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

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

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

Thioglycolic acid on the gold (111) surface and Raman vibrational spectra

The interaction of thioglycolic acid with the Au(111) surface is investigaged, and it is found that at the low coverage the molecule lies down on the substrate. If the mercaptan-hydrogen atom is eliminated, the resulting SCH_2COOH molecule is randomly oriented on the surface. If the carboxylic acid group in the HSCH_2COOH molecule is deprotonated instead, the HSCH_2COO^ molecule lies down on the surface. However, when the mercaptan-hydrogen atom in the HSCH_2COO^- molecule is removed, the resulting SCH_2COO^- molecule rises up to a certain level on the substrate. The calculated Raman vibrational spectra decipher which compounds and atomic displacements contribute to the corresponding frequencies. We thus propose a consistent mechanism for the deposition of thioglycolic acid on the Au(111) surface.Comment: 18 pages, 5 figures, submitted to J. Chem. Phy

Killing gauge for the 0-brane on AdS2×S2AdS_2 \times S^2 coset superspace

How to gauge fix \k-symmetry for the super 0-brane action on $AdS_2 \times S^2$ in Killing gauge properly is discussed in order to find the superconformal mechanics which describes super 0-brane probes moving on $AdS_2 \times S^2$. The dependence on the coordinate frame for the proper Killing gauge is considered and the subtleties of gauge-fixing \k-symmetry in Killing gauge are analysed explicitly. It is found that the Killing gauge works indeed without the imcompatibility if the magnetic charge of the super 0-brane is nonzero.Comment: 14 pages, LaTeX2