11,095 research outputs found
Lessons from the Andean Community Integration. Jean Monnet/Robert Schuman Paper Series. Vol. 6, No. 12 June 2006
[From the Introduction]. Ever since it was born in the sixties, the Andean Regional Integration Process has attempted to become a strategy to promote a harmonious and balanced development among the Andean Countries. This paper has tree mains goals: (a) To explain and analyse the theoretical concept of the Andean New Regionalism in the framework of Latin American region in a comparative perspective with the European Model of Regional Integration; (b) To show the coexistence of two different regional integration models. Where the dominating one during the sixties was known as old regionalism, and the other that is currently being used is known as new regionalism, and (c) To analyse the way in which this coexistence appears to be an obstacle for the Andean countries to define their regional integration model and to advance toward their main goal: the balanced and harmonious development of each and every country member
Nonlocality and entanglement in qubit systems
Nonlocality and quantum entanglement constitute two special aspects of the
quantum correlations existing in quantum systems, which are of paramount
importance in quantum-information theory. Traditionally, they have been
regarded as identical (equivalent, in fact, for pure two qubit states, that is,
{\it Gisin's Theorem}), yet they constitute different resources. Describing
nonlocality by means of the violation of several Bell inequalities, we obtain
by direct optimization those states of two qubits that maximally violate a Bell
inequality, in terms of their degree of mixture as measured by either their
participation ratio or their maximum eigenvalue
. This optimum value is obtained as well, which coincides with
previous results. Comparison with entanglement is performed too. An example of
an application is given in the XY model. In this novel approximation, we also
concentrate on the nonlocality for linear combinations of pure states of two
qubits, providing a closed form for their maximal nonlocality measure. The case
of Bell diagonal mixed states of two qubits is also extensively studied.
Special attention concerning the connection between nonlocality and
entanglement for mixed states of two qubits is paid to the so called maximally
entangled mixed states. Additional aspects for the case of two qubits are also
described in detail. Since we deal with qubit systems, we will perform an
analogous study for three qubits, employing similar tools. Relation between
distillability and nonlocality is explored quantitatively for the whole space
of states of three qubits. We finally extend our analysis to four qubit
systems, where nonlocality for generalized Greenberger-Horne-Zeilinger states
of arbitrary number of parties is computed.Comment: 16 pages, 3 figure
The Standard Model instability and the scale of new physics
We apply a general formalism for the improved effective potential with
several mass scales to compute the scale M of new physics which is needed to
stabilize the Standard Model potential in the presence of a light Higgs. We
find, by imposing perturbativity of the new physics, that M can be as large as
one order of magnitude higher than the instability scale of the Standard Model.
This implies that, with the present lower bounds on the Higgs mass, the new
physics could easily (but not necessarily) escape detection in the present and
future accelerators.Comment: latex2e, 12 pages, 3 figure
Triple Cohomology of Lie-Rinehart Algebras and the Canonical Class of Associative Algebras
We introduce a bicomplex which computes the triple cohomology of
Lie--Rinehart algebras. We prove that the triple cohomology is isomorphic to
the Rinehart cohomology \cite{Ri} provided the Lie--Rinehart algebra is
projective over the corresponding commutative algebra. As an application we
construct a canonical class in the third dimensional cohomology corresponding
to an associative algebra
Cooper pair dispersion relation in two dimensions
The Cooper pair binding energy {\it vs.} center-of-mass-momentum dispersion
relation for Bose-Einstein condensation studies of superconductivity is found
in two dimensions for a renormalized attractive delta interaction. It crosses
over smoothly from a linear to a quadratic form as coupling varies from weak to
strong.Comment: 2 pages, 1 figure, new version published in Physica
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