Exploring Vacuum Structure around Identity-Based Solutions

We explore the vacuum structure in bosonic open string field theory expanded around an identity-based solution parameterized by $a(>=-1/2)$. Analyzing the expanded theory using level truncation approximation up to level 20, we find that the theory has the tachyon vacuum solution for $a>-1/2$. We also find that, at $a=-1/2$, there exists an unstable vacuum solution in the expanded theory and the solution is expected to be the perturbative open string vacuum. These results reasonably support the expectation that the identity-based solution is a trivial pure gauge configuration for $a>-1/2$, but it can be regarded as the tachyon vacuum solution at $a=-1/2$.Comment: 12 pages, 5 figures; new numerical data up to level (20,60) included; Contribution to the proceedings of "Second International Conference on String Field Theory and Related Aspects" (Steklov Mathematical Institute, Moscow, Russia, April 12-19, 2009

Open String Field Theory around Universal Solutions

We study the physical spectrum of cubic open string field theory around universal solutions, which are constructed using the matter Virasoro operators and the ghost and anti-ghost fields. We find the cohomology of the new BRS charge around the solutions, which appear with a ghost number that differs from that of the original theory. Considering the gauge-unfixed string field theory, we conclude that open string excitations perturbatively disappear after the condensation of the string field to the solutions.Comment: 14 pages, LaTeX with ptptex.cls, typos correcte

Susceptibility of the Spin 1/2 Heisenberg Antiferromagnetic Chain

Highly accurate results are presented for the susceptibility, $\chi (T)$ of the $s=1/2$ Heisenberg antiferromagnetic chain for all temperatures, using the Bethe ansatz and field theory methods. After going through a rounded peak, $\chi (T)$ approaches its asympotic zero-temperature value with infinite slope.Comment: 8 pages and 3 postscript figures appended (uuencoded), Revtex, Report #:UBCTP-94-00

Hierarchical Mass Matrices in a Minimal SO(10) Grand Unification I

We consider a minimal SO(10) unified model with horizontal Peccei-Quinn symmetry. The hierarchical structure of quark-lepton mass matrices is naturally implemented by the remnants of certain irrelevant terms. Georgi-Jarlskog relations are also realized due to the horizontal symmetry.Comment: phyzzx and tables, 15 pages, KUNS 125

Regularization of identity based solution in string field theory

We demonstrate that an Erler-Schnabl type solution in cubic string field theory can be naturally interpreted as a gauge invariant regularization of an identity based solution. We consider a solution which interpolates between an identity based solution and ordinary Erler-Schnabl one. Two gauge invariant quantities, the classical action and the closed string tadpole, are evaluated for finite value of the gauge parameter. It is explicitly checked that both of them are independent of the gauge parameter.Comment: 9 pages, minor typos corrected and references adde

Nonlinearly Realized Extended Supergravity

We provide nonlinear realization of supergravity with an arbitrary number of supersymmetries by means of coset construction. The number of gravitino degrees of freedom counts the number of supersymmetries, which will be possibly probed in future experiments. We also consider goldstino embedding in the construction to discuss the relation to nonlinear realization with rigid supersymmetries.Comment: 19 page

Pre-K-Edge Structure on Anomalous X-Ray Scattering in LaMnO3

We study the pre-K-edge structure of the resonant X-ray scattering for forbidden reflections (anomalous scattering) in LaMnO3, using the band calculation based on the local density approximation. We find a two-peak structure with an intensity approximately 1/100 of that of the main peak. This originates from a mixing of 4p states of Mn to 3d states of neighboring Mn sites. The effect is enhanced by an interference with the tail of the main peak. The effect of the quadrupole transition is found to be one order of magnitude smaller than that of the dipole transition, modifying slightly the azimuthal-angle dependence.Comment: 4 pages, 5 figures, submitted to J. Phys. Soc. Jp