UV physics from IR features: New prospects from top flavor violation
Wolfgang Altmannshofer, Stefania Gori, Benjamin V. Lehmann, Jianhong Zuo
Abstract
New physics in the rare top decays $t\ensuremath{\rightarrow}q{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ is currently very weakly constrained. We show that in a large class of Standard Model extensions, existing experimental constraints on new physics in flavor-conserving processes imply strong indirect bounds on new physics contributions to flavor-violating processes of the form $t\ensuremath{\rightarrow}q{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$. These indirect bounds arise from basic principles of quantum field theory together with a few generic conditions on the UV structure of the theory, and are roughly an order of magnitude stronger than the present experimental bounds on the same processes. These constraints provide a theoretically motivated target for experimental searches for $t\ensuremath{\rightarrow}q{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$: violation of these bounds would exclude a large class of new physics models, and would provide nontrivial insight into the UV behavior of the new physics.