Xin-Hui Zhang

Localization of matters on pure geometrical thick branes

In the literatures, several types of thick smooth brane configurations in a pure geometric Weyl integrable 5-dimensional space time have been presented. The Weyl geometry is a non-Riemannian modification of 5-dimensional Kaluza-Klein (KK) theory. All these thick brane solutions preserve 4-dimensional Poincare invariance, and some of them break Z2-symmetry along the extra dimension. In this paper, we study localization of various matter fields on these pure geometrical thick branes, which also localize the graviton. We present the shape of the potential of the corresponding Schrodinger problem and obtain the lowest KK mode. It is shown that, for both spin 0 scalars and spin 1 vectors, there exists a continuum gapless spectrum of KK states with m2 > 0. But only the massless mode of scalars is found to be normalizable on the brane. However, for the massless left or right chiral fermion localization, there must be some kind of Yukawa coupling. For a special coupling, there exist a series of discrete massive KK modes with m2 > 0. It is also showed that for a given coupling constant only one of the massless chiral modes is localized on the branes.

Fermions in self-dual vortex background on a string-like defect

Abstract By using the self-dual vortex background on extra two-dimensional Riemann surfaces in 5 + 1 dimensions, the localization mechanism of bulk fermions on a string-like defect with the exponentially decreasing warp-factor is obtained. We give the conditions under which localized spin 1/2 and 3/2 fermions can be obtained.

LOCALIZATION OF FERMIONIC FIELDS ON BRANEWORLDS WITH BULK TACHYON MATTER

Recently, Pal and Skar in Ref. 33 proposed a mechanism to arise the warped braneworld models from bulk tachyon matter, which are endowed with a thin brane and a thick brane. In this framework, we investigate localization of fermionic fields on these branes. As in the 1/2-spin case, the field can be localized on both the thin and thick branes with inclusion of scalar background. In the 3/2-spin extension, the general supergravity action coupled to chiral supermultiplets is considered to produce the localization on both the branes as a result.

DETECTING EXTRA DIMENSION BY HELIUM-LIKE IONS

Considering that gravitational force might deviate from Newtons inverse-square law and become much stronger in small scale, we present a method to detect the possible existence of extra dimensions in the ADD model. By making use of an effective variational wave function, we obtain the nonrelativistic ground energy of a helium atom and its isoelectronic sequence. Based on these results, we calculate gravity correction of the ADD model. Our calculation may provide a rough estimation about the magnitude of the corresponding frequencies which could be measured in later experiments.

TOPOLOGICAL ASPECT OF BLACK HOLE WITH SKYRME HAIR

Based on the ϕ-mapping topological current theory, we show that the presence of the black hole leaves fractional baryon charge outside the horizon in the Einstein–Skyrme theory. A topological current is derived from the Einstein–Skyrme system, which corresponds to the monopoles around the black hole. The branch process (splitting, merging and intersection) is simply discussed during the evolution of the monopoles.

HYPERNUCLEAR SPECTROSCOPY WITH ELECTRON BEAM AT JLab HALL C

Hypernuclear spectroscopy with electron beam at JLab Hall C has been studied since 2000. The first experiment, JLab E89-009, demonstrated the possibility of the (e, e′ K+) reaction for hypernuclear spectroscopy by achieving an energy resolution of better than 1 MeV (FWHM). The second experiment, JLab E01-011 employed a newly constructed high resolution kaon spectrometer and introduced a vertically tilted electron arm setup to avoid electrons from bremsstrahlung and Moeller scattering. The setup allowed us to have 10 times yield rate and 4 times better signal to accidental ratio with expected energy resolution of 400 keV (FWHM). The third experiment, JLab E05-115 will be performed in 2009 with employing newly constructed high resolution electron spectrometer and a new charge-separation magnet. With the fully customized third generation experimental setup, we can study a variety of targets up to medium-heavy ones such as 52Cr.

Knotted solitons in a charged two-condensate Bose system

By making use of the decomposition of U(1) gauge potential theory and the {phi}-mapping method, we propose that a charged two-condensate Bose system possesses vortex lines and two classes of knotted solitons. The topological charges of the vortex lines are characterized by the Hopf indices and the Brower degrees of {phi}-mapping, and the knotted solitons are described by the nontrivial Hopf invariant and the BF action, respectively.

NOVEL TOPOLOGICAL INVARIANT IN THE U(1) GAUGE FIELD THEORY

Based on the decomposition of U(1) gauge potential theory and the ϕ-mapping topological current theory, the three-dimensional knot invariant and a four-dimensional new topological invariant are discussed in the U(1) gauge field.