Effective Operator Bases for Beyond Standard Model Scenarios: An EFT compendium for discoveries

TL;DR

This paper develops a comprehensive framework called BSMEFT that extends the Standard Model with additional light particles and constructs the effective field theory including dimension-6 operators, aiding future experimental searches.

Contribution

It introduces the BSMEFT framework incorporating light non-SM particles and provides explicit Lagrangians up to dimension 6 for various extended scenarios.

Findings

Constructed BSMEFT Lagrangians for three extended scenarios.

Identified CP, baryon, and lepton number violating operators.

Provided tools for phenomenological analysis of BSM models.

Abstract

It is not only conceivable but likely that the spectrum of physics beyond the Standard Model (SM) is non-degenerate. The lightest non-SM particle may reside close enough to the electroweak scale that it can be kinematically probed at high-energy experiments and on account of this, it must be included as an infrared (IR) degree of freedom (DOF) along with the SM ones. The rest of the non-SM particles are heavy enough to be directly experimentally inaccessible and can be integrated out. Now, to capture the effects of the complete theory, one must take into account the higher dimensional operators constituted of the SM DOFs and the minimal extension. This construction, BSMEFT, is in the same spirit as SMEFT but now with extra IR DOFs. Constructing a BSMEFT is in general the first step after establishing experimental evidence for a new particle. We have investigated three different scenarios where the SM is extended by additional (i) uncolored, (ii) colored particles, and (iii) abelian gauge symmetries. For each such scenario, we have included the most-anticipated and phenomenologically motivated models to demonstrate the concept of BSMEFT. In this paper, we have provided the full EFT Lagrangian for each such model up to mass dimension 6. We have also identified the $CP$, baryon ($B$), and lepton ($L$) number violating effective operators.