Resonant multiscalar production in the generic complex singlet model in the multi-TeV region

• Published in: Physical review. D 2024-09, Vol.110 (5), Article 055017
• Main Authors: Lane, Samuel D., Lewis, Ian M., Sullivan, Matthew
• Format: Article
• Language: English
• ISSN: 2470-0010; 2470-0029
• DOI: 10.1103/PhysRevD.110.055017

We develop benchmarks for resonant discalar production in the generic complex singlet scalar extension of the Standard Model (SM) with no additional symmetries, which contains two new scalars. These benchmarks maximize discalar resonant production modes at future p p colliders: p p → h 2 → h 1 h 1 , p p → h 2 → h 1 h 3 , and p p → h 2 → h 3 h 3 , where h 1 is the observed SM-like Higgs boson and h 2 , 3 are new scalars. The decays h 2 → h 1 h 3 and h 2 → h 3 h 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 + HL -LHC, IL C 500 + HL -LHC) constraints on this model are used to produce benchmarks at the HL-LHC for h 2 masses between 250 GeV and 1 TeV and a future p p collider (FCC-hh) for h 2 masses between 250 GeV and 12 TeV. We update the current LHC bounds on the singlet-Higgs boson mixing angle for these benchmarks. As the mass of h 2 approaches the multi-TeV region, certain limiting behaviors of the maximum rates are uncovered due to theoretical constraints on the parameters. These limits, which can be derived analytically, are BR ( h 2 → h 1 h 1 ) → 0.25 , BR ( h 2 → h 3 h 3 ) → 0.5 , and BR ( h 2 → h 1 h 3 ) → 0 . It can also be shown that the maximum rates of p p → h 2 → h 1 h 1 and p p → h 2 → h 3 h 3 approach the same value. Hence, all three h 2 → h i h j decays are promising discovery modes for h 2 masses at and below O ( 1 TeV ) , while above O ( 1 TeV ) the decays h 2 → h 1 h 1 and h 2 → h 3 h 3 are more encouraging. We choose benchmark masses for h 3 to produce a large range of decay signatures including multi- b , multivector boson, and multi-SM-like Higgs production. As we will show, the behavior of the maximum rates leads to the surprising conclusion that in the multi-TeV region this model may be discovered in the Higgs quartet production mode via h 2 → h 3 h 3 → 4 h 1 decays before Higgs triple production is observed. The maximum di- and four Higgs production rates are similar in the multi-TeV range.