An exact inflationary solution in the chaotic model with non-minimal coupling

This paper presents a new exact inflationary solution to the non-minimMly coupled scalar field. The inflation is driven by the evolution of a scalar field with inflation potential V（φ） = （λ/4）φ4 ＋ b1φ2 ＋ b2 ＋ b3φ-2 ＋ b4φ-4. The spectral index of the scalar density fluctuations ns is consistent with the result of WMAP3 （Wilkinson Microwave Anisotropy Probe 3） for ACDM （Lambda-Cold Dark Matter）. This model relaxes the constraint to the quartic coupling constant. And it can enter smoothly into a radiation-dominated stage when inflation ends.

Approximate solution of the spin-one Duffin-Kemmer-Petiau(DKP) equation under a non-minimal vector Yukawa potential in(1+1)-dimensions

We solve the Duffin-Kemmer-Petiau （DKP） equation with a non-minimal vector Yukawa potential in （1＋1）- dimensional spa^e-time for spin-1 particles. The Nikiforov Uvarov method is used in the calculations, and the eigen- functions as well as the energy eigenvalues are obtained in a proper Pekeris-type approximation.

Holographic superconductor models in the non-minimal derivative coupling theory

We study a general class of holographic superconductor models via the Stiickelberg mechanism in the non-minimal derivative coupling theory in which the charged scalar field is kinetically coupling to Einstein＇s tensor. We explore the effects of the coupling parameter on the critical temperature, the order of phase transitions and the critical expo- nents near the second-order phase transition point. Moreover, we compute the electrical conductivity using the probe approximation and check the ratios wg/Tc for the different coupling parameters.

Gravitational constant in f(R) theories of gravity with non-minimal coupling between matter and geometry

We study the effect of the non-minimal coupling between matter and geometry on the gravitational constant in the context of f(R) theories of gravity on cosmic scales. For a class of f(R) models,the result shows that the value of the gravitational constant not only changes over time but also has the dampened oscillation behavior.Compared with the result of the standard ACDM model, the consequence suggests that the coupling between matter and geometry should be weak.

Dark Energy Model with Non-Minimal Coupling and Cosmological Constant Boundary

In this paper,we study a kind of dark energy models in the framework of the non-minimal coupling.With this kind of models,dark energy could cross the cosmological constant boundary,and at early time,dark energy could have 'tracking' behavior.

Higgs inflation model with non-minimal coupling in hybrid Palatini approach

In this paper,we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field.We derive Einstein’s field equations,i.e.,the equations of motion of the scalar field.Furthermore,the background and perturbative parameters are obtained by means of Friedmann equations in the slow roll regime.The analysis of cosmological perturbations allowed us to obtain the main inflationary parameters,e.g.,the scalar spectral index and tensor to scalar ratio r.From this perspective,as an application of our analysis,we consider the Higgs field with quartic potential,which plays the inflaton role,and show that predictions of Higgs hybrid inflation are in good agreement with recent observational data[Astron.Astrophys.641,61(2020)].

Constant-roll inflation with non-minimally derivative coupling

We investigate the constant-roll inflation with non-minimally kinetic coupling to the Einstein tensor.With the slow-roll parameterηφ=-φ/(Hφ)being a constant,we calculate the power spectra for scalar and tensor perturbations,and derive the expressions for the scalar spectral tilt n_(s),the tensor spectral tilt n_(T),and the tensor-to-scalar ratio r.We find that the expressions for n_(s)are different with different ordering of taking the derivative of the scalar power spectrum with respect to the scale k and the horizon crossing condition c_(sk)=a H in the constant-roll inflation,the consistency relation r=-8n_(T)does not hold if|η_(φ)|is not small,and the duality of the tensorto-scalar ratio between the slow-roll inflation and ultra-slow-roll inflation does not exist in inflationary models with non-minimally derivative coupling.The result offers a fresh perspective on the understanding of the inflationary models with non-minimally derivative coupling and is helpful for the production of scalar induced gravitational waves in the framework of ultra-slowroll inflation with non-minimally derivative coupling.

Primordial black holes generated by the non-minimal spectator field

We improve and generalize the non-minimal curvaton model originally proposed in arXiv:2112.12680 to a model in which a spectator field non-minimally couples to an inflaton field and the power spectrum of the perturbation of spectator field at small scales is dramatically enhanced by the sharp feature in the form of non-minimal coupling.At or after the end of inflation,the perturbation of the spectator field is converted into curvature perturbation and leads to the formation of primordial black holes(PBHs).Furthermore,for example,we consider three phenomenological models for generating PBHs with mass function peaked at~10^(-12) M_(⊙)and representing all the cold dark matter in our universe and find that the scalar induced gravitational waves generated by the curvature perturbation can be detected by the future space-borne gravitational-wave detectors such as Taiji,Tian Qin,and LISA.

Tachyon Cosmology with Gauss–Bonnet and Non-Minimal Kinetic Couplings

We consider a tachyonic model of dark energy in which scalar field non-minimally coupled with curvature and kinetic part of its Lagrangian density.Additionally the model contains the Gauss–Bonnet coupling to the scalar field through an arbitrary function.The non-minimal Gauss–Bonnet coupling function and scalar field potential have been obtained for power-law solution and then for a dynamically varying equation of state.We have extracted the required condition for the so-called phantom divide line crossing in the model and represented such a crossing numerically.

Novel Rotating Hairy Black Hole in (2 + 1) Dimensions

We present some novel rotating hairy black hole metric in （2 ＋ 1） dimensions, which is an exact solution to the field equations of the Einstein-scalar-AdS theory with a non-minimal coupling. The scalar potential is determined by the metric ansatz and consistency of the field equations and cannot be prescribed arbitrarily. In the simplified, critical ease, the scalar potential contains two independent constant parameters, which are respectively related to the mass and angular momentum of the black hole in a particular way. As long as the angular momentum does not vanish, the metric can have zero, one or two horizons. The case with no horizon is physically uninteresting because of the curvature singularity lying at the origin. We identify the necessary conditions for at least one horizon to be present in the solution, which imposes some bound on the mass-angular momentum ratio. For some particular choice of pararneters our solution degenerates into some previously known black hole solutions.

Scalar Tensor Cosmology With Kinetic, Gauss-Bonnet and Nonminimal Derivative Couplings and Supersymmetric Loop Corrected Potential

We discuss a particular four-dimensional cosmology based on non-minimal scalar tensor theories characterized by a supersymmetric loop corrected potential and a Hubble parameter defined as a function of the scalar field.Power-law solutions are obtained in the FRW background giving rise to acceleratedly expanding universe characterized by a scale factor and a scalar field depending both on the non-minimal coupling parameterξ.Based on SNeIa data and on Hubble data X-ray gas mass fraction measurements,we find 0.116<ξ<0.225 which results on a universe dominated by vacuum energy.

Localization of five-dimensional Elko spinors on dS/AdS thick branes

Owing to the special structure of a five-dimensional Elko spinor,its localization on a brane with codimension one becomes completely different from that of a Dirac spinor.By introducing the coupling between the Elko spinor and the scalar field that can generate the brane,we have two types of localization mechanism for the five-dimensional Elko spinor zero mode on a brane.One is the Yukawa-type coupling,and the other is the non-minimal coupling.In this study,we investigate the localization of the Elko zero mode on de Sitter and Anti-de Sitter thick branes with the two localization mechanisms,respectively.The results show that both the mechanisms can achieve localization.The forms of the scalar coupling function in both localization mechanisms have similar properties,and they play a similar role in localization.

Quadratic, Higgs and hilltop potentials in Palatini gravity

In this work,we study the theory of inflation with the non-minimally coupled quadratic,standard model Higgs,and hilltop potentials,throughξφ~2R term in Palatini gravity.We first analyze observational parameters of the Palatini quadratic potential as functions ofξfor the high-N scenario.In addition to this,taking into account that the inflaton field f has a non-zero vacuum expectation value v after inflation,we display observational parameters of well-known symmetry-breaking potentials.The types of potentials considered are the Higgs potential and its generalizations,namely hilltop potentials in the Palatini formalism for the high-N scenario and the low-N scenario.We calculate inflationary parameters for the Palatini Higgs potential as functions of v for differentξvalues,where inflaton values are bothφ>v andφ<v during inflation,as well as calculating observational parameters of the Palatini Higgs potential in the induced gravity limit for high-N scenario.We illustrate differences between the Higgs potential’s effect onξversus hilltop potentials,which agree with the observations for the inflaton values forφ<v andξ,in which v<<1 for both these high and low N scenarios.For each considered potential,we also display ns-r values fitted to the current data given by the Keck Array/BICEP2 and Planck collaborations.