arXiv subjects

Akira Fujii

Publications and source records attributed to Akira Fujii.

9 recordsLinked to original sources

arXiv2001

Supersymmetry, Spectrum and Fate of D0-Dp Systems with B-field

It has been shown that D0-D$p$ $(p=2, 4, 6, 8)$ systems can be BPS in the presence of $B$-field even if they are not otherwise. We review the number of remaining supersymmetries, the open string ground state spectrum and the construction of the D0-D$p$ systems as solitonic solutions in the noncommutative super Yang-Mills theory. We derive the complete mass spectrum of the fluctuations to discuss the stability of the systems. The results are found to agree with the analysis in the string picture. In particular, we show that supersymmetry is enhanced in D0-D8 depending on the $B$-fields and it is consistent with the degeneracy of mass spectrum. We also derive potentials and discuss their implications for these systems.

hep-th↗

arXiv2000

Instantons, Monopoles and the Flux Quantization in the Faddeev-Niemi Decomposition

We study how instantons arise in the low energy effective theory of the SU(2) Yang-Mills theory in the context of the non-linear sigma model recently propose by Faddeev and Niemi. We find a simple relation between the instanton number $ν$ and the charge m of the monopole that appears in the effective theory. It is given by $ν= m Φ/(2π)$, where $Φ$ is the quantized flux associated with a U(1) gauge field passing through the loop formed by the singularity of the monopole.

hep-th↗

arXiv1999

D=5 Simple Supergravity on AdS_2 \times S^3

The Kaluza-Klein spectrum of D=5 simple supergravity compactified on S^3 is studied. A classical background solution which preserves maximal supersymmetry is fulfilled by the geometry of AdS_2\times S^3. The physical spectrum of the fluctuations is classified according to SU(1,1|2)\times SU(2) symmetry, which has a very similar structure to that in the case of compactification on AdS_3\times S^2.

hep-th↗

arXiv1998

Anti-Symmetrically Fused Model and Non-Linear Integral Equations in the Three-State Uimin-Sutherland Model

We derive the non-linear integral equations determining the free energy of the three-state pure bosonic Uimin-Sutherland model. In order to find a complete set of auxiliary functions, the anti-symmetric fusion procedure is utilized. We solve the non-linear integral equations numerically and see that the low-temperature behavior coincides with that predicted by conformal field theory. The magnetization and magnetic susceptibility are also calculated by means of the non-linear integral equation.

cond-mat.stat-mech↗

arXiv1997

Stochastic Model and Equivalent Ferromagnetic Spin Chain with Alternation

We investigate a non-equilibrium reaction-diffusion model and equivalent ferromagnetic spin 1/2 XY spin chain with alternating coupling constant. The exact energy spectrum and the n-point hole correlations are considered with the help of the Jordan-Wigner fermionization and the inter-particle distribution function method. Although the Hamiltonian has no explicit translational symmetry, the translational invariance is recovered after long time due to the diffusion. We see the scaling relations for the concentration and the two-point function in finite size analysis.

cond-mat.stat-mech↗

arXiv1995

Toda Lattice Models with Boundary

We consider the soliton solutions in 1- and (1+1)-dimensional Toda lattice models with a boundary. We make use of the solutions already known on a full line by means of the Hirota's method. We explicitly construct the solutions satisfying the boundary conditions. The ${\bf Z}_{\infty}$-symmetric boundary condition can be introduced by the two-soliton solutions naturally.

hep-th↗

arXiv1994

Finite-size Analysis of $O(N)$ Nonlinear $σ$ Model on Semi-compact Spaces

Fisher's phenomenological renormalization method is used to calculate the mass gap and the correlation length of the $O(N)$ nonlinear $σ$ model on a semi-compact space $S^{1}\times {\bf R}^{2}$. This shows that the ultraviolet momentum cut-off does not conflict with the infrared cut-off along the $S^{1}$ direction. The mass gap on $S^{2}\times {\bf R}$ is also discussed.

hep-th↗

arXiv1994

Finite Size Effects and Conformal Symmetry of $O(N)$ Nonlinear $σ$ Model in Three Dimensions

We study the $O(N)$ nonlinear $σ$ model on a three-dimensional compact space $S^1 \times S^2$ (of radii $L$ and $R$ respectively) by means of large $N$ expansion, focusing on the finite size effects and conformal symmetries of this model at the critical point. We evaluate the correlation length and the Casimir energy of this model and study their dependence on $L$ and $R$. We examine the modular transformation properties of the partition function, and study the dependence of the specific heat on the mass gap in view of possible extension of the $C-$theorem to three dimensions.

hep-th↗

arXiv1992

Yang-Baxter Equation for $A^{(1)}_{n-1}$ Broken ${\Bf Z}_N $ Models

We construct a factorized representation of the $\frak g \frak l _n$-Sklyanin algebra from the vertex-face correspondence. Using this representation, we obtain a new solvable model which gives an $\frak s \frak l _n$-generalization of the broken $\bz _N $ model. We further prove the Yang-Baxter equation for this model.

hep-th↗