${\Lambda }_c\to N$ form factors from lattice QCD and phenomenology of ${\Lambda }_c\to n{\ell }^{+}{\nu }_{\ell }$ and ${\Lambda }_c\to p{\mu }^{+}{\mu }^{-}$ decays

Abstract

A lattice QCD determination of the ${\Lambda }_c\to N$ vector, axial vector, and tensor form factors is reported. The calculation was performed with $2+1$ flavors of domain wall fermions at lattice spacings of $a\approx 0.11\mathrm{fm},0.085\mathrm{fm}$ and pion masses in the range $230\mathrm{MeV}\lesssim m_{\pi }\lesssim 350$ MeV. The form factors are extrapolated to the continuum limit and the physical pion mass using modified $z$ expansions. The rates of the charged-current decays ${\Lambda }_c\to n{e}^{+}{\nu }_e$ and ${\Lambda }_c\to n{\mu }^{+}{\nu }_{\mu }$ are predicted to be $\left(0.405\pm 0.016_{\mathrm{stat}}\pm 0.020_{\mathrm{syst}}\right)|V_{cd}{|}^2{\mathrm{ps}}^{-1}$ and $\left(0.396\pm 0.016_{\mathrm{stat}}\pm 0.020_{\mathrm{syst}}\right)|V_{cd}{|}^2{\mathrm{ps}}^{-1}$, respectively. The phenomenology of the rare charm decay ${\Lambda }_c\to p{\mu }^{+}{\mu }^{-}$ is also studied. The differential branching fraction, the fraction of longitudinally polarized dimuons, and the forward-backward asymmetry are calculated in the Standard Model and in an illustrative new-physics scenario.

Comments: 21 pages, 7 figures, form factor parameters included as ancillary files. This version: corrected lepton-mass contributions to F_L