19,860 research outputs found
On the splitting of nucleon effective masses at high isospin density: reaction observables
We review the present status of the nucleon effective mass splitting
in asymmetric matter, with controversial predictions within both
non-relativistic relativistic approaches to the effective in medium
interactions. Based on microscopic transport simulations we suggest some rather
sensitive observables in collisions of asymmetric (unstable) ions at
intermediate () energies: i) Energy systematics of Lane Potentials; ii)
Isospin content of fast emitted nucleons; iii) Differential Collective Flows.
Similar measurements for light isobars (like ) could be also
important.Comment: 13 pages, 10 figures; NSCL/RIA Workshop on "Reaction Mechanisms for
Rare Isotope Beams", March 2005, AIP Proc. Latex Styl
Limits on Non-Linear Electrodynamics
In this paper we set a framework in which experiments whose goal is to test
QED predictions can be used in a more general way to test non-linear
electrodynamics (NLED) which contains low-energy QED as a special case. We
review some of these experiments and we establish limits on the different free
parameters by generalizing QED predictions in the framework of NLED. We finally
discuss the implications of these limits on bound systems and isolated charged
particles for which QED has been widely and successfully tested
Fragmentation paths in dynamical models
We undertake a quantitative comparison of multi-fragmentation reactions, as
modeled by two different approaches: the Antisymmetrized Molecular Dynamics
(AMD) and the momentum-dependent stochastic mean-field (SMF) model. Fragment
observables and pre-equilibrium (nucleon and light cluster) emission are
analyzed, in connection to the underlying compression-expansion dynamics in
each model. Considering reactions between neutron-rich systems, observables
related to the isotopic properties of emitted particles and fragments are also
discussed, as a function of the parametrization employed for the isovector part
of the nuclear interaction. We find that the reaction path, particularly the
mechanism of fragmentation, is different in the two models and reflects on some
properties of the reaction products, including their isospin content. This
should be taken into account in the study of the density dependence of the
symmetry energy from such collisions.Comment: 11 pages, 13 figures, submitted to Phys. Rev.
Large Deviations in the Free-Energy of Mean-Field Spin-Glasses
We compute analytically the probability distribution of large deviations in
the spin-glass free energy for the Sherrington-Kirkpatrick mean field model,
i.e. we compute the exponentially small probability of finding a system with
intensive free energy smaller than the most likely one. This result is obtained
by computing the average value of the partition function to the power as a
function of . At zero temperature this absolute prediction displays a
remarkable quantitative agreement with the numerical data.Comment: version to be submitted to PRL plus full power series in the
appendix, added references and minor correction
Direct Searches of New Physics at CLIC
The multi-TeV e+e- collider CLIC may allow for the direct study of new
neutral gauge bosons or Kaluza-Klein states in the TeV range. We discuss some
of the experimental aspects for the study of such resonances. Further we
discuss briefly the effects of soft branes in scenarios with Large Extra
Dimensions, and the production of Black Holes at CLIC.Comment: 9 pages, 4 figures, to appear in the proceedings of the LCWS02
Worksho
Characterization of the Vacuum Birefringence Polarimeter at BMV: Dynamical Cavity Mirror Birefringence
We present the current status and outlook of the optical characterization of
the polarimeter at the Bir\'{e}fringence Magn\'etique du Vide (BMV) experiment.
BMV is a polarimetric search for the QED predicted anisotropy of vacuum in the
presence of external electromagnetic fields. The main challenge faced in this
fundamental test is the measurement of polarization ellipticity on the order of
induced in linearly polarized laser field per pass through a
magnetic field having an amplitude and length
. This challenge is addressed by
understanding the noise sources in precision cavity-enhanced polarimetry. In
this paper we discuss the first investigation of dynamical birefringence in the
signal-enhancing cavity as a result of cavity mirror motion.Comment: To appear in the 2019 CPEM special issue of IEEE Transactions on
Instrumentation and Measuremen
Graviton Production at CLIC
Direct production of Kaluza-Klein states in the TeV range is studied for the
experimental environment at the multi-TeV collider CLIC. The
sensitivity of such data to model parameters is discussed for the
Randall-Sundrum(RS) and TeV scale extra dimensional models.Comment: 5 pages, 5 figures, to appear on the Proceedings of the Snowmass 2001
Summer Study, Snowmass CO (USA), July 200
Two-Loop Corrections to Large Order Behavior of Theory
We consider the large order behavior of the perturbative expansion of the
scalar field theory in terms of a perturbative expansion around an
instanton solution. We have computed the series of the free energy up to
two-loop order in two and three dimension. Topologically there is only an
additional Feynman diagram with respect to the previously known one dimensional
case, but a careful treatment of renormalization is needed. The propagator and
Feynman diagrams were expressed in a form suitable for numerical evaluation. We
then obtained explicit expressions summing over distinct eigenvalues
determined numerically with the corresponding eigenfunctions.Comment: 12 pages, 2 figure
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