Simple Standard Model Extension by Heavy Charged Scalar

TL;DR

This paper explores a simple extension of the Standard Model with a heavy charged scalar, analyzing its production, decay, and experimental bounds, highlighting its potential as a long-lived particle detectable at current and future colliders.

Contribution

It introduces a gauge-invariant charged scalar extension of the Standard Model, providing detailed collider production and decay analyses, and deriving current and projected experimental bounds.

Findings

Current bounds exclude scalar masses below 300-320 GeV.

Future colliders could probe masses up to 2.7 TeV with high luminosity.

The charged scalar is a long-lived particle with suppressed interactions, making it a unique search target.

Abstract

We consider a Standard Model extension by a heavy charged scalar gauged only under the $U_{Y}(1)$ weak hypercharge gauge group. Such an extension, being gauge invariant with respect to the SM gauge group, is a simple special case of the well known Zee model. Since the interactions of the charged scalar with the Standard Model fermions turn out to be significantly suppressed compared to the Standard Model interactions, the charged scalar provides an example of a long-lived charged particle being interesting to search for at the LHC. We present the pair and single production cross sections of the charged scalar at different colliders and the possible decay widths for various boson masses. It is shown that the current ATLAS and CMS searches at 8 and 13 TeV collision energy lead to the bounds on the scalar boson mass of about 300--320 GeV. The limits are expected to be much larger for higher collision energies and, assuming $15~ab^{-1}$ integrated luminosity, reach about 2.7 TeV at future 27 TeV LHC thus covering the most interesting mass region.