Logarithmic Correction to Newton Potential in Randall-Sundrum Scenario

Using a fixed-energy amplitude in Randall-Sundrum single brane scenario, we compute the Newton potential on the brane. It is shown that the correction terms to the Newton potential involve a logarithmic factor. Especially, when the distance between two point masses are very small compared to $AdS$ radius, the contribution of KK spectrum becomes dominant compared to the usual inversely square law. This fact may be used to prove the existence of an extra dimension experimentally.Comment: 7 pages, 1 figur

Supersphere

The spherical D2-brane solution is obtained without RR external background. The solution is shown to preserve $(1/4)$ supersymmetries. The configurations obtained depend on the integration constant $R_0$. For $R_0 \neq 0$ the shape of the solution is a deformed sphere. When, however, $R_0 = 0$, the D2-brane system seems to exhibit a brane-anti-brane configuration.Comment: 11 pages, 2 figure

Tunneling of Born-Infeld Strings to D2-Branes

A Born-Infeld theory describing a D2-brane coupled to a 4-form RR field strength is considered, and the general solutions of the static and Euclidean time equations are derived and discussed. The period of the bounce solutions is shown to allow a consideration of tunneling and quantum-classical transitions in the sphaleron region. The order of such transitions, depending on the strength of the RR field strength, is determined. A criterion is then derived to confirm these findings.Comment: 20 pages, 7 postscript figures, will appear in NP

General Criterion for the existence of Supertube and BIon in Curved Target Space

The supertube and BIon spike solutions are examined in a general curved target space. The criteria for the existence of these solutions are explicitly derived. Also the equation which the general BIon solution should satisfy is derived.Comment: 12 pages, no figur

Propagator for spinless and spin-1/2 Aharonov-Bohm-Coulomb systems

The propagator of the spinless Aharonov-Bohm-Coulomb system is derived by following the Duru-Kleinert method. We use this propagator to explore the spin-1/2 Aharonov-Bohm-Coulomb system which contains a point interaction as a Zeeman term. Incorporation of the self-adjoint extension method into the Green's function formalism properly allows us to derive the finite propagator of the spin-1/2 Aharonov-Bohm-Coulomb system. As a by-product, the relation between the self-adjoint extension parameter and the bare coupling constant is obtained. Bound-state energy spectra of both spinless and spin-1/2 Aharonov-Bohm-Coulomb systems are examined.Comment: Slightly changed, to appear in Annals of Physics. 18 pages, Late

Single 3-Brane Brane-World in Six Dimension

The single 3-brane brane world at six dimension is examined when the extra dimensions are not compact. Although the warp factor diverges at the asymptotic region of the extra dimension, the normalizable zero mode and higher KK spectrum exist in the gravitational fluctuation. We compute the zero mode analytically and KK spectrum numerically. It is explicitly proven that our solution does not obey `brane world sum rule'.Comment: 16 pages, 1 figure, version to appear in NP

Winding Number Transitions in the Mottola-Wipf Model on a Circle

Winding number transitions from quantum to classical behavior are studied in the case of the {1+1} dimensional Mottola-Wipf model with the space coordinate on a circle for exploring the possibility of obtaining transitions of second order. The model is also studied as a prototype theory which demonstrates the procedure of such investigations. In the model at hand we find that even on a circle the transitions remain those of first order.Comment: 17pages + 5 ps figures, final version to appear in Nucl. Phys.

D2-branes with magnetic flux in the presence of RR fields

D2-branes are studied in the context of Born-Infeld theory as a source of the 3-form RR gauge potential. Considering the static case with only a radial magnetic field it is shown that a locally stable hemispherical deformation of the brane exists which minimises the energy locally. Since the D2-brane carries also the charge of D0-branes, and the RR spacetime potential is unbounded from below, these can tunnel to condense on the D2-brane. The corresponding instanton-like configuration and the tunneling rate are derived and discussed.Comment: 24 pages, 1 figure included, version to appear in NP

Newton Law in DGP Brane-World with Semi-Infinite Extra Dimension

Newton potential for DGP brane-world scenario is examined when the extra dimension is semi-infinite. The final form of the potential involves a self-adjoint extension parameter $\alpha$, which plays a role of an additional mass (or distance) scale. The striking feature of Newton potential in this setup is that the potential behaves as seven-dimensional in long range when $\alpha$ is nonzero. For small $\alpha$ there is an intermediate range where the potential is five-dimensional. Five-dimensional Newton constant decreases with increase of $\alpha$ from zero. In the short range the four-dimensional behavior is recovered. The physical implication of this result is discussed in the context of the accelerating behavior of universe.Comment: 13 pages, no figur

Spatial Compactification and Decay-Rate Behavior

The pahse transition from instanton-dominated quantum tunneling regime to sphaleron-dominated classical crossover regime is explored in (1+1)-dimensional scalar field theory when spatial coordinate is compactified. It is shown that the type of sphaleron transition is critically dependent on the circumference of the spatial coordinate.Comment: 12 pages, 6 postscript figures included, accepted version in PL