On analytical study of holographic superconductors with Born–Infeld electrodynamics

Based on the Sturm–Liouville eigenvalue problem, Banerjee et al. proposed a perturbative approach to analytically investigate the properties of the ( 2+1 )-dimensional superconductor with Born–Infeld 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 Born–Infeld electrodynamics. We observe that the higher Born–Infeld 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 Born–Infeld 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>−</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>−</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 Ginzburg–Landau 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 Gödel black hole. In the rotating squashed KK black hole spacetime, the marginally circular photon radius ρ ps , the coefficient $\overline{a}$ , $\overline{b}$ , the deflection angle α ( θ ) in the ϕ 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 ρ 0 , the marginally circular photon radius ρ ps and the angular position of the relativistic images θ ∞ first decreases and then increases in the rotating squashed KK black hole for fixed rotation parameter b , but in the squashed KK Gödel black hole they increase for the smaller global rotation parameter j and decrease for the larger one. In the extremely squashed case ρ 0 = 0, the coefficient a in the rotating squashed KK black hole increases monotonously with the rotation parameter, but in the squashed KK Gödel black hole it is a constant and independent of the global rotation of the Gödel 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

Theoretical analysis of direct CP violation and differential decay width in D±→π±π+π- in phase space around the resonances ρ0(770) and f0(500)

We perform a theoretical study on direct CP violation in D±→π±π+π- in phase space around the intermediate states ρ0(770) and f0(500) . The possible interference between the amplitudes corresponding to the two resonances is taken into account, and the relative strong phase of the two amplitudes is treated as a free parameter. Our analysis shows that by a properly chosen strong phase, both the CP violation strength and the differential decay width accommodate the experimental results

DsJ(2860) from the semileptonic decays of Bs mesons

In the framework of heavy quark effective theory, the leading-order Isgur–Wise form factors relevant to semileptonic decays of the ground state b¯s meson Bs into orbitally excited D -wave c¯s mesons, including the newly observed narrow Ds1∗(2860) and Ds3∗(2860) states by the LHCb Collaboration, are calculated with the QCD sum rule method. With these universal form factors, the decay rates and branching ratios are estimated. We find that the decay widths are Γ(Bs→Ds1∗ℓν¯)=1.25-0.60+0.80×10-19GeV , Γ(Bs→Ds2′ℓν¯)=1.49-0.73+0.97×10-19GeV , Γ(Bs→Ds2ℓν¯)=4.48-0.94+1.05×10-17GeV , and Γ(Bs→Ds3∗ℓν¯)=1.52-0.31+0.35×10-16GeV . The corresponding branching ratios are B(Bs→Ds1∗ℓν¯)=2.85-1.36+1.82×10-7 , B(Bs→Ds2′ℓν¯)=3.40-1.66+2.21×10-7 , B(Bs→Ds2ℓν¯)=1.02-0.21+0.24×10-4 , and B(Bs→Ds3∗ℓν¯)=3.46-0.70+0.80×10-4 . The decay widths and branching ratios of corresponding Bs∗ semileptonic processes are also predicted

Thermal Casimir effect in Kerr space–time

We investigate the thermal Casimir effect of a massless scalar field for two parallel plates moving in the equatorial orbit in Kerr space–time. 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 space–time. 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 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

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

Holographic entanglement entropy in metal/superconductor phase transition with Born–Infeld electrodynamics

We investigate the holographic entanglement entropy in the metal/superconductor phase transition for the Born–Infeld electrodynamics with full backreaction and note that the entropy is a good probe to study the properties of the phase transition. For the operator 〈O−〉 , we find that the entanglement entropy decreases (or increases) with the increase of the Born–Infeld parameter b in the metal (or superconducting) phase. For the operator 〈O+〉 , we observe that, with the increase of the Born–Infeld 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