arXiv subjects

Shigenori Seki

Publications and source records attributed to Shigenori Seki.

28 records · Page 2Linked to original sources

arXiv2006

Superconformal Symmetry in Linear Sigma Model on Supermanifolds

We consider a gauged linear sigma model in two dimensions with Grassmann odd chiral superfields. We investigate the Konishi anomaly of this model and find out the condition for realization of superconformal symmetry on the world-sheet. When this condition is satisfied, the theory is expected to flow into conformal theory in the infrared limit. We construct superconformal currents explicitly and study some properties of this world-sheet theory from the point of view of conformal field theories.

hep-th↗

arXiv2005

Comments on the D-instanton calculus in (p,p+1) minimal string theory

The FZZT and ZZ branes in (p,p+1) minimal string theory are studied in terms of continuum loop equations. We show that systems in the presence of ZZ branes (D-instantons) can be easily investigated within the framework of the continuum string field theory developed by Yahikozawa and one of the present authors (hep-th/9609210). We explicitly calculate the partition function of a single ZZ brane for arbitrary p. We also show that the annulus amplitudes of ZZ branes are correctly reproduced.

hep-th↗

arXiv2005

Gauged Linear Sigma Model on Supermanifold

We formulate a gauged linear sigma model on a supermanifold. The structure of classical vacua is investigated and one-loop corrections are calculated for an auxiliary D-field. We find out a constraint for the one-loop divergence to vanish, which is consistent with a Ricci flatness condition for the supermanifold. Two types of D-branes are obtained by analysing supersymmetric boundary conditions. We also provide extensions to a non-abelian gauged linear sigma model and a (0,2) supersymmetric model.

hep-th↗

arXiv2003

Proposal for Generic Size of Large Extra Dimensions

In order to resolve the hierarchy problem, large extra dimensions have been introduced, and it has been suggested that the size of extra dimensions is sub-millimeter. On the other hand, we assume in this paper that the cosmological constant comes from the Casimir energy of extra dimensions and estimate the size of extra dimensions in terms of the value of the cosmological constant discovered by the recent WMAP observations. We demonstrate that this size is consistent with the one derived from the hierarchy problem and propose that there may be a generic size of large extra dimensions when the number of extra dimensions is equal to two.

hep-ph↗

arXiv2002

Comments on Quiver Gauge Theories and Matrix Models

Dijkgraaf and Vafa have conjectured the correspondences between topological string theories, ${\cal N}=1$ gauge theories and matrix models. By the use of this conjecture, we calculate the quantum deformations of Calabi-Yau threefolds with ADE singularities from ADE multi-matrix models. We obtain the effective superpotentials of the dual quiver gauge theories in terms of the geometric engineering for the deformed geometries. We find the Veneziano-Yankielowicz terms in the effective superpotentials.

hep-th↗

arXiv2002

D5-brane in Anti-de Sitter Space and Penrose Limit

We consider the Penrose limit of the solution of D5-brane given in the Anti-de Sitter space and analyse the shape of the D5-brane in the pp-wave background. We find that the D5-brane leads to the branes and the throats connecting the branes. The branes spread on R^4 with periodic values of the light-cone time x^+ and the throats lie along x^+. We also give some comments on holography.

hep-th↗

arXiv2001

Discrete Torsion and Branes in M-theory from Mathematical Viewpoint

We study orbifold group actions on locally defined fields upon M-theory branes in a three-form C-fields background. We derive some constraints from the consistency of the orbifold group actions. We show the possibility of the existence of M-theory discrete torsion for the fields on the worldvolume and discuss its features.

hep-th↗

arXiv2000

Gravitational Stability and Screening Effect from D Extra Timelike Dimensions

We study (3+1)+D dimensional spacetime, where D extra dimensions are timelike. Compactification of the D timelike dimensions leads to tachyonic Kaluza-Klein gravitons. We calculate the gravitational self-energies of massive spherical bodies due to the tachyonic exchange, discuss their stability, and find that the gravitational force is screened in a certain number of the extra dimensions. We also derive the exact relationship between the Newton constants in the full 4+D dimensional spacetime with the D extra times and the ordinary Newton constant of our 4 dimensional world.

hep-th↗

arXiv2000

Gravitational Stability and Extra Timelike Dimensions

Tachyonic Kaluza-Klein modes normally appear from the compactification of extra timelike dimensions with scale $L$ and lead to some instabilities of physical systems. We calculate the contribution of tachyonic gravitons to the self energies of spherical massive bodies of radius $R$ and discuss their possible gravitational stability. We find that some spherical bodies can be stable at critical radii $R=2πL p$ for some positive integers $p$. We also prove the generic property of massive bodies that for the range $0<R\leqπL$ the gravitational force due to the ordinary massless graviton exchange is screened by the Kaluza-Klein mode exchange of tachyonic gravitons.

hep-ph↗

arXiv1999

Baryon Configurations in the UV and IR Regions of Type 0 String Theory

The Type 0 string theory is considered as a dual model of a non-supersymmetric gauge theory. A background geometry with N electric D3-branes is calculated in UV/IR regions. In this paper, we study a D5-brane around N D3-branes from the D5-brane world volume action as in the Type IIB case, and we obtain some baryon configurations at UV/IR regions.

hep-th↗