Interference effects of two scalar boson propagators on the LHC search for the singlet fermion DM

TL;DR

This paper investigates how interference between two scalar mediators affects dark matter production signals at the LHC, revealing significant impacts on search sensitivity and jet characteristics.

Contribution

It introduces a gauge-invariant UV-complete model with two scalar mediators and analyzes their interference effects on collider phenomenology.

Findings

Interference can be constructive or destructive depending on masses.

Interference softens the final state jets.

Current LHC sensitivity is an order of magnitude above the model's predicted cross section.

Abstract

A gauge invariant UV-completion for singlet fermion DM interacting with the standard model (SM) particles involves a new singlet scalar. Therefore the model contains two scalar mediators, mixtures of the SM Higgs boson and a singlet scalar boson. Collider phenomenology of the interference effect between these two scalar propagators is studied in this work. This interference effect can be either constructive or destructive in the DM production cross section depending on both singlet scalar and DM masses, and it will soften the final state jets in the full mass region. Applying the CMS mono-jet search to our model, we find the interference effect plays a very important role in the DM search sensitivity, and the DM production cross section of our model is more than one order of magnitude below the LHC sensitivity at current stage.