New Higgses at the Electroweak Scale and Differential $t\bar{t}$ Distributions

Abstract

Indications for new Higgs bosons at 95\,GeV and 152\,GeV with significance of 3.8$\sigma$ and $4.3\sigma$, respectively, have been obtained. While the former contains the inclusive $\gamma \gamma$ channel, the latter is obtained by combining several modes of associated di-photon production, i.e. $\gamma \gamma +X$ with $X=\ell ,\ell b,\mathrm{MET},\tau ,...$, within the $\Delta$SM (the Standard Model extended by a real triplet). Such a triplet predicts a positive definite shift in the $W$ mass, in agreement with the current global electroweak fit, and its neutral component decays dominantly to $W$ bosons (for small mixing angles). This offers a connection to $t\bar{t}$ differential distributions whose experimental signature is $WWb\bar{b}$: A simplified model with a new scalar $H$, produced via gluon fusion and decaying to $S$ and $S^{\prime }$ with subsequent (dominant) decays to $WW$ and $b\bar{b}$, respectively, has the same final state. In fact, adding this new physics polution to the Standard Model describes the leptonic $t\bar{t}$ distributions better by at least $5.8\sigma$. Furthermore, assuming that $S^{\prime }$ is an $SU(2{)}_L$ singlet, the resulting di-photon signal strength is compatible with the 95\,GeV $\gamma \gamma$ measurements. A possible UV completion of this simplified model is the $\Delta$2HDMS, i.e. a 2HDM supplemented with a singlet and a real triplet, which can successfully accommodate electroweak scale Baryogenesis.

Comments: Contribution to the 2024 Electroweak and QCD sessions of the 58th Rencontres de Moriond