The (Weak) Evidence For Extra Higgs Bosons

The 95 GeV bump is suspiciously close to the mass of the Z boson plus the mass of the b-quark. The 152 GeV bump is close to the mass of two W bosons reduced by the mass of two b-quarks. 

The implication of these coincidences is that there could be an explanation along the lines of diphoton signals that are missing decay products that prevent them from accurately reflecting the true source of the diphoton signals. 

Also, given the modest statistical significant of these alleged resonances, it could be that these are simply the product of statistical flukes in the background estimations or some other sort of measurement errors.

After the Higgs discovery, the question of whether particles beyond those of the Standard Model exist is more pressing than ever. In this context, the scalar sector is particularly promising, since it lies at the core of the internal problems of the Standard Model, while extensions of it allow us to resolve them and can provide explanations for Dark matter, non-zero neutrino masses, inflation etc. 

In these proceedings, we review the indications for new Higgs bosons at the electroweak scale with masses of ≈95 GeV and ≈152 GeV. These excesses are most significant in the di-photon channel but are supported by weaker-than-expected limits in other decay modes. 

While for the 95 GeV candidate the production mechanism is mostly unknown, the (hypothetical) 152 GeV Higgs is dominantly produced in association with leptons, (b) jets and missing energy, pointing towards the Drell-Yan production of an SU(2)L triplet with Y=0. Interestingly, this model predicts t→H±b with H±→WZ, which resembles the signature of tt¯Z production in the Standard Model and is in fact preferred by current data. 

Finally, we investigate the possibility that the significant tensions between the Standard Model predictions and the measurements in differential top-quark distributions are due to contamination from new physics involving both the 152 GeV and the 95 GeV scalar.

Andreas Crivellin, et al., "Indications for New Higgs Bosons" arXiv:2605.04233 (May 5, 2026) (Proceedings of the Corfu Summer Institute 2025 "School and Workshops on Elementary Particle Physics and Gravity" (CORFU2025)).