The talk tries to address the question: how to construct a local field
theory with infinite many fields. First the effective action method is
presented. It is shown how it naturally leads to the definition of
(generally non-local) field theories. It has however strong technical
limitations. Then the more powerful and systematic worldline approach is
introduced, which carries the...
We examined in the previous paper whether winding number could be defined
in CSFT. We have found that the quantity N=\int (UQU^-1)^3 has many desirable properties as topological quantity. However, N could not realize an arbitrary integer
value, since it is not possible to suppress the anomaly.
This time, by generalizing the KBc-type solution, we were able to obtain N with arbitorary integer...
We review some of the older as well as more recent progress in attempts to construct and study classical solutions in string field theory.
We show that apart from the conventional Dp-branes and their supersymmetric bound states, the weakly coupled type II superstring compactified on a 4-torus admits new stable non-BPS fundamental D-branes. We construct the corresponding elementary superconformal boundary states at special values of closed string moduli for which the worldsheet theory admits a Gepner-like description and check a...
Closed string theory amplitudes display the remarkable property of presenting only single-valued multiple zeta in its low-energy expansion. At genus zero we show how this emerges by identifying the building blocks of any closed string amplitudes with the value at z=1 of single-valued correlation functions in two dimensional conformal field theory. We use the single-valuedness condition to...
After discussing some proposals for a string world-sheet manifestly invariant under the $O(D,D)$ Abelian T-duality, the more general notion of Poisson-Lie T-duality will be introduced together with the one of Drinfeld double that constitutes the algebraic structure necessary to the existence of such duality. As illustrating examples, the three-dimensional Isotropic Rigid Rotor and the...
One of biggest and most difficult problems in the subject of Gromov-Witten
theory is to compute higher genus Gromov-Witten theory of compact Calabi-Yau 3-fold.
There have been a collection of remarkable conjecture from physics for so called 14 one-parameter models,
simplest compact Calabi-Yau 3-folds similar to the quintic 3-folds. These conjectures were
originated from universal properties...
Inspired by the analogy between different types of differential forms
on supermanifolds and string fields in superstring theory,
I describe new multilinear non-associative products of forms
which yield an A-infinity algebra for any supermanifold.
In open bosonic string field theory with the cubic interaction in terms of the star product a gauge-invariant operator can be defined for each on-shell closed string state. In the theory on N coincident D-branes we claim that the evaluation of correlation functions of the gauge-invariant operators in the 1/N expansion can be interpreted as a closed string perturbation theory in a low-energy...
Previous attempts to determine the worldsheet origin of the pure spinor formalism were not completely successful, but introduced important concepts that seem to be connected to its fundamental structure. I will present here a new proposal for the underlying gauge theory of the pure spinor superstring, based on an extension of Berkovits' twistor-like constraint. I will start with a quick review...
This talk is dedicated to one-loop amplitudes in open, closed and heterotic string theories
and aims to illustrate connections between their low-energy expansions. For open strings,
the coefficients in the one-loop alpha’-expansion are elliptic multiple zeta values which arise
from moduli-space integrals over punctured cylinders. Closed and heterotic strings in turn
It has long been known that intersection theory on the moduli space of punctured Riemann surfaces computes all observables in the two-dimensional quantum gravity. It is natural to ask whether interacting theories could also admit a similar description. In the genus-zero case we construct a twisted version of intersection theory on the moduli space and propose that it gives rise to tree-level...
We extract a light-cone string field theory from Witten’s covariant string field theory.
The covariant string field splits into the light-cone string field and trivial excitations of BRST quartets:
The latter generates the gauge symmetry and covariance.
A new light-cone theory, which has an A-infinity type action, is obtained by path-integrating it out from the Witten theory.
We show that...
We present a series of new gauge invariant quantities in Witten's open string field theory. They are defined against a set of open-string states which satisfy the physical state condition around a classical solution. We discuss that, for known classical solutions, these gauge invariant quantities compute the on-shell tree-level scattering amplitudes on a D-brane configuration represented by...
We revisit the identity-based solutions for tachyon condensation in
open bosonic string field theory (SFT) from the viewpoint of the
sine-square deformation (SSD). We show that the open string system with
SSD exhibits decoupling of the left and right moving modes and so it
behaves like a system with a periodic boundary condition. With a method
developed by Ishibashi and Tada, we construct...
I will discuss the marginal deformation describing the blow-up of a zero-size D-brane within super string field theory as well as the world sheet description. By analyzing the equations of motion of superstring field theory we find that this marginal deformation is obstructed, at third order in the size of the D- brane. This obstruction is due to subtleties in the integration over odd moduli...
We construct a complete heterotic string field theory that includes
both the Neveu-Schwarz and Ramond sectors. We give a construction
of general string products, which realizes a cyclic L-infinity structures
and thus provides with a gauge invariant action in the homotopy
algebraic formulation. Through a map of the string fields, we also
give the Wess-Zumino-Witten-like action in the large...
We prove crossing symmetry of superstring amplitudes to all orders in
perturbation theory. This is achieved by showing that the Green
functions are analytic in a specific region of the complex momentum
space ("primitive domain") and making use of results from Bros, Epstein
and Glaser. The original derivation relies on locality and causality of
the underlying QFT in position space: since this...