Resonant Multi-Scalar Production in the Generic Complex Singlet Model in the Multi-TeV Region

• Published in: arXiv.org 2024-09
• Main Authors: Lane, Samuel D, Lewis, Ian M, Sullivan, Matthew
• Format: Article
• Language: English
• Subjects: Benchmarks; Higgs bosons; Large Hadron Collider; Quarks; Scalars
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2403.18003

We develop benchmarks for resonant di-scalar production in the generic complex singlet scalar extension of the Standard Model (SM), which contains two new scalars. These benchmarks maximize di-scalar resonant production: \(pp\rightarrow h_2 \rightarrow h_1 h_1/h_1h_3/h_3h_3\), where \(h_1\) is the observed SM-like Higgs boson and \(h_{2,3}\) are new scalars. The decays \(h_2\rightarrow h_1h_3\) and \(h_2\rightarrow h_3h_3\) may be the only way to discover \(h_3\), leading to a discovery of two new scalars at once. Current LHC and projected future collider (HL-LHC, FCC-ee, ILC500) constraints are used to produce benchmarks at the HL-LHC for \(h_2\) masses between 250 GeV and 1 TeV and a future \(pp\) collider for \(h_2\) masses between 250 GeV and 12 TeV. We update the current LHC bounds on the singlet-Higgs boson mixing angle. As the mass of \(h_2\) increases, certain limiting behaviors of the maximum rates are uncovered due to theoretical constraints on the parameters. These limits, which can be derived analytically, are \({\rm BR}(h_2\rightarrow h_1h_1)\rightarrow 0.25\), \({\rm BR}(h_2\rightarrow h_3h_3)\rightarrow 0.5\), and \({\rm BR}(h_2\rightarrow h_1h_3) \rightarrow 0\). It can also be shown that the maximum rates of \(pp\rightarrow h_2\rightarrow h_1h_1/h_3h_3\) approach the same value. Hence, all three \(h_2\rightarrow h_ih_j\) decays are promising discovery modes for \(h_2\) masses below \(\mathcal{O}(1\,{\rm TeV})\), while above \(\mathcal{O}(1\,{\rm TeV})\) the decays \(h_2\rightarrow h_1h_1/h_3h_3\) are more encouraging. Masses for \(h_3\) are chosen to produce a large range of signatures including multi-b, multi-vector boson, and multi-\(h_1\) production. The behavior of the maximum rates imply that in the multi-TeV region this model may be discovered in the Higgs quartet production mode before Higgs triple production is observed. The maximum di- and four Higgs production rates are similar in the multi-TeV range.