Proof of entropy principle in Einstein-Maxwell theory

Fang, Xiongjun; Gao, Sijie

doi:10.1103/physrevd.92.024044

Cited by 20 publications

(23 citation statements)

References 22 publications

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“…However, since the superconducting gap is highly anisotropic with line nodes in KFe 2 As 2 , it is difficult to estimate the ratio of the supercondcuting gap and resonance energy. According to ARPES measurements, the maximum of the gap magnitude on the middle and inner pockets is about ∆ max ≈ 0.75 meV and 1.5 meV at 2 K, respectively [17], which is broadly consistent with scanning tunneling spectroscopy measurements that reveal an average superconducting gap of ∆ avg = 1 meV at a lower temperature of 0.5 K [30]. Interestingly, ratio E R /2∆ avg ≈ 0.6 (L = 0.5) is close to the universal ratio of ∼ 0.64 [31].…”

supporting

confidence: 82%

Neutron Spin Resonance in the Heavily Hole-Doped KFe2As2 Superconductor

Shen

Zhang

et al. 2020

Phys. Rev. Lett.

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We report high-resolution neutron scattering measurements of the low energy spin fluctuations of KFe2As2, the end member of the hole-doped Ba1−xKxFe2As2 family with only hole pockets, above and below its superconducting transition temperature Tc (∼ 3.5 K). Our data reveals clear spin fluctuations at the incommensurate wave vector (0.5 ± δ, 0, L), (δ = 0.2)(1-Fe unit cell), which exhibit L-modulation peaking at L = 0.5. Upon cooling to the superconducting state, the incommensurate spin fluctuations gradually open a spin-gap and form a sharp spin resonance mode. The incommensurability (2δ = 0.4) of the resonance mode (∼ 1.2 meV) is considerably larger than the previously reported value (2δ ≈ 0.32) at higher energies (≥∼ 6 meV). The determination of the momentum structure of spin fluctuation in the low energy limit allows a direct comparison with the realistic Fermi surface and superconducting gap structure. Our results point to an s-wave pairing with a reversed sign between the hole pockets near the zone center in KFe2As2. PACS numbers:

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supporting

confidence: 82%

Neutron Spin Resonance in the Heavily Hole-Doped KFe2As2 Superconductor

Shen

Zhang

et al. 2020

Phys. Rev. Lett.

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“…T hermo and C 7 T hermo by P 6 T hermo and P 7 T hermo , respectively. Select all terms contain b 2 in Eq.…”

Section: Dynmentioning

confidence: 92%

“…Verlinder suggested that the gravity is the entropy force [3]. In recent years, the proofs of the maximum entropy principle showed that the gravitational equation can be derived from the constraint equation and the maximum of total entropy [5][6][7][8][9][10]. All these researches are trying to establish a correspona e-mail: fangxj@hunnu.edu.cn b e-mail: hexiaokai77@163.com c e-mail: jljing@hunn.edu.cn dence between the first variation of thermodynamic quantities and gravitational equation.…”

Section: Introductionmentioning

confidence: 99%

Consistency between dynamical and thermodynamical stabilities for perfect fluid in f(R) theories

Fang

Jing

2018

Eur. Phys. J. C

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We investigate the stability criterions for perfect fluid in f (R) theories which is an important generalization of general relativity. Firstly, using Wald's general variation principle, we recast Seifert's work and obtain the dynamical stability criterion. Then using our generalized thermodynamical criterion, we obtain the concrete expressions of the criterion. We show that the dynamical stability criterion is exactly the same as the thermodynamical stability criterion to spherically symmetric perturbations of static spherically symmetric background solutions. This result suggests that there is an inherent connection between the thermodynamics and gravity in f (R) theories. It should be pointed out that using the thermodynamical method to determine the stability for perfect fluid is simpler and more directly than the dynamical method.

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“…Note that if the Lagrangian contains other scalar or vector parts, Eq. (1) need to be modified [6], which shows that the criterion for thermodynamical stability also needs to be modified. …”

Section: Summary and Discussionmentioning

confidence: 99%

“…Meanwhile, a series of papers proved that the maximum entropy principle for a perfect fluid holds in different theories. This principle shows that if the constraint equation and some thermodynamic conditions are satisfied, the gravitational field equations could be derived by the extrema of the total entropy [3][4][5][6][7][8][9]. Recently, Jacobson proposed the "causal diamond" structure and considered entanglement equilibrium to imply the Einstein equations [10].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamical stability for a perfect fluid

Fang

Jing

2017

Eur. Phys. J. C

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According to the maximum entropy principle, it has been proved that the gravitational field equations could be derived by the extrema of the total entropy for a perfect fluid, which implies that thermodynamic relations contain information as regards gravity. In this manuscript, we obtain a criterion for the thermodynamical stability of an adiabatic, self-gravitating perfect fluid system by the second variation of the total entropy. We show, for Einstein's gravity with spherical symmetry spacetime, that the criterion is consistent with that for the dynamical stability derived by Chandrasekhar and Wald. We also find that the criterion could be applied to cases without spherical symmetry, or under general perturbations. The result further establishes the connection between thermodynamics and gravity.

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Proof of entropy principle in Einstein-Maxwell theory

Abstract: We consider a static self-gravitating charged perfect fluid system in the Einstein-Maxwell theory.

Cited by 20 publications

References 22 publications

Neutron Spin Resonance in the Heavily Hole-Doped KFe2As2 Superconductor

Neutron Spin Resonance in the Heavily Hole-Doped KFe2As2 Superconductor

Consistency between dynamical and thermodynamical stabilities for perfect fluid in f(R) theories

Thermodynamical stability for a perfect fluid

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