34 research outputs found
An Analytic Method for -Expansion involving Resonance and Reduction
In this paper we describe an analytic method able to give the multiplication
table(s) of the set(s) involved in an -expansion process (with either
resonance or -resonant-reduction) for reaching a target Lie (super)algebra
from a starting one, after having properly chosen the partitions over subspaces
of the considered (super)algebras. This analytic method gives us a simple set
of expressions to find the partitions over the set(s) involved in the process.
Then, we use the information coming from both the initial (super)algebra and
the target one for reaching the multiplication table(s) of the mentioned
set(s). Finally, we check associativity with an auxiliary computational
algorithm, in order to understand whether the obtained set(s) can describe
semigroup(s) or just abelian set(s) connecting two (super)algebras. We also
give some interesting examples of application, which check and corroborate our
analytic procedure and also generalize some result already presented in the
literature.Comment: v3, 47 pages, misprints corrected in Fortschritte der Physik,
Published online 7 November 201
Non-relativistic three-dimensional supergravity theories and semigroup expansion method
In this work we present an alternative method to construct diverse non-relativistic Chern-Simons supergravity theories in three spacetime dimensions. To this end, we apply the Lie algebra expansion method based on semigroups to a supersymmetric extension of the Nappi-Witten algebra. Two different families of non-relativistic superalgebras are obtained, corresponding to generalizations of the extended Bargmann superalgebra and extended Newton-Hooke superalgebra, respectively. The expansion method considered here allows to obtain known and new non-relativistic supergravity models in a systematic way. In particular, it immediately provides an invariant tensor for the expanded superalgebra, which is essential to construct the corresponding Chern-Simons supergravity action. We show that the extended Bargmann supergravity and its Maxwellian generalization appear as particular subcases of a generalized extended Bargmann supergravity theory. In addition, we demonstrate that the generalized extended Bargmann and generalized extended Newton-Hooke supergravity families are related through a contraction process
QED vacuum fluctuations and induced electric dipole moment of the neutron
Quantum fluctuations in the QED vacuum generate non-linear effects, such as
peculiar induced electromagnetic fields. In particular, we show here that an
electrically neutral particle, possessing a magnetic dipole moment, develops an
induced electric dipole-type moment with unusual angular dependence, when
immersed in a quasistatic, constant external electric field. The calculation of
this effect is done in the framework of the Euler-Heisenberg effective QED
Lagrangian, corresponding to the weak field asymptotic expansion of the
effective action to one-loop order. It is argued that the neutron might be a
good candidate to probe this signal of non-linearity in QED.Comment: A misprint has been corrected, and three new references have been
adde
Induced electromagnetic fields in non-linear QED
The Euler–Heisenberg effective Lagrangian is used to obtain general expressions for electric and magnetic fields induced by nonlinearity, to leading order in the nonlinear expansion parameter, and for quasistatic situations. These expressions are then used to compute the induced electromagnetic fields due to a spherical shell with uniform charge distribution on the surface, in the presence of an external constant magnetic field. The induced electric field contains several multipole terms with unusual angular dependences. Most importantly, the leading term of the induced magnetic field is due to an induced magnetic dipole moment.Instituto de Física La Plat
QED vacuum fluctuations and induced electric dipole moment of the neutron
Quantum fluctuations in the QED vacuum generate nonlinear effects, such as peculiar induced electromagnetic fields. In particular, we show here that an electrically neutral particle, possessing a magnetic dipole moment, develops an induced electric dipole-type moment with unusual angular dependence, when immersed in a quasistatic, constant external electric field. The calculation of this effect is done in the framework of the Euler-Heisenberg effective QED Lagrangian, corresponding to the weak field asymptotic expansion of the effective action to one-loop order. It is argued that the neutron might be a good candidate to probe this signal of nonlinearity in QED.Instituto de Física La Plat
Tests fuer die Bestimmung der detonativen Leistungseigenschaften von kunststoffgebundenen Sprengladungen
26 figs.Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
The paragone debate and sixteenth-century Italian art
In 2 vols.SIGLEAvailable from British Library Document Supply Centre-DSC:D193933 / BLDSC - British Library Document Supply CentreGBUnited Kingdo