61 research outputs found
On analytical study of holographic superconductors with BornāInfeld electrodynamics
Based on the SturmāLiouville eigenvalue problem, Banerjee et al. proposed a perturbative approach to analytically investigate the properties of the ( 2+1 )-dimensional superconductor with BornāInfeld electrodynamics (Banerjee et al., 2013) [29] . By introducing an iterative procedure, we will further improve the analytical results and the consistency with the numerical findings, and can easily extend the analytical study to the higher-dimensional superconductor with BornāInfeld electrodynamics. We observe that the higher BornāInfeld corrections make it harder for the condensation to form but do not affect the critical phenomena of the system. Our analytical results can be used to back up the numerical computations for the holographic superconductors with various condensates in BornāInfeld electrodynamics
Notes on analytical study of holographic superconductors with Lifshitz scaling in external magnetic field
We employ the matching method to analytically investigate the holographic superconductors with Lifshitz scaling in an external magnetic field. We discuss systematically the restricted conditions for the matching method and find that this analytic method is not always powerful to explore the effect of external magnetic field on the holographic superconductors unless the matching point is chosen in an appropriate range and the dynamical exponent z satisfies the relation <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>z</mi><mo>=</mo><mi>d</mi><mo>ā</mo><mn>1</mn></math> or <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>z</mi><mo>=</mo><mi>d</mi><mo>ā</mo><mn>2</mn></math> . From the analytic treatment, we observe that Lifshitz scaling can hinder the condensation to be formed, which can be used to back up the numerical results. Moreover, we study the effect of Lifshitz scaling on the upper critical magnetic field and reproduce the well-known relation obtained from GinzburgāLandau theory
Absorption cross section and Hawking radiation of the electromagnetic field with Weyl corrections
We have investigated the absorption cross section and the Hawking radiation of electromagnetic field with Weyl correction in the background of a four-dimensional Schwarzschild black hole spacetime. Our results show that the properties of the absorption cross section and the Hawking radiation depend not only on the Weyl correction parameter, but also on the parity of the electromagnetic field, which is quite different from those of the usual electromagnetic field without Weyl correction in the four-dimensional spacetime. With increase of Weyl correction parameter, the absorption probability, the absorption cross section, the power emission spectra and the luminosity of Hawking radiation decreases with Weyl correction parameter for the odd-parity electromagnetic field and increases with the even-parity electromagnetic field
Strong gravitational lensing in a rotating Kaluza-Klein black hole with squashed horizons
We have investigated the strong gravitational lensing in a rotating squashed Kaluza-Klein (KK) black hole spacetime. Our result show that the strong gravitational lensings in the rotating squashed KK black hole spacetime have some distinct behaviors from those in the backgrounds of the four-dimensional Kerr black hole and of the squashed KK Gƶdel black hole. In the rotating squashed KK black hole spacetime, the marginally circular photon radius Ļ ps , the coefficient , , the deflection angle Ī± ( Īø ) in the Ļ direction and the corresponding observational variables are independent of whether the photon goes with or against the rotation of the background, which is different with those in the usual four-dimensional Kerr black hole spacetime. Moreover, we also find that with the increase of the scale of extra dimension Ļ 0 , the marginally circular photon radius Ļ ps and the angular position of the relativistic images Īø ā first decreases and then increases in the rotating squashed KK black hole for fixed rotation parameter b , but in the squashed KK Gƶdel black hole they increase for the smaller global rotation parameter j and decrease for the larger one. In the extremely squashed case Ļ 0 = 0, the coefficient a in the rotating squashed KK black hole increases monotonously with the rotation parameter, but in the squashed KK Gƶdel black hole it is a constant and independent of the global rotation of the Gƶdel Universe. These information could help us to understand further the effects of the rotation parameter and the scale of extra dimension on the strong gravitational lensing in the black hole spacetimes
Ehrenfest scheme for complex thermodynamic systems in full phase space
For a thermodynamic system with multiple pairs of intensive/extensive variables and the thermodynamical coefficients attain finite or infinite values on the phase boundary, we obtain the two classes of Ehrenfest equations in the full phase space, and find that the rank of the matrix for these equations can tell us the dimensions of the phase boundary. We also apply this treatment to the RN-AdS black hole
Thermal Casimir effect in Kerr spaceātime
We investigate the thermal Casimir effect of a massless scalar field for two parallel plates moving in the equatorial orbit in Kerr spaceātime. Under the assumption that the typical cavity size is much smaller than the orbital radius, proposed by Sorge, we deduce the analytical expression of the renormalized free energy in this curved spaceātime. We also get the analytical representation for the renormalized internal energy, and find that there is a thermal correction to the Casimir energy, which depends on the proper temperature and the proper geometrical parameters of the plates. The asymptotic behavior of the Casimir free energy, entropy and internal energy at low temperature is also investigated
Holographic entanglement entropy in metal/superconductor phase transition with BornāInfeld electrodynamics
We investigate the holographic entanglement entropy in the metal/superconductor phase transition for the BornāInfeld electrodynamics with full backreaction and note that the entropy is a good probe to study the properties of the phase transition. For the operator ā©OāāŖ , we find that the entanglement entropy decreases (or increases) with the increase of the BornāInfeld parameter b in the metal (or superconducting) phase. For the operator ā©O+āŖ , we observe that, with the increase of the BornāInfeld parameter, the entanglement entropy in the metal phase decreases monotonously but the entropy in the superconducting phase first increases and forms a peak at some threshold bT , then decreases continuously. Moreover, the value of bT becomes smaller as the width of the subsystem A decreases
Holographic entanglement entropy in general holographic superconductor models
We study the entanglement entropy of general holographic dual models both in AdS soliton and AdS black hole backgrounds with full backreaction. We find that the entanglement entropy is a good probe to explore the properties of the holographic superconductors and provides richer physics in the phase transition. We obtain the effects of the scalar mass, model parameter and backreaction on the entropy, and argue that the jump of the entanglement entropy may be a quite general feature for the first order phase transition. In strong contrast to the insulator/superconductor system, we note that the backreaction coupled with the scalar mass can not be used to trigger the first order phase transition if the model parameter is below its bottom bound in the metal/superconductor system
Condensation for non-relativistic matter in HoÅavaāLifshitz gravity
We study condensation for non-relativistic matter in a HoÅavaāLifshitz black hole without the condition of the detailed balance. We show that, for the fixed non-relativistic parameter Ī±2 (or the detailed balance parameter Ļµ ), it is easier for the scalar hair to form as the parameter Ļµ (or Ī±2 ) becomes larger, but the condensation is not affected by the non-relativistic parameter Ī²2 . We also find that the ratio of the gap frequency in conductivity to the critical temperature decreases with the increase of Ļµ and Ī±2 , but increases with the increase of Ī²2 . The ratio can reduce to the HorowitzāRoberts relation Ļg/Tcā8 obtained in the Einstein gravity and Cai's result Ļg/Tcā13 found in a HoÅavaāLifshitz gravity with the condition of the detailed balance for the relativistic matter. Especially, we note that the ratio can arrive at the value of the BCS theory Ļg/Tcā3.5 by taking proper values of the parameters
Observation of Electromagnetic Dalitz decays J/Ļ\to P e^+e^-
Based on a sample of (225.3\pm2.8)\times 10^{6} J/\psi events collected with
the BESIII detector, the electromagnetic Dalitz decays of J/\psi \to P
e^+e^-(P=\eta'/\eta/\pi^0) are studied. By reconstructing the pseudoscalar
mesons in various decay modes, the decays J/\psi \to \eta' e^+e^-, J/\psi \to
\eta e^+e^- and J/\psi \to \pi^0 e^+e^- are observed for the first time. The
branching fractions are determined to be \mathcal{B}(J/\psi\to \eta' e^+e^-) =
(5.81\pm0.16\pm0.31)\times10^{-5}, \mathcal{B}(J/\psi\to \eta e^+e^-) =
(1.16\pm0.07\pm0.06)\times10^{-5}, and \mathcal{B}(J/\psi\to \pi^0
e^+e^-)=(7.56\pm1.32\pm0.50)\times10^{-7}, where the first errors are
statistical and the second ones systematic
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