Realization of D4-Branes at Angles in Super Yang-Mills Theory

An explicit solution in super Yang-Mills theory, which after T-duality describes two sets of D4-branes at angles, is constructed. The gauge configuration possesses 3/16 unbroken supersymmetry for the equal magnitudes of field strengths, and can be considered as the counterpart of the solution of D=11 supergravity with the same amount of supersymmetry in the solutions given by Gauntlett et al. The energy of the Born-Infeld action of the gauge configuration gives further evidence for the geometrical interpretation as two sets of D4-branes at angles. The energy of super Yang-Mills theory is shown to coincide with that of M(atrix) theory. This fact shows that the configuration with 3/16 supersymmetry can be realized in M(atrix) theory, which describes two sets of longitudinal M5-branes (with common string direction) at angles.Comment: 13 pages, Latex, discussion of matrix model energy is modified and references adde

Λ\Lambda-symmetry and background independence of noncommutative gauge theory on Rn\mathbb R^n

Background independence of noncommutative Yang-Mills theory on $\mathbb R^n$ is discussed. The quantity $\theta \hat F \theta - \theta$ is found to be background dependent at subleading order, and it becomes background independent only when the ordinary gauge field strength $F$ is constant. It is shown that, at small values of $B$, the noncommutative Dirac-Born-Infeld action possesses $\Lambda$-symmetry at least to subleading order in $\theta$ if $F$ damps fast enough at infinity.Comment: 16 pages, LaTeX2e, minor revisions (version published in JHEP

Thermalization of Poincar\'{e} Vacuum State and Fermion Emission from AdS_3 Black Holes in Bulk-Boundary Correspondence

The greybody factors for spin 1/2 particles in the BTZ black holes are discussed from 2D CFT in bulk-boundary correspondence. It is found that the initial state of spin 1/2 particle in the BTZ black holes can be described by the Poincar\'{e} vacuum state in boundary 2D CFT, and the nonlinear coordinate transformation causes the thermalization of the Poincar\'{e} vacuum state. For special case, our results for the greybody factors agree with the semiclassical calculation.Comment: 14 pages, Latex, discussions adde