SAIP2025

Triboson Excesses in light of a Real Higgs Triplet Model

9 Jul 2025, 09:20

20m

Solomon Mahlangu House (University of the Witwatersrand, Johannesburg)

Oral Presentation Track B - Nuclear, Particle and Radiation Physics Nuclear, Particle and Radiation Physics-2

Speaker

Dr Srimoy Bhattacharya (School of Physics and Institute for Collider Particle Physics, University of the Witwatersrand)

Description

In recent years, the ``multilepton anomalies'' have emerged, consisting of several persistent tensions in channels with multiple electrons and/or muons in the final states, with missing transverse energy and ($b$-) jets. These anomalies have prompted growing interest in the possibility of a new scalar particle beyond the Standard Model (SM).
In this context, excesses have been observed in the diphoton, $Z\gamma $ and $WW$ spectra, pointing toward the presence of a Higgs-like scalar $ S$ with mass $ m_S \approx 152 \pm 1 $ GeV.

While these excesses suggest the existence of a new resonance, the $ ZZ $ final state remains consistent with Standard Model predictions, showing no significant deviation. This consistency can be naturally explained if the scalar $ S $ belongs to a Real Higgs Triplet (RHT) with hypercharge $ Y = 0 $, which does not couple to a pair of $ Z $ bosons at tree level. In such a scenario, charged and neutral triplet scalars can be produced via Drell-Yan processes and decay into electroweak gauge bosons, leading to enhancements in triboson final states such as $WWW $, $ WWZ $, and $ WZZ $.

Recent ATLAS and CMS measurements of triboson processes report observed (expected) significances of $ 6.4\sigma ( 4.7\sigma $) in the $ VVZ $ channel and $ 4.4\sigma ( 3.6\sigma )$ in $ WWZ $. These can be interpreted as a possible link to the extended Higgs sector. In this study, we investigate whether the RHT Model with hypercharge $Y = 0$ can accommodate these triboson excesses through Drell-Yan production of triplet scalars, which subsequently decay into electroweak bosons, leading to an enhancement in triboson final states. We explore the parameter space where $S$ is identified as a component of the extended Higgs sector, with a small but nonzero diphoton branching ratio. Using Monte Carlo simulations, we analyze the predicted cross-sections for $WWZ$, $WZZ$, and $WWW$ production and compare them with current experimental data.