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Triyanta

Publications and source records attributed to Triyanta.

13 recordsLinked to original sources
arXiv2023

Localization of matters coupled nonminimally to gravity on scalar thick branes

We are investigating the localization of matter that interacts nonminimally with gravity within thick braneworld models generated by a scalar bulk. Our review focuses on two models of scalar thick branes. The natural mechanism is used to analyze the localization of the fields. Without losing the point of field localization, we examine matter field localizations by considering the asymptotic behavior of the warp function on z towards infinity. Both massless and massive modes of the nonminimally coupled scalar field are localized on the brane in both models. When the coupling is minimal, the scalar field is localized for the massless mode. A nonminimally coupled vector field behaves similarly to the nonminimally coupled scalar field, the massless and massive modes in both models are localized. For a nonminimally coupled spinor field, in model 1, we observe localization of the spinor for massive mode, while in model 2, only the massless spinor field is localized.

hep-th↗
arXiv2017

Gravitoelectromagnetism in Teleparallel Equivalent of General Relativity: A New Alternative

Spaniol and Andrade introduced grvitoelectromagnetism in TEGR by considering superpotentials, times the determinant of tetrads, as the gravitoelectromagnetic fields. However, since this defined gravitoelectromagnetic field strength does not give rise to a complete set of Maxwell-like equations, we propose an alternative definition of the gravitoelectromagnetic field strength: instead of superpotentials, torsions are taken as the gravitoelectromagnetic field strengths. Based on this new proposal we are able to derive a complete set of Maxwell-like equations. We then apply them to obtain explicit expressions of the gravitoelectromagnetic fields both in Schwarzchilds spacetime and for gravitational waves.

gr-qc↗
arXiv2017

Localization of Interacting Fields in Five-Dimensional Braneworld Models

We study localization properties of fundamental fields which are coupled to one another through the gauge mechanism both in the original Randall-Sundrum (RS) and in the modified Randall-Sundrum (MRS) braneworld models: scalar-vector, vector-vector, and spinor-vector configuration systems. For this purpose we derive conditions of localization, namely the finiteness of integrals over the extra coordinate in the action of the system considered. We also derive field equations for each of the systems and then obtain their solutions corresponding to the extra dimension by a separation of variable method for every field involved in each system. We then insert the obtained solutions into the conditions of localization to seek whether or not the solutions are in accordance with the conditions of localization. We obtain that not all of the configuration systems considered are localizable on the brane of the original RS model while, on the contrary, they are localizable on the MRS braneworld model with some restrictions. In terms of field localizability on the brane, this result shows that the MRS model is much better than the original RS model.

hep-th↗
arXiv2013

Field localization and mass generation in an alternative 5-dimensional brane model

This proceedings is based on a talk given at the APS DPF 2013 on an alternative 5-dimensional brane world model which is related to but has some physically distinct features from the Randall-Sundrum brane world model. The spin dependent localization of 5D fields for the alternative model are different and in some ways superior to the original Randall- Sundrum Model. The alternative model also exhibits a cutoff in the lo-calization of massive scalar fields not seen in the Randall-Sundrum and includes a self consistent mass prediction of two possible scalar bosons. Setting the warping factor in the new model consistent with a 126 GeV localized scalar boson predicts the existence of a second scalar boson at 177 GeV. This second scalar boson could be localized or non localized depending on the type of warping factor.

hep-th↗
arXiv2013

Effect of circular Unruh radiation on bound nucleons and a possible answer to the Lithium 7 puzzle

In the shell model of nuclei, protons and neutrons move in a phenomenological nuclear potential much in the same manner as electrons move in Coulomb based potential in the shell model of atoms. As in the atomic case, the protons and neutrons of certain nuclear energy levels will have a non-zero orbital angular momentum (i.e. l =/= 0) and will therefore experience a centripetal potential and a centripetal acceleration. We advance the hypothesis, based on justification via the path integral formalism, that if one associates an Unruh temperature with this quantum centripetal acceleration then there is a potentially experimentally observable effect on certain nuclei -- the shifting of the naive expectations of the relative occupation of the ground and lowest lying energy levels. In particular we find that this effect should be most prominent in Li-7 nuclei. We speculate that this effect of the Unruh temperature might offer an answer to the Li-7 problem in Big Bang Nucleosynthesis.

nucl-th↗
arXiv2013

Field localization and Nambu Jona-Lasinio mass generation mechanism in an alternative 5-dimensional brane model

We consider a 5-dimensional brane world model with a single brane which is distinct from the well known Randall-Sundrum model. We discuss the similarities and differences between our brane model and the Randall-Sundrum brane model. In particular we focus on the localization of 5D fields with different spins -- spin 0, spin 1/2, spin 1 -- to the brane, and a self-consistent mass generation mechanism. We find that the brane model studied here has different (and in some cases superior) localization properties for fields/particles with different spins to the brane, as compared to the original 5-dimensional brane models. In addition this alternative 5D brane model exhibits a self generation mechanism which recalls the self-consistent approach of Nambu and Jona-Lasinio.

gr-qc↗
arXiv2013

Bosonic Part of 4d N=1 Supersymmetric Gauge Theory with General Couplings: Local Existence

In this paper, we prove the local existence of the bosonic part of N=1 supersymmetric gauge theory in four dimensions with general couplings. We start with the Lagrangian of the vector and chiral multiplets with general couplings and scalar potential turned on. Then, for the sake of simplicity, we set all fermions vanish at the level of equations of motions, so we only have the bosonic parts of the theory. We apply Segal's general theory to show the local existence of solutions of equations of motions by taking Kahler potential to be bounded above by U(n) symmetric Kahler potential and the first derivative of gauge couplings to be at most linear growth functions.

math-ph↗
arXiv2009

Cosmological evolution of interacting dark energy in Lorentz violation

The cosmological evolution of an interacting scalar field model in which the scalar field interacts with dark matter, radiation, and baryon via Lorentz violation is investigated. We propose a model of interaction through the effective coupling $\barβ$. Using dynamical system analysis, we study the linear dynamics of an interacting model and show that the dynamics of critical points are completely controlled by two parameters. Some results can be mentioned as follows. Firstly, the sequence of radiation, the dark matter, and the scalar field dark energy exist and baryons are sub dominant. Secondly, the model also allows the possibility of having a universe in the phantom phase with constant potential. Thirdly, the effective gravitational constant varies with respect to time through $\barβ$. In particular, we consider a simple case where $\barβ$ has a quadratic form and has a good agreement with the modified $Λ$CDM and quintessence models. Finally, we also calculate the first post--Newtonian parameters for our model.

hep-th↗
arXiv2009

Semiclassical Methods for Hawking Radiation from a Vaidya Black Hole

We derive the general form of Hawking temperature for Vaidya black hole in the tunneling pictures. This kind of black hole is regarded as the description of a more realistic one since it's time dependent decreasing mass due to the evaporation process. Clearly, the temperature would be time dependent as our findings. We use the semiclassical methods, namely radial null geodesic and complex paths methods. Both methods are found to give the same results. Then, we discuss the possible form of corresponding entropy.

gr-qc↗
arXiv2008

Tetrahedron Diagram and Perturbative Calculation in Chern-Simons-Witten Theory

We investigate extended Wilson loop operators, in particular tetrahedron operator in (2 + 1)-dimensional Chern-Simons-Witten theory. This operator emerges naturally from the contribution terms in twoparticle scattering amplitude. We evaluate this diagram non-perturbatively in terms of vacuum expectation values of Wilson loop operators, especially for gauge group SU(N) with specific choices of representations. On the other hand, we also discuss the perturbative calculation of vacuum expectation value in this theory. We show that, up to the third order, this values of unknotted Wilson loop operators are identical to the non-perturbative result.

hep-th↗
arXiv2008

Attractor Solutions in Lorentz Violating Scalar-Vector-Tensor Theory

We investigate properties of attractors for scalar field in the Lorentz violating scalar-vector-tensor theory of gravity. In this framework, both the effective coupling and potential functions determine the stabilities of the fixed points. In the model, we consider the constants of slope of the effective coupling and potential functions which lead to the quadratic effective coupling vector with the (inverse) power-law potential. For the case of purely scalar field, there are only two stable attractor solutions in the inflationary scenario. In the presence of a barotropic fluid, the fluid dominated solution is absent. We find two scaling solutions: the kinetic scaling solution and the scalar field scaling solutions. We show the stable attractors in regions of ($γ$, $ξ$) parameter space and in phase plane plot for different qualitative evolutions. From the standard nucleosynthesis, we derive the constraints for the value of the coupling parameter.

hep-th↗
arXiv2007

Some Impacts of Lorentz Violation on Cosmology

The impact of Lorentz violation on the dynamics of a scalar field is investigated. In particular, we study the dynamics of a scalar field in the scalar-vector-tensor theory where the vector field is constrained to be unity and time like. By taking a generic form of the scalar field action, a generalized dynamical equation for the scalar-vector-tensor theory of gravity is obtained to describe the cosmological solutions. We present a class of exact solutions for an ordinary scalar field or phantom field corresponding to a power law coupling vector and the Hubble parameter. As the results, we find a constant equation of state in de Sitter space-time and power law expansion with the quadratic of coupling vector, while a dynamic equation of state is obtained for $n> 2$. Then, we consider the inflationary scenario based on the Lorentz violating scalar-vector-tensor theory of gravity with general power-law coupling vector and two typical potentials: inverse power-law and power-law potentials. In fact, both the coupling vector and the potential models affect the dynamics of the inflationary solutions. Finally, we use the dynamical system formalism to study the attractor behavior of a cosmological model containing a scalar field endowed with a quadratic coupling vector and a chaotic potential.

hep-th↗