45 research outputs found
The Quantum Galilei Group
The quantum Galilei group is defined. The bicrossproduct
structure of and the corresponding Lie algebra is revealed. The
projective representations for the two-dimensional quantum Galilei group are
constructed.Comment: AMSTe
Global Symmetries of Noncommutative Space-time
The global counterpart of infinitesimal symmetries of noncommutative
space-time is discussed.Comment: 7 pages, no figures; minor changes in the bibliography; final version
accepted for publication in Phys. Rev.
Kappa-contraction from to
We present contraction prescription of the quantum groups: from to
. Our strategy is different then one chosen in ref. [P. Zaugg,
J. Phys. A {\bf 28} (1995) 2589]. We provide explicite prescription for
contraction of and generators of and arrive at
Hopf algebra .Comment: 3 pages, plain TEX, harvmac, to be published in the Proceedings of
the 4-th Colloqium Quantum Groups and Integrable Systems, Prague, June 1995,
Czech. J. Phys. {\bf 46} 265 (1996
On the definition of velocity in doubly special relativity theories
We discuss the definition of particle velocity in doubly relativity theories.
The general formula relating velocity and four-momentum of particle is given.Comment: 7 page
Noncommutative Differential Forms on the kappa-deformed Space
We construct a differential algebra of forms on the kappa-deformed space. For
a given realization of the noncommutative coordinates as formal power series in
the Weyl algebra we find an infinite family of one-forms and nilpotent exterior
derivatives. We derive explicit expressions for the exterior derivative and
one-forms in covariant and noncovariant realizations. We also introduce
higher-order forms and show that the exterior derivative satisfies the graded
Leibniz rule. The differential forms are generally not graded-commutative, but
they satisfy the graded Jacobi identity. We also consider the star-product of
classical differential forms. The star-product is well-defined if the
commutator between the noncommutative coordinates and one-forms is closed in
the space of one-forms alone. In addition, we show that in certain realizations
the exterior derivative acting on the star-product satisfies the undeformed
Leibniz rule.Comment: to appear in J. Phys. A: Math. Theo
The Out-of-Equilibrium Time-Dependent Gutzwiller Approximation
We review the recently proposed extension of the Gutzwiller approximation, M.
Schiro' and M. Fabrizio, Phys. Rev. Lett. 105, 076401 (2010), designed to
describe the out-of-equilibrium time-evolution of a Gutzwiller-type variational
wave function for correlated electrons. The method, which is strictly
variational in the limit of infinite lattice-coordination, is quite general and
flexible, and it is applicable to generic non-equilibrium conditions, even far
beyond the linear response regime. As an application, we discuss the quench
dynamics of a single-band Hubbard model at half-filling, where the method
predicts a dynamical phase transition above a critical quench that resembles
the sharp crossover observed by time-dependent dynamical mean field theory. We
next show that one can actually define in some cases a multi-configurational
wave function combination of a whole set of mutually orthogonal Gutzwiller wave
functions. The Hamiltonian projected in that subspace can be exactly evaluated
and is equivalent to a model of auxiliary spins coupled to non-interacting
electrons, closely related to the slave-spin theories for correlated electron
models. The Gutzwiller approximation turns out to be nothing but the mean-field
approximation applied to that spin-fermion model, which displays, for any
number of bands and integer fillings, a spontaneous symmetry breaking
that can be identified as the Mott insulator-to-metal transition.Comment: 25 pages. Proceedings of the Hvar 2011 Workshop on 'New materials for
thermoelectric applications: theory and experiment
Five-headed superior omohyoid
The omohyoid is an infrahyoid muscle with two bellies. It is responsible for lowering and positioning of the hyoid bone. It is morphologically variable in the origin, insertion and morphology of its bellies. Quantitative variations of the superior belly of the omohyoid muscle are not common. We present a case of a five-headed superior omohyoid, and a short clinical review related to this muscle. All the bellies had their origin in an intermediate tendon and were attached to the hyoid bone. The volume of its superior part was greater than usual. Knowledge of the anatomy of this muscle is important, especially for surgeons operating in the anterolateral neck region
Noncommutative Parameters of Quantum Symmetries and Star Products
The star product technique translates the framework of local fields on
noncommutative space-time into nonlocal fields on standard space-time. We
consider the example of fields on - deformed Minkowski space,
transforming under -deformed Poincar\'{e} group with noncommutative
parameters. By extending the star product to the tensor product of functions on
-deformed Minkowski space and -deformed Poincar\'{e} group we
represent the algebra of noncommutative parameters of deformed relativistic
symmetries by functions on classical Poincar\'{e} group.Comment: LaTeX2e, 10 pages. To appear in the Proceedings of XXIII
International Colloquium on Group-Theoretical Methods in Physics, July 31-
August 5, Dubna, Russia". The names of the authors correcte
Local D=4 Field Theory on --Deformed Minkowski Space
We describe the local D=4 field theory on --deformed Minkowski space
as nonlocal relativistic field theory on standard Minkowski space--time. For
simplicity the case of -deformed scalar field with the
interaction is considered, and the --deformed
interaction vertex is described. It appears that fundamental mass parameter
plays a role of regularizing imaginary Pauli--Villars mass in
--deformed propagator.Comment: revtex, 2 figures.The text has been enlarged by two pages, mostly the
explicite description of local scalar field on -deformed Minkowski
space has been extended. One figure adde
Doubly Special Relativity theories as different bases of --Poincar\'e algebra
Doubly Special Relativity (DSR) theory is a theory with two
observer-independent scales, of velocity and mass (or length). Such a theory
has been proposed by Amelino--Camelia as a kinematic structure which may
underline quantum theory of relativity. Recently another theory of this kind
has been proposed by Magueijo and Smolin. In this paper we show that both these
theories can be understood as particular bases of the --Poincar\'e
theory based on quantum (Hopf) algebra. This observation makes it possible to
construct the space-time sector of Magueijo and Smolin DSR. We also show how
this construction can be extended to the whole class of DSRs. It turns out that
for all such theories the structure of space-time commutators is the same. This
results lead us to the claim that physical predictions of properly defined DSR
theory should be independent of the choice of basis.Comment: 13 pages, LaTe