16,312 research outputs found
Boundary states for moving D-branes
We determine the boundary state for both the NS-NS and R-R sectors of
superstring theory. We show how they are modified under a boost. The boosted
boundary state is then used for computing the interaction of two D-branes
moving with constant velocity reproducing with a completely different method a
recent calculation by Bachas.Comment: 10 pages, LaTeX, no figures; Eqs. (47) and (48) correcte
Summability of Superstring Theory
Several arguments are given for the summability of the superstring
perturbation series. Whereas the Schottky group coordinatization of moduli
space may be used to provide refined estimates of large-order bosonic string
amplitudes, the super-Schottky group variables define a measure for the
supermoduli space integral which leads to upper bounds on superstring
scattering amplitudes.Comment: 11 pages, TeX. A remark about C-cycles and dividing cycles and two
references have been added to the pape
Bosonization of World-Sheet Fermions in Minkowski Space-Time
We propose a way of bosonizing free world-sheet fermions for -dimensional
heterotic string theory formulated in Minkowski space-time. We discuss the
differences as compared to the standard bosonization performed in Euclidean
space-time.Comment: 1+9 pages, TeX macros include
Derivative corrections to D-brane actions with constant background fields
We study derivative corrections to the effective action for a single D-brane
in type II superstring theory coupled to constant background fields. In
particular, within this setting we determine the complete expression for the
(disk level) four-derivative corrections to the Born-Infeld part of the action.
We also determine 2n-form 2n-derivative corrections to the Wess-Zumino term.
Both types of corrections involve all orders of the gauge field strength, F.
The results are obtained via string sigma-model loop calculations using the
boundary state operator language. The corrections can be succinctly written in
terms of the Riemann tensor for a non-symmetric metric.Comment: 28 pages, LaTeX (uses pstricks); v2: minor typos corrected,
references adde
Path Integral Approach to Fermionic Vacuum Energy in Non-parallel D1-Branes
The fermionic one loop vacuum energy of the superstring theory in a system of
non-parallel D1-branes is derived by applying the path integral formalism.Comment: 7 pages, no figur
Microscopic string analysis of the D0-D8 brane system and dual R-R states
Using the boundary state formalism, we perform a microscopic string analysis
of the interaction between two D-branes and provide a local interpretation for
the R-R force in the D0-D8 brane system. To do so, we construct BRST invariant
vertex operators for the massless R-R states in the asymmetric picture that are
proportional to potentials rather than field strengths. The Hilbert space of
such R-R states contains combinations of two vectors that decouple from all
physical amplitudes, even in the presence of boundaries. Identifying these
vectors, we remove the null states and recover duality relations among R-R
potentials. If we specify to the D0-D8 brane system, this mechanism implies
that the R-R 1-form state has a non-zero overlap with both the D0-brane and the
D8-brane, thus explaining from a local point of view the non-vanishing R-R
contribution in the interaction for the D0-D8 brane system and those related to
it by duality.Comment: 31 pages, final version to be published in Nucl. Phys.
Pfaffian-like ground states for bosonic atoms and molecules in one-dimensional optical lattices
We study ground states and elementary excitations of a system of bosonic
atoms and diatomic Feshbach molecules trapped in a one-dimensional optical
lattice using exact diagonalization and variational Monte Carlo methods. We
primarily study the case of an average filling of one boson per site. In
agreement with bosonization theory, we show that the ground state of the system
in the thermodynamic limit corresponds to the Pfaffian-like state when the
system is tuned towards the superfluid-to-Mott insulator quantum phase
transition. Our study clarifies the possibility of the creation of exotic
Pfaffian-like states in realistic one-dimensional systems. We also present
preliminary evidence that such states support non-Abelian anyonic excitations
that have potential application for fault-tolerant topological quantum
computation.Comment: 10 pages, 10 figures. Matching the version published Phys.Rev.
Charge sum rules in N=2 theories
Some errors in section 4 are corrected. No change in the results.Comment: 25 page
String techniques for the calculation of renormalization constants in field theory
We describe a set of methods to calculate gauge theory renormalization
constants from string theory, all based on a consistent prescription to
continue off shell open bosonic string amplitudes. We prove the consistency of
our prescription by explicitly evaluating the renormalizations of the two,
three and four-gluon amplitudes, and showing that they obey the appropriate
Ward identities. The field theory limit thus performed corresponds to the
background field method in Feynman gauge. We identify precisely the regions in
string moduli space that correspond to different classes of Feynman diagrams,
and in particular we show how to isolate contributions to the effective action.
Ultraviolet divergent terms are then encoded in a single string integral over
the modular parameter . Finally, we derive a multiloop expression for the
effective action by computing the partition function of an open bosonic string
interacting with an external non-abelian background gauge field.Comment: 54 pages, Latex, uses FEYNMAN.te
Mixed Branes Interaction in Compact Spacetime
We present a general description of two mixed branes interactions. For this
we consider two mixed branes with dimensions p_1 and p_2, in external field
B_{\mu\nu} and arbitrary gauge fields A^1_{\alpha_1} and A^2_{\alpha_2} on the
world volume of them, in spacetime in which some of its directions are
compactified on circles with different radii. Some examples are considered to
clear these general interactions. Finally contribution of the massless states
on the interactions is extracted. Closed string with mixed boundary conditions
and boundary state formalism, provide useful tools for calculation of these
interactions.Comment: 22 pages, to appear in Nucl. Phys.
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