3,493 research outputs found
Aspects of AdS Quantum Gravity and the Karch-Randall Braneworld
In this paper, we use the Karch-Randall braneworld to study theories of
quantum gravity in two dimensional (nearly) anti-de Sitter space (AdS). We
focus on effective gravitational theories in the setup with two Karch-Randall
branes embedded in an asymptotically AdS bulk forming a wedge. We find the
appearance of two-dimensional Einstein-Hilbert gravity (or the Lorenzian
version of Marolf-Maxfield theory) when the branes are rigid but the emergence
of a class of dilaton gravity models parameterized by the tensions of the two
branes when brane fluctuations are accounted for. A special case of our result
is Jackiw-Teitelboim (JT) gravity, which has been proven useful to address many
important problems in quantum gravity. An important implication of our work is
that these models have holographic duals as one-dimensional quantum mechanics
systems. At the end, we discuss a puzzle regarding the energy spectrum and its
resolution.Comment: 39 Pages, 11 figures, comments are welcome; references adde
Entropy, Entanglement Islands and Swampland Bounds in the Karch-Randall Braneworld
Motivated by the study of entanglement island in the Karch-Randall
braneworld, it has been conjectured and proven in general that entanglement
island is not consistent with long-range (massless) gravity. In this paper, we
provide a careful check of this conclusion in a model of massless gravity that
is constructed using the Karch-Randall braneworld. We show that there is indeed
no entanglement island and hence not a nontrivial Page curve due to the
diffeomorphism invariance if we are studying the correct question which is
though subtle. Moreover, we show that this conclusion is not affected by
deforming the setup with the Dvali--Gabadadze--Porrati (DGP) terms.
Furthermore, we show that the consistency of holography in this model will
provide nontrivial constraints to the DGP parameters. This study provides an
example that causality and holography in anti-de Sitter space can be used to
constrain low energy effective theories. At the end, we clarify several
subtleties in the braneworld gravity which are overlooked in the literature and
we discuss the robustness of the above results against possible coarse-graining
protocols to define a subregion in a gravitational theory.Comment: 23 pages, 7 figures, comments are welcom
Inverse-Chirp Imprint of Gravitational Wave Signals in Scalar Tensor Theory
The scalar tensor theory contains a coupling function connecting the
quantities in the Jordan and Einstein frames, which is constrained to guarantee
a transformation rule between frames. We simulate the supernovae core collapse
with different choices of coupling functions defined over the viable region of
the parameter space and find that a generic inverse-chirp feature of the
gravitational waves in the scalar tensor scenario.Comment: 13 pages, 4 figures, revised version accepted by EPJ
Crowdsourcing Argumentation Structures in Chinese Hotel Reviews
Argumentation mining aims at automatically extracting the premises-claim
discourse structures in natural language texts. There is a great demand for
argumentation corpora for customer reviews. However, due to the controversial
nature of the argumentation annotation task, there exist very few large-scale
argumentation corpora for customer reviews. In this work, we novelly use the
crowdsourcing technique to collect argumentation annotations in Chinese hotel
reviews. As the first Chinese argumentation dataset, our corpus includes 4814
argument component annotations and 411 argument relation annotations, and its
annotations qualities are comparable to some widely used argumentation corpora
in other languages.Comment: 6 pages,3 figures,This article has been submitted to "The 2017 IEEE
International Conference on Systems, Man, and Cybernetics (SMC2017)
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