Exploring charm decays with missing energy in leptoquark models

Abstract

We investigate the possibility that scalar leptoquarks generate consequential effects on the flavor-changing neutral-current decays of charmed hadrons into final states with missing energy carried away by either standard model or sterile neutrinos. We focus on scenarios involving the R2, {tilde{R}}_2 , and {overline{S}}_1 leptoquarks and take into account various pertinent constraints, learning that meson-mixing ones and those inferred from collider searches can be of significance. We find in particular that the branching fractions of charmed meson decays D →, M = π, ρ, and Ds→ and singly charmed baryon decays {Lambda}_c^{+} → and Ξc→ are presently allowed to attain the 10−7-10−6 levels if induced by R2 and that the impact of {tilde{R}}_2 is comparatively much less. In contrast, the contributions of {overline{S}}_1 , which couples to right-handed up-type quarks and the sterile neutrinos, could lead to branching fractions as high as order 10−3. This suggests that these charmed hadron decays might be within reach of the BESIII and Belle II experiments or future super charm-tau factories and could serve as potentially promising probes of leptoquark interactions with sterile neutrinos.