Effective Field Theory for Heavy Vector Resonances Coupled to the Standard Model

TL;DR

This paper develops an effective field theory framework, SCET_BSM, for analyzing decays of heavy vector resonances into Standard Model particles, enabling systematic resummation of large logarithms and detailed decay predictions.

Contribution

It introduces SCET_BSM, an extension of SCET, for precise description and resummation of decay processes of heavy vector resonances in BSM scenarios.

Findings

Resummation of large logarithms in decay processes.

Application to Z' and Kaluza-Klein gluon decays.

Matching with a UV-complete model.

Abstract

We construct an effective field theory describing the decays of a heavy vector resonance $V$ into Standard Model particles. The effective theory is built using an extension of Soft-Collinear Effective Theory called SCET$_{\rm BSM}$, which provides a rigorous framework for parameterizing decay matrix elements with manifest power counting in the ratio of the electroweak scale and the mass of the resonance, $\lambda\sim v/m_V$. Using the renormalization-group evolution of the couplings in the effective Lagrangian, large logarithms associated with this scale ratio can be resummed to all orders. We consider in detail the two-body decays of a heavy $Z'$ boson and of a Kaluza-Klein gluon at leading and subleading order in $\lambda$. We illustrate the matching onto SCET$_{\rm BSM}$ with a concrete example of a UV-complete new-physics model.