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Kiyoshi Shiraishi

Publications and source records attributed to Kiyoshi Shiraishi.

At least 73 records · Page 4Linked to original sources
arXiv2015

Effect of Self-Interaction on Vacuum Energy for Yang-Mills System in Kaluza-Klein Theory

We calculate the vacuum energy for Yang--Mills (YM) system in the background space-time $M^4 \times S^3$, taking the effect of self-interaction of the YM fields into account. The compactification scale obtained by Candelas--Weinberg mechanism becomes large if the YM coupling is large. The case with an extra space $S^3/Z_2$ is also considered, and it is shown that the vacuum associated with broken gauge symmetry is unstable.

hep-th↗
arXiv2015

Quantum Corrections to Scattering Amplitude in Conical Space-time

It is known that the vacuum polarization of zero-point field arises around a conical singularity generated by an infinite, straight cosmic string. In this paper we study quantum electromagnetic corrections to the gravitational Aharonov-Bohm effect around a cosmic string. We find the scattering amplitude from a conical defect for charged Klein-Gordon field.

hep-th↗
arXiv2015

More on quantum kinks in gauge theories on $R^2 \otimes S^1$

Quantum kinks in gauge theories on $R^2\otimes S^1$ space-time are studied. To obtain the, explicit profile of the kinks, we calculated effective actions including derivative corrections for vacuum gauge fields on $S^1$ at zero, and finite temperature up to one-loop level. It is found that there are soliton solutions in scalar QED. We also find that the derivative correction tends to make the vacuum unstable in $SU(2)$ Yang-Mills theory.

math-ph↗
arXiv2015

Double Compactification

A cosmological scenario according to which our universe experienced space-time compactifications twice in its early development is investigated through toy models. In this scenario gauge configurations on an extra space play essential roles to bring about a change of the dimensionality of the compactified space. Simple models are offered and their behaviour at finite temperature is examined. A possibility of causing inflation and problems on our scenario is argued briefly.

gr-qc↗
arXiv2015

The Universe as a Topological Defect in a Higher-Dimensional Einstein-Yang-Mills Theory

An interpretation is suggested that a spontaneous compactification of space-time can be regarded as a topological defect in a higher-dimensional Einstein-Yang-Mills (EYM) theory. We start with $D$-dimensional EYM theory in our present analysis. A compactification leads to a $D-2$ dimensional effective action of Abelian gauge-Higgs theory. We find a "vortex" solution in the effective theory. Our universe appears to be confined in a center of a "vortex", which has $D-4$ large dimensions. In this paper we show an example with $SU(2)$ symmetry in the original EYM theory, and the resulting solution is found to be equivalent to the "instanton-induced compactification". The cosmological implication is also mentioned.

gr-qc↗
arXiv2015

The phase synchronization of an axion and a superconductor

The effects of the axion field have been widely studied in theoretical physics, particularly in particle physics. Considering the phase synchronization and the mean free path of the axion, the bulk of the phase coherent superconductor is regarded as the weak link region of the Josephson junction.It is expected that the axion mass influences the London penetration depth.There is a slight possibility of detecting this effect because the effect becomes more significant in superconductor with a low carrier density $n_s$.The differences due to the choice of axion model and the axion mass are discussed.

cond-mat.supr-con↗
arXiv2014

A New Vector-Tensor Theory and Higher-Dimensional Cosmology

A new vector-tensor model of classical gravity, which contains coupling between the field strength of the vector field and the curvature tensors in six dimensions, is proposed. Cosmological solutions of the scale factors in this model with the compactified space are obtained. The generalization of the model is also considered.

gr-qc↗
arXiv2014

Wilson-Loop Symmetry Breaking Reexamined

The splitting in energy of gauge field vacua on the non-simply connected space $S^3/Z_2$ is reconsidered. We show the calculation to the one-loop level for a Yang-Mills vector with a ghost field. We confirm our previous result and give a solution to the question posed by Freire, Romão and Barroso.

hep-th↗
arXiv2014

Gauge Fields on Torus and Partition Function of Strings

In this paper we consider the interrelation between compactified string theories on torus and gauge fields on it. We start from open string theories with background gauge fields and derive partition functions by path integral. Since the effects of background fields and compactification correlate only through string zero modes, we investigate these zero modes. From this point of view, we discuss the Wilson loop mechanism at finite temperature. For the closed string, only a few comments are mentioned.

hep-th↗
arXiv2014

Finite Temperature Effect on Wilson Loop Mechanism

We evaluate the energy splitting of vacua appearing in the gauge theory in the space $M_4\times S^N/Z_2$ ($N=2,3,4,5,6$ and $7$). One-loop quantum effects which come from scalar and gauge fields are considered. We calculate them at zero temperature as well as in high-temperature limit. We find that in these situations there is no breakdown of the gauge symmetry.

hep-th↗
arXiv2014

Moduli space metric for maximally-charged dilaton black holes

The system consisting of slowly-moving, maximally charged, nonrotating dilaton black holes is investigated. We obtain the metric on the moduli space of the system in the low-velocity limit. We find that: (1) only two-body interactions exist between the extreme black holes in string theory; (2) the mutual interaction between the black holes vanishes if the dilaton can be interpreted as a Kaluza-Klein scalar; and (3) for general dilaton couplings, there exist many-body interactions among the extreme black holes. We analyze the low-energy classical scattering of the two extreme black holes in string theory by utilizing the moduli space metric.

gr-qc↗
arXiv2014

Spontaneous Compactification of Bimetric Theory

We propose a model of bimetric gravity in which the mixing of metrics naturally gives a mass to a graviton by the compactification with flux of two gauge fields in extra dimensions. We assume that each metric in the solution for the background geometry describes the four-dimensional Minkowski spacetime with an $S^2$ extra space, though the two radii of $S^2$ for two metrics take different values in general. The solution is derived by the effective potential method in the presence of the magnetic fluxes on the extra spheres. We find that the a massive graviton is governed by the Fierz-Pauli Lagrangian in the weak field limit and one massless graviton left in four dimensions.

hep-th↗
arXiv2014

On Instability of Squashed Spheres in the Kaluza-Klein Theory

We study in Kaluza-Klein theories stability of the extra space against "squashing", in other words, the homogeneous deformation. Quantum fluctuations of matter fields at one-loop level are taken into consideration. We calculate the effective potential in models of the type, $M^4\times S^3$ and $M^4\times S^7$. It is found that in the case of scalar matter fields the stability depends on the coupling to the scalar curvature.

hep-th↗
arXiv2014

A Model of BPS Black Holes in a Discrete Space

We examine a model of BPS black holes lying on a discrete extra space. The geometry is obtained from the discretization of the harmonic equation. We study the scattering amplitudes of two types of scalar fields, which correspond to fields in a bulk and on a brane. We conclude that the two types of scattering can be distinguished in the region of large transfer momentum.

gr-qc↗
arXiv2014

Multicentered solution for maximally charged dilaton black holes in arbitrary dimensions

A family of static multicentered solutions to modified Einstein-Maxwell equations coupled with a dilaton is constructed in $(1+N)$ dimensional space-time ($N\ge 2$). For $N\ge 3$, the solutions are generalizations of the Majumdar-Papapetrou solution. We also find the solution in $(1+2)$ dimensions, where the scalar and vector forces cancel each other in the static case. The interaction between two extreme charged dilaton black holes in the low-energy limit is investigated in $(1+N)$ dimensions ($N\ge 3$). We find that there remains the residual velocity-dependent force in general cases, except for the case with $N=a^2$.

gr-qc↗
arXiv2014

Magnetic Moment of Electrons near Cosmic Strings

We study the effect of background geometry generated by a thin cosmic string on the anomalous magnetic moment of the electron. We find that the magnitude of the quantum correction to the magnetic moment depends on the distance from the cosmic string as well as on the deficit angle.

hep-th↗