arXiv subjects
Publications and source records attributed to Takayuki Hirayama.
We present a simple brane-world model in five dimensions. In this model we do not need any fine-tuning between the five dimensional cosmological constant and the brane tension to obtain four dimensional flat Minkowski space. The space-time of our solution has no naked singularities. Further the compactification scale of the fifth direction is automatically determined.
In the five-dimensional Einstein gravity with negative cosmological constant in the presence/absence of a {\it non-fine-tuned} 3-brane, we have investigated the classical stability of black string solutions which are foliations of four-dimensional $AdS/dS$-Schwarzschild black holes. Such black strings are generically unstable as in the well-known Gregory-Laflamme instability. For $AdS$ black strings, however, it turns out that they become stable if the longitudinal size of horizon is larger than the order of the $AdS_4$ radius. Even in the case of unstable black strings, the $AdS$ black strings have a very different feature of string fragmentations from that in the flat brane world. Some implications of our results on the Gubser-Mitra conjecture are also discussed.
We revisit the non-linear BPS equation: the Dirac monopole of the Born-Infeld theory in the B-field background. The rotation used in our previous papers to discuss the scalar field by transforming the BPS equation into a linear one is extended to the case of gauge field. We also find that this transformation is a symmetry of the action. Moreover using the Legendre-dual formalism we present a simple expression of the BPS equation.
We study BPS Dirac monopole in U(1) gauge theory on non-commutative spacetime. The corresponding brane configuration is obtained in the equivalent ordinary gauge theory through the map proposed by Seiberg and Witten. This configuration coincides exactly with a tilted D-string as predicted. This study provides an interesting check of the equivalence of the non-commutative and ordinary gauge theories.
In this paper we investigate N=1 supersymmetric gauge theories with a product gauge group. By using smoothly confining dynamics, we can find new dualities which include higher-rank tensor fields, and in which the dual gauge group is simple, not a product. Some of them are dualities between chiral and non-chiral gauge theories. We also discuss some applications to dynamical supersymmetry breaking phenomena and new confining theories with a tree-level superpotential.
We study deformations of dualities in finite N=2 supersymmetric QCD. Adding mass terms for some quarks and the adjoint matter to the finite N=2 theory, which is known to have dual descriptions, the correspondence of gauge invariant operators between the original and dual theory is deformed. As a result, we naturally obtain N.Seiberg's N=1 duality. Furthermore, we discuss the origin of the meson and superpotential in the dual theory. This approach can be applied to SU(N), SO(N), and USp(2N) gauge theories, and we analyze all these cases.