320 research outputs found
Boundary States of c=1 and 3/2 Rational Conformal Field Theories
We study the boundary states for the rational points in the moduli spaces of
c=1 conformal and c=3/2 superconformal field theories, including the isolated
Ginsparg points. We use the orbifold and simple-current techniques to relate
the boundary states of different theories and to obtain symmetry-breaking,
non-Cardy boundary states. We show some interesting examples of fractional and
twisted branes on orbifold spaces.Comment: Latex, 46 pages, 1 figur
Twisted boundary states in c=1 coset conformal field theories
We study the mutual consistency of twisted boundary conditions in the coset
conformal field theory G/H. We calculate the overlap of the twisted boundary
states of G/H with the untwisted ones, and show that the twisted boundary
states are consistently defined in the diagonal modular invariant. The overlap
of the twisted boundary states is expressed by the branching functions of a
twisted affine Lie algebra. As a check of our argument, we study the diagonal
coset theory so(2n)_1 \oplus so(2n)_1/so(2n)_2, which is equivalent with the
orbifold S^1/\Z_2. We construct the boundary states twisted by the
automorphisms of the unextended Dynkin diagram of so(2n), and show their mutual
consistency by identifying their counterpart in the orbifold. For the triality
of so(8), the twisted states of the coset theory correspond to neither the
Neumann nor the Dirichlet boundary states of the orbifold and yield the
conformal boundary states that preserve only the Virasoro algebra.Comment: 44 pages, 1 figure; (v2) minor change in section 2.3, references
adde
Conformal Orbifold Partition Functions from Topologically Massive Gauge Theory
We continue the development of the topological membrane approach to open and
unoriented string theories. We study orbifolds of topologically massive gauge
theory defined on the geometry , where is a generic
compact Riemann surface. The orbifold operations are constructed by gauging the
discrete symmetries of the bulk three-dimensional field theory. Multi-loop
bosonic string vacuum amplitudes are thereby computed as bulk correlation
functions of the gauge theory. It is shown that the three-dimensional
correlators naturally reproduce twisted and untwisted sectors in the case of
closed worldsheet orbifolds, and Neumann and Dirichlet boundary conditions in
the case of open ones. The bulk wavefunctions are used to explicitly construct
the characters of the underlying extended Kac-Moody group for arbitrary genus.
The correlators for both the original theory and its orbifolds give the
expected modular invariant statistical sums over the characters.Comment: 47 pages LaTeX, 3 figures, uses amsfonts and epsfig; v2: Typos
corrected, reference added, clarifying comments on modular invariance
inserted; v3: Further comments on modular invariance added; to be published
in JHE
Quantization of Wilson loops in Wess-Zumino-Witten models
We describe a non-perturbative quantization of classical Wilson loops in the
WZW model. The quantized Wilson loop is an operator acting on the Hilbert space
of closed strings and commuting either with the full Kac-Moody chiral algebra
or with one of its subalgebras. We prove that under open/closed string duality,
it is dual to a boundary perturbation of the open string theory. As an
application, we show that such operators are useful tools for identifying fixed
points of the boundary renormalization group flow.Comment: 24 pages. Version published in JHE
Generalised permutation branes
We propose a new class of non-factorising D-branes in the product group GxG
where the fluxes and metrics on the two factors do not necessarily coincide.
They generalise the maximally symmetric permutation branes which are known to
exist when the fluxes agree, but break the symmetry down to the diagonal
current algebra in the generic case. Evidence for the existence of these branes
comes from a Lagrangian description for the open string world-sheet and from
effective Dirac-Born-Infeld theory. We state the geometry, gauge fields and, in
the case of SU(2)xSU(2), tensions and partial results on the open string
spectrum. In the latter case the generalised permutation branes provide a
natural and complete explanation for the charges predicted by K-theory
including their torsion.Comment: 33 pages, 6 figures, v2: Extended discussion of K-theory
interpretation of our branes for products of higher rank groups in the
conclusions; v3: Correction of formula (35) and adjustment of the discussion
below equation (45) (no change of result). Footnote 9 points out a previously
unnoticed subtlety and provides a reference to a more detailed discussio
Coulomb-gas formulation of SU(2) branes and chiral blocks
We construct boundary states in WZNW models using the bosonized
Wakimoto free-field representation and study their properties. We introduce a
Fock space representation of Ishibashi states which are coherent states of
bosons with zero-mode momenta (boundary Coulomb-gas charges) summed over
certain lattices according to Fock space resolution of . The Virasoro
invariance of the coherent states leads to families of boundary states
including the B-type D-branes found by Maldacena, Moore and Seiberg, as well as
the A-type corresponding to trivial current gluing conditions. We then use the
Coulomb-gas technique to compute exact correlation functions of WZNW primary
fields on the disk topology with A- and B-type Cardy states on the boundary. We
check that the obtained chiral blocks for A-branes are solutions of the
Knizhnik-Zamolodchikov equations.Comment: 14 pages, 3 figures, revtex4. Essentially the published versio
Ethics, space, and somatic sensibilities: comparing relationships between scientific researchers and their human and animal experimental subjects
Drawing on geographies of affect and nature-society relations, we propose a radical rethinking of how scientists, social scientists, and regulatory agencies conceptualise human and animal participants in scientif ic research. The scientific rationale for using animal bodies to simulate what could be done in human bodies emphasises shared somatic capacities that generate comparable responses to clinical interventions. At the same time, regulatory guidelines and care practices stress the differences between human and animal subjects. In this paper we consider the implications of this differentiation between human and animal bodies in ethical and welfare protocols and practices. We show how the bioethical debates around the use of human subjects tend to focus on issues of consent and language, while recent work in animal welfare reflects an increasing focus on the affectual dimensions of ethical practice. We argue that this attention to the more-than-representational dimensions of ethics and welfare might be equally important for human subjects. We assert that paying attention to these somatic sensibilities can offer insights into how experimental environments can both facilitate and restrict the development of more care-full and response-able relations between researchers and their experimental subjects. <br/
Loop Operators and the Kondo Problem
We analyse the renormalisation group flow for D-branes in WZW models from the
point of view of the boundary states. To this end we consider loop operators
that perturb the boundary states away from their ultraviolet fixed points, and
show how to regularise and renormalise them consistently with the global
symmetries of the problem. We pay particular attention to the chiral operators
that only depend on left-moving currents, and which are attractors of the
renormalisation group flow. We check (to lowest non-trivial order in the
coupling constant) that at their stable infrared fixed points these operators
measure quantum monodromies, in agreement with previous semiclassical studies.
Our results help clarify the general relationship between boundary transfer
matrices and defect lines, which parallels the relation between
(non-commutative) fields on (a stack of) D-branes and their push-forwards to
the target-space bulk.Comment: 22 pages, 2 figure
Notes on Orientifolds of Rational Conformal Field Theories
We review and develop the construction of crosscap states associated with
parity symmetries in rational conformal field theories. A general method to
construct crosscap states in abelian orbifold models is presented. It is then
applied to rational U(1) and parafermion systems, where in addition we study
the geometrical interpretation of the corresponding parities.Comment: 67 pages, 1 figure, LaTe
- …