1,262 research outputs found
Two-Loop Beta Functions Without Feynman Diagrams
Starting from a consistency requirement between T-duality symmetry and
renormalization group flows, the two-loop metric beta function is found for a
d=2 bosonic sigma model on a generic, torsionless background. The result is
obtained without Feynman diagram calculations, and represents further evidence
that duality symmetry severely constrains renormalization flows.Comment: 4 pp., REVTeX. Added discussion on scheme (in)dependence; final
version to appear in Phys. Rev. Let
Evaluation of the diagnostic accuracy of prototype rapid tests for human African trypanosomiasis
Peer reviewedPublisher PD
Differential geometry with a projection: Application to double field theory
In recent development of double field theory, as for the description of the
massless sector of closed strings, the spacetime dimension is formally doubled,
i.e. from D to D+D, and the T-duality is realized manifestly as a global O(D,D)
rotation. In this paper, we conceive a differential geometry characterized by a
O(D,D) symmetric projection, as the underlying mathematical structure of double
field theory. We introduce a differential operator compatible with the
projection, which, contracted with the projection, can be covariantized and may
replace the ordinary derivatives in the generalized Lie derivative that
generates the gauge symmetry of double field theory. We construct various gauge
covariant tensors which include a scalar and a tensor carrying two O(D,D)
vector indices.Comment: 1+22 pages, No figure; a previous result on 4-index tensor removed,
presentation improve
An Equivalence Between Momentum and Charge in String Theory
It is shown that for a translationally invariant solution to string theory,
spacetime duality interchanges the momentum in the symmetry direction and the
axion charge per unit length. As one application, we show explicitly that
charged black strings are equivalent to boosted (uncharged) black strings. The
extremal black strings (which correspond to the field outside of a fundamental
macroscopic string) are equivalent to plane fronted waves describing strings
moving at the speed of light.Comment: 10 page
Gravitational instantons and black plane solutions in 4-d string theory
We consider gauged Wess-Zumino models based on the non compact group
. It is shown that by vector gauging the maximal compact subgroup
the resulting backgrounds obey the gravity-dilaton one loop string
vacuum equations of motion in four dimensional euclidean space. The torsionless
solution is then interpreted as a pseudo-instanton of the Liouville
theory coupled to gravity. The presence of a traslational isometry in the model
allows to get another string vacuum backgrounds by using target duality that we
identify with those corresponding to the axial gauging. We also compute the
exact backgrounds. Depending on the value of , they may be interpreted as
instantons connecting a highly singular big bang like universe with a static
singular or regular black plane geometry.Comment: 29 page
D-branes in Generalized Geometry and Dirac-Born-Infeld Action
The purpose of this paper is to formulate the Dirac-Born-Infeld (DBI) action
in a framework of generalized geometry and clarify its symmetry. A D-brane is
defined as a Dirac structure where scalar fields and gauge field are treated on
an equal footing in a static gauge. We derive generalized Lie derivatives
corresponding to the diffeomorphism and B-field gauge transformations and show
that the DBI action is invariant under non-linearly realized symmetries for all
types of diffeomorphisms and B-field gauge transformations. Consequently, we
can interpret not only the scalar field but also the gauge field on the D-brane
as the generalized Nambu-Goldstone boson.Comment: 32 pages, 4 figures, ver2:typos corrected, references adde
Two-Vierbein Formalism for String-Inspired Axionic Gravity
Using independent left and right vierbeins to describe graviton plus axion as
suggested by string mechanics, O(d,d) duality can be realized linearly.Comment: 14 pg., (uuencoded dvi file; fixed uuencoding so file is unprotected)
ITP-SB-93-
Exact monopole instantons and cosmological solutions in string theory from abelian dimensional reduction
We compute the exact string vacuum backgrounds corresponding to the
non-compact coset theory . The conformal field theory defined by
the level results in a five dimensional singular solution that
factorizes in an asymptotic region as the linear dilaton solution and a
model. It presents two abelian compact isometries that allow to reinterpreting
it from a four dimensional point of view as a stationary and magnetically
charged space-time resembling in some aspects the Kerr-Newman solution of
general relativity. The theory on the other hand describes a
cosmological solution that interpolates between a singular phase at short times
and a universe after some planckian times.Comment: 18 pages, section 5 replaced by 5 and 6, references added; to appear
in Phys. Rev.
Corporal diagnostic work and diagnostic spaces: Clinicians' use of space and bodies during diagnosis
© 2015 The Authors. Sociology of Health & Illness © 2015 Foundation for the Sociology of Health & Illness/John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.An emerging body of literature in sociology has demonstrated that diagnosis is a useful focal point for understanding the social dimensions of health and illness. This article contributes to this work by drawing attention to the relationship between diagnostic spaces and the way in which clinicians use their own bodies during the diagnostic process. As a case study, we draw upon fieldwork conducted with a multidisciplinary clinical team providing deep brain stimulation (DBS) to treat children with a movement disorder called dystonia. Interviews were conducted with team members and diagnostic examinations were observed. We illustrate that clinicians use communicative body work and verbal communication to transform a material terrain into diagnostic space, and we illustrate how this diagnostic space configures forms of embodied 'sensing-and-acting' within. We argue that a 'diagnosis' can be conceptualised as emerging from an interaction in which space, the clinician-body, and the patient-body (or body-part) mutually configure one another. By conceptualising diagnosis in this way, this article draws attention to the corporal bases of diagnostic power and counters Cartesian-like accounts of clinical work in which the patient-body is objectified by a disembodied medical discourse.The Wellcome Trust (Wellcome Trust Biomedical Strategic Award 086034
Fermionic T-duality in the pp-wave limit
AdS5 X S5 and its pp-wave limit are self-dual under transformations involving
eight fermionic T-dualities, a property which accounts for symmetries seen in
scattering amplitudes in N=4 super-Yang-Mills. Despite strong evidence for
similar symmetries in the amplitudes of three-dimensional N=6 ABJM theory, a
corresponding self-duality in the dual geometry AdS4 X CP3 currently eludes us.
Here, working with the type IIA pp-wave limit of AdS4 X CP3 preserving twenty
four supercharges, we show that the pp-wave is self-dual with respect to eight
commuting fermionic T-dualities and not the six expected. In addition, we show
the same symmetry can be found in a superposition pp-wave and a generic pp-wave
with twenty and sixteen unbroken supersymmetries respectively, strongly
suggesting that self-duality under fermionic T-duality may be a symmetry of all
pp-waves.Comment: 21 pages, typos fixe
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