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

TL;DR

The paper reports potential evidence for new Higgs bosons at 95 GeV and 152 GeV, linking these to anomalies in top quark pair distributions and proposing a model that extends the Standard Model with additional scalar fields.

Contribution

It introduces a simplified model with a new scalar explaining Higgs signals and top quark distribution anomalies, and suggests a UV completion via a 2HDM with triplet and singlet fields.

Findings

Evidence for Higgses at 95 GeV and 152 GeV with high significance.

Improved fit to $t\bar t$ distributions with new physics contributions.

Compatibility of the model with observed di-photon signals.

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 $X=\ell,\,\ell b,\,{\rm MET},\,\tau,\,...$, 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 $WW b\bar b$: 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.