10,414 research outputs found
Massive Hyper-Kahler Sigma Models and BPS Domain Walls
With the non-Abelian Hyper-Kahler quotient by U(M) and SU(M) gauge groups, we
give the massive Hyper-Kahler sigma models that are not toric in the N=1
superfield formalism. The U(M) quotient gives N!/[M! (N-M)!] (N is a number of
flavors) discrete vacua that may allow various types of domain walls, whereas
the SU(M) quotient gives no discrete vacua. We derive BPS domain wall solution
in the case of N=2 and M=1 in the U(M) quotient model.Comment: 16 pages, 1 figure, contribution to the Proceedings of the
International Conference on "Symmetry Methods in Physics (SYM-PHYS10)" held
at Yerevan, Armenia, 13-19 Aug. 200
Non-ohmicity and energy relaxation in diffusive 2D metals
We analyze current-voltage characteristics taken on Au-doped indium-oxide
films. By fitting a scaling function to the data, we extract the
electron-phonon scattering rate as function of temperature, which yields a
quadratic dependence of the electron-phonon scattering rate on temperature from
1K down to 0.28K. The origin of this enhanced electron-phonon scattering rate
is ascribed to the mechanism proposed by Sergeev and Mitin.Comment: 7 pages, 6 figure
An extension of Fourier analysis for the n-torus in the magnetic field and its application to spectral analysis of the magnetic Laplacian
We solved the Schr{\"o}dinger equation for a particle in a uniform magnetic
field in the n-dimensional torus. We obtained a complete set of solutions for a
broad class of problems; the torus T^n = R^n / {\Lambda} is defined as a
quotient of the Euclidean space R^n by an arbitrary n-dimensional lattice
{\Lambda}. The lattice is not necessary either cubic or rectangular. The
magnetic field is also arbitrary. However, we restrict ourselves within
potential-free problems; the Schr{\"o}dinger operator is assumed to be the
Laplace operator defined with the covariant derivative. We defined an algebra
that characterizes the symmetry of the Laplacian and named it the magnetic
algebra. We proved that the space of functions on which the Laplacian acts is
an irreducible representation space of the magnetic algebra. In this sense the
magnetic algebra completely characterizes the quantum mechanics in the magnetic
torus. We developed a new method for Fourier analysis for the magnetic torus
and used it to solve the eigenvalue problem of the Laplacian. All the
eigenfunctions are given in explicit forms.Comment: 32 pages, LaTeX, minor corrections are mad
Brans-Dicke model constrained from Big Bang nucleosynthesis and magnitude redshift relations of Supernovae
The Brans-Dicke model with a variable cosmological term () has
been investigated with use of the coupling constant of .
Parameters inherent in this model are constrained from comparison between Big
Bang nucleosynthesis and the observed abundances. Furthermore, the magnitude
redshift () relations are studied for with and without another
constant cosmological term in a flat universe. Observational data of Type Ia
Supernovae are used in the redshift range of . It is found that our
model with energy density of the constant cosmological term with the value of
0.7 can explain the SNIa observations, though the model parameters are
insensitive to the relation.Comment: Submitted to A&A, 4 pages, 3 figure
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