5,543 research outputs found
Influence of correlated visual cues on auditory signal detection
Influence of correlated visual cues on auditory signal detectio
Cosmology as Relativistic Particle Mechanics: From Big Crunch to Big Bang
Cosmology can be viewed as geodesic motion in an appropriate metric on an
`augmented' target space; here we obtain these geodesics from an effective
relativistic particle action. As an application, we find some exact (flat and
curved) cosmologies for models with N scalar fields taking values in a
hyperbolic target space for which the augmented target space is a Milne
universe. The singularities of these cosmologies correspond to points at which
the particle trajectory crosses the Milne horizon, suggesting a novel
resolution of them, which we explore via the Wheeler-deWitt equation.Comment: 17 pages, 3 figures, references and comments adde
Cosmology as Geodesic Motion
For gravity coupled to N scalar fields with arbitrary potential V, it is
shown that all flat (homogeneous and isotropic) cosmologies correspond to
geodesics in an (N+1)-dimensional `augmented' target space of Lorentzian
signature (1,N), timelike if V>0, null if V=0 and spacelike if V<0.
Accelerating cosmologies correspond to timelike geodesics that lie within an
`acceleration subcone' of the `lightcone'. Non-flat (k=-1,+1) cosmologies are
shown to evolve as projections of geodesic motion in a space of dimension
(N+2), of signature (1,N+1) for k=-1 and signature (2,N) for k=+1. This
formalism is illustrated by cosmological solutions of models with an
exponential potential, which are comprehensively analysed; the late-time
behviour for other potentials of current interest is deduced by comparison.Comment: 26 pages, 2 figures, journal version with additional reference
Response to a rabies epidemic in Bali, Indonesia
Emergency vaccinations and culling failed to contain an outbreak of rabies in Bali, Indonesia, during 2008–2009. Subsequent island-wide mass vaccination (reaching 70% coverage, >200,000 dogs) led to substantial declines in rabies incidence and spread. However, the incidence of dog bites remains high, and repeat campaigns are necessary to eliminate rabies in Bali
Staying true with the help of others: doxastic self-control through interpersonal commitment
I explore the possibility and rationality of interpersonal mechanisms of doxastic self-control, that is, ways in which individuals can make use of other people in order to get themselves to stick to their beliefs. I look, in particular, at two ways in which people can make interpersonal epistemic commitments, and thereby willingly undertake accountability to others, in order to get themselves to maintain their beliefs in the face of anticipated “epistemic temptations”. The first way is through the avowal of belief, and the second is through the establishment of collective belief. I argue that both of these forms of interpersonal epistemic commitment can function as effective tools for doxastic self-control, and, moreover, that the control they facilitate should not be dismissed as irrational from an epistemic perspective
N=1 Non-Abelian Tensor Multiplet in Four Dimensions
We carry out the N=1 supersymmetrization of a physical non-Abelian tensor
with non-trivial consistent couplings in four dimensions. Our system has three
multiplets: (i) The usual non-Abelian vector multiplet (VM) (A_\mu{}^I,
\lambda^I), (ii) A non-Abelian tensor multiplet (TM) (B_{\mu\nu}{}^I, \chi^I,
\varphi^I), and (iii) A compensator vector multiplet (CVM) (C_\mu{}^I, \rho^I).
All of these multiplets are in the adjoint representation of a non-Abelian
group G. Unlike topological theory, all of our fields are propagating with
kinetic terms. The C_\mu{}^I-field plays the role of a Stueckelberg compensator
absorbed into the longitudinal component of B_{\mu\nu}{}^I. We give not only
the component lagrangian, but also a corresponding superspace reformulation,
reconfirming the total consistency of the system. The adjoint representation of
the TM and CVM is further generalized to an arbitrary real representation of
general SO(N) gauge group. We also couple the globally N=1 supersymmetric
system to supergravity, as an additional non-trivial confirmation.Comment: 18 pages, no figur
String/-brane Duality and Duality as Symmetries of Actions
We realize the string/-brane duality on the action level between the
-compactified heterotic string effective action and the -
brane effective action in dimensions by managing a Lagrange multiplier
field. A dual dictionary is composed to be available for the translation
between the elementary or solitonic solutions of the dual pair of actions. In
the same way the duality is also reconstructed on the action level as a
double dualization for the -compactified heterotic string effective
action.Comment: 9 pages, latex, no figure
Multiple M0-brane system in an arbitrary eleven dimensional supergravity background
The equations of motion of multiple M0{brane (multiple M-wave or mM0) system
in an arbitrary D = 11 supergravity superspace, which generalize the Matrix
model equations for the case of inter- action with a generic 11D supergravity
background, are obtained in the frame of superembedding approach. We also
derive the BPS equations for supersymmetric bosonic solutions of these mM0
equations and show that the set of 1/2 BPS solutions contain a fuzzy sphere
modeling M2 brane as well as that the Nahm equation appears as a particular
case of the 1/4 BPS equations.Comment: RevTeX4, 20 pages, no figures. V2: misprints corrected, minor
changes, published in Phys. Rev. D82, 105030 (2010)). V3. Dec. 2011 :
misprints in coeffs of Eqs.(5.10) correcte
Supersymmetric Two-Time Physics
We construct an Sp(2,R) gauge invariant particle action which possesses
manifest space-time SO(d,2) symmetry, global supersymmetry and kappa
supersymmetry. The global and local supersymmetries are non-abelian
generalizations of Poincare type supersymmetries and are consistent with the
presence of two timelike dimensions. In particular, this action provides a
unified and explicit superparticle representation of the superconformal groups
OSp(N/4), SU(2,2/N) and OSp(8*/N) which underlie various AdS/CFT dualities in
M/string theory. By making diverse Sp(2,R) gauge choices our action reduces to
diverse one-time physics systems, one of which is the ordinary (one-time)
massless superparticle with superconformal symmetry that we discuss explicitly.
We show how to generalize our approach to the case of superalgebras, such as
OSp(1/32), which do not have direct space-time interpretations in terms of only
zero branes, but may be realizable in the presence of p-branes.Comment: Latex, 18 page
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