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Modified Friedmann equations in braneworld scenario
http://inspirehep.net/record/1665646
J.Phys.Conf.Ser. 988 (2018) 012007<br /><br />by: Pardede, Kevin F.S. (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />Firstly we present a brief discussion about braneworld model and the derivation of Friedmann equations in the braneworld scenario. Next we carry out a dynamical analysis of the modified Friedmann equations. Lastly, we perform a numerical computation using the Metropolis-Hastings algorithm to compute several free parameters of the modified Friedmann equations. Among others, we found that the brane tension is not large enough to support a nucleosynthesis process which correctly reproduce the abundance of present light elements. Also, we found a negative dark-radiation energy density, and thus indicating a possibility of non-singular initial universe.Pardede, Kevin F.S.Tue, 03 Apr 2018 14:25:15 GMThttp://inspirehep.net/record/16656462018-03-27CFT duals on extremal rotating NUT black holes
http://inspirehep.net/record/1643053
hep-tharXiv:1712.04751<br />Int.J.Mod.Phys. D27 (2018) 1850109<br /><br />by: Sakti, M.F.A.R. (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />We investigate the Kerr–Newman–NUT black hole solution obtained from Plebański–Demiański solutions with several assumptions. The origin of the microscopic entropy of this black hole is investigated using the conjectured Kerr/CFT correspondence which is originally proposed for extremal Kerr black holes. The isometry of the near-horizon extremal Kerr–Newman–NUT black hole shows that the asymptotic symmetry group may be implemented to compute the central charge of the Virasoro algebra. Furthermore, by assuming the Frolov–Thorne vacuum, the conformal temperatures can be obtained. Then by using the Cardy formula, the microscopic entropy is gained which matches the Bekenstein–Hawking entropy. We also employ the Cardy prescription to find the logarithmic correction of the entropy. Then at limit a → 0, the extremal Reissner–Nordström–NUT solution is recovered and by enhancing with the fibered coordinate we find the five-dimensional (5D) solution. The second dual CFT is applied to this black hole to gain the entropy. Finally, the microscopic entropy is still in agreement with the area law of 5D black hole solution. Hence, the extremal Reissner–Nordström–NUT solution is holographically dual to the CFT.Sakti, M.F.A.R.Thu, 14 Dec 2017 06:13:13 GMThttp://inspirehep.net/record/16430532018-06-11First-order perturbative approach to Q-balls with massive gauge field
http://inspirehep.net/record/1602789
J.Phys.Conf.Ser. 856 (2017) 012009<br /><br />by: Sakti, M.F.A.R. (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />In this paper, we examine the properties of massive U(1) gauged Q-balls. For finding the field solutions, we use first-order perturbative approach where the coupling constant q is used as pertubation parameter. We also compare our result to the massless case to see the effects of the gauge field mass. Finally, we obtain the mass-charge relation of the Q-balls.Sakti, M.F.A.R.Tue, 06 Jun 2017 13:44:10 GMThttp://inspirehep.net/record/16027892017-06-02Power function inflation potential analysis for cosmological model with Gauss-Bonnet term
http://inspirehep.net/record/1602787
J.Phys.Conf.Ser. 856 (2017) 012006<br /><br />by: Hikmawan, Getbogi (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />Inflation is still an interesting topic in the study of our universe. An interesting inflation scenario named Gauss-Bonnet inflation proposed without inflation potential has been shown unstable. In this work, we consider the general power function inflation potential, V(ϕ) = mϕ(n) in the model, then the solution is analyzed according to the inflation scenario. Using the stability condition, inflation potential with m positive and 0 ≤ n < 5 give proper solution for the inflation scenario.Hikmawan, GetbogiTue, 06 Jun 2017 13:44:09 GMThttp://inspirehep.net/record/16027872017-06-02Near Horizon Extreme Magnetized Kerr Geometry
http://inspirehep.net/record/1501472
hep-tharXiv:1612.00701<br /><br />by: Sakti, Muhammad F A R (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />The conjectured magnetized Kerr/CFT correspondence states that the quantum theory of gravity in the near horizon of extreme Kerr black holes immersed by the magnetic field, Near Horizon Extreme Magnetized Kerr black holes, is holographic dual to a two-dimensional chiral conformal field theory. To obtain Near Horizon Extreme Magnetized Kerr geometry, the extreme limit of the magnetized Kerr metric is taken so, $ a=M $ and then continued by transforming the coordinates to have a warped and twisted product of $ \textrm{AdS}_2 \times \textrm{S}^2 $, and also with the Near Horizon Extreme Kerr metric one. Consequently, we can obtain also the new Ernst potentials for those geometries. Finally, the transformed central charge from the extremal non-magnetized one to the magnetized one in the Ernst-Papapetrou formalism is obtained.Sakti, Muhammad F A RMon, 05 Dec 2016 04:08:21 GMThttp://inspirehep.net/record/1501472Energy Conditions of the Five Dimensional with NMDC and Acelerating Universe
http://inspirehep.net/record/1488013
J.Phys.Conf.Ser. 739 (2016) 012049<br /><br />by: Hikmawan, G.<br /><strong>Abstract:</strong> <br />The Energy condition is studied for five dimensional cosmological model with nonminimal derivative coupling (NMDC) between scalar field and curvature tensor. We assume that the scale factors of three dimensional space (a(t)) and the extra dimension (b(t)) is related by b(t) = (a(t))(γ), where γ is a constant. We apply the Null Energy Condition (NEC), Weak Energy Condition (WEC), Strong Energy Condition (SEC) and Dominant Energy Condition (DEC) to our model and investigate some constraint in order the energy condition violated. The constraint that we found is appropriate with cosmological model in which the four-dimensional universe expands with positive acceleration and the extra dimension decays.Hikmawan, G.Mon, 26 Sep 2016 13:16:25 GMThttp://inspirehep.net/record/14880132016-09-23Comment on “Gauss-Bonnet inflation”
http://inspirehep.net/record/1407447
hep-tharXiv:1512.00222<br />Phys.Rev. D93 (2016) 068301<br /><br />by: Hikmawan, Getbogi (Kobe U.) et al.<br /><br /><strong>Abstract:</strong> <br />Recently, an interesting inflationary scenario, named Gauss-Bonnet inflation, was proposed by Kanti et al. [Phys. Rev. D 92, 041302 (2015); Phys. Rev. D 92, 083524 (2015)]. In the model, there is no inflaton potential, but the inflaton couples to the Guass-Bonnet term. In the case of quadratic coupling, they find inflation occurs with a graceful exit. The scenario is attractive because of the natural setup. However, we show there exists a gradient instability in the tensor perturbations in this inflationary model. We further prove the no-go theorem for Gauss-Bonnet inflation without an inflaton potential.Hikmawan, GetbogiWed, 02 Dec 2015 03:40:53 GMThttp://inspirehep.net/record/14074472016-03-18Cosmological perturbation analysis of nonminimal derivative coupling of scalar and tensor fields in five dimensions
http://inspirehep.net/record/1396226
AIP Conf.Proc. 1677 (2015) 040008<br /><br />by: Hikmawan, Getbogi (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />Perturbation is studied for non-minimal derivative coupling between a scalar fields and curvature tensor in five dimensions. We apply this analysis in flat universal five dimensional spacetime, generate the field equations and consider special cases at early universe, to get an exact form of the perturbation parameters. The solutions is used to explain the coupling parameter of non-minimal derivative coupling with curvature tensor. We find that for case of static extradimension at early time, the coupling parameter is approximately have value of ξ ≈ 0, 0274.Hikmawan, GetbogiTue, 06 Oct 2015 12:44:48 GMThttp://inspirehep.net/record/13962262015-09-30Energy conditions for the four dimensional cosmological model with nonminimal derivative coupling of scalar field
http://inspirehep.net/record/1396224
AIP Conf.Proc. 1677 (2015) 040001<br /><br />by: Suroso, Agus (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />The energy conditions is a set of linear equations of energy density ρ and pressure p which ensure the the field(s) that we used in our model is physically “reasonable”. We study the energy conditions for four dimensional nonminimal derivative coupling of scalar field and curvature tensor. Considering the scalar field as a perfect fluid, we find some constraint for the coupling constant ξ in order the energy conditions is satisfied or violated. We find that strong energy conditions (SEC) is violated if −1/9H2 ≤ ξ < 1/18H2. For de Sitter solution a ∝ eH0tfor some constant H0, we find that while null, weak, and dominant energy conditions violated when ξ<−[12H02(2+9H02)]−1. The accelerating universe is exist for the power law solution (a ∝ tpfor constant p) if ξ < 0.Suroso, AgusTue, 06 Oct 2015 12:44:47 GMThttp://inspirehep.net/record/13962242015-09-30Stability analysis of the nonminimal derivative coupling in five dimensional universal extra dimensions
http://inspirehep.net/record/1362268
AIP Conf.Proc. 1656 (2015) 050007<br /><br />by: Suroso, Agus (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />We study a nonminimal derivative coupling (NMDC) of scalar field, where the scalar field is coupled to curvature tensor in the five dimensional universal extra dimension model. We apply the Einstein equation in and find the stability of our model. From the stability analysis, we find that the extradimension, if it exist, can not be static and always shrink with expansion of four dimensional spacetime.Suroso, AgusTue, 21 Apr 2015 09:55:46 GMThttp://inspirehep.net/record/13622682015-04-16Randall-Sundrum cosmological model with nonminimal derivative coupling of scalar field
http://inspirehep.net/record/1362267
AIP Conf.Proc. 1656 (2015) 050006<br /><br />by: Widiyani, Agustina (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />Nonminimal derivative coupling (NMDC) of scalar field in time-dependent Randall-Sundrum model is investigated. Firstly, we take a simple relation between the scale factor on the brane,a(t), and the scale factor of the extradimension, b(t), as b = aγwhere γ is a constant. Then, we derive the Einstein equation and find its cosmological solution for a special case of static extra dimension, γ = 0. As the result, we find that de Sitter solution is a typical solution of our model. We also find that the brane tension which is related to cosmological constant on the brane is related to the coupling constant of the model.Widiyani, AgustinaTue, 21 Apr 2015 09:55:46 GMThttp://inspirehep.net/record/13622672015-04-16Spherical symmetric extremal black holes in 4d N=1 supergravity
http://inspirehep.net/record/1362265
AIP Conf.Proc. 1656 (2015) 050004<br /><br />by: Gunara, Bobby E. (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />Extremal black holes of four dimensional N = 1 supergravity coupled to vector and chiral multiplets can be viewed as solitonic solutions of the theory. In this paper, we particularly study a static spherical symmetric black holes. In the asymptotic region the complex scalars are frozen which can be viewed as the critical points of the black hole and the scalar potentials with vanishing scalar charges. then, it turns out that the asymptotic geometries have a constant scalar curvature which in general are not Einstein. These spaces are boundaries of the black holes which could also correspond to the near horizon geometries if the value of the scalars in both regions coincides.Gunara, Bobby E.Tue, 21 Apr 2015 09:55:45 GMThttp://inspirehep.net/record/13622652015-04-16Vanishing Dimensions in Four Dimensional Cosmology with Nonminimal Derivative Coupling of Scalar Field
http://inspirehep.net/record/1307816
physics.gen-pharXiv:1407.6624<br />Adv.Stud.Theor.Phys. 9 (2015) 423-431<br /><br />by: Suroso, Agus (Indonesia Ctr. Theor. Math. Phys.) et al.<br /><br /><strong>Abstract:</strong> <br />We discussed a mechanism that allows the universe to start from lower dimension ($d < 4$) in its very early era and evolves to four dimension at the end of the process. The mechanism is generated by a nonminimal derivative coupling of scalar field, where derivative terms of the scalar field coupled to curvature tensor. We solve the Einstein equations for a limit of large and nearly constant Hubble parameter and analyze the evolution of the Hubble parameter in this limit. The lower-dimensionality in early universe has advantages in the context of unification theory.Suroso, AgusFri, 25 Jul 2014 09:36:36 GMThttp://inspirehep.net/record/13078162015Varying gravitational constant in five dimensional universal extra dimension with nonminimal derivative coupling of scalar field
http://inspirehep.net/record/1226361
Adv.Stud.Theor.Phys. 6 (2012) 1337-1344<br /><br />by: Suroso, Agus (Bandung Inst. Tech.) et al.<br />Suroso, AgusWed, 03 Apr 2013 12:21:01 GMThttp://inspirehep.net/record/1226361Cosmological model with nonminimal derivative coupling of scalar fields in five dimensions
http://inspirehep.net/record/1216790
gr-qcarXiv:1404.7492<br />Gen.Rel.Grav. 45 (2013) 799-809<br /><br />by: Suroso, Agus (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />We study a nonminimal derivative coupling (NMDC) of scalar field, where the scalar field is coupled to curvature tensor in the five dimensional universal extra dimension model. We apply the Einstein equation and find its solution. First, we consider a special case of pure free scalar field without NMDC and we find that for static extradimension, the solution is equivalent to the standard cosmology with stiff matter. For a general case of pure free scalar field with NMDC, we find that the de Sitter solution is the solution of our model. For this solution, the scalar field evolves linearly in time. In the limit of small Hubble parameter, the general case give us the same solution as in the pure free scalar field. Finally, we perform a dynamical analysis to determine the stability of our model. We find that the extradimension, if it exist, can not be static and always shrinks with the expansion of four dimensional spacetime.Suroso, AgusTue, 29 Jan 2013 23:00:00 GMThttp://inspirehep.net/record/1216790Nonminimal derivative coupling in five dimensional universal extra dimensions and recovering the cosmological constant
http://inspirehep.net/record/1127424
AIP Conf.Proc. 1454 (2011) 47-50<br /><br />by: Suroso, Agus (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />We study a nonminimal derivative coupling (NMDC) of scalar field, where the scalar field is coupled to curvature tensor in the five dimensional universal extra dimension (UED) model. We choose an ansatz metric which contain a homogenous extra spatial dimension and solve the Einstein equation in the bulk. Under two assumptions concerning the scalar field and scale factors, we get the de Sitter universe and recover the cosmological constant from the coupling constant of NMDC. We also discuss how the extra dimension evolve in time.Suroso, AgusMon, 13 Aug 2012 22:00:00 GMThttp://inspirehep.net/record/1127424Some Aspects of Spherical Symmetric Extremal Dyonic Black Holes in 4d N=1 Supergravity
http://inspirehep.net/record/879592
hep-tharXiv:1012.0971<br />Int.J.Mod.Phys. A28 (2013) 1350084<br /><br />by: Gunara, Bobby E. (Bandung Inst. Tech.) et al.<br /><br /><strong>Abstract:</strong> <br />In this paper, we study several aspects of extremal spherical symmetric black hole solutions of four-dimensional N = 1 supergravity coupled to vector and chiral multiplets with the scalar potential turned on. In the asymptotic region, the complex scalars are fixed and regular which can be viewed as the critical points of the black hole and the scalar potentials with vanishing scalar charges. It follows that the asymptotic geometries are of a constant and nonzero scalar curvature which are generally not Einstein. These spaces could also correspond to the near horizon geometries which are the product spaces of a two anti-de Sitter surface and the two sphere if the value of the scalars in both regions coincide. In addition, we prove the local existence of nontrivial radius dependent complex scalar fields which interpolate between the horizon and the asymptotic region. We finally give some simple \BbbCn-models with both linear superpotential and gauge couplings.Gunara, Bobby E.Sun, 05 Dec 2010 23:00:00 GMThttp://inspirehep.net/record/879592