4,752,159 research outputs found
Open string field theory without open strings
Witten's cubic open string field theory is expanded around the perturbatively
stable vacuum, including all scalar fields at levels 0, 2, 4 and 6. The
(approximate) BRST cohomology of the theory is computed, giving strong evidence
for the absence of physical open string states in this vacuum.Comment: 12 pages, 1 figure, LaTeX; v2: reference adde
Open-closed field algebras
We introduce the notions of open-closed field algebra and open-closed field
algebra over a vertex operator algebra V. In the case that V satisfies certain
finiteness and reductivity conditions, we show that an open-closed field
algebra over V canonically gives an algebra over a \C-extension of the
Swiss-cheese partial operad. We also give a tensor categorical formulation and
categorical constructions of open-closed field algebras over V.Comment: 55 pages, largely revised, an old subsection is deleted, a few
references are adde
Unoriented Open-Closed String Field Theory
The string field theory for unoriented open-closed string mixed system is
constructed up to quadratic order based on the joining-splitting type vertices.
The gauge invariance with closed string transformation parameter is proved. The
infinity cancellation mechanism between disk and projective plane amplitudes
plays an essential role for the gauge invariance of the theory.Comment: 40 pages, LaTeX with PTPTeX.sty, 19 eps figure
Delays in Open String Field Theory
We study the dynamics of light-like tachyon condensation in a linear dilaton
background using level-truncated open string field theory. The equations of
motion are found to be delay differential equations. This observation allows us
to employ well-established mathematical methods that we briefly review. At
level zero, the equation of motion is of the so-called retarded type and a
solution can be found very efficiently, even in the far light-cone future. At
levels higher than zero however, the equations are not of the retarded type. We
show that this implies the existence of exponentially growing modes in the
non-perturbative vacuum, possibly rendering light-like rolling unstable.
However, a brute force calculation using exponential series suggests that for
the particular initial condition of the tachyon sitting in the false vacuum in
the infinite light-cone past, the rolling is unaffected by the unstable modes
and still converges to the non-perturbative vacuum, in agreement with the
solution of Hellerman and Schnabl. Finally, we show that the growing modes
introduce non-locality mixing present with future, and we are led to conjecture
that in the infinite level limit, the non-locality in a light-like linear
dilaton background is a discrete version of the smearing non-locality found in
covariant open string field theory in flat space.Comment: 48 pages, 14 figures. v2: References added; Section 4 augmented by a
discussion of the diffusion equation; discussion of growing modes in Section
4 slightly expande
Field quantization for open optical cavities
We study the quantum properties of the electromagnetic field in optical
cavities coupled to an arbitrary number of escape channels. We consider both
inhomogeneous dielectric resonators with a scalar dielectric constant
and cavities defined by mirrors of arbitrary shape. Using
the Feshbach projector technique we quantize the field in terms of a set of
resonator and bath modes. We rigorously show that the field Hamiltonian reduces
to the system--and--bath Hamiltonian of quantum optics. The field dynamics is
investigated using the input--output theory of Gardiner and Collet. In the case
of strong coupling to the external radiation field we find spectrally
overlapping resonator modes. The mode dynamics is coupled due to the damping
and noise inflicted by the external field. For wave chaotic resonators the mode
dynamics is determined by a non--Hermitean random matrix. Upon including an
amplifying medium, our dynamics of open-resonator modes may serve as a starting
point for a quantum theory of random lasing.Comment: 16 pages, added references, corrected typo
Supersymmetry in Open Superstring Field Theory
We realize the 16 unbroken supersymmetries on a BPS D-brane as invariances of
the action of the corresponding open superstring field theory. We work in the
small Hilbert space approach, where a symmetry of the action translates into a
symmetry of the associated cyclic structure. We compute the
supersymmetry algebra, being careful to disentangle the components which
produce a translation, a gauge transformation, and a symmetry transformation
which vanishes on-shell. Via the minimal model theorem, we illustrate how
supersymmetry of the action implies supersymmetry of the tree level open string
scattering amplitudes.Comment: 37 page
Open Descendants in Conformal Field Theory
Open descendants extend Conformal Field Theory to unoriented surfaces with
boundaries. The construction rests on two types of generalizations of the
fusion algebra. The first is needed even in the relatively simple case of
diagonal models. It leads to a new tensor that satisfies the fusion algebra,
but whose entries are signed integers. The second is needed when dealing with
non-diagonal models, where Cardy's ansatz does not apply. It leads to a new
tensor with positive integer entries, that satisfies a set of polynomial
equations and encodes the classification of the allowed boundary operators.Comment: 19 pages, LATEX, 4 eps figures. Contribution to the Proceedings of
the CERN Meeting on STU Dualities, Dec. 9
Witten's Open String Field Theory in Constant B-Field Background
In this paper we consider Witten's bosonic open string field theory in the
presence of a constant background of the second-rank antisymmetric tensor field
. We extend the operator formulation of Gross and Jevicki in this
situation and construct the overlap vertices explicitly. As a result we find a
noncommutative structure of the Moyal type only in the zero-mode sector, which
is consistent with the result of the correlation functions among vertex
operators in the world sheet formulation. Furthermore we find out a certain
unitary transformation of the string field which absorbs the Moyal type
noncommutative structure. It can be regarded as a microscopic origin of the
transformation between the gauge fields in commutative and noncommutative gauge
theories discussed by Seiberg and Witten.Comment: 35 pages, LaTeX, no figures, Arguments about string coupling
constants are modified. final version to be published in JHE
Multi-field open inflation model and multi-field dynamics in tunneling
We consider a multi-field open inflation model, in which one of the fields
dominates quantum tunneling from a false vacuum while the other field governs
slow-roll inflation within the bubble nucleated from false vacuum decay. We
call the former the tunneling field and the latter the inflaton field. In the
limit of a negligible interaction between the two fields, the false vacuum
decay is described by a Coleman-De Luccia instanton. Here we take into account
the coupling between the two fields and construct explicitly a multi-field
instanton for a simple quartic potential model. We also solve the evolution of
the scalar fields within the bubble. We find our model realizes open inflation
successfully. This is the first concrete, viable model of open inflation
realized with a simple potential. We then study the effect of the multi-field
dynamics on the false vacuum decay, specifically on the tunneling rate. We find
the tunneling rate increases in general in comparison with the single field
case, though the increase is small unless the inflaton affects the instanton
solution substantially.Comment: 13 pages, 4 figure
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