation of the Semileptonic Decay ${\Lambda }_c^{+}\to p{K}^{-}{e}^{+}{\nu }_e$
• Pole trajectories of the $\Lambda (1405)$ helps establish its dynamical nature
• ${\Xi }_c\to \Xi$ form factors from lattice QCD with domain-wall quarks: A new piece in the puzzle of ${\Xi }_c^0$ decay rates
• Evidence for the semileptonic decays ${\Lambda }_c^{+}\to {\Sigma }^{\pm }{\pi }^{\mp }{e}^{+}{\nu }_e$