151 research outputs found
Realistic interpretation of a superposition state does not imply a mixture
Contrary to previous claims, it is shown that, for an ensemble of either
single-particle systems or multi-particle systems, the realistic interpretation
of a superposition state that mathematically describes the ensemble does not
imply that the ensemble is a mixture. Therefore it cannot be argued that the
realistic interpretation is wrong on the basis that some predictions derived
from the mixture are different from the corresponding predictions derived from
the superposition state
Parton Branching in Color Mutation Model
The soft production problem in hadronic collisions as described in the
eikonal color mutation branching model is improved in the way that the initial
parton distribution is treated. Furry branching of the partons is considered as
a means of describing the nonperturbative process of parton reproduction in
soft interaction. The values of all the moments, and , for q=2,...,5,
as well as their energy dependences can be correctly determined by the use of
only two parameters.Comment: 8 pages (LaTeX) + 2 figures (ps files), submitted to Phys. Rev.
Quenched Spin Tunneling and Diabolical Points in Magnetic Molecules: II. Asymmetric Configurations
The perfect quenching of spin tunneling first predicted for a model with
biaxial symmetry, and recently observed in the magnetic molecule Fe_8, is
further studied using the discrete phase integral (or
Wentzel-Kramers-Brillouin) method. The analysis of the previous paper is
extended to the case where the magnetic field has both hard and easy
components, so that the Hamiltonian has no obvious symmetry. Herring's formula
is now inapplicable, so the problem is solved by finding the wavefunction and
using connection formulas at every turning point. A general formula for the
energy surface in the vicinity of the diabolo is obtained in this way. This
formula gives the tunneling apmplitude between two wells unrelated by symmetry
in terms of a small number of action integrals, and appears to be generally
valid, even for problems where the recursion contains more than five terms.
Explicit results are obtained for the diabolical points in the model for Fe_8.
These results exactly parallel the experimental observations. It is found that
the leading semiclassical results for the diabolical points appear to be exact,
and the points themselves lie on a perfect centered rectangular lattice in the
magnetic field space. A variety of evidence in favor of this perfect lattice
hypothesis is presented.Comment: Revtex; 4 ps figures; follow up to cond-mat/000311
The decay constants of pseudoscalar mesons in a relativistic quark model
The decay constants of pseudoscalar mesons are calculated in a relativistic
quark model which assumes that mesons are made of a valence quark antiquark
pair and of an effective vacuum like component. The results are given in terms
of quark masses and of some free parameters entering the expression of the
internal wave functions of the mesons. By using the pion and kaon decay
constants to fix the parameters of the
model one gets for the light quark masses
and the heavy quark masses in the
range: . In the case of
light neutral mesons one obtains with the same set of parameters
. The
values are in agreement with the experimental data and other theoretical
results.Comment: 11 pages, LaTe
Bell inequalities for entangled kaons and their unitary time evolution
We investigate Bell inequalities for neutral kaon systems from Phi resonance
decay to test local realism versus quantum mechanics. We emphasize the unitary
time evolution of the states, that means we also include all decay product
states, in contrast to other authors. Only this guarantees the use of the
complete Hilbert space. We develop a general formalism for Bell inequalities
including both arbitrary "quasi spin" states and different times; finally we
analyze Wigner-type inequalities. They contain an additional term, a correction
function h, as compared to the spin 1/2 or photon case, which changes
considerably the possibility of quantum mechanics to violate the Bell
inequality. Examples for special "quasi spin" states are given, especially
those which are sensitive to the CP parameters epsilon and epsilon'.Comment: REVTeX, 22 page
Self-consistent solution for the polarized vacuum in a no-photon QED model
We study the Bogoliubov-Dirac-Fock model introduced by Chaix and Iracane
({\it J. Phys. B.}, 22, 3791--3814, 1989) which is a mean-field theory deduced
from no-photon QED. The associated functional is bounded from below. In the
presence of an external field, a minimizer, if it exists, is interpreted as the
polarized vacuum and it solves a self-consistent equation.
In a recent paper math-ph/0403005, we proved the convergence of the iterative
fixed-point scheme naturally associated with this equation to a global
minimizer of the BDF functional, under some restrictive conditions on the
external potential, the ultraviolet cut-off and the bare fine
structure constant . In the present work, we improve this result by
showing the existence of the minimizer by a variational method, for any cut-off
and without any constraint on the external field.
We also study the behaviour of the minimizer as goes to infinity
and show that the theory is "nullified" in that limit, as predicted first by
Landau: the vacuum totally kills the external potential. Therefore the limit
case of an infinite cut-off makes no sense both from a physical and
mathematical point of view.
Finally, we perform a charge and density renormalization scheme applying
simultaneously to all orders of the fine structure constant , on a
simplified model where the exchange term is neglected.Comment: Final version, to appear in J. Phys. A: Math. Ge
Local/Non-Local Complementarity in Topological Effects
In certain topological effects the accumulation of a quantum phase shift is
accompanied by a local observable effect. We show that such effects manifest a
complementarity between non-local and local attributes of the topology, which
is reminiscent but yet different from the usual wave-particle complementarity.
This complementarity is not a consequence of non-commutativity, rather it is
due to the non-canonical nature of the observables. We suggest that a
local/non-local complementarity is a general feature of topological effects
that are ``dual'' to the AB effect.Comment: 4 page
Neutrino oscillations and neutrinoless double beta decay
The relation between neutrino oscillation parameters and neutrinoless double
beta decay is studied, assuming normal and inverse hierarchies for Majorana
neutrino masses. For normal hierarchy the crucial dependence on U_{e3} is
explored. The link with tritium beta decay is also briefly discussed.Comment: RevTex, 9 pages with 3 figures. Few comments and references adde
Photon Exchange in Nucleus-Nucleus Collisions
The strong electromagnetic fields in peripheral heavy ion collisions give
rise to photon-photon and photon-nucleus interactions. I present a general
survey of the photon-photon and photon-hadron physics accessible in these
collisions. Among these processes I discuss the nuclear fragmentation through
the excitation of giant resonances, the Coulomb dissociation method for
application in nuclear astrophysics, and the production of particles.Comment: 51 pages, 16 figure
A Cryogenic Underground Observatory for Rare Events: Cuore, an Update
CUORE is a proposed tightly packed array of 1000 TeO_{2} bolometers, each
being a cube 5 cm on a side with a mass of 750 gms. The array consists of 25
vertical towers, arranged in a square, of 5 towers by 5 towers, each containing
10 layers of 4 crystals. The design of the detector is optimized for ultralow-
background searches for neutrinoless double beta decay of ^{130}Te (33.8%
abundance), cold dark matter, solar axions, and rare nuclear decays. A
preliminary experiment involving 20 crystals of various sizes (MIBETA) has been
completed, and a single CUORE tower is being constructed as a smaller scale
experiment called CUORICINO. The expected performance and sensitivity, based on
Monte Carlo simulations and extrapolations of present results, are reported.Comment: in press: Nucl. Phys. of Russian Academy of Sc
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