740 research outputs found
String Field Theory Vertices for Fermions of Integral Weight
We construct Witten-type string field theory vertices for a fermionic first
order system with conformal weights (0,1) in the operator formulation using
delta-function overlap conditions as well as the Neumann function method. The
identity, the reflector and the interaction vertex are treated in detail paying
attention to the zero mode conditions and the U(1) charge anomaly. The Neumann
coefficients for the interaction vertex are shown to be intimately connected
with the coefficients for bosons allowing a simple proof that the
reparametrization anomaly of the fermionic first order system cancels the
contribution of two real bosons. This agrees with their contribution c=-2 to
the central charge. The overlap equations for the interaction vertex are shown
to hold. Our results have applications in N=2 string field theory, Berkovits'
hybrid formalism for superstring field theory, the \eta\xi-system and the
twisted bc-system used in bosonic vacuum string field theory.Comment: 1+28 pages, minor improvements, references adde
1-FerrocenylmethÂyl-1H-imidazole
In the title compound, [Fe(C5H5)(C9H9N2)], the distances of the Fe atom from the centroids of the unsubstituted and the substituted cycloÂpentaÂdienyl (cp) rings are 1.639 (1) and 1.647 (1) Å, respectively. The ferrocenyl unit deviates from an eclipsed geometry with tilted cp rings; the interÂplanar angle between the cp and imidazole rings is 114.11 (4)°
Rolling Closed String Tachyons and the Big Crunch
We study the low-energy effective field equations that couple gravity, the
dilaton, and the bulk closed string tachyon of bosonic closed string theory. We
establish that whenever the tachyon induces the rolling process, the string
metric remains fixed while the dilaton rolls to strong coupling. For negative
definite potentials we show that this results in an Einstein metric that
crunches the universe in finite time. This behavior is shown to be rather
generic even if the potentials are not negative definite. The solutions are
reminiscent of those in the collapse stage of a cyclic universe cosmology where
scalar field potentials with negative energies play a central role.Comment: 13 pages, 2 figures, LaTeX. Replaced version: one reference adde
Exact Solutions in SFT and Marginal Deformation in BCFT
In this note we will study solution of open bosonic string field theory based
on action of operators from chiral algebra of boundary conformal field theory
on identity element of string field theory star algebra. We will demonstrate
that the string field theory action for fluctuation fields around this
classical solution can be mapped to the string field theory action defined
through the new boundary conformal field theory that arises from the original
one through the marginal deformation inserted on the world-sheet boundary.Comment: 15 pages, references adde
Integrability in SFT and new representation of KP tau-function
We are investigating the properties of vacuum and boundary states in the CFT
of free bosons under the conformal transformation. We show that transformed
vacuum (boundary state) is given in terms of tau-functions of dispersionless KP
(Toda) hierarchies. Applications of this approach to string field theory is
considered. We recognize in Neumann coefficients the matrix of second
derivatives of tau-function of dispersionless KP and identify surface states
with the conformally transformed vacuum of free field theory.Comment: 25 pp, LaTeX, reference added in the Section 3.
Brane-Antibrane Systems at Finite Temperature and Phase Transition near the Hagedorn Temperature
In order to study the thermodynamic properties of brane-antibrane systems, we
compute the finite temperature effective potential of tachyon T in this system
on the basis of boundary string field theory. At low temperature, the minimum
of the potential shifts towards T=0 as the temperature increases. In the
D9-antiD9 case, the sign of the coefficient of |T|^2 term of the potential
changes slightly below the Hagedorn temperature. This means that a phase
transition occurs near the Hagedorn temperature. On the other hand, the
coefficient is kept negative in the Dp-antiDp case with p <= 8, and thus a
phase transition does not occur. This leads us to the conclusion that only a
D9-antiD9 pair and no other (lower dimensional) brane-antibrane pairs are
created near the Hagedorn temperature. We also discuss a phase transition in
NS9B-antiNS9B case as a model of the Hagedorn transition of closed strings.Comment: 28 pages, 3 figures, minor errors correcte
Stable Exact Solutions in Cosmological Models with Two Scalar Fields
The stability of isotropic cosmological solutions for two-field models in the
Bianchi I metric is considered. We prove that the sufficient conditions for the
Lyapunov stability in the Friedmann-Robertson-Walker metric provide the
stability with respect to anisotropic perturbations in the Bianchi I metric and
with respect to the cold dark matter energy density fluctuations. Sufficient
conditions for the Lyapunov stability of the isotropic fixed points of the
system of the Einstein equations have been found. We use the superpotential
method to construct stable kink-type solutions and obtain sufficient conditions
on the superpotential for the Lyapunov stability of the corresponding exact
solutions. We analyze the stability of isotropic kink-type solutions for string
field theory inspired cosmological models.Comment: 23 pages, v3:typos corrected, references adde
The Schr\"odinger Wave Functional and S-branes
In this paper we will consider the minisuperspace approach to S-branes
dynamics in the Schr\"odinger picture description. Time-evolution of vacuum
wave functional for quantum field theory on S-brane is studied. Open string
pair production is calculated. The analysis of density matrix for mixed states
is also performed.Comment: 27 page
Finite Temperature Systems of Brane-Antibrane on a Torus
In order to study the thermodynamic properties of brane-antibrane systems in
the toroidal background, we compute the finite temperature effective potential
of tachyon T in this system on the basis of boundary string field theory. We
first consider the case that all the radii of the target space torus are about
the string scale. If the Dp-antiDp pair is extended in all the non-compact
directions, the sign of the coefficient of |T|^2 term of the potential changes
slightly below the Hagedorn temperature. This means that a phase transition
occurs near the Hagedorn temperature. On the other hand, if the Dp-antiDp pair
is not extended in all the non-compact directions, the coefficient is kept
negative, and thus a phase transition does not occur. Secondly, we consider the
case that some of the radii of the target space torus are much larger than the
string scale and investigate the behavior of the potential for each value of
the radii and the total energy. If the Dp-antiDp pair is extended in all the
non-compact directions, a phase transition occurs for large enough total
energy.Comment: 23 pages, 3 figures, minor errors corrected, version to appear in
JHE
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