scholarly journals Asymptotically free AdS3/CFT2

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Bruno Balthazar ◽  
Amit Giveon ◽  
David Kutasov ◽  
Emil J. Martinec

Abstract We propose a new AdS3/CFT2 duality, in which the bulk string theory has a target spacetime AdS3 times a squashed three-sphere $$ {\mathbbm{S}}_{\flat}^3 $$ S ♭ 3 , and the dual CFT2 is a symmetric product of sigma models on ℝϕ×$$ {\mathbbm{S}}_{\flat}^3 $$ S ♭ 3 , deformed by a ϕ-dependent ℤ2 twist operator. The duality maps the asymptotic region of AdS3 to the region ϕ → ∞, where the twist interaction in the CFT2 turns off. The AdS3 backgrounds in question have RAdS< ℓs, and so lie on the string side of the string/black hole correspondence transition. As a consequence, the high energy density of states consists of a string gas in AdS3 rather than an ensemble of BTZ black holes. This property allows us to derive the dual CFT2 by a systematic analysis of the worldsheet string theory on AdS3.

This paper concerns itself with the possibility of thermal equilibrium between a black hole and a heat bath implied by Hawking’s discovery of black hole emission. We argue that in an isolated box of radiation, for sufficiently high energy density a black hole will condense out. We introduce thermal Green functions to discuss this equilibrium and are able to extend the original arguments, that the equilibrium is possible based on fields interacting solely with the external gravitational field, to the case when mutual and self interactions are included.


2008 ◽  
Vol 17 (03n04) ◽  
pp. 551-555 ◽  
Author(s):  
E. I. GUENDELMAN

It is argued that high energy density excitations, responsible for UV divergences in quantum field theories, including quantum gravity, are likely to be the source of child universes which carry them out of the original space–time. This decoupling prevents the high UV excitations from having any influence on physical amplitudes. Child universe production could therefore be responsible for UV regularization in quantum field theories which take into account gravitational effects. Finally, we discuss child universe production in the last stages of black hole evaporation, the prediction of the absence of trans-Planckian primordial perturbations, the connection with the minimum length hypothesis, and in particular the connection with the maximal curvature hypothesis.


1966 ◽  
Author(s):  
S. CHODOSH ◽  
E. KATSOULIS ◽  
M. ROSANSKY

2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.


2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.


2013 ◽  
Vol 28 (11) ◽  
pp. 1207-1212 ◽  
Author(s):  
Jian-Wen LI ◽  
Ai-Jun ZHOU ◽  
Xing-Quan LIU ◽  
Jing-Ze LI

2018 ◽  
Vol 28 (5) ◽  
pp. 273-278
Author(s):  
Beomhee Kang ◽  
Soonhyun Hong ◽  
Hongkwan Yoon ◽  
Dojin Kim ◽  
Chunjoong Kim

2000 ◽  
Author(s):  
Robert J. Schmitt ◽  
Jeffrey C. Bottaro ◽  
Mark Petrie ◽  
Paul E. Penwell

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