Leptonic Scalars and Collider Signatures in a UV-complete Model

TL;DR

This paper explores the collider signatures of leptonic scalars in a UV-complete model with neutrino interactions, proposing search strategies at the HL-LHC and future colliders to detect new particles and measure their properties.

Contribution

It introduces a UV-complete model with leptonic scalars, detailing their collider signatures and providing strategies to detect and measure these particles at current and future colliders.

Findings

Doubly-charged scalar $H^{ iny ext{±±}}$ can be detected up to 800 GeV at HL-LHC with 2σ significance.

Mass reach extends to 3.8 TeV at a 100 TeV collider for $H^{ iny ext{±±}}$.

The scalar $oldsymbol{ extphi}$ mass can be measured with about 10% accuracy at the LHC.

Abstract

We study the non-standard interactions of neutrinos with light leptonic scalars ($\phi$) in a global $(B-L)$-conserved ultraviolet (UV)-complete model. The model utilizes Type-II seesaw motivated neutrino interactions with an $SU(2)_L$-triplet scalar, along with an additional singlet in the scalar sector. This UV-completion leads to an enriched spectrum and consequently new observable signatures. We examine the low-energy lepton flavor violation constraints, as well as the perturbativity and unitarity constraints on the model parameters. Then we lay out a search strategy for the unique signature of the model resulting from the leptonic scalars at the hadron colliders via the processes $H^{\pm\pm} \to W^\pm W^\pm \phi$ and $H^\pm \to W^\pm \phi$ for both small and large leptonic Yukawa coupling cases. We find that via these associated production processes at the HL-LHC, the prospects of doubly-charged scalar $H^{\pm\pm}$ can reach up to 800 (500) GeV and 1.1 (0.8) TeV at the $2\sigma \ (5\sigma)$ significance for small and large Yukawa couplings, respectively. A future 100 TeV hadron collider will further increase the mass reaches up to 3.8 (2.6) TeV and 4 (2.7) TeV, at the $2\sigma \ (5\sigma)$ significance, respectively. We also demonstrate that the mass of $\phi$ can be determined at about 10% accuracy at the LHC for the large Yukawa coupling case even though it escapes as missing energy from the detectors.