arXiv subjects

Phongpichit Channuie

Publications and source records attributed to Phongpichit Channuie.

At least 73 records · Page 4Linked to original sources

arXiv2021

Exact Solutions of (deformed) Jackiw-Teitelboim Gravity

It is well known that Jackiw-Teitelboim (JT) gravity posses the simplest theory on 2-dimensional gravity. The model has been fruitfully studied in recent years. In the present work, we investigate exact solutions for both JT and deformed JT gravity recently proposed in the literature. We revisit exact Euclidean solutions for Jackiw-Teitelboim gravity using all the non-zero components of the dilatonic equations of motion using proper integral transformation over Euclidean time coordinate. More precisely, we study exact solutions for hyperbolic coverage, cusp geometry and another compact sector of the AdS$_2$ spacetime manifold.

hep-th↗

arXiv2021

Warm Higgs-Starobinsky inflation

In this work, we investigate the Higgs-Starobinsky (HS) model in the context of warm inflation scenario. The dissipative parameter as a linear form of temperature of warm inflation is considered with strong and weak regimes. We study the HS model in the Einstein frame with the slow-roll inflation framework. We compute the inflationary observables and then compare with the Plank 2018 data. With the sizeable number of e-folds and proper choices of parameters, we discover that the predictions of warm HS model present in this work are in very good agreement with the latest Planck 2018 results. More importantly, the parameters of the HS model are also constrained by using the data in order to make warm HS inflation successful.

gr-qc↗

arXiv2021

Fold bifurcation entangled surfaces for one-dimensional Kitaev lattice model

We investigate feasible holography with the Kitaev model using dilatonic gravity in AdS$_2$. We propose a generic dual theory of gravity in the AdS$_2$ and suggest that this bulk action is a suitable toy model in studying quantum mechanics in the Kitaev model using gauge/gravity duality. This gives a possible equivalent description for the Kitaev model in the dual gravity bulk. Scalar and tensor perturbations are investigated in detail. In the case of near AdS perturbation, we show that the geometry still "freezes" as is AdS, while the dilation perturbation decays at the AdS boundary safely. The time-dependent part of the perturbation is an oscillatory model. We discover that the dual gravity induces an effective and renormalizable quantum action. The entanglement entropy for bulk theory is computed using extremal surfaces. We prove that these surfaces have a fold bifurcation regime of criticality. Our approach shows directly that chaos in AdS$_2$ can be understood via fold bifurcation minimal surfaces.

hep-th↗

arXiv2021

Noether Symmetry Approach in Eddington-inspired Born-Infeld gravity

In this work, we take a short recap of a formal framework of the Eddington-inspired Born-Infeld (EiBI) theory of gravity and derive the point-like Lagrangian for underlying theory based on the use of Noether gauge symmetries (NGS). We study a Hessian matrix and quantify Euler-Lagrange equations of EiBI universe. We discuss the NGS approach for the Eddington-inspired Born-Infeld theory and show that there exists the de Sitter solution in this gravity model.

gr-qc↗

arXiv2020

Strange Quark Stars in 4D Einstein-Gauss-Bonnet Gravity

The existence of strange matter in compact stars may pose striking sequels of the various physical phenomena. As an alternative to neutron stars, a new class of compact stars called strange stars should exist if the strange matter hypothesis is true. In the present article, we investigate the possible construction of the strange stars in quark matter phases based on the MIT bag model. We consider scenarios in which strange stars have no crusts. Then we apply two types of equations of state to quantify the mass-radius diagram for static strange star models performing the numerical calculation to the modified Tolman-Oppenheimer-Volkoff (TOV) equations in the context of $4D$ Einstein-Gauss-Bonnet gravity. It is worth noting that the GB term gives rise to a non-trivial contribution to the gravitational dynamics in the limit $D \to 4$. However, the claim that the resulting theory is of pure graviton was cast in doubt by several grounds. Thus, we begin our discussion with showing the regularized $4D$ EGB theory has an equivalent action as the novel $4D$ EGB in a spherically symmetric spacetime. We also study the effects of coupling constant $α$ on the physical properties of the constructed strange stars including the compactness and criterion of adiabatic stability. Finally, we compare our results to those obtained from the standard GR.

gr-qc↗

arXiv2020

On Nash theory of gravity with matter contents

Although it was proved that the Nash theory doesn't have classical Einstein limits, it has been proven to be formally divergent free and considered to be of interest in constructing theories of quantum gravity. The original Nash gravity without matter contents can't explain the current accelerated expansion of the Universe. A possible extension of theory is by adding some matter contents to the model. In this work, we generalize the Nash theory of gravity by adding the matter fields. In order to examine the effects of this generalization, we first derive the equations of motion in the flat FLRW spacetime and examine the behaviors of the solutions by invoking specific forms of the Hubble parameter. We also classify the physical behaviors of the solutions by employing the stability analysis and check the consistency of the model by considering particular cosmological parameters.

gr-qc↗

arXiv2020

Quark Stars in 4D Einstein-Gauss-Bonnet gravity with an Interacting Quark Equation of State

The detection of gravitational waves (GWs) from the binary neutron star (BNS) has opened a new window on the gravitational wave astronomy. With current sensitivities, detectable signals coming from compact objects like neutron stars turn out to be a crucial ingredient for probing their structure, composition, and evolution. Moreover, the astronomical observations on the pulsars and their mass-radius relations put important constraints on the dense matter equation of state (EoS). In this paper, we consider a homogeneous and unpaired charge-neutral $3$-flavor interacting quark matter with $\mathcal{O}(m_s^4)$ corrections that account for the moderately heavy strange quark instead of the naive MIT bag model. In this article, we perform a detailed analysis of strange quark star in the context of recently proposed $4D$ Einstein-Gauss-Bonnet (EGB) theory of gravity. However, this theory does not have standard four-dimensional field equations. Thus, we thoroughly show that the equivalence of the actions in the regularized $4D$ EGB theory and in the original one is satisfied for a spherically symmetric spacetime. We pay particular attention to the possible existence of massive neutron stars of mass compatible with $M \sim 2 M_{\odot}$. Our findings suggest that the fourth-order corrections parameter ($a_4$) of the QCD perturbation and coupling constant $α$ of the GB term play an important role in the mass-radius relation as well as the stability of the quark star. Finally, we compare the results with the well-measured limits of the pulsars and their mass and radius extracted from the spectra of several X-ray compact sources.

gr-qc↗

arXiv2020

Gravitational phase transition mediated by thermalon in Einstein-Gauss-Bonnet-Maxwell-Kalb-Ramond gravity

In this work, we study the possible existence of gravitational phase transition from AdS to dS asymptotic geometries in Einstein-Gauss-Bonnet gravity by adding the Maxwell one-form field ($A_μ$) and the Kalb-Ramond two-form field ($B_{μν}$) as impurity substitutions. The phase transitions proceed via the bubble nucleation of spherical thin-shells described by different branches of the solutions which host a dS black hole in the interior and asymptotic thermal AdS state in the exterior. We analyze the phase diagrams of the free energy and temperature to demonstrate the existence of the phase transitions in the grand canonical ensemble (fixed electrical potential). The phase transitions of having the one-form and two-form charges are possible in which the critical temperature is lower than that of the neutral case. Comparing results with existing literature, more importantly, our analyses show that the critical temperature and the Gauss-Bonnet coupling $λ$ of the phase transitions get decreased by adding more types of the charges.

gr-qc↗

arXiv2020

Inflation from $f(R)$ theories in gravity's rainbow

In this work, we study the $f(R)$ models of inflation in the context of gravity's rainbow theory. We choose three types of $f(R)$ models: $f(R)=R+α(R/M)^{n},\,f(R)=R+αR^{2}+βR^{2}\log(R/M^{2})$ and the Einstein-Hu-Sawicki model with $n,\,α,\,β$ being arbitrary real constants. Here $R$ and $M$ are the Ricci scalar and mass scale, respectively. For all models, the rainbow function is written in the power-law form of the Hubble parameter. We present a detailed derivation of the spectral index of curvature perturbation and the tensor-to-scalar ratio and compare the predictions of our results with the latest Planck 2018 data. With the sizeable number of e-foldings and proper choices of parameters, we discover that the predictions of all $f(R)$ models present in this work are in excellent agreement with the Planck analysis.

gr-qc↗

arXiv2020

Generalized gravitational phase transition in novel 4D Einstein-Gauss-Bonnet gravity

In this work, we present the possible existence of thermal phase transition between AdS to dS asymptotic geometries in vacuum in the context of novel 4D Einstein-Gauss-Bonnet (EGB) gravity. The phase transition proceeds through the thermalon (the Euclidean sector of the bubble thin-shell) formation having a black hole inside the interior of dS spacetime and a thermal AdS spacetime in the exterior without introducing any matter field. According to our analysis, we find that the gravitational phase transitions using novel 4D EGB gravity always take place for all existences of the 4D EGB coupling. In contrast to 5-dimensional EGB gravity, the existence of phase transition requires a narrow range of the 4D EGB coupling with particular critical values, while the 5-dimension sector has a wider range of its coupling for the existences of the thermalon and there also exist critical values for the emergence of the phase transition.

gr-qc↗

arXiv2020

Traversable wormholes in $f(R)$-massive gravity

In this work, the study of traversable wormholes in $f(R)$-massive gravity with the function $f(R)=R+α_{1} R^{n}$, where $α_{1}$ and $n$ are arbitrary constants, is considered. We choose the modified shape function $b(r)$. We consider a spherically symmetric and static wormhole metric and derive field equations. Moreover, we visualize the wormhole geometry using embedding diagrams. Furthermore, we check the null, weak, dominant and strong energy conditions at the wormhole throat with a radius $r_{0}$ invoking three types of redshift functions, $Φ={\rm constant},γ_{1}/r,\,\log(1+γ_{2}/r)$ with $γ_{1}$ and $γ_{2}$ are arbitrary real constants. We also compute the volume integral quantifier to calculate the amount of the exotic matter near the constructed wormhole throat.

gr-qc↗

arXiv2020

Unraveling the vertical motion of Dipterocarpus alatus seed using Tracker

We perform analytical and experimental investigation of the vertical motion of Dipterocarpus alatus seed, locally called Yang-na in Thailand. In this work, we assume the drag forces exerting on the Yang-na seeds depend only on the velocity. We derive equations of motion (EoMs) to physically parametrize the vertical motion of the seed and analytically solve to obtain the exact solutions. Interestingly, we observe that our predicted solutions are in agreement with the experimental data. More precisely, the entire trajectory of the falling seed of Yang-na can be described by our predicted solutions. We also determine terminal velocity of the seeds. Remarkably, this work reasonably proves that seed dispersal characteristics of Yang-na is inherently straight downward. Finally, we believe that our achievement will be valuable to the large community of STEM/STEAM education to promote an understanding in the topic integrating mathematics, physics, biology, art and technology. Our framework constitutes learning model to improve the ability of creative thinking, analytical thinking and problem solving skills on the concept of forces and motion applicable from high school to college levels.

physics.ed-ph↗

arXiv2020

Traversable Wormholes Supported by GUP Corrected Casimir Energy

In this paper, we investigate the effect of the Generalized Uncertainty Principle (GUP) in the Casimir wormhole spacetime recently proposed by Garattini [Eur. Phys. J. C (2019) 79: 951]. In particular, we consider three types of the GUP relations, firstly the Kempf, Mangano and Mann (KMM) model, secondly the Detournay, Gabriel and Spindel (DGS) model, and finally the so called type II model for GUP principle. To this end, we consider three specific models of the redshift function along with two different EoS of state given by $\mathcal{P}_r(r)=ω_r(r) ρ(r)$ along with $\mathcal{P}_t(r)=ω_t (r)\mathcal{P}_r(r)$ and obtain a class of asymptotically flat wormhole solutions supported by Casimir energy under the effect of GUP. Furthermore we check the null, weak, and strong condition at the wormhole throat with a radius $r_0$, and show that in general the classical energy condition are violated by some arbitrary quantity at the wormhole throat. Importantly, we examine the wormhole geometry with semi-classical corrections via embedding diagrams. We also consider the ADM mass of the wormhole, the volume integral quantifier to calculate the amount of the exotic matter near the wormhole throat, and the deflection angle of light.

gr-qc↗

arXiv2020

Gravitational AdS to dS phase transition in Einstein-Maxwell-Gauss-Bonnet gravity

In this work, we revisit a toy model proposed by Camanho {\it et.al.} [JHEP 10 (2015) 179] and extensively study the possible existence of gravitational phase transition from AdS to dS geometries by adding the Maxwell field as an impurity substitution. We show that the phase transitions proceed via the bubble nucleation of spherical thin-shells described by different branches of the solution which host a black hole in the interior. In order to demonstrate the existence of the phase transition, we examine how the free energy and temperature depend on the higher-order gravity coupling $(λ)$ indicating the possibility of thermalon mediated phase transition. We observe that the phase transitions of the charged case is possible in which the required (maximum) temperature is lower than that of the neutral case. Interestingly, we also discover that the critical temperature and the coupling $λ$ of the phase transitions are modified when having the charge. In addition, our results agree with the claim that the generalized gravitational phase transition is a generic behavior of the higher-order gravity theories even the matter field is added.

gr-qc↗

arXiv2020

Thin-shell wormholes in de Rham-Gabadadze-Tolley massive gravity

In this work, we study the thin-shell wormholes in dRGT massive gravity. In order to joint two bulks of the spacetime geometry, we first derive junction conditions of the dRGT spacetime. This results the dynamics of the spherical thin-shell wormholes in the dRGT theory. We show that the massive graviton correction term of the dRGT theory in the Einstein equation is represented in terms of the effective anisotropic pressure fluid. However, if there is only this correction term, without invoking exotic fluids, we find that the thin-shell wormholes can not be stabilized. We then examine the stability conditions of the wormholes by introducing four existing models of the exotic fluids at the throat. In addition, we analyze the energy conditions for the thin-shell wormholes in the dRGT massive gravity by checking the null, weak, and strong conditions at the wormhole throat. We show that in general the classical energy conditions are violated by introducing all existing models of the exotic fluids. Moreover, we quantify the wormhole geometry by using the embedding diagrams to represent a thin-shell wormhole in the dRGT massive gravity.

gr-qc↗

arXiv2019

Composite Nambu--Jona-Lasinio inflation near infrared fixed point of the Horava-Lifshitz theory

In this work, we first propose a cosmological scenario inherently based on the effective Nambu--Jona-Lasio (NJL) model near the infrared (IR) limit of the Hořava-Lifshitz (HL) theory. Having used the one-loop correction, we employ the NJL framework in the ultraviolet (UV) limit of the HL theory, with critical exponent $z=3$, to demonstrate in the IR limit that the symmetry of the potential at the critical coupling value is broken at $z=1$. We also derive the effective Higgs-like potential in the low energy regimes. Here the symmetry of the effective potential will be broken near $z=1$ at a certain value of the critical coupling. In our scenario, the scalar channel of the NJL model plays the role of a composite inflaton. We find that the Lorentz invariance (LI) appears at the IR regime of the HL theory and employ the standard inflationary (slow-roll) paradigm as a probe of physics at very high energy. We compute inflationary parameters and compare them with recent Planck 2015 data. Interestingly, we discover that the predictions of the model are in perfect agreement with the Planck analysis. Our salient feature is that we used inflation to quantify the IR and UV fixed points of the underlying theory. We discover that the IR fixed point of HL gravity is compatible with the grand unified energy scale; whilst the UV fixed point is the Planck energy scale.

hep-th↗

arXiv2019

Chaos in balanced and unbalanced holographic s+p superconductors

In this work, we propose a toy model for a mixture of superconductors with competitive s and p modes using gauge/gravity duality. We demonstrate that the model undergoes phase transitions with the proper choice of different values for chemical potentials. We consider both balanced and unbalanced cases. We propose that the condensate field in the bulk toy model for a mixing s+p phase of high temperature superconductors undergoes a chaotic phase space scenario. Using a suitable measure function for chaos, we demonstrate the existence of chaotic dynamics via condensate fields. As an alternative method, we also investigate the phase portrait in the extended phase space for the condensates.

hep-th↗

arXiv2019

Generalized Conformal Transformation and Inflationary Attractors

We investigate the inflationary attractors in models of inflation inspired from general conformal transformation of general scalar-tensor theories to the Einstein frame. The coefficient of the conformal transformation in our study depends on both the scalar field and its kinetic term. Therefore the relevant scalar-tensor theories display the subset of the class I of the degenerate higher-order scalar-tensor theories in which both the scalar field and its kinetic term can non-minimally couple to gravity. We find that if the conformal coefficient $Ω$ takes a multiplicative form such that $Ω\equiv w(ϕ)W(X)$ where $X$ is the kinetic term of the field $ϕ$, the theoretical predictions of the proposed model can have usual universal attractor independent of any functions of $W(X)$. For the case where $Ω$ takes an additive form, such that $Ω\equiv w(ϕ) + k(ϕ) Ξ(X)$, we find that there are new $ξ$ attractors in addition to the universal ones. We analyze the inflationary observables of these models and compare them to the latest constraints from the Planck collaboration. We find that the observable quantities associated to these new $ξ$ attractors do not satisfy the constraints from Planck data at a strong coupling limit.

gr-qc↗