Abstract
Examining the Higgs sector at high energy scales through off-shell Higgs production can potentially shed light on the naturalness problem of the Higgs boson mass. We propose such a study at the LHC by utilizing a representative model with a new scalar field (S) coupled to the standard model Higgs doublet (H) in a form |S|^{2}|H|^{2}. In the process pp→h^{*}→ZZ, the dominant momentum-dependent part of the one-loop scalar singlet corrections, especially above the new threshold at 2m_{S}, leads to a measurable deviation in the differential distribution of the Z-pair invariant mass, in accordance with the quadratic divergence cancellation to the Higgs mass. We find that it is conceivable to probe such new physics at the 5σ level at the high-luminosity LHC, improving further with the upgraded 27TeV LHC, without requiring the precise measurement of the Higgs boson total width. The discovery of such a Higgs portal could also have important implications for thermal dark matter as well as for electroweak baryogenesis.
Highlights
Examining the Higgs sector at high energy scales through off-shell Higgs production can potentially shed light on the naturalness problem of the Higgs boson mass. We propose such a study at the LHC by utilizing a representative model with a new scalar field (S) coupled to the standard model Higgs doublet (H) in a form jSj2jHj2
We find that it is conceivable to probe such new physics at the 5σ level at the high-luminosity LHC, improving further with the upgraded 27 TeV LHC, without requiring the precise measurement of the Higgs boson total width
Couplings applies for all assignments of the gauge or global quantum numbers of the scalar field, it constitutes a modelindependent probe to a maximally hidden portal sector, in which the scalars are standard model (SM) gauge singlets, do not mix with the Higgs boson after electroweak symmetry breaking, are stable, and have masses above the threshold for on-shell Higgs decays. Such a singlet Higgs portal can be responsible for generating a thermal dark matter relic, and it can drive a strongly first-order phase transition to realize electroweak baryogenesis [6,8,9]. With this simple scenario in view, we point out for the first time that the presence of such a scalar field leads to measurable deviations in the differential rates for off-shell Higgs production, especially at energy scales above the 2mS threshold, the amount of deviation from the SM prediction being in accordance with the quadratic divergence cancellation to the Higgs mass
Summary
In the process pp → hà → ZZ, the dominant momentum-dependent part of the one-loop scalar singlet corrections, especially above the new threshold at 2mS, leads to a measurable deviation in the differential distribution of the Z-pair invariant mass, in accordance with the quadratic divergence cancellation to the Higgs mass.
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