480 research outputs found
Prepotentials for local mirror symmetry via Calabi-Yau fourfolds
In this paper, we first derive an intrinsic definition of classical triple
intersection numbers of K_S, where S is a complex toric surface, and use this
to compute the extended Picard-Fuchs system of K_S of our previous paper,
without making use of the instanton expansion. We then extend this formalism to
local fourfolds K_X, where X is a complex 3-fold. As a result, we are able to
fix the prepotential of local Calabi-Yau threefolds K_S up to polynomial terms
of degree 2. We then outline methods of extending the procedure to non
canonical bundle cases.Comment: 42 pages, 7 figures. Expanded, reorganized, and added a theoretical
background for the calculation
Fractional two-branes, toric orbifolds and the quantum McKay correspondence
We systematically study and obtain the large-volume analogues of fractional
two-branes on resolutions of orbifolds C^3/Z_n. We study a generalisation of
the McKay correspondence proposed in hep-th/0504164 called the quantum McKay
correspondence by constructing duals to the fractional two-branes. Details are
explicitly worked out for two examples -- the crepant resolutions of C^3/Z_3
and C^3/Z_5.Comment: 34 pages, 2 figures, LaTeX (JHEP3 style); (v2) typos corrected; (v3)
sec 3 reorganise
Fractional Branes in Non-compact Type IIA Orientifolds
We study fractional D-branes in the Type-IIA theory on a non-compact
orientifold of the orbifold C^3/Z_3 in the boundary state formalism. We find
that the fractional D0-branes of the orbifold theory become unstable due to the
presence of a tachyon, while there is a stable D-instanton whose tachyon gets
projected out. We propose that the D-instanton is obtained after tachyon
condensation. We evidence this by calculating the Whitehead group of the
Abelian category of objects corresponding to the boundary states as being
isomorphic to Z_2.Comment: 29 pages, Latex2e minor corrections. references updated. Version
accepted in JHE
The Vector Analyzing Power in Elastic Electron-Proton Scattering
We compute the vector analyzing power (VAP) for the elastic scattering of
transversely polarized electrons from protons at low energies using an
effective theory of electrons, protons, and photons. We study all contributions
through second order in , where and are the electron energy and
nucleon mass, respectively. The leading order VAP arises from the imaginary
part of the interference of one- and two-photon exchange amplitudes.
Sub-leading contributions are generated by the nucleon magnetic moment and
charge radius as well as recoil corrections to the leading-order amplitude.
Working to , we obtain a prediction for that is free of
unknown parameters and that agrees with the recent measurement of the VAP in
backward angle scattering.Comment: 24 pages, 11 figures. Typos fixe
On D0-branes in Gepner models
We show why and when D0-branes at the Gepner point of Calabi-Yau manifolds
given as Fermat hypersurfaces exist.Comment: 22 pages, substantial improvements in sections 2 and 3, references
added, version to be publishe
BPS branes in discrete torsion orbifolds
We investigate D-branes in a Z_3xZ_3 orbifold with discrete torsion. For this
class of orbifolds the only known objects which couple to twisted RR potentials
have been non-BPS branes. By using more general gluing conditions we construct
here a D-brane which is BPS and couples to RR potentials in the twisted and in
the untwisted sectors.Comment: 20 pages, LaTe
Constrained superpotentials in harmonic gauge theories with 8 supercharges
We consider D-dimensional supersymmetric gauge theories with 8 supercharges
(D<6,) in the framework of harmonic superspaces. The effective
Abelian low-energy action for D=5 contains the free and Chern-Simons terms.
Effective superfield actions for D<4 can be written in terms of
the superpotentials satisfying the superfield constraints and (6-D)-dimensional
Laplace equations. The role of alternative harmonic structures is discussed.Comment: LATEX file, 9 pages, version published in Teor. Mat. Fi
A note on the M2-M5 brane system and fuzzy spheres
This note covers various aspects of recent attempts to describe membranes
ending on fivebranes using fuzzy geometry. In particular, we examine the
Basu-Harvey equation and its relation to the Nahm equation as well as the
consequences of using a non-associative algebra for the fuzzy three-sphere.
This produces the tantalising result that the fuzzy funnel solution
corresponding to Q coincident membranes ending on a five-brane has
degrees of freedom.Comment: 17 pages, late
D-instantons and Closed String Tachyons in Misner Space
We investigate closed string tachyon condensation in Misner space, a toy
model for big bang universe. In Misner space, we are able to condense tachyonic
modes of closed strings in the twisted sectors, which is supposed to remove the
big bang singularity. In order to examine this, we utilize D-instanton as a
probe. First, we study general properties of D-instanton by constructing
boundary state and effective action. Then, resorting to these, we are able to
show that tachyon condensation actually deforms the geometry such that the
singularity becomes milder.Comment: 24 pages, 1 figure, minor change
Nilpotent Marsh and SUSY QM
We consider the nilpotent additions to classical trajectories in
supersymmetric and nonsupersymmetric theories. The condition of anilpotence of
action on some generalized solutions leads to the Witten supersymmetric
Lagrangian. The condition of anilpotence of topological charge is the same as
one of superpotential with spontaneous broken supersymmetry. We should vanish
half of Grassmann constants of integration, because in this case only we obtain
the same number of normalized bosonic and fermionic zero modes.Comment: 8 pages, Latex 2.09. Talk given at the conference in memory of V.I.
Ogievetski, Dubna, July, 1997. To be published in the Proceeding
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