Browsing by Author "Ishihara, Masafumi"

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Accelerated quark and holography for confining gauge theory
(2011-01-18)
Ghoroku, Kazuo
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Ishihara, Masafumi
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Kubo, Kouki
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Taminato, Tomoki
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電子物理學系
We show a constantly accelerated quark as a string solution of the Nambu-Goto action, which is embedded in the bulk background dual to the N = 2 supersymmetric confining Yang-Mills theory. The induced metric of the world sheet for this string solution has an event horizon specified by the fifth coordinate. By an extended Rindler transformation proposed by Xiao, we move to the comoving frame of the accelerated quark string. Then we find that this horizon is transferred to the event horizon of the bulk and the causal part of the accelerated quark is transformed to a static free quark in the Rindler coordinate. As a result, the confinement of the Minkowski vacuum is lost in the Rindler vacuum. This point is assured also by studying the potential between the quark and antiquark. However, the remnants of the original confining force are seen in various thermal quantities. We also discuss the consistency of our results and the claim that the Green's functions will not be changed by the Rindler transformation.
Refined holographic entanglement entropy for the AdS solitons and AdS black holes
(2013-07-21)
Ishihara, Masafumi
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Lin, Feng-Li
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Ning, Bo
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電子物理學系
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Department of Electrophysics
We consider the refinement of the holographic entanglement entropy for the holographic dual theories to the AdS solitons and AdS black holes, including the corrected ones by the Gauss-Bonnet term. The refinement is obtained by extracting the UV-independent piece of the holographic entanglement entropy, the so-called renormalized entanglement entropy which is independent of the choices of UV cutoff. Our main results are: (i) the renormalized entanglement entropies of the AdS(d+1) soliton for d = 4, 5 are neither monotonically decreasing along the RG flow nor positive-definite, especially around the deconfinement/confinement phase transition; (ii) there is no topological entanglement entropy for AdS(5) soliton even with Gauss-Bonnet correction; (iii) for the AdS black holes, the renormalized entanglement entropy obeys an expected volume law at IR regime, and the transition between UV and IR regimes is a smooth crossover even with Gauss-Bonnet correction; (iv) based on AdS/MERA conjecture, we postulate that the IR fixed-point state for the non-extremal AdS soliton is a trivial product state. (C) 2013 Elsevier B.V. All rights reserved.