Gravitational wave footprints from Higgs-portal scalegenesis with multiple dark chiral scalars

We discuss the gravitational wave(GW)spectra predicted from the electroweak scalegenesis of the Higgs portal type with a large number of dark chiral flavors,which many flavor QCD would underlie and give the dynamical explanation of the negative Higgs portal coupling required to trigger the electroweak symmetry breaking.We employ the linear-sigma model as the low-energy description of dark many flavor QCD and show that the model undergoes ultra-supercooling due to the produced strong first-order thermal phase transition along the(approximately realized)flat direction based on the Gildener-Weinberg mechanism.Passing through evaluation of the bubble nucleation/percolation,we address the reheating and relaxation processes,which are generically non-thermal and nonadiabatic.Parametrizing the reheating epoch in terms of the e-folding number,we propose proper formulae for the redshift effects on the GW frequencies and signal spectra.It then turns out that the ultra-supercooling predicted from the Higgs-portal scalegenesis generically yields none of GW signals with the frequencies as low as nano Hz,unless the released latent heat is transported into another sector other than reheating the universe.Instead,models of this class prefer to give the higher frequency signals and still keeps the future prospected detection sensitivity,like at LISA,BBO,and DECIGO,etc.We also find that with large flavors in the dark sector,the GW signals are made further smaller and the peak frequencies higher.Characteristic phenomenological consequences related to the multiple chiral scalars include the prediction of dark pions with the mass much less than TeV scale,which is also briefly addressed.

F(R) gravity in the early Universe: electroweak phase transition and chameleon mechanism

It is widely believed that the screening mechanism is an essential feature for the modified gravity theory. Although this mechanism has been examined thoroughly in the past decade, their analyses are based on a conventional fluid prescription for the matter-sector configuration. In this paper, we demonstrate a new formulation of the chameleon mechanism in F(R) gravity theory, to shed light on quantum-field theoretical effects on the chameleon mechanism as well as the related scalaron physics, induced by the matter sector. We show a possibility that the chameleon mechanism is absent in the early Universe based on a scale-invariant-extended scenario beyond the standard model of particle physics, in which a realistic electroweak phase transition, yielding the right amount of baryon asymmetry of Universe today, simultaneously breaks the scale invariance in the early Universe. We also briefly discuss the oscillation of the scalaron field and indirect generation of non-tensorial gravitational waves induced by the electroweak phase transition.

Towards a unified interpretation of the early Universe in R^(2)-corrected dark energy model of F(R)gravity

R^(2)-corrected dark energy(DE)models in F(R)gravity have been widely investigated in recent years,which not only removes the weak singularity potentially present in DE models but also provide us with a unified picture of the cosmic history,including the inflationary and DE epochs.Towards the unified interpretation of dynamical DE all over the cosmic history in the class of R^(2)-corrected DE models,we explore the universal features of the scalaron dynamics in the radiation-dominated epoch,along with the chameleon mechanism,by keeping our eyes on the inflationary and DE epochs.We show that the scalaron evolution does not follow a surfing solution and is mostly adiabatic before big bang nucleosynthesis(BBN),even properly including the kick by the nonperturbative QCD phase transition,hence a catastrophic consequence claimed in the literature is not applied to this class of DE models.This is due to the presence of the gigantic scale hierarchy between R^(2) correction and DE,so is the universal feature for the class of R^(2)-corrected DE models.The prospects for the post-or onset-inflationary epoch would be pretty different from what the standard R^(2) inflationary scenario undergoes due to the presence of the chameleon mechanism.

Unified interpretation of scalegenesis in conformally extended standard models:a dynamical origin of Higgs portal

We present a universal interpretation of a class of conformal extended standard models that include Higgs portal interactions as realized in low-energy effective theories.The scale generation mechanism in this class(scalegenesis)arises along the(nearly)conformal/flat direction for breaking scale symmetry,where the electroweak symmetry-breaking structure arises similarly as in the standard model.A dynamical origin for the Higgs portal coupling can provide the discriminator for the low-energy“universality class,”to be probed in forthcoming collider experiments.