Relaxation of Higgs mass and cosmological constant with four-form fluxes and reheating
Hyun Min Lee
备注：
14 pages, no figures, v2: discussion on reheating revised, conclusions unchanged, references added, v3: extended and improved discussion on reheating before and after last membrane nucleation, To be published in JHEP. arXiv admin note: substantial text overlap with arXiv:1910.09171
We consider the most general effective action for the four-form fluxes in the Standard Model coupled to gravity. The Higgs mass parameter can be relaxed to a correct value due to the four-form coupling to the Higgs field and it stops changing due to an extremely suppressed transition probability from the observed cosmological constant to AdS space. We first introduce a non-minimal four-form coupling to gravity and discuss the role of a new scalar field as the inflaton and the conditions for a successful reheating at the end of relaxation.
We study the post-inflationary dynamics for reheating and freeze-in dark matter in the Higgs-$R^2$ inflation model. Taking the perturbative approach for reheating, we determine the evolution of the temperature for radiation bath produced during reheating and determine the maximum and reheating temperatures of the Universe. Adopting a singlet scalar dark matter with a conformal non-minimal coupling and a vanishing Higgs-portal coupling, we discuss the freeze-in production of dark matter both from the non-thermal scattering during reheating and the thermal scattering after reheating. We find tha…
We consider the cosmological relaxation of the Higgs mass and the cosmological constant due to the four-form fluxes in four dimensions. We present a general class of models with a singlet scalar field containing four-form couplings where the Higgs mass is relaxed to a right value and the Universe reheats to a sufficiently high reheating temperature after the last membrane nucleation. We also discuss some of interesting features in the cases of singlet scalar fields with non-minimal or minimal couplings to gravity and show how the new scalar fields can play a role for dark matter production.
The preheating process in the mixed Higgs-$ R^2 $ model has been investigated in depth recently, but the analysis of perturbative reheating is still missing. In this paper, we discuss the effect of perturbative decay during (p)reheating in this model. It is shown that perturbative decay can play an important role throughout the whole reheating process. Depending on the model parameters, perturbative decay can affect different stages of the reheating. We study the perturbative reheating with and without the presence of early preheating stage, and calculate the reheating temperature and the dura…
We consider the possibility that the dark energy responsible for inflation is deposited into extra dimensions outside of our observable universe. Reheating and all matter can then be obtained from the MSSM flat direction condensate involving the Higgses $H_u$ and $H_d$, which acquires large amplitude by virtue of quantum fluctuations during inflation. The reheat temperature is $T_{RH} \lesssim 10^9$ GeV so that there is no gravitino problem. We find a spectral index $n_s\approx 1$ with a very weak dependence on the Higgs potential.
We extend our previous study of supersymmetric Higgs inflation in the context of no-scale supergravity and grand unification, to include models based on the flipped SU(5) and the Pati-Salam group. Like the previous SU(5) GUT model, these yield a class of inflation models whose inflation predictions interpolate between those of the quadratic chaotic inflation and Starobinsky-like inflation, while avoiding tension with proton decay limits. We further analyse the reheating process in these models, and derive the number of e-folds, which is independent of the reheating temperature. We derive the c…
The Standard Model Higgs boson, which has previously been shown to develop an effective vacuum expectation value during inflation, can give rise to large particle masses during inflation and reheating, leading to temporary blocking of the reheating process and a lower reheat temperature after inflation. We study the effects on the multiple stages of reheating: resonant particle production (preheating) as well as perturbative decays from coherent oscillations of the inflaton field. Specifically, we study both the cases of the inflaton coupling to Standard Model fermions through Yukawa interacti…
Within the framework of RG improved inflationary cosmology motivated by asymptotically safe gravity, we study the dynamics of a scalar field which can be interpreted as the Higgs field. The background trajectories of this model can provide sufficient inflationary e-folds and a graceful exit to a radiation dominated phase. We study the possibility of generating primordial curvature perturbations through the Standard Model Higgs boson. This can be achieved under finely tuned parameter choices by making use of the modulated reheating mechanism. The primordial non-gaussianity is expected to be siz…
A reheating phase in the early universe is an essential part of all inflationary models during which not only the Standard Model (SM) quanta are produced but it can also shed light on the production of dark matter. In this work, we explore a class of reheating models where the reheating is induced by a cubic interaction of the inflaton $ϕ$ to the SM Higgs boson ${\textbf h}$ of the form $g_{hϕ} M_{\rm Pl} ϕ|{\textbf h}|^2$ adopting the $α$-attractor T-model of inflation. Assuming inflaton as a background field such interaction implies a $ϕ$-dependent mass term of the Higgs boson and a non-triv…
We study the role of the Standard Model Higgs condensate, formed during cosmological inflation, in the epoch of reheating that follows. We focus on the scenario where the inflaton decays slowly and perturbatively, so that there is a long period between the end of inflation and the beginning of radiation domination. The Higgs condensate decays non-perturbatively during this period, and we show that it heats the primordial plasma to much higher temperatures than would result from the slowly-decaying inflaton alone. We discuss the effect of this hot plasma on the thermalization of the inflaton's …
The flatness of the inflaton potential and lightness of the Higgs could have the common origin of the breaking of a global symmetry. This scenario provides a unified framework of Goldstone Inflation and Composite Higgs, where the inflaton and the Higgs both have a pseudo--Goldstone boson nature. The inflaton reheats the Universe via decays to the Higgs and subsequent secondary production of other SM particles via the top and massive vector bosons. We find that inflationary predictions and perturbative reheating conditions are consistent with CMB data for sub--Planckian values of the fields, as…
It is shown that a positive non-minimal coupling of the Higgs field to gravity can solve the two problems in inflation models in which postinflationary universe is dominated by an energy with stiff equation of state such as a kination, namely, overproduction of gravitons in gravitational reheating scenario, and overproduction of curvature perturbation from Higgs condensation. Furthermore, we argue that the non-minimal coupling parameter can be constrained more stringently with the progress in observations of large-scale structure and cosmic microwave background.
Current Higgs boson and top quark data favor metastability of our vacuum which raises questions as to why the Universe has chosen an energetically disfavored state and remained there during inflation. In this Letter, we point out that these problems can be solved by a Higgs-inflaton coupling which appears in realistic models of inflation. Since an inflaton must couple to the Standard Model particles either directly or indirectly, such a coupling is generated radiatively, even if absent at tree level. As a result, the dynamics of the Higgs field can change dramatically.
Current measurements of the Higgs boson mass and top Yukawa coupling suggest that the effective Higgs potential develops an instability below the Planck scale. If the energy scale of inflation is as high as the GUT scale, inflationary quantum fluctuations of the Higgs field can easily destabilize the standard electroweak vacuum and produce a lot of AdS domains. This destabilization during inflation can be avoided if a relatively large nonminimal Higgs-gravity or inflaton-Higgs coupling is introduced. Such couplings generate a large effective mass term for the Higgs, which can raise the effecti…
We propose a new way of studying the Higgs potential at extremely high energies. The Standard Model (SM) Higgs boson, as a light spectator field during inflation in the early Universe, can acquire large field values from its quantum fluctuations which vary among different causal (Hubble) patches. Such a space dependence of the Higgs after the end of inflation leads to space-dependent SM particle masses and hence variable efficiency of reheating, when the inflaton decays to Higgsed SM particles. Inhomogeneous reheating results in (observable) temperature anisotropies. Further, the resulting tem…
Virtual Institute of Astroparticle Physics（虚拟天体粒子物理研究所）；MG Science Institute, Gujarat University（古吉拉特大学 MG 科学研究所）；Department of Physics and Astronomy, Vanderbilt University（范德堡大学物理与天文系）；National Research Nuclear University MEPhI（俄罗斯国立核研究大学莫斯科工程物理学院）；Research Institute of Physics, Southern Federal University（南联邦大学物理研究所）
Spontaneous breaking of conformal symmetry has been widely exploited in successful model building of both inflationary cosmology and particle physics phenomenology. Conformal Grand Unified Theory (CGUT) inflation provides the same scalar tilt and tensor-to-scalar ratio as of Starobinsky and Higgs inflation. Moreover, it predicts a proton life time compatible with the current experimental bound. In this paper, we extend CGUT to account for the production of dark matter and the reheating of the Standard Model. To this end, we introduce a hidden sector directly coupled to the inflaton, whereas th…
We revisit the inflection point inflation with an extended discussion to large field values and consider the reheating effects on the inflationary predictions. Parametrizing the reheating dynamics in terms of the reheating temperature and the equation of state during inflation, we show how the observationally favored parameter space of inflection point inflation is affected by reheating dynamics. Consequently, we apply the general results to the inflation models with non-minimal coupling, such as the SM Higgs inflation and the $B-L$ Higgs inflation.
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We propose a scenario of spontaneous leptogenesis in Higgs inflation with help from two additional operators: the Weinberg operator (Dim 5) and the derivative coupling of the Higgs field and the current of lepton number (Dim 6). The former is responsible for lepton number violation and the latter induces chemical potential for lepton number. The period of rapidly changing Higgs field, naturally realized in Higgs inflation during the reheating, allows large enhancement in the produced asymmetry in lepton number, which is eventually converted into baryon asymmetry of the universe. This scenario …
The analysis of theories with non-minimal coupling of Higgs field to gravity revealed that they enter into strong coupling regime above certain Higgs-dependent cutoff, which may be considerably below the Planck scale. Assuming that the effective theory, complementing the Standard Model or its minimal extension--the nuMSM--contains a set of higher dimensional operators suppressed by the Higgs-dependent cutoff, we analyse the reheating of the Universe after the Higgs inflation. We show that extra terms do not spoil the Higgs inflation, but can lead to baryogenesis and to warm sterile neutrino da…
We study the Standard Model Higgs field as a source for the primordial curvature perturbation, particularly in the curvaton and modulated reheating scenario. We conclude that the Higgs cannot play as a curvaton due to the small energy density when it decays, however the modulated reheating by Higgs can be a viable scenario. In the latter case, the non-Gaussianity is inevitably generated and strongly constrains the type of potential of inflaton field and Higgs-dependent interaction term. For the quadratic potential of the inflaton field with decay rate which non-linearly depends on the Higgs va…
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Low-reheating scenario in dark Higgs inflation and its impact on dark photon dark matter production
Aliah University（阿利亚大学）；Chung-Ang University（中央大学）；University of Shanghai for Science and Technology（上海理工大学）；Tongji University（同济大学）；Korea Institute for Advanced Study（韩国高等研究院）
We study models in which reheating happens only through non-perturbative processes. The energy transferred can be exponentially suppressed unless the inflaton is coupled to a particle with a parametrically small mass. Additionally, in some models a light scalar with a negative mass squared parameter leads to much more efficient reheating than one with a positive mass squared of the same magnitude. If a theory contains many sectors similar to the Standard Model coupled to the inflaton via their Higgses, such dynamics can realise the Nnaturalness solution to the hierarchy problem. A sector conta…
We consider models for inflation with a stable inflaton. Reheating is achieved through scattering processes such as $ϕϕ\to h h$, where $h$ is the Standard Model Higgs boson. We consider the reheating process in detail and show that for a relatively large coupling (needed for the late annihilations of the inflaton during freeze-out), reheating is almost instantaneous leading to a relatively high reheating temperature. The process $ϕϕ\leftrightarrow h h$ brings the inflaton back into equilibrium, leading to a well studied scalar singlet dark matter candidate and Higgs portal model. We argue that…
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We consider $R^2$ inflation in the Palatini gravity assuming the existence of scalar fields, coupled to gravity in the most general manner. These theories, in the Einstein frame, and for one scalar field $h$, share common features with $K$ - inflation models. We apply this formalism for the study of popular inflationary models, whose potentials are monomials, $ V \sim h^{n} $, with $ n $ a positive even integer. We also study the Higgs model non-minimally coupled to gravity. Although these have been recently studied, in the framework of the Palatini approach, we show that the scalar power spec…
Reheating the FCC: Probing Early Matter Domination with Long-Lived Particles
New York University Abu Dhabi（阿布扎比纽约大学）；Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Millennium Institute for Subatomic Physics at the High Energy Frontier (SAPHIR)（高能前沿亚原子物理千年研究所 (SAPHIR)）
We study radiative plateau-like inflation \& Z$_{BL}$-portal freeze-in fermionic dark matter (DM) in a minimal B-L extended model. The U(1)$_{B-L}$ Higgs, responsible for heavy neutrino masses, also drives inflation in the early universe, thanks to radiative corrections from the heavy neutrinos \& the Z$_{BL}$ gauge boson. In our benchmark choice for the U(1)$_{B-L}$ gauge coupling $g_{B-L}\sim10^{-4}$, a light Z$_{BL}$ boson can be explored by current and future lifetime frontier experiments, such as FASER and FASER 2 at the LHC, SHiP, Belle II and LHCb. For the benchmark, the Hubble scale of…
Warm dark matter (WDM) of order keV mass may be able to resolve the disagreement between structure formation in cold dark matter simulations and observations. The detailed properties of WDM will depend upon its energy distribution, in particular how it deviates from the thermal distribution usually assumed in WDM simulations. Here we focus on WDM production via the Ultra-Violet (UV) freeze-in mechanism, for the case of fermionic Higgs portal dark matter $ψ$ produced via the portal interaction $\barψψH^{\dagger}H/Λ$. We introduce a new method to simplify the computation of the non-thermal energ…
Inflaton Regeneration via Scalar Couplings: Generic Models and the Higgs Portal
Faculty of Education, Niigata University（新潟大学教育学部）；Department of Physics, Saga University（佐贺大学物理学系）；Graduate School of Science and Engineering, Saga University（佐贺大学理工学研究科）
We revisit Higgs inflation in the framework of a minimal extension of the Standard Model gauge symmetry by a $U(1)_{B-L}$ factor. Various aspects are taken into account with particular focus on the role of the supersymmetry breaking (SUSY) scale and the cosmological constraints associated with the gravitino. The scalar potential of the model is considered in the context of no-scale supergravity consisting of the F-part constructed from the Kähler function, the D-terms and soft SUSY contributions. We investigate several limiting cases and by varying the SUSY scale from a few TeV up to intermedi…
The inflation within the MSSM is proposed, where the inflaton field is a combination of the Higgs, squark and slepton states. While the inflationary phase is fully governed by the electron Yukawa superpotential coupling, the fields' condensates float along the flat $D$-term trajectory. This predicts the MSSM parameter $\tan β\simeq 13.1$ determined via the value of the curvature perturbation amplitude. The values of the scalar spectral index and the tensor-to-scalar ratio are predicted to be $n_s\simeq 0.966$ and $r=0.00118$. The postinflation reheating of the Universe proceeds by the radiativ…
Probing displaced (dark)photons from low reheating freeze-in at the LHC
Facultad de Ingeniería, Universidad San Sebastián（塞巴斯蒂安大学工程学院）；Millennium Institute for Subatomic Physics at the High-Energy Frontier (SAPHIR)（高能前沿亚原子物理千年研究所（SAPHIR））；Instituto de Física, Pontificia Universidad Católica de Chile（智利天主教大学物理研究所）；Instituto de Física, Facultad de Ciencias, Universidad de la República（共和国大学理学院物理研究所）；Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú（秘鲁天主教大学科学院物理组）
We consider reheating driven by volume modulus decays in the LARGE Volume Scenario. Such reheating always generates non-zero dark radiation through the decays to the axion partner, while the only competitive visible sector decays are Higgs pairs via the Giudice-Masiero term. In the framework of sequestered models where the cosmological moduli problem is absent, the simplest model with a shift-symmetric Higgs sector generates 1.56 < N_{eff} - N_{eff,SM} < 1.74. For more general cases, the known experimental bounds on N_{eff} strongly constrain the parameters and matter content of the models.
We discuss the Yukawa couplings in 6D gauge-Higgs unification models on $T^2/Z_N$ in the presence of magnetic fluxes. We provide general formulae for them, and numerically evaluate their magnitude in a specific model on $T^2/Z_3$. Thanks to the nontrivial profiles of the zero-mode wave functions, the top quark Yukawa coupling can be reproduced without introducing a large representation of the gauge group for matter fields. However, it is difficult to realize small Yukawa couplings only by the magnetic fluxes and the Wilson-line phases because of the complicated structure of the mode functions …
We present a model for viable gravitational reheating involving a scalar field directly coupled to the Ricci curvature scalar. Crucial to the model is a period of kination after inflation, which causes the Ricci scalar to change sign thus inducing a tachyonic effective mass $m^{2} \propto -H^2$ for the scalar field. The resulting tachyonic growth of the scalar field provides the energy for reheating, allowing for temperatures high enough for thermal leptogenesis. Additionally, the required period of kination necessarily leads to a blue-tilted primordial gravitational wave spectrum with the pot…
By using a No-Scale Supergravity model, which was proved well to explain WMAP observations appropriately, a mechanism of preheating just after the end of inflation is investigated. By using the canonically normalized and diagonalized scalars, the decay rates of these fields are calculated inflaton $S$ into gauge sector fields. The reheating temperature is estimated by both the stability condition of Boltzmann equation and the instant preheating mechanism. The both of reheating temperatures are almost the same order of magnitude $\sim O(10^{10})$ GeV. Because two mechanisms are completely indep…
The quantum fluctuations of the Higgs field during inflation could be a source of primordial density perturbations through Higgs-dependent inflaton decay. By measuring primordial non-Gaussianities, this so-called Higgs-modulated reheating scenario provides us a unique chance to probe Higgs interactions at extremely high energy scale, which we call the Cosmological Higgs Collider (CHC). We realize CHC in a simple scenario where the inflaton decays into Higgs-portal scalars, taking account of the decay of the Higgs fluctuation amplitude after inflation. We also calculate the CHC signals of Stand…
