Abstract
Cascade decays of new scalars into final states with multiple photons and possibly quarks may lead to distinctive experimental signatures at high-energy colliders. Such signals are even more striking if the scalars are highly boosted, as when produced from the decay of a much heavier resonance. We study this type of events within the framework of the minimal stealth boson model, an anomaly-free text {U}(1)_{Y'} extension of the Standard Model with two complex scalar singlets. It is shown that, while those signals may have cross sections that might render them observable with LHC Run 2 data, they have little experimental coverage. We also establish a connection with a CMS excess observed in searches for new scalars decaying into diphoton final states near 96 GeV. In particular, we conclude that the predicted multiphoton signatures are compatible with such excess.
Highlights
The scalar sector of the Standard Model (SM) contains one scalar doublet which spontaneously breaks the gauge symmetry via the Brout–Englert–Higgs mechanism [1,2,3], predicting the existence of the so-called Higgs boson
In Ref. [10] we have proposed the simplest model that accounts for the said cascade decays – the minimal stealth boson model (MSBM) – in which the SM gauge symmetry is enlarged with an extra U(1)Y coupling to baryon number up to an arbitrary normalisation constant
We restrict ourselves to the case with λ7−9 = 0 in Eq (1), which corresponds to having the Z2 symmetry softly broken by the term m
Summary
The scalar sector of the Standard Model (SM) contains one scalar doublet which spontaneously breaks the gauge symmetry via the Brout–Englert–Higgs mechanism [1,2,3], predicting the existence of the so-called Higgs boson. The scalar sector comprises two complex SM singlets χ1,2 that, upon U(1)Y symmetry breaking, provide masses to the Z boson and to the new fermions. Besides the pp → Hi → γ γ signals from direct production of the new scalars, the presence of a heavy Z resonance opens up the possibility of several conspicuous signals from cascade decays, like those involving collimated photons and/or jets containing hard photons Their features will be discussed in Sect. We explore the possibility that the same scalar decays mostly into bb In such case, an excess observed at the Large Electron-Positron (LEP) collider around the same mass [17] can be accommodated.
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