7,970 research outputs found
"Only decent girls are employed": the respectability, decency and virtue of the garment workers on the Witwatersrand during the thirties.
Paper presented at the Wits History Workshop: The Making of Class, 9-14 February, 198
Players Indifferent to Cooperate and Characterizations of the Shapley Value
In this paper we provide new axiomatizations of the Shapley value for TU-games using axioms that are based on relational aspects in the interactions among players. Some of these relational aspects, in particular the economic or social interest of each player in cooperating with each other, can be found embedded in the characteristic function. We define a particular relation among the players that it is based on mutual indifference. The first newaxiom expresses that the payoffs of two playerswho are not indifferent to each other are affected in the same way if they become enemies and do not cooperate with each other anymore. The second new axiom expresses that the payoff of a player is not affected if players to whom it is indifferent leave the game. We show that the Shapley value is characterized by these two axioms together with the well-known efficiency axiom. Further, we show that another axiomatization of the Shapley value is obtained if we replace the second axiom and efficiency by the axiom which applies the efficiency condition to every class of indifferent players. Finally, we extend the previous results to the case of weighted Shapley values. © Springer-Verlag Berlin Heidelberg 2012
The BLG Theory in Light-Cone Superspace
The light-cone superspace version of the d=3, N=8 superconformal theory of
Bagger, Lambert and Gustavsson (BLG) is obtained as a solution to constraints
imposed by OSp(2,2|8) superalgebra. The Hamiltonian of the theory is shown to
be a quadratic form of the dynamical supersymmetry transformation.Comment: 45 pages, v2: reference added, minor typos corrected, published
versio
Supertraces on the algebra of observables of the rational Calogero model based on the classical root system
A complete set of supertraces on the algebras of observables of the rational
Calogero models with harmonic interaction based on the classical root systems
of B_N, C_N and D_N types is found. These results extend the results known for
the case A_N. It is shown that there exist Q independent supertraces where
Q(B_N)=Q(C_N) is a number of partitions of N into a sum of positive integers
and Q(D_N) is a number of partitions of N into a sum of positive integers with
even number of even integers.Comment: 10 pages, LATE
Photoassociation spectra and the validity of the dipole approximation for weakly bound dimers
Photoassociation (PA) of ultracold metastable helium to the 2s2p manifold is
theoretically investigated using a non-perturbative close-coupled treatment in
which the laser coupling is evaluated without assuming the dipole
approximation. The results are compared with our previous study [Cocks and
Whittingham, Phys. Rev. A 80, 023417 (2009)] that makes use of the dipole
approximation. The approximation is found to strongly affect the PA spectra
because the photoassociated levels are weakly bound, and a similar impact is
predicted to occur in other systems of a weakly bound nature. The inclusion or
not of the approximation does not affect the resonance positions or widths,
however significant differences are observed in the background of the spectra
and the maximum laser intensity at which resonances are discernable. Couplings
not satisfying the dipole selection rule |J-1| <= J' <= |J+1| do not lead to
observable resonances.Comment: 5 pages, 2 figures; Minor textual revision
Non conventional screening of the Coulomb interaction in low dimensional and finite size system
We study the screening of the Coulomb interaction in non polar systems by
polarizable atoms. We show that in low dimensions and small finite size systems
this screening deviates strongly from that conventionally assumed. In fact in
one dimension the short range interaction is strongly screened and the long
range interaction is anti-screened thereby strongly reducing the gradient of
the Coulomb interaction and therefore the correlation effects. We argue that
this effect explains the success of mean field single particle theories for
large molecules.Comment: 4 pages, 5 figure
The Jacobi identity for Dirac-like brackets
For redundant second-class constraints the Dirac brackets cannot be defined
and new brackets must be introduced. We prove here that the Jacobi identity for
the new brackets must hold on the surface of the second-class constraints. In
order to illustrate our proof we work out explicitly the cases of a fractional
spin particle in 2+1 dimensions and the original Brink-Schwarz massless
superparticle in D=10 dimensions in a Lorentz covariant constraints separation.Comment: 14 pages, Latex. Final version to be published in Int. J. Mod. Phys.
Spacetime Encodings II - Pictures of Integrability
I visually explore the features of geodesic orbits in arbitrary stationary
axisymmetric vacuum (SAV) spacetimes that are constructed from a complex Ernst
potential. Some of the geometric features of integrable and chaotic orbits are
highlighted. The geodesic problem for these SAV spacetimes is rewritten as a
two degree of freedom problem and the connection between current ideas in
dynamical systems and the study of two manifolds sought. The relationship
between the Hamilton-Jacobi equations, canonical transformations, constants of
motion and Killing tensors are commented on. Wherever possible I illustrate the
concepts by means of examples from general relativity. This investigation is
designed to build the readers' intuition about how integrability arises, and to
summarize some of the known facts about two degree of freedom systems. Evidence
is given, in the form of orbit-crossing structure, that geodesics in SAV
spacetimes might admit, a fourth constant of motion that is quartic in momentum
(by contrast with Kerr spacetime, where Carter's fourth constant is quadratic).Comment: 11 pages, 10 figure
Constraints on Scalar Phantoms
We update the constraints on the minimal model of dark matter, where a stable
real scalar field is added to the standard model Lagrangian with a
renormalizable coupling to the Higgs field. Once we fix the dark matter
abundance, there are only two relevant model parameters, the mass of the scalar
field and that of the Higgs boson. The recent data from the CDMS II experiment
have excluded a parameter region where the scalar field is light such as less
than about 50 GeV. In a large parameter region, the consistency of the model
can be tested by the combination of future direct detection experiments and the
LHC experiments.Comment: 7 pages, 1 figur
A relativistic treatment of pion wave functions in the annihilation antiproton-proton -> pi^-pi^+
Quark model intrinsic wave functions of highly energetic pions in the
reaction \bar pp->\pi^-\pi^+ are subjected to a relativistic treatment. The
annihilation is described in a constituent quark model with A2 and R2
flavor-flux topology and the annihilated quark-antiquark pairs are in 3P_0 and
3S_1 states. We study the effects of pure Lorentz transformations on the
antiquark and quark spatial wave functions and their respective spinors in the
pion. The modified quark geometry of the pion has considerable impact on the
angular dependence of the annihilation mechanisms.Comment: 10 pages in revtex format, 3 figure
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