We present the supersymmetric extension of the unified model for inflation and Dark Matter studied in Ref. arXiv:1811.02302. The scenario is based on the incomplete decay of the inflaton field into right-handed (s)neutrino pairs. By imposing a discrete interchange symmetry on the inflaton and the right-handed (s)neutrinos, one can ensure the stability of the inflaton field at the global minimum today, while still allowing it to partially decay and reheat the Universe after inflation. Compatibility of inflationary predictions, BBN bounds and obtaining the right DM abundance for the inflaton Dark Matter candidate typically requires large values of its coupling to the neutrino sector, and we use supersymmetry to protect the inflaton from potentially dangerous large radiative corrections which may spoil the required flatness of its potential. In addition, the inflaton will decay now predominatly into sneutrinos during reheating, which in turn give rise both to the thermal bath made of Standard Model particles, and inflaton particles. We have performed a through analyses of the reheating process following the evolution of all the partners involved, identifying the different regimes in the parameter space for the final Dark Matter candidate. This as usual can be a WIMP-like inflaton particle or an oscillating condensate, but we find a novel regime for a FIMP-like candidate.
The primordial inflation dilutes all matter except the quantum fluctuations which we see in the cosmic microwave background (CMB) radiation. Therefore the last phases of inflation must be embedded within a beyond the Standard Model (SM) sector where the inflaton can directly excite the SM quarks and leptons. In this paper we consider two inflaton candidates LLe and udd whose decay can naturally excite all the relevant degrees of freedom besides thermalizing the lightest supersymmetric particle (LSP) during and after reheating. In particular, we present the regions of the parameter space which …
We present a model where the inflaton can naturally account for all the dark matter in the Universe within the warm inflation paradigm. In particular, we show that the symmetries of the Warm Little Inflaton scenario (i) avoid large thermal and radiative corrections to the scalar potential, (ii) allow for sufficiently strong dissipative effects to sustain a radiation bath during inflation that becomes dominant at the end of the slow-roll regime, and (iii) enable a stable inflaton remnant in the post-inflationary epochs. The latter behaves as dark radiation until parametrically before matter-rad…
We present a scenario of vector dark matter production during inflation containing a complex inflaton field which is charged under a dark gauge field and which has a symmetry breaking potential. As the inflaton field rolls towards the global minimum of the potential the dark photons become massive with a mass which can be larger than the Hubble scale during inflation. The accumulated energy of the quantum fluctuations of the produced dark photons gives the observed relic density of the dark matter for a wide range of parameters. Depending on the parameters, either the transverse modes or the l…
It is shown that perturbative reheating can reach a sufficiently high temperature with small or negligible inflaton decay rate provided that the inflaton potential becomes negative after inflation. In our model, inflaton and dark energy field are two independent scalar fields, and, depending on the mass of the inflaton and its coupling to matter fields, there is a possibility that the remaining inflaton after reheating can become a dark matter candidate.
We present a model where the inflaton field behaves like quintessence at late times, generating the present phase of accelerated expansion. This is achieved within the framework of warm inflation, in particular the Warm Little Inflaton scenario, where the underlying symmetries guarantee a successful inflationary period in a warm regime sustained by dissipative effects without significant backreaction on the scalar potential. This yields a smooth transition into a radiation-dominated epoch, at which point dissipative effects naturally shut down as the temperature drops below the mass of the fer…
Dissipative effects can lead to a friction term in the equation of motion for an inflaton field during the inflationary era. The friction term may be linear and localised, in which case it is described by a dissipation coefficient. The dissipation coefficient is calculated here in a supersymmetric model with a two stage decay process in which the inflaton decays into a thermal gas of light particles through a heavy intermediate. At low temperatures, the dissipation coefficient $\propto T^3$ in a thermal approximation. Results are also given for a non-equilibrium anzatz. The dissipation coeffic…
We show that the decay of the inflaton field may be incomplete, while nevertheless successfully reheating the universe and leaving a stable remnant that accounts for the present dark matter abundance. We note, in particular, that since the mass of the inflaton decay products is field-dependent, one can construct models, endowed with an appropriate discrete symmetry, where inflaton decay is kinematically forbidden at late times and only occurs during the initial stages of field oscillations after inflation. We show that this is sufficient to ensure the transition to a radiation-dominated era an…
In this paper, we investigate the parameter space in the framework of hilltop supernatural inflation in which the inflaton field can play the role of Affleck-Dine field to produce successful baryogenesis. The suitable value of reheating temperature could coincide with the reheating temperature required to produce lightest supersymmetric particle dark matter. The baryon isocurvature perturbation is shown to be negligible. We consider $p=3$, $p=4$, and $p=6$ type III hilltop inflation and discuss how to connect the models to supersymmetric theories.
We consider a supersymmetric hybrid inflation model with two inflaton fields. The superpotential during inflation is dominated by W=(κS+κ' S')M^2, where S, S' are inflatons carrying the same U(1)_R charge, κ, κ' are dimensionless couplings, and M (\sim 10^{15-16} GeV) is a dimensionful parameter associated with a symmetry breaking scale. One light mass eigenstate drives inflation, while the other heavier mass eigenstate is stuck to the origin. The smallness of the lighter inflaton mass for the scalar spectral index n_s\approx 0.96, which is the center value of WMAP7, can be controlled by the r…
We present a model where inflation and Dark Matter takes place via a single scalar field phi. Without introducing any new parameters we are able unify inflation and Dark Matter using a scalar field phi that accounts for inflation at an early epoch while it gives a Dark Matter WIMP particle at low energies. After inflation our universe must be reheated and we must have a long period of radiation dominated before the epoch of Dark Matter. Typically the inflaton decays while it oscillates around the minimum of its potential. If the inflaton decay is not complete or sufficient then the remaining e…
We show the effects of supersymmetric higher derivative terms on inflation models in supergravity. The results show that such terms generically modify the effective kinetic coefficient of the inflaton during inflation if the cut off scale of the higher derivative operators is sufficiently small. In such a case, the $η$-problem in supergravity does not occur, and we find that the effective potential of the inflaton generically becomes a power type potential with a power smaller than two.
We consider the possibility that the inflaton is part of the dark sector and interacts with the standard model through a portal interaction with a heavy complex scalar field in equilibrium with the standard model at high energies. The inflaton and dark matter are encapsulated in a single complex field and both scalar sectors are charged under different (approximate) global U(1)'s such that the dark matter, as well as the visible pseudo-scalar are taken to be relatively light, as pseudo Nambu-Goldstone bosons of the theory. The dark matter relic density is populated by Freeze-In productions thr…
It has been shown that hybrid inflation may end with the formation of non-topological solitons of inflaton field. As a first step towards a fully realistic picture of the post-inflation era and reheating in supersymmetric hybrid inflation models, we study the classical scalar field equations of a supersymmetric hybrid inflation model using a semi-analytical ansatz for the spatial dependence of the fields. Using the minimal D-term inflation model as an example, the inflaton field is evolved using the full 1-loop effective potential from the slow-rolling era to the U(1)_{FI} symmetry-breaking ph…
We discuss a minimal extension of the Standard Model (SM) where a single real scalar field serves as both inflaton and dark matter. The corresponding Lagrangian contains the renormalizable interactions of the inflaton field. Quantum effects generally induce a non-minimal coupling to gravity which facilitates inflation consistent with the PLANCK constraints. A large fraction of the inflaton quanta produced after inflation must be converted into the SM radiation reheating the Universe and the rest remains dark matter today. We consider thermal and non-thermal production of inflaton dark matter. …
We address an issue what kind of tuning realizes a flat potential for inflaton in supergravity. We restrict ourselves to the case that inflationary dynamics is not affected by separate supersymmetry-breaking effects, and consider examples of a single chiral superfield as an inflaton with its vacuum of the vanishing cosmological constant. The examples potentially include the cases of Polonyi field or right-handed sneutrino as an inflaton.
We study scalar dark matter production and reheating via renormalizable inflaton couplings, which include both quartic and trilinear interactions. These processes often depend crucially on collective effects such as resonances, backreaction and rescattering of the produced particles. To take them into account, we perform lattice simulations and map out parameter space producing the correct (non-thermal) dark matter density. We find that the inflaton-dark matter system can reach a quasi-equilibrium state during preheating already at very small couplings, in which case the dark matter abundance …
We discuss the possibility of producing a light dark photon dark matter through a coupling between the dark photon field and the inflaton. The dark photon with a large wavelength is efficiently produced due to the inflaton motion during inflation and becomes non-relativistic before the time of matter-radiation equality. We compute the amount of production analytically. The correct relic abundance is realized with a dark photon mass extending down to $10^{-21} \, \rm eV$.
We consider supersymmetric inflation with the hybrid-type potential. In the absence of the symmetry that forbids Hubble-induced mass terms, the inflaton mass will be as large as the Hubble scale during inflation. We consider gravitational decay of the trigger field as the least decay mode and find that the damping caused by the dissipation can dominate the friction of the inflaton when the heavy trigger field is coupled to the inflaton. The dissipative damping provides a solution to the traditional $η$ problem without introducing additional symmetry and interactions. Considering the spatial in…
We study a recently proposed running kinetic inflation model in which the inflaton potential becomes flat due to rapid growth of the kinetic term at large inflaton field values. As concrete examples, we build a variety of chaotic inflation models in supergravity with e.g. quadratic, linear, and fractional-power potentials. The power of the potential generically increases after inflation, and the inflaton is often massless at the potential minimum in the supersymmetric limit, which leads to many interesting phenomena. First, the light inflaton mass greatly relaxes severe thermal and non-thermal…
We discuss a scenario that gravitinos produced non-thermally by an inflaton decay constitute dark matter in the present universe. We find that this scenario is realized for wide ranges of the inflaton mass and the vacuum expectation value. What is intriguing about this scenario is that the gravitino dark matter can have a relatively large free streaming length at matter-radiation equality, which can be probed by future observation on QSO-galaxy strong lens system.
We study a new model of quintessential inflation which is inspired by supergravity and string theory. The model features a kinetic pole, which gives rise to the inflationary plateau, and a runaway quintessential tail. We envisage a coupling between the inflaton and the Peccei-Quinn (PQ) field which terminates the roll of the runaway inflaton and traps the latter at an enhanced symmetry point (ESP), thereby breaking the PQ symmetry. The kinetic density of the inflaton is transferred to the newly created thermal bath of the hot big bang due to the decay of PQ particles. The model successfully ac…
We propose a simple mechanism of light dark matter (DM) production from the decay of the oscillating inflaton condensation. If the reheating temperature after inflation is higher than the inflaton mass, which is of the same order of the momentum of the DM at the time of the production, the DM momentum can be suppressed compared to the temperature of the thermal plasma if the interaction of the DM is weak enough. Consequently, the DM can be cold enough to avoid the observational constraints on the warm DM, like the Lyman-$α$ bound even if the DM mass is small. We study the bosonic and fermionic…
Motivated by Refs \cite{am1,am2}, we analyze how the inflaton decay reheats the Universe within supersymmetry. In a non-supersymmetric case the inflaton usually decays via preheating unless its couplings to other fields are very small. Naively one would expect that supersymmetry enhances bosonic preheating as it introduces new scalars such as squarks and sleptons. On the contrary, we point out that preheating is unlikely within supersymmetry. The reason is that flat directions in the scalar potential, classified by gauge invariant combinations of slepton and squark fields, are generically disp…
A generic prediction of the Coleman-Weinberg inflation is the existence of a heavy particle sector whose interactions with the inflaton, the lightest state in this sector, generate the inflaton potential at loop level. For typical interactions the heavy sector may contain stable states whose relic abundance is generated at the end of inflation by the gravity alone. This general feature, and the absence of any particle physics signal of dark matter so far, motivates us to look for new directions in the dark sector physics, including scenarios in which dark matter is super-heavy. In this article…
We investigate multi-field signatures of the nonminimally coupled supersymmetric Higgs inflation-type cosmological scenario, focusing on the two-field Higgs-lepton inflation model as a concrete example. This type of inflationary model is realized in a theory beyond the Standard Model embedded in supergravity with a noncanonical Kähler potential. We employ the backward $δN$ formalism to compute cosmological observables, including the scalar and tensor power spectra, the spectral indices, the tensor-to-scalar ratio and the local-type nonlinearity parameter. The trajectory of the inflaton is cont…
Gravitational waves signatures from dynamical scalar field configurations provide a compelling observational window on the early universe. Here we identify intriguing connections between dark matter and scalars fields that emit gravitational waves, either through a first order phase transition or oscillating after inflation. To study gravitational waves from first order phase transitions, we investigate a simplified model consisting of a heavy scalar coupled to a vector and fermion field. We then compute gravitational wave spectra sourced by inflaton field configurations oscillating after E-Mo…
The recent XENON1T excess in the electron recoil data can be explained by anomaly-free axion-like particle (ALP) dark matter with mass $m_ϕ= 2.3 \pm 0.2\,$keV and the decay constant $f_ϕ/q_e \simeq 2 \times 10^{10} \sqrt{Ω_ϕ/Ω_{\rm DM}}\,{\rm GeV}$. Intriguingly, the suggested mass and decay constant are consistent with the relation, $f_ϕ\sim 10^3 \sqrt{m_ϕM_p}$, predicted in a scenario where the ALP plays the role of the inflaton. This raises a possibility that the ALP dark matter responsible for the XENON1T excess also drove inflation in the very early universe. We study implications of the …
We explore the possibility that the dark-matter relic abundance is generated in a context where the inflaton is the only mediator between the visible and the hidden sectors of our universe. Due to the relatively large mass of the inflaton field, such a portal leads to an extremely feeble interaction between the dark and the visible sectors suggesting that the dark sector cannot reach any thermal equilibrium with the visible sector. After the two sectors are populated by the decay of the inflaton, a heavy dark-matter particle thermally decouples within the dark sector. Later, a lighter dark par…
We examine the particle production via preheating at the end of inflation in supersymmetric theories. The inflaton and matter scalars are now necessarily complex fields, and their relevant interactions are restricted by holomorphy. In general this leads to major changes both in the inflaton dynamics and in the efficiency of the preheating process. In addition, supersymmetric models generically contain multiple isolated vacua, raising the possibility of non-thermal production of dangerous topological defects. Because of these effects, the success of leptogenesis or WIMPZILLA production via preh…
We study the minimal extension of the SM by a scalar with quartic interaction serving as an inflaton. For the model where scale symmetry is broken only in the inflaton sector, the mass of the inflaton is constrained to be relatively low. Here, we analysed the previously omitted situation of the inflaton masses $m_χ\gtrsim 250\text{ GeV}$. Therefore, we provide a window of inflaton masses with viable inflationary properties that evade direct observational constraints, due to their small mixing with the Higgs sector. The addition of heavy neutral leptons with Majorana masses induced by the inter…
We examine an intriguing possibility that a single field is responsible for both inflation and dark matter, focussing on the minimal set-up where inflation is driven by a scalar coupling to curvature. We study in detail the reheating process in this framework, which amounts mainly to particle production in a quartic potential, and distinguish thermal and non-thermal dark matter options. In the non-thermal case, the reheating is impeded by backreaction and rescattering, making this possibility unrealistic. On the other hand, thermalized dark matter is viable, yet the unitarity bound forces the …
The gravitino problem gives a severe constraint on the thermal leptogenesis scenario. This problem leads us to consider some alternatives to it if we try to keep the gravitino mass around the weak scale $m_{3/2} \sim 100$ GeV. We consider, in this paper, the non-thermal leptogenesis scenario in the framework of a minimal supersymmetric SO(10) model. Even if we start with the same minimal SO(10) model, we have different predictions for low-energy phenomenologies dependent on the types of seesaw mechanism. This is the case for leptogenesis: it is shown that the type-I see-saw model gives a consi…
In supersymmetric models of warm inflation, the large temperature of the radiation bath produced by the dissipative motion of the inflaton field may induce a significant thermal abundance of potentially dangerous gravitinos. While previous discussions of this problem focused on gravitino production only at the end of warm inflation, similarly to conventional reheating scenarios, we study the full evolution of the gravitino abundance during and after inflation for simple monomial potentials, taking into account the enhanced gravitino and possibly gaugino masses due to supersymmetry breaking dur…
Inflation, as currently understood, requires the presence of fields with very flat potentials. Supersymmetric models in which supersymmetry breaking is communicated by supergravity naturally yield such fields, but the scales are typically not suitable for obtaining both sufficient inflation and a suitable fluctuation spectrum. In the context of recent ideas about gauge mediation, there are new candidates for the inflaton. We present a simple model for slow-rollover inflation where the vacuum energy driving inflation is related to the same F-term responsible for the spectrum of supersymmetric p…
We discuss the production of radiation and dark matter assuming a time-dependent inflaton decay rate during the reheating period. It is shown that the time dependence of the inflaton decay rate can substantially modify the reheating dynamics. As an illustration, a leading interaction between the inflaton $ϕ$ and the Higgs doublet ${\boldsymbol h}$ of the form $ϕ|{\boldsymbol h}|^2$ was adopted. In the presence of such interaction, the Higgs doublet acquires a $ϕ$-dependent mass which generates vacuum-expectation-value due to inflaton oscillations and breaks the Standard Model gauge symmetry. T…
In this talk we will discuss how inflation can be embedded within a minimal extension of the Standard Model where the inflaton carries the Standard Model charges. There is no need of an ad-hoc scalar field to be introduced in order to explain the temperature anisotropy of the cosmic microwave background radiation, all the ingredients are present within a minimal supersymmetric Standard Model. For the first time inflaton properties can be directly linked to the particle phenomenology, dark matter, and the baryons of the Standard Model.
We show that, by adding a gauge singlet scalar S to the standard model which is nonminimally coupled to gravity, S can act both as the inflaton and as thermal relic dark matter. We obtain the allowed region of the (m_s, m_h) parameter space which gives a spectral index in agreement with observational bounds and also produces the observed dark matter density while not violating vacuum stability or nonperturbativity constraints. We show that, in contrast to the case of Higgs inflation, once quantum corrections are included the spectral index is significantly larger than the classical value (n = …
We analyse the dark Higgs inflation model with curvature corrections and explore the possibility to test its predictions by the particle physics experiments at LHC. We show that the dark Higgs inflation model with curvature corrections is strongly favoured by the present cosmological observations. The cosmological predictions of this model, including the quantum corrections of dark Higgs coupling constants and the uncertainty in estimation of the reheating temperature, lead to the dark Higgs mass $m_ϕ=0.919 \pm$ 0.211 GeV and the mixing angle $θ=1.492 \pm$ 0.045 (at 68\% CL). We evaluate the F…
We propose a non-thermal scenario for the generation of baryon number asymmetry in a radiative neutrino mass model which is modified to realize inflation at the early Universe. In this scenario, inflaton plays a crucial role in both generation of neutrino masses and lepton number asymmetry. Lepton number asymmetry is firstly generated in the dark matter sector through direct decay of inflaton. It is transferred to the lepton sector via the dark matter annihilation and then converted to the baryon number asymmetry due to the sphaleron interaction. All of the neutrino masses, the baryon number a…
Decay of the inflaton or moduli which dominated the energy density of the universe at early times leads to a matter to radiation transition epoch. We consider non-thermal sterile dark matter particles produced as decay product during such transitions. The particles have a characteristic energy distribution - that associated with decays taking place in a matter dominated universe evolving to radiation domination. We primarily focus on the case when the particles are hot dark matter, and study their effects on the Cosmic Microwave Background (CMB) and Large Scale Structure (LSS), explicitly taki…
We study the mechanism of generation of 7 keV sterile neutrino Dark Matter (DM) in the model with light inflaton $χ$, which serves as a messenger of scale invariance breaking. In this model the inflaton, in addition to providing reheating to the Standard Model (SM) particles, decays directly into sterile neutrinos. The latter are responsible for the active neutrino oscillations via seesaw type I like formula. While the two sterile neutrinos may also produce the lepton asymmetry in the primordial plasma and hence explain the baryon asymmetry of the Universe, the third one being the lightest may…
We study the possibility that, after inflation, the inflaton reaches thermal equilibrium with the Standard Model thermal bath and eventually freezes-out in the non-relativistic regime. When the inflaton decay is the sole source of (non-thermal) dark matter, its relic density is automatically suppressed. We delineate parameter space leading to the correct dark matter abundance. The model allows for a significant Higgs-inflaton coupling which may lead to invisible Higgs decay into inflaton pairs at the LHC.
Bulk dark energy properties are determined by the redshift evolution of its pressure-to-density ratio, $w_{de}(z)$. An experimental goal is to decide if the dark energy is dynamical, as in the quintessence (and phantom) models treated here. We show that a three-parameter approximation $w_{de}(z; ε_s, ε_{ϕ\infty}, ζ_s)$ fits well the ensemble of trajectories for a wide class of late-inflaton potentials $V(ϕ)$. Markov Chain Monte Carlo probability calculations are used to confront our $w_{de}(z)$ trajectories with current observational information on Type Ia supernova, Cosmic Microwave Backgroun…
Post-inflationary reheating is a widely discussed mechanism for non-thermal production of dark matter (DM). In this scenario the momentum distribution of the produced DM particles is usually taken to be the one obtained at reheating, red-shifted at later times due to the expansion of the Universe. However, since in such a scenario both the DM and the standard model (SM) fields couple to the inflaton, the DM particles necessarily undergo self-scatterings, as well as elastic and inelastic scattering reactions with the SM bath, all of which proceed through $s-$channel or $t-$channel inflaton exch…
We consider the possibility of using one of the $D$-flat directions in the minimal supersymmetric standard model (MSSM) as the inflaton. We show that the flat direction consisting of (first generation) left- and right-handed up-squarks as well as the up-type Higgs boson may play the role of the inflaton if dominant part of the up-quark mass is radiatively generated from supersymmetric loop diagrams. We also point out that, if the R-parity violating Yukawa coupling is of $O(10^{-7})$, $R$-odd $D$-flat directions may be another possible candidate of the inflaton. Such inflation models using $D$-…
We study a leptogenesis scenario in which the heavy Majorana neutrinos are produced non-thermally in inflaton decays in the supersymmetric economical SU(3)_C X SU(3)_L X U(1)_X model with inflationary scenario, and for this purpose neutrino masses play the key role. Due to the inflaton with mass in the GUT scale, the model under consideration provides successful neutrino masses, which is different from ones without inflationary scenario. The lepton-number-violating interactions among the inflaton and right-handed neutrinos appear at the one-loop level, and this is a reason for non-thermal lept…
We study the possibility of cogenesis of baryon and dark matter (DM) from the out-of-equilibrium CP violating decay of right handed neutrino (RHN) that are dominantly of non-thermal origin. While the RHN and its heavier partners can take part in light neutrino mass generation via Type-I seesaw mechanism, the decay of RHN into dark and visible sectors can create respective asymmetries simultaneously. The non-thermal sources of RHN considered are {\bf (a)} on-shell decay of inflaton, and {\bf (b)} evaporation of ultralight primordial black holes (PBH). After setting up the complete set of Boltzm…
We propose a simple model where a {\it gauge invariant inflaton} is responsible for cosmic inflation and generates the seed for structure formation, while its relic {\it thermal} abundance explains the missing matter of the universe in the form of cold dark matter. The inflaton self-coupling also explains the observed neutrino masses. All the virtues can be attained in a minimal extension of the Standard Model gauge group around the TeV scale. We can also unveil these properties of an inflaton in forthcoming space and ground based experiments.
We investigate characteristic features of realistic parameter choice for primordial inflation with supersymmetric Higgs inflaton as an example of particle physics inflation model. We discuss constraints from observational results and analyze the degree of fine tuning needed to induce slow-roll inflation for wide range of soft supersymmetry breaking scale. The observed amplitude of density fluctuations implies that the minimal fine tuning for the combined electroweak scale and inflaton flatness predicts the spectral index of 0.950--0.965, which includes the central value from observational data…
We propose a two-phase reheating scenario where the initial preheating dynamics is described by an effective dynamics followed by the standard perturbative reheating. Some of the important universal results of lattice simulation during preheating have been considered as crucial inputs in our two-phase dynamics. In this framework, detailed phenomenological constraints have been obtained on the inflaton couplings with reheating fields, and dark matter parameters in terms of CMB constrained inflationary scalar spectral index. It is observed that the conventional reheating scenario generically pre…
In this paper, we studied the phenomenological consequences of recently proposed swampland conjecture on the inflationary models though constraints on reheating. If dark matter is assumed to be produced during reheating, the conjecture will provide further constraints on the dark matter parameter space through its current relic abundance. As has been pointed out already and also analyzed in our present paper any successful inflationary scenario is in clear tension with the aforementioned conjecture in its current form. However considering the swampland parameters to be free and constrained by …
We study preheating in plateau inflation in the Palatini formulation of general relativity, in a special case that resembles Higgs inflation. It was previously shown that the oscillating inflaton field returns to the plateau repeatedly in this model, and this leads to tachyonic production of inflaton particles. We show that a minimally coupled spectator scalar field can be produced even more efficiently by a similar mechanism. The mechanism is purely gravitational, and the scalar field mass can be of order $10^{13}$ GeV, larger than the Hubble scale by many orders of magnitude, making this a c…
