Speaker
Description
We study the radiative decay $S \to W^{+}W^{-}\gamma$, motivated by the multi-lepton anomalies at the LHC and by the emergence of a statistically significant narrow scalar resonance at $152 \pm 1$~GeV in the $\gamma\gamma$, $Z\gamma$, and $W^{+}W^{-}$ channels in association with leptons, missing transverse momentum, and $(b)$-jets. This motivates a search for a corresponding excess in the $m_{\ell\ell\gamma}$ spectrum in events with associated $b$-jets. We observe such an excess with a global significance of $4.7\sigma$, with a preferred mass of $160^{+10}_{-35}$\,GeV in a topology consistent with that suggested by the earlier anomalies. This provides further support for a unified interpretation of the multi-lepton anomalies, the narrow resonance, and its radiative decay, consolidating the significance of the narrow resonance hypothesis solidly above $5\sigma$. The measured ratio $\sigma(S \to W^{+}W^{-}\gamma)/\sigma(S \to W^{+}W^{-}) = 3 \pm 0.75\%$ is compatible with an enhancement from physics beyond the Standard Model. Our result also motivates a dedicated theoretical assessment of the cancellation of $t\bar{t}$ threshold effects in the ratio $t\bar{t}\gamma/t\bar{t}$, which would sharpen the Standard Model prediction and strengthen the interpretation of any residual excess as a signal of new physics.
| Apply for student award at which level: | None |
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| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |