11,911 research outputs found
New Physics Signals through CP Violation in B -> rho,pi
We describe here a method for detecting physics beyond the standard model via
CP violation in B->rho,pi decays. Using a Dalitz-plot analysis to obtain alpha,
along with an analytical extraction of the various tree (T) and penguin (P)
amplitudes, we obtain a criterion for the absence of new physics (NP). This
criterion involves the comparison of the measured |P/T| ratio with its value as
predicted by QCD factorization. We show that the detection of NP via this
method has a good efficiency when compared with the corresponding technique
using B->pi,pi decays.Comment: 8 pages, 4 figures, talk given at MRST 2004: From Quarks to
Cosmology, Concordia University, Montreal, May 200
Electrodynamics of superconductors
An alternate set of equations to describe the electrodynamics of
superconductors at a macroscopic level is proposed. These equations resemble
equations originally proposed by the London brothers but later discarded by
them. Unlike the conventional London equations the alternate equations are
relativistically covariant, and they can be understood as arising from the
'rigidity' of the superfluid wave function in a relativistically covariant
microscopic theory. They predict that an internal 'spontaneous' electric field
exists in superconductors, and that externally applied electric fields, both
longitudinal and transverse, are screened over a London penetration length, as
magnetic fields are. The associated longitudinal dielectric function predicts a
much steeper plasmon dispersion relation than the conventional theory, and a
blue shift of the minimum plasmon frequency for small samples. It is argued
that the conventional London equations lead to difficulties that are removed in
the present theory, and that the proposed equations do not contradict any known
experimental facts. Experimental tests are discussed.Comment: Small changes following referee's and editor's comments; to be
published in Phys.Rev.
Symmetries and collective excitations in large superconducting circuits
The intriguing appeal of circuits lies in their modularity and ease of
fabrication. Based on a toolbox of simple building blocks, circuits present a
powerful framework for achieving new functionality by combining circuit
elements into larger networks. It is an open question to what degree modularity
also holds for quantum circuits -- circuits made of superconducting material,
in which electric voltages and currents are governed by the laws of quantum
physics. If realizable, quantum coherence in larger circuit networks has great
potential for advances in quantum information processing including topological
protection from decoherence. Here, we present theory suitable for quantitative
modeling of such large circuits and discuss its application to the fluxonium
device. Our approach makes use of approximate symmetries exhibited by the
circuit, and enables us to obtain new predictions for the energy spectrum of
the fluxonium device which can be tested with current experimental technology
Predicted electric field near small superconducting ellipsoids
We predict the existence of large electric fields near the surface of
superconducting bodies of ellipsoidal shape of dimensions comparable to the
penetration depth. The electric field is quadrupolar in nature with significant
corrections from higher order multipoles. Prolate (oblate) superconducting
ellipsoids are predicted to exhibit fields consistent with negative (positive)
quadrupole moments, reflecting the fundamental charge asymmetry of matter.Comment: To be published in Phys.Rev.Let
Entropic lattice Boltzmann methods
We present a general methodology for constructing lattice Boltzmann models of
hydrodynamics with certain desired features of statistical physics and kinetic
theory. We show how a methodology of linear programming theory, known as
Fourier-Motzkin elimination, provides an important tool for visualizing the
state space of lattice Boltzmann algorithms that conserve a given set of
moments of the distribution function. We show how such models can be endowed
with a Lyapunov functional, analogous to Boltzmann's H, resulting in
unconditional numerical stability. Using the Chapman-Enskog analysis and
numerical simulation, we demonstrate that such entropically stabilized lattice
Boltzmann algorithms, while fully explicit and perfectly conservative, may
achieve remarkably low values for transport coefficients, such as viscosity.
Indeed, the lowest such attainable values are limited only by considerations of
accuracy, rather than stability. The method thus holds promise for
high-Reynolds number simulations of the Navier-Stokes equations.Comment: 54 pages, 16 figures. Proc. R. Soc. London A (in press
United States v. Fidel Castro-Verdugo: Unlawfully Sentenced Defendant Is Procedurally Barred From Relief
In United States v. Fidel Castro-Verdugo, the Ninth Circuit held that the court lacks the jurisdiction to correct an underlying unlawful sentence imposed by the district court in the context of a probation revocation appeal. Despite clear error on the part of the sentencing judge, Defendant-Appellant (Defendant) did not timely file a petition for a writ of habeas corpus; therefore, no remedy was available to him. The dissenting opinion asserted that the court did have jurisdiction to correct the error because Defendant appealed from a later sentence erroneously based on the underlying unlawful sentence. Noting that it is the role of appellate courts to correct errors made by lower courts, the dissent disagreed strongly with the majority’s decision to uphold a known error
The Difference Between Homogeneous Grouping and Heterogeneous Grouping in Gifted Students’ Reading Achievement
The educational focus of the United States is on ensuring that all students are proficient in the areas of reading and math. Most academically gifted and talented students are placed in heterogeneously grouped classrooms; thereby, ignoring the needs of these talented readers. This quantitative causal-comparative study sought to determine if a difference existed between the reading achievement growth of gifted elementary students who were homogeneously grouped for reading instruction as compared to gifted elementary students who were heterogeneously grouped for reading instruction with a sample size of 119 gifted elementary students in the State of Georgia. Additionally, it looked at differences in pre- and posttest scores of each group individually. The participants were divided into two groups (homogeneous and heterogeneous) according to reading instruction type. An analysis of covariance determined that there was no significant difference between the homogeneous and heterogeneous groups. Paired samples t-test determined that there were differences in pre- and posttest scores for both the homogeneous group and the heterogeneous groups. Recommendations for future research are to conduct research with a larger sample and controlling for such things as teacher experience, teacher certifications, instructional methods, testing, and grouping
United States v. Fidel Castro-Verdugo: Unlawfully Sentenced Defendant Is Procedurally Barred From Relief
In United States v. Fidel Castro-Verdugo, the Ninth Circuit held that the court lacks the jurisdiction to correct an underlying unlawful sentence imposed by the district court in the context of a probation revocation appeal. Despite clear error on the part of the sentencing judge, Defendant-Appellant (Defendant) did not timely file a petition for a writ of habeas corpus; therefore, no remedy was available to him. The dissenting opinion asserted that the court did have jurisdiction to correct the error because Defendant appealed from a later sentence erroneously based on the underlying unlawful sentence. Noting that it is the role of appellate courts to correct errors made by lower courts, the dissent disagreed strongly with the majority’s decision to uphold a known error
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