5,415 research outputs found
Interference Effects, Time Reversal Violation and Search for New Physics in Hadronic Weak Decays
We propose some methods for studying hadronic sequential two-body decays
involving more spinning particles. It relies on the analysis of T-odd and
T-even asymmetries, which are related to interference terms. The latter
asymmetries turn out to be as useful as the former ones in inferring time
reversal violating observables; these in turn may be sensitive, under some
particular conditions, to possible contributions beyond the standard model. Our
main result is that one can extract such observables even after integrating the
differential decay width over almost all of the available angles. Moreover we
find that the correlations based exclusively on momenta are quite general,
since they provide as much information as those involving one or more spins. We
generalize some methods already proposed in the literature for particular decay
channels, but we also pick out a new kind of time reversal violating
observables. Our analysis could be applied, for example, to data of LHCb
experiment.Comment: 35 page
Self-organized Vortex State in Two-dimensional Dictyostelium Dynamics
We present results of experiments on the dynamics of Dictyostelium discoideum
in a novel set-up which constraints cell motion to a plane. After aggregation,
the amoebae collect into round ''pancake" structures in which the cells rotate
around the center of the pancake. This vortex state persists for many hours and
we have explicitly verified that the motion is not due to rotating waves of
cAMP. To provide an alternative mechanism for the self-organization of the
Dictyostelium cells, we have developed a new model of the dynamics of
self-propelled deformable objects. In this model, we show that cohesive energy
between the cells, together with a coupling between the self-generated
propulsive force and the cell's configuration produces a self-organized vortex
state. The angular velocity profiles of the experiment and of the model are
qualitatively similar. The mechanism for self-organization reported here can
possibly explain similar vortex states in other biological systems.Comment: submitted to PRL; revised version dated 3/8/9
On the Use of Minimum Volume Ellipsoids and Symplectic Capacities for Studying Classical Uncertainties for Joint Position-Momentum Measurements
We study the minimum volume ellipsoid estimator associates to a cloud of
points in phase space. Using as a natural measure of uncertainty the symplectic
capacity of the covariance ellipsoid we find that classical uncertainties obey
relations similar to those found in non-standard quantum mechanics
Oxygen isotope effect on the in-plane penetration depth in underdoped La_{2-x}Sr_{x}CuO_{4} single crystals
We report measurements of the oxygen isotope effect (OIE) on the in-plane
penetration depth \lambda_{ab}(0) in underdoped La_{2-x}Sr_{x}CuO_{4} single
crystals. A highly sensitive magnetic torque sensor with a resolution of \Delta
\tau ~ 10^{-12} Nm was used for the magnetic measurements on microcrystals with
a mass of ~ 10 microg. The OIE on \lambda_{ab}^{-2}(0) is found to be -10(2)%
for x = 0.080 and -8(1)% for x = 0.086. It arises mainly from the oxygen mass
dependence of the in-plane effective mass m_{ab}*. The present results suggest
that lattice vibrations are important for the occurrence of high temperature
superconductivity.Comment: 4 pages, 3 figures, submitted to PR
A high-pressure hydrogen time projection chamber for the MuCap experiment
The MuCap experiment at the Paul Scherrer Institute performed a
high-precision measurement of the rate of the basic electroweak process of
nuclear muon capture by the proton, . The
experimental approach was based on the use of a time projection chamber (TPC)
that operated in pure hydrogen gas at a pressure of 10 bar and functioned as an
active muon stopping target. The TPC detected the tracks of individual muon
arrivals in three dimensions, while the trajectories of outgoing decay (Michel)
electrons were measured by two surrounding wire chambers and a plastic
scintillation hodoscope. The muon and electron detectors together enabled a
precise measurement of the atom's lifetime, from which the nuclear muon
capture rate was deduced. The TPC was also used to monitor the purity of the
hydrogen gas by detecting the nuclear recoils that follow muon capture by
elemental impurities. This paper describes the TPC design and performance in
detail.Comment: 15 pages, 13 figures, to be submitted to Eur. Phys. J. A; clarified
section 3.1.2 and made minor stylistic corrections for Eur. Phys. J. A
requirement
Outcome Measures for Interventions to Reduce Inappropriate Chronic Drugs: A Narrative Review
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163374/3/jgs16697-sup-0001-Supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163374/2/jgs16697_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163374/1/jgs16697.pd
Fuzzy Torus via q-Parafermion
We note that the recently introduced fuzzy torus can be regarded as a
q-deformed parafermion. Based on this picture, classification of the Hermitian
representations of the fuzzy torus is carried out. The result involves
Fock-type representations and new finite dimensional representations for q
being a root of unity as well as already known finite dimensional ones.Comment: 12pages, no figur
Bound-to-bound and bound-to-continuum optical transitions in combined quantum dot - superlattice systems
By combining band gap engineering with the self-organized growth of quantum
dots, we present a scheme of adjusting the mid-infrared absorption properties
to desired energy transitions in quantum dot based photodetectors. Embedding
the self organized InAs quantum dots into an AlAs/GaAs superlattice enables us
to tune the optical transition energy by changing the superlattice period as
well as by changing the growth conditions of the dots. Using a one band
envelope function framework we are able, in a fully three dimensional
calculation, to predict the photocurrent spectra of these devices as well as
their polarization properties. The calculations further predict a strong impact
of the dots on the superlattices minibands. The impact of vertical dot
alignment or misalignment on the absorption properties of this dot/superlattice
structure is investigated. The observed photocurrent spectra of vertically
coupled quantum dot stacks show very good agreement with the calculations.In
these experiments, vertically coupled quantum dot stacks show the best
performance in the desired photodetector application.Comment: 8 pages, 10 figures, submitted to PR
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