Speaker
Description
The multi-lepton anomalies observed at the LHC have motivated models with new scalar resonances, predicting a scalar at $150\pm5$ GeV. A narrow excess near $m_S=152\pm1$ GeV was observed in Run 2 data in the $\gamma\gamma$, $Z\gamma$, and $W^+W^-$ channels with a significance surpassing $5\sigma$. In this work, we investigate a new excess in the ATLAS Run 3 data using diphoton production in association with two jets, focusing on event topologies similar to vector-boson fusion (VBF). The excess is studied using two simplified models, a singlet extension of the two-Higgs-doublet model (2HDM+S) and the Higgs Triplet Model (HTM). Following the recent ATLAS publication, a three-class neural network is used to separate VBF, gluon-gluon fusion, and non-resonant $\gamma\gamma+jj$ production. The published ATLAS analysis is recast by fitting the $m_{\gamma\gamma}$ spectrum near $152$ GeV, giving a combined significance of $2.5\sigma$ using a part of the Run 3 dataset. The corresponding fiducial cross sections for HTM and 2HDM+S are $9.44\pm4.74$ fb and $7.41\pm3.54$ fb, respectively. The observed Run 3 excess is consistent and serves as further confirmation of the scalar candidate identified in Run 2, motivating further investigation with the full Run 3 dataset.
