Monday, April 8, 2024

A Hint Of A Heavy Higgs Boson?

Every claim of a newly detected novel kind of particle should be viewed with a grain of salt. But the resonance seen is not crowded with background alternatives, and has a mass consistent with a theoretical prediction that isn't off the wall. So, it deserves careful attention.
As an alternative to the metastability of the electroweak vacuum, resulting from perturbative calculations, one can consider a non-perturbative effective potential which, as at the beginning of the Standard Model, is restricted to the pure Φ4 sector yet consistent with the known analytical and numerical studies. 

In this approach, where the electroweak vacuum is now the lowest-energy state, besides the resonance of mass mh= 125 GeV defined by the quadratic shape of the potential at its minimum, the Higgs field should exhibit a second resonance with mass (MH)Theor=690(30) GeV associated with the zero-point energy determining the potential depth. In spite of its large mass, this resonance would couple to longitudinal Ws with the same typical strength as the low-mass state at 125 GeV and represent a relatively narrow resonance, mainly produced at LHC by gluon-gluon fusion.

In this Letter, we review LHC data suggesting a new resonance of mass (MH)EXP∼682(10) GeV, with a statistical significance that is far from negligible.
Maurizio Consoli, George Rupp, "A new 700 GeV scalar in the LHC data?" arXiv:2404.03711 (April 4, 2024) (accepted for publication in LHEP. arXiv admin note: substantial text overlap with arXiv:2308.01429).

The body text makes the following claims about the experimental data:
Let us summarise our review of LHC data: 

i) The ATLAS ggF-like four-lepton events reported in Table 1 show a definite excess-defect sequence, suggesting the existence of a new resonance. The same pattern is also visible in the ATLAS cross section; see Table 2 and the ∆σ in Fig. 2. The combined statistical deviation in the latter analysis is at the 3σ level and indicates a resonance mass MH = 677+30 −14 GeV. 

ii) Observing the +3σ excess at 684(16) GeV in the inclusive ATLAS γγ events, a fit to these data was performed. The resulting mass is MH = 696(12) GeV. 

iii) An overall +2σ effect in the (b¯ b + γγ) channel is obtained by combining the excess of events observed by ATLAS at 650(25) GeV and the corresponding excess observed by CMS at 675(25) GeV. 

iv) A +3σ excess is present at 650(40) GeV in the distribution of CMS-TOTEM γγ events produced in pp diffractive scattering. 

By combining the above determinations i)-iv), the resulting estimate (MH)EXP ∼ 682(10) GeV, is in very good agreement with our expectation (MH)Theor = 690(30) GeV. We stress again that, when comparing with a definite prediction, one should look for deviations from the background nearby, so that local significance is not downgraded by the so called “look elsewhere” effect. Therefore, since the correlation of the above measurements is small, the combined statistical evidence for a new resonance in the expected mass range is far from negligible and close to (if not above) the traditional 5σ level. We also emphasise that the determinations i) and ii) above were obtained by fitting the numerical data to the general expressions Eqs. (3) and (4). This is very different from comparing with other Beyond-Standard-Model scenarios (such as supersymmetry, extra-dimensions, ...), whose exclusion limits assume built-in constraints (such as mass-width and/or mass-couplings relations) that are not valid in our approach. For this reason, we look forward to new precise data on which we can carry out the same general analysis as with the ATLAS papers.

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