Quantum Effects near Charged Dilatonic Black Holes
The expectation value $\langleφ^2\rangle$ in the Hartle-Hawking vacuum is calculated for minimally-coupled neutral scalar fields at the horizon of a charged dilatonic black hole.
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arXiv subjects
Kiyoshi Shiraishi
Publications and source records attributed to Kiyoshi Shiraishi.
Cosmological String Theory with Thermal Energy
An attempt to construct a cosmological scenario directly from string theory is made. Cosmological string theory was presented by Antoniadis, Bachas, Ellis and Nanopoulos. They also expect loop effects on cosmological string theory. In this paper, we point out the other importance of the one-loop effect, the finite temperature effect. The equations of motion for background geometry at finite temperature are given. We address a problem on derivation of the effective action at nonzero temperature.
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Decaying Domain Walls in an Extended Gravity Model and Cosmology
We investigate cosmological consequences of an extended gravity model which belongs to the same class studied by Accetta and Steinhardt in an extended inflationary scenario. But we do not worry about inflation in our model; instead, we focus on a topological object formed during cosmological phase transitions. Although domain walls appear during first-order phase transitions such as QCD transition, they decay at the end of the phase transition. Therefore the "domain wall problem" does not exist in the suitable range of pameters and, on the contrary, the "fragments" of walls may become seeds of dark matter. A possible connection to "oscillating universe" model offered by Morikawa et al. is also discussed.
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Born-Infeld Monopoles and Instantons
We show that in certain non-Abelian Born-Infeld-Higgs theories there are monopole solutions obeying Bogomol'nyi-like equations in the Prasad-Sommerfield limit. We also discuss the existence of instanton solution in an SU(2) Born-Infeld theory.
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Thermodynamic potential for compactified bosonic strings
We discuss the inclusion of chemical potentials of the Kaluza-Klein charges in the partition function of the bosonic string with a compactified dimension on a circle. The construction of the thermodynamic potential is achieved by the path integral method at one-loop level. Duality symmetry in the dependence on compactification scale is examined. A modular-invariant expression for the thermodynamic potential is also presented.
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Simple Models in Supersymmetric Quantum Mechanics on a Graph
We study some sorts of dimensionally-deconstructed models for supersymmetric (Euclidean) quantum mechanics, or zero-dimensional field theory. In these models, we assign bosonic and fermionic variables to vertices and edges of a graph. We investigate a discrete version for the Gaussian model and the Wess-Zumino-type model on a graph. The topological index as a multiple integral is discussed on these models. In addition, we propose simple examples for supersymmetric extensions of the Lee-Wick model and the Galileon model. A model with two supersymmetries is also provided and generalization to `local' supersymmtric models is examined.
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Hosotani model in closed-string theory
The Hosotani mechanism in the closed-string theory with current algebra symmetry is described by the (old covariant) operator method. We compare the gauge symmetry breaking mechanism in a string theory which contains SU(2) symmetry originated from current algebra with the one in an equivalent compactified closed-string theory. We also investigate the difference between the Hosotani mechanism and the Higgs mechanism in closed-string theories by calculation of a four-point amplitude of `Higgs' bosons at tree level.
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Critical Higher Order Gravities in Higher Dimensions
We show that the higher order gravity model proposed by Meissner and Olechowski has a graviton mode, a massive spin-two excitation and no scalar mode in a maximally symmetric spacetime; therefore, by choosing the coefficients, we can construct a Lagrangian for `critical gravity' from higher order terms of curvatures in higher dimensions. We also give a comment on construction of the theory with multi-criticality in higher order gravities.
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Superradiance from a Charged Dilaton Black Hole
We study the behavior of the wave function of charged Klein-Gordon field around a charge dilaton black hole. The rate of spontaneous charge loss is estimated for large black hole case.
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Quantum Corrections to Entropy of Charged Dilatonic Black Holes in Arbitrary Dimensions
The quantum contribution of a scalar field to entropy of a dilatonic black hole is calculated in the brick wall model by the WKB method and analyzed by a high-temperature expansion. If the cutoff distance from the horizon approaches zero, the leading divergent piece of entropy turns out to be proportional to the "area" of the horizon surface (which has (N-1)-dimensional extension in (N+1)-dimensional space-time) and independent of other properties of black holes even in the case of general dilaton coupling. There is also qualitative argument with the known result of subleading divergence for N=3.
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U(infinity) Gauge Theory from Higher Dimensions
We show that classical U(infinity) gauge theories can be obtained from the dimensional reduction of a certain class of higher-derivative theories. In general, the exact symmetry is attained in the limit of degenerate metric; otherwise, the infinite-dimensional symmetry can be taken as spontaneously broken. Monopole solutions are examined in the model for scalar and gauge fields. An extension to gravity is also discussed.
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Compactification of spacetime in SU($\infty$) Yang-Mills theory
The compactification on a torus in $SU(\infty)$ Yang-Mills theory is considered. A special form of the configuration of a gauge field on a torus is examined. The vacuum energy and free energy in the presence of fermions coupled with this background in the theory are derived and possible symmetry breaking is investigated.
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Kac-Moody Symmetry in Hosotani Model
The symmetry of the massive tower of fields in higher-dimensional Yang-Mills theory compactified on a space-time of the form M_d x S^1 is clarified. The transformations form a loop algebra, a class of Kac-Moody algebras. Since the symmetry is spontaneously broken, vector fields "eat" Goldstone bosons and acquire masses. The field of zero-mass mode can also become massive provided that the field of the internal component develops a vacuum expectation value. The relation between the "restoration" of the symmetry in massive modes and the gauge transformation of the zero-mode vacuum field is discussed.
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Bose-Einstein Condensation in Compactified Spaces
We discuss the thermodynamic potential of a charged Bose gas with the chemical potential in arbitrary dimensions. The critical temperature for Bose-Einstein condensation is investigated. In the case of the compactified background metric, it is shown that the critical temperature depends on the size of the extra spaces. The asymmetry of the "Kaluza-Klein charge" is also discussed.
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Finite Temperature and Density Effects in Higher Dimensions with and without Compactifications
Expressions for the thermodynamic potential of a Dirac fermion gas are represented at finite temperature with the chemical potential in an ultrastatic space $R^d\times S^N$. The high- and low- temperature expansions for the thermodynamic potential are obtained and, in particular, strongly degenerate fermi gas is investigated. For the Candelas-Weinberg model, sufficiently high "charge" density prevents the compactification of the extra space.
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Can Virtual Cosmic Strings Shift the Hawking Temperature?
The amount of the Hawking radiation in Hartle-Hawking vacuum around the Schwarzschild black hole is calculated in the presence of the cloud of virtual-cosmic-string loops near the black hole. Recently, Coleman, Preskill and Wilczek have discussed the black-hole temperature in such situation. We show, in this letter, it is hardly possible to find any deviation in the Hawking radiation even if the virtual cosmic strings exist.
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Wilson Loops in Open String Theory
Wilson loop elements on torus are introduced into the partition function of open strings as Polyakov's path integral at one-loop level. Mass spectra from compactification and expected symmetry breaking are illustrated by choosing the correct weight for the contributions from annulus and Möbius strip. We show that Jacobi's imaginary transformation connects the mass spectra with the Wilson loops. The application to thermopartition function and cosmological implications are briefly discussed.
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Hosotani mechanism in higher dimensional Lee-Wick theory
Hosotani mechanism in higher-dimensional Lee-Wick theory is investigated. The symmetry breaking mechanism proposed by Hosotani is studied at one-loop level through a toy model in this theory. We find that the phase diagram of symmetry and masses of fields are modified from the original one if masses of Lee-Wick particles are in the same order of the inverse of the compactification scale.
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