Dirac Sea for Bosons I -- Formulation of Negative Energy Sea for Bosons

It is proposed to make formulation of second quantizing a bosonic theory by generalizing the method of filling the Dirac negative energy sea for fermions. We interpret that the correct vacuum for the bosonic theory is obtained by adding minus one boson to each single particle negative energy states while the positive energy states are empty. The boson states are divided into two sectors ; the usual positive sector with positive and zero numbers of bosons and the negative sector with negative numbers of bosons. Once it comes into the negative sector it cannot return to the usual positive sector by ordinary interaction due to a barrier. It is suggested to use as a playground model in which the filling of empty fermion Dirac sea and the removal of boson from the negative energy states are not yet performed. We put forward such a naive vacuum world in the present paper. The successive paper will concern a CPT-like Theorem in the naive vacuum world.Comment: 24 pages, 2 figures, Latex; added refereces, corrected typo

Brane-worlds and theta-vacua

Reductions from odd to even dimensionalities ($5\to 4$ or $3\to 2$), for which the effective low-energy theory contains chiral fermions, present us with a mismatch between ultraviolet and infrared anomalies. This applies to both local (gauge) and global currents; here we consider the latter case. We show that the mismatch can be explained by taking into account a change in the spectral asymmetry of the massive modes--an odd-dimensional analog of the phenomenon described by the Atiyah-Patodi-Singer theorem in even dimensionalities. The result has phenomenological implications: we present a scenario in which a QCD-like $\theta$-angle relaxes to zero on a certain (possibly, cosmological) timescale, despite the absence of any light axion-like particle.Comment: 44 pages, 4 figure

Web-based Decision Support System for Rural Land Use Planning-WebLUP-a Prototype

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 8 (2006): Web-based Decision Support System for Rural Land Use Planning-WebLUP-a Prototype. Manuscript IT 05 005. Vol. VIII. March, 2006

Phase transitions in spin-orbital coupled model for pyroxene titanium oxides

We study the competing phases and the phase transition phenomena in an effective spin-orbital coupled model derived for pyroxene titanium oxides ATiSi2O6 (A=Na, Li). Using the mean-field-type analysis and the numerical quantum transfer matrix method, we show that the model exhibits two different ordered states, the spin-dimer and orbital-ferro state and the spin-ferro and orbital-antiferro state. The transition between two phases is driven by the relative strength of the Hund's-rule coupling to the onsite Coulomb repulsion and/or by the external magnetic field. The ground-state phase diagram is determined. There is a keen competition between orbital and spin degrees of freedom in the multicritical regime, which causes large fluctuations and significantly affects finite-temperature properties in the paramagnetic phase.Comment: 4 pages, 6 figures, proceedings submitted to SPQS200

Fermion Condensate and Vacuum Current Density Induced by Homogeneous and Inhomogeneous Magnetic Fields in (2+1)-Dimensions

We calculate the condensate and the vacuum current density induced by external static magnetic fields in (2+1)-dimensions. At the perturbative level, we consider an exponentially decaying magnetic field along one cartesian coordinate. Non-perturbatively, we obtain the fermion propagator in the presence of a uniform magnetic field by solving the Schwinger-Dyson equation in the rainbow-ladder approximation. In the large flux limit, we observe that both these quantities, either perturbative (inhomogeneous) and non-perturbative (homogeneous), are proportional to the external field, in agreement with early expectations.Comment: 8 pages, 2 figures. Accepted for publication in Phys. Rev.

Method of double averaging for modeling PFC switching converters

Author name used in this publication: S. C. WongAuthor name used in this publication: C. K. TseAuthor name used in this publication: M. OrabiAuthor name used in this publication: T. NinomiyaRefereed conference paper2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

The method of double averaging : an approach for modeling power-factor-correction switching converters

Author name used in this publication: Chi K. Tse2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Chromomagnetism in nuclear matter

Quarks are color charged particles. Due to their motion there is a strong possibility of generation of color magnetic field. It is shown that however hadrons are color singlet particles they may have non-zero color magnetic moment. Due to this color magnetic moment hadrons can show color interaction. In this paper we have studied the chromomagnetic properties of nuclear matter.Comment: 6 pages, 1 figure, accepted for publication in Int. J. Theor. Phy