Abstract
We develop an effective-model description arising from a recently proposed scale-invariant hidden scalar-QCD, which has been used to explain the dynamical origin of the electroweak scale. In addition to the previous works, our new effective model includes the dynamical scale-anomaly effect from the hidden QCD gluons, to explicitly break the classical-scale invariance at the level of an effective field theory, which is known as the leading-order scale-symmetry (LOSS). In the phenomenological analysis, the proposed model predicts a light composite dilaton composed of hidden scalar quarks and gluons with the mass around electroweak scale (around 280 GeV), and has only one input parameter, which is the mixing angle between the Higgs boson and the composite dilaton. Our result for the dilaton mass is in accord with the lattice simulation for scalar QCD, where the scalar-quark bound states acquire a large effective mass from the hidden gluon contribution. Furthermore, we predict several significant deviations from the SM, like the diHiggs production cross sections (maximally about 10 times larger than the SM prediction), that could be directly tested at the high luminosity LHC. It is also the first study for the diHiggs production signal predicted from a scale(conformal)-invariant hidden sector, even from dark/hidden QCD. Our proposed effective model is thus significantly different than the conventional realization of scale-invariant hidden-scalar QCD without the scale anomaly effect, and can potentially provide a competitive explanation for many exotic phenomena beyond the standard model, such as new dark matter candidates and a strongly first-order electroweak phase transition.
Highlights
It is no doubt that the standard model (SM) meets perfectly with most of the experimental results in high-energy physics
We propose an effective model for hidden scalar QCD at the leading-order scale symmetry (LOSS) limit with the gluonic effect incorporated as the nonperturbative scale anomaly
We constructed an effective model for a hidden scalar QCD at the leading-order scale-symmetry (LOSS) limit, which properly includes a crucial gluoncondensate effect as the nonperturbative scale anomaly term, and is in accordance with the indications from the lattice simulation and other nonperturbative analysis of the scalar QCD
Summary
It is no doubt that the standard model (SM) meets perfectly with most of the experimental results in high-energy physics. The hidden scalar QCD possesses the potential to explain the dynamical origin of the EW scalegenesis and provides rich related phenomenological consequences accessible in the future experiments This scenario may still lack important ingredients. We propose an effective model for hidden scalar QCD at the LOSS limit with the gluonic effect incorporated as the nonperturbative scale anomaly. Demonstrated that the proposed model based on the LOSS gives a definite prediction to di-Higgs signals at the LHC, in correlation with a significant deviation from the SM on the Higgs coupling measurement This result is manifestly a smoking gun of the LOSS limit, which will open a new avenue for the phenomenological probe of the hidden scalar QCD scenario, other than those so far explored, such as DM physics, a strongly first-order EW phase transition, and gravitational waves detectability. IV is devoted to a summary of this paper and the prospect of the LOSS for some future research on the DM, as well as an issue on the EW phase transition
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