A holographic proof of the universality of corner entanglement for CFTs

There appears a universal logarithmic term of entanglement entropy, i.e., $-a(\Omega) \log(H/\delta)$, for 3d CFTs when the entangling surface has a sharp corner. $a(\Omega)$ is a function of the corner opening angle and behaves as $a(\Omega\to \pi)\simeq \sigma (\pi-\Omega)^2$ and $a(\Omega\to 0)\simeq \kappa/\Omega$, respectively. Recently, it is conjectured that $\sigma/C_T=\pi^2/24$, where $C_T$ is central charge in the stress tensor correlator, is universal for general CFTs in three dimensions. In this paper, by applying the general higher curvature gravity, we give a holographic proof of this conjecture. We also clarify some interesting problems. Firstly, we find that, in contrast to $\sigma/C_T$, $\kappa/C_T$ is not universal. Secondly, the lower bound $a_E(\Omega)/C_T$ associated to Einstein gravity can be violated by higher curvature gravity. Last but not least, we find that there are similar universal laws for CFTs in higher dimensions. We give some holographic tests of these new conjectures.Comment: 22 pages, 0 figures, typos corrected, accepted by JHE

The covariant and on-shell statistics in kappa-deformed spacetime

It has been a long-standing issue to construct the statistics of identical particles in $\kappa$-deformed spacetime. In this letter, we investigate different ideas on this problem. Following the ideas of Young and Zegers, we obtain the covariant and on-shell kappa two-particle state in 1+1 D in a simpler way. Finally, a procedure to get such state in higher dimension is proposed.Comment: 16 page

Universal Terms of Entanglement Entropy for 6d CFTs

We derive the universal terms of entanglement entropy for 6d CFTs by applying the holographic and the field theoretical approaches, respectively. Our formulas are conformal invariant and agree with the results of [34,35]. Remarkably, we find that the holographic and the field theoretical results match exactly for the $C^2$ and $Ck^2$ terms. Here $C$ and $k$ denote the Weyl tensor and the extrinsic curvature, respectively. As for the $k^4$ terms, we meet the splitting problem of the conical metrics. The splitting problem in the bulk can be fixed by equations of motion. As for the splitting on the boundary, we assume the general forms and find that there indeed exists suitable splitting which can make the holographic and the field theoretical $k^4$ terms match. Since we have much more equations than the free parameters, the match for $k^4$ terms is non-trivial.Comment: 38 pages, no figures, add more details of the derivations, typos corrected, accepted by JHE

A Note on Holographic Weyl Anomaly and Entanglement Entropy

We develop a general approach to simplify the derivation of the holographic Weyl anomaly. As an application, we derive the holographic Weyl anomaly from general higher derivative gravity in asymptotically $AdS_{5}$ and $AdS_{7}$. Interestingly, to derive all the central charges of 4d and 6d CFTs, we make no use of equations of motion. Following Myers' idea, we propose a formula of holographic entanglement entropy for higher derivative gravity in asymptotically $AdS_5$. Applying this formula, we obtain the correct universal term of entanglement entropy for 4d CFTs. It turns out that our formula is the leading term of Dong's proposal in asymptotically $AdS_5$. Since only the leading term contributes to the universal log term, we actually prove that Dong's proposal yields the correct universal term of entanglement entropy for 4d CFTs. This is a nontrivial test of Dong's proposal.Comment: 20 pages, no figures, accepted by Classical and Quantum Gravity, prove that Dong's proposal [arXiv: arXiv:1310.5713] gives the correct universal term of entanglement entropy for 4d CFT

Generalized Gravitational Entropy from Total Derivative Action

We investigate the generalized gravitational entropy from total derivative terms in the gravitational action. Following the method of Lewkowycz and Maldacena, we find that the generalized gravitational entropy from total derivatives vanishes. We compare our results with the work of Astaneh, Patrushev, and Solodukhin. We find that if total derivatives produced nonzero entropy, the holographic and the field-theoretic universal terms of entanglement entropy would not match. Furthermore, the second law of thermodynamics could be violated if the entropy of total derivatives did not vanish.Comment: 24 pages; v2: added references, Sec. 5.2 for corner entanglement, a toy model in Sec. 5.3, and minor corrections; v3: added one reference, published versio