Physicists searched for a new, light scalar particle that would leave a visible imprint when it decays to a pair of W bosons plus a photon. The search focuses on the invariant mass of two opposite-sign leptons (electrons or muons) together with a photon — a quantity denoted m_{ℓℓγ} — in events that also contain b-tagged jets. Using public CMS measurements of top–antitop plus photon (t t̄ γ) production, the authors look for a localized bump in m_{ℓℓγ} that would match the radiative decay S → W+W−γ of a scalar S with mass near 152 ± 1 GeV.

To test this idea the team simulated both the Standard Model backgrounds and a possible signal. They used MadGraph5 for the hard collisions, Pythia 8.3 for how particles shower and decay, and Delphes 3.5 for a fast detector simulation. They applied the same event selection as the CMS analysis: two charged leptons with pT thresholds of 25 GeV (leading) and 20 or 15 GeV (subleading, depending on flavour), exactly one photon with pT > 20 GeV, at least two jets with pT > 30 GeV and at least one b-tagged jet, and a dilepton mass above 40 GeV. The known background prediction was normalized to data in the region m_{ℓℓγ} > 120 GeV (a scale factor of 0.98 was found).

After subtracting the normalized Standard Model expectation, the data show a localized excess in m_{ℓℓγ} just below 110 GeV, which is what one would expect from S → W+W−γ if S has a mass around 152 GeV. Quantitatively, the excess is compatible with a narrow scalar at m_S = 152 GeV with a global significance of 2.7 standard deviations (2.7σ). From the fit the authors extract the ratio of radiative to non-radiative rates in association with at least one b-jet, σ(S → W+W−γ) / σ(S → W+W−) = (2.14 ± 0.77)%, a value the paper notes could be larger than the Standard Model expectation and so might arise in scenarios beyond the Standard Model.