3,497 research outputs found
Phase Diagram Of The Biham-Middleton-Levine Traffic Model In Three Dimensions
We study numerically the behavior of the Biham-Middleton-Levine traffic model
in three dimensions. Our extensive numerical simulations show that the phase
diagram for this model in three dimensions is markedly different from that in
one and two dimensions. In addition to the full speed moving as well as the
completely jamming phases, whose respective average asymptotic car speeds
equal one and zero, we observe an extensive region of car densities with
a low but non-zero average asymptotic car speed. The transition from this
extensive low average asymptotic car speed region to the completely jamming
region is at least second order. We argue that this low speed region is a
result of the formation of a spatially-limited-extended percolating cluster.
Thus, this low speed phase is present in dimensional
Biham-Middleton-Levine model as well.Comment: Minor clarifications, 1 figure adde
Exclusive Hadronic D Decays to eta' and eta
Hadronic decay modes and
are studied in the generalized
factorization approach. Form factors for transitions
are carefully evaluated by taking into account the wave function normalization
of the eta and eta'. The predicted branching ratios are generally in agreement
with experiment except for and
; the calculated decay rates for the first two decay modes
are too small by an order of magnitude. We show that the weak decays and followed by resonance-induced final-state
interactions (FSI), which are amenable technically, are able to enhance the
branching ratios of and dramatically
without affecting the agreement between theory and experiment for and . We argue that it is difficult to understand
the observed large decay rates of and
simultaneously; FSI, W-annihilation and the production of excess eta' from
gluons are not helpful in this regard. The large discrepancy between the
factorization hypothesis and experiment for the ratio of
and remains as an enigma.Comment: 15 pages, 1 figure, to appear in Phys. Rev. D. Form factors for D to
eta and eta' transitions are slightly change
CP violation and CKM phases from angular distributions for decays into admixtures of CP eigenstates
We investigate the time-evolutions of angular distributions for decays
into final states that are admixtures of CP-even and CP-odd configurations. A
sizable lifetime difference between the mass eigenstates allows a probe
of CP violation in time-dependent untagged angular distributions. Interference
effects between different final state configurations of , determine the Wolfenstein parameter from
untagged data samples, or -- if one uses as an additional
input -- the notoriously difficult to measure CKM angle . Another
determination of is possible by using isospin symmetry of strong
interactions to relate untagged data samples of
and . We note that the untagged angular
distribution for provides interesting information about
electroweak penguins.Comment: 19 pages, LaTeX, no figure
Final-State Phases in Charmed Meson Two-Body Nonleptonic Decays
Observed decay rates indicate large phase differences among the amplitudes
for the charge states in and but
relatively real amplitudes in the charge states for . This
feature is traced using an SU(3) flavor analysis to a sign flip in the
contribution of one of the amplitudes contributing to the latter processes in
comparison with its contribution to the other two sets. This amplitude may be
regarded as an effect of rescattering and is found to be of magnitude
comparable to others contributing to charmed particle two-body nonleptonic
decays.Comment: 19 pages, latex, 4 figures, to be submitted to Phys. Rev.
On the B\"acklund Transformation for the Moyal Korteweg-de Vries Hierarchy
We study the B\"acklund symmetry for the Moyal Korteweg-de Vries (KdV)
hierarchy based on the Kuperschmidt-Wilson Theorem associated with second
Gelfand-Dickey structure with respect to the Moyal bracket, which generalizes
the result of Adler for the ordinary KdV.Comment: 9 pages, Revte
Key distillation from quantum channels using two-way communication protocols
We provide a general formalism to characterize the cryptographic properties
of quantum channels in the realistic scenario where the two honest parties
employ prepare and measure protocols and the known two-way communication
reconciliation techniques. We obtain a necessary and sufficient condition to
distill a secret key using this type of schemes for Pauli qubit channels and
generalized Pauli channels in higher dimension. Our results can be applied to
standard protocols such as BB84 or six-state, giving a critical error rate of
20% and 27.6%, respectively. We explore several possibilities to enlarge these
bounds, without any improvement. These results suggest that there may exist
weakly entangling channels useless for key distribution using prepare and
measure schemes.Comment: 21 page
Branching Ratio and CP Violation of B to pi pi Decays in Perturbative QCD Approach
We calculate the branching ratios and CP asymmetries for B^0 to pi^+pi^-, B^+
to pi^+pi^0 and B^0 to pi^0pi^0 decays, in a perturbative QCD approach. In this
approach, we calculate non-factorizable and annihilation type contributions, in
addition to the usual factorizable contributions. We found that the
annihilation diagram contributions are not very small as previous argument. Our
result is in agreement with the measured branching ratio of B to pi^+pi^- by
CLEO collaboration. With a non-negligible contribution from annihilation
diagrams and a large strong phase, we predict a large direct CP asymmetry in
B^0 to pi^+pi^-, and pi^0pi^0, which can be tested by the current running B
factories.Comment: Latex, 28 pages including 11 figures; added contents and figures,
corrected typo
Information Content in Decays and the Angular Moments Method
The time-dependent angular distributions of decays of neutral mesons into
two vector mesons contain information about the lifetimes, mass differences,
strong and weak phases, form factors, and CP violating quantities. A
statistical analysis of the information content is performed by giving the
``information'' a quantitative meaning. It is shown that for some parameters of
interest, the information content in time and angular measurements combined may
be orders of magnitude more than the information from time measurements alone
and hence the angular measurements are highly recommended. The method of
angular moments is compared with the (maximum) likelihood method to find that
it works almost as well in the region of interest for the one-angle
distribution. For the complete three-angle distribution, an estimate of
possible statistical errors expected on the observables of interest is
obtained. It indicates that the three-angle distribution, unraveled by the
method of angular moments, would be able to nail down many quantities of
interest and will help in pointing unambiguously to new physics.Comment: LaTeX, 34 pages with 9 figure
Large scale correlations in normal and general non-Hermitian matrix ensembles
We compute the large scale (macroscopic) correlations in ensembles of normal
random matrices with an arbitrary measure and in ensembles of general
non-Hermition matrices with a class of non-Gaussian measures. In both cases the
eigenvalues are complex and in the large limit they occupy a domain in the
complex plane. For the case when the support of eigenvalues is a connected
compact domain, we compute two-, three- and four-point connected correlation
functions in the first non-vanishing order in 1/N in a manner that the
algorithm of computing higher correlations becomes clear. The correlation
functions are expressed through the solution of the Dirichlet boundary problem
in the domain complementary to the support of eigenvalues. The two-point
correlation functions are shown to be universal in the sense that they depend
only on the support of eigenvalues and are expressed through the Dirichlet
Green function of its complement.Comment: 16 pages, 1 figure, LaTeX, submitted to J. Phys. A special issue on
random matrices, minor corrections, references adde
Wolfenstein Parametrization Re-examined
The Wolfenstein parametrization of the Kobayashi-Maskawa (KM)
matrix is modified by keeping its unitarity up to the accuracy of
. This modification can self-consistently lead to the
off-diagonal asymmetry of : =
with , which is comparable in magnitude with the Jarlskog parameter of
violation . We constrain the ranges of
and by using the current experimental data, and point out that the
possibility of a symmetric KM matrix has almost been ruled out.Comment: 5 Latex pages including a figure; Two references are adde
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