32,239 research outputs found
Revisiting the Hanbury Brown-Twiss set-up for fractional statistics
The Hanbury Brown-Twiss experiment has proved to be an effective means of
probing statistics of particles. Here, in a set-up involving edge-state
quasiparticles in a fractional quantum Hall system, we show that a variant of
the experiment composed of two sources and two sinks can be used to unearth
fractional statistics. We find a clear cut signature of the statistics in the
equal-time current-current correlation function for quasiparticle currents
emerging from the two sources and collected at the sinks.Comment: 4 pages, 3 figure
Microarray-based ultra-high resolution discovery of genomic deletion mutations
BACKGROUND: Oligonucleotide microarray-based comparative genomic hybridization (CGH) offers an attractive possible route for the rapid and cost-effective genome-wide discovery of deletion mutations. CGH typically involves comparison of the hybridization intensities of genomic DNA samples with microarray chip representations of entire genomes, and has widespread potential application in experimental research and medical diagnostics. However, the power to detect small deletions is low. RESULTS: Here we use a graduated series of Arabidopsis thaliana genomic deletion mutations (of sizes ranging from 4 bp to ~5 kb) to optimize CGH-based genomic deletion detection. We show that the power to detect smaller deletions (4, 28 and 104 bp) depends upon oligonucleotide density (essentially the number of genome-representative oligonucleotides on the microarray chip), and determine the oligonucleotide spacings necessary to guarantee detection of deletions of specified size. CONCLUSIONS: Our findings will enhance a wide range of research and clinical applications, and in particular will aid in the discovery of genomic deletions in the absence of a priori knowledge of their existence
The effect of 3He impurities on the nonclassical response to oscillation of solid 4He
We have investigated the influence of impurities on the possible supersolid
transition by systematically enriching isotopically-pure 4He (< 1 ppb of 3He)
with 3He. The onset of nonclassical rotational inertia is broadened and shifts
monotonically to higher temperature with increasing 3He concentration,
suggesting that the phenomenon is correlated to the condensation of 3He atoms
onto the dislocation network in solid 4He.Comment: 4 page
Consistency between renormalization group running of chiral operator and counting rule -- Case of chiral pion production operator --
In nuclear chiral perturbation theory (ChPT), an operator is defined in a
space with a cutoff which may be varied within a certain range. The operator
runs as a result of the variation of the cutoff [renormalization group (RG)
running]. In order for ChPT to be useful, the operator should run in a way
consistent with the counting rule; that is, the running of chiral counter terms
have to be of natural size. We vary the cutoff using the Wilsonian
renormalization group (WRG) equation, and examine this consistency. As an
example, we study the s-wave pion production operator for NN\to d pi, derived
in ChPT. We demonstrate that the WRG running does not generate any
chiral-symmetry-violating (CSV) interaction, provided that we start with an
operator which does not contain a CSV term. We analytically show how the
counter terms are generated in the WRG running in case of the infinitesimal
cutoff reduction. Based on the analytic result, we argue a range of the cutoff
variation for which the running of the counter terms is of natural size. Then,
we numerically confirm this.Comment: 28 pages, 5 figures, significantly changed, published versio
Vibration-induced granular segregation: a phenomenon driven by three mechanisms
The segregation of large spheres in a granular bed under vertical vibrations
is studied. In our experiments we systematically measure rise times as a
function of density, diameter and depth; for two different sinusoidal
excitations. The measurements reveal that: at low frequencies, inertia and
convection are the only mechanisms behind segregation. Inertia (convection)
dominates when the relative density is greater (less) than one. At high
frequencies, where convection is suppressed, fluidization of the granular bed
causes either buoyancy or sinkage and segregation occurs.Comment: 4 pages. 3 figures, revtex4, to appear in PRL (in press
Proton-Rich Nuclear Statistical Equilibrium
Proton-rich material in a state of nuclear statistical equilibrium (NSE) is
one of the least studied regimes of nucleosynthesis. One reason for this is
that after hydrogen burning, stellar evolution proceeds at conditions of equal
number of neutrons and protons or at a slight degree of neutron-richness.
Proton-rich nucleosynthesis in stars tends to occur only when hydrogen-rich
material that accretes onto a white dwarf or neutron star explodes, or when
neutrino interactions in the winds from a nascent proto-neutron star or
collapsar-disk drive the matter proton-rich prior to or during the
nucleosynthesis. In this paper we solve the NSE equations for a range of
proton-rich thermodynamic conditions. We show that cold proton-rich NSE is
qualitatively different from neutron-rich NSE. Instead of being dominated by
the Fe-peak nuclei with the largest binding energy per nucleon that have a
proton to nucleon ratio close to the prescribed electron fraction, NSE for
proton-rich material near freeze-out temperature is mainly composed of Ni56 and
free protons. Previous results of nuclear reaction network calculations rely on
this non-intuitive high proton abundance, which this paper will explain. We
show how the differences and especially the large fraction of free protons
arises from the minimization of the free energy as a result of a delicate
competition between the entropy and the nuclear binding energy.Comment: 4 pages, 7 figure
Muon Anomalous and Gauged Models
In this paper we study contribution to of the muon anomalous
magnetic dipole moment in gauged models. Here are
the lepton numbers. We find that there are three classes of models which can
produce a large value of to account for possible discrepancy between the
experimental data and the Standard Model prediction. The three classes are: a)
Models with an exact . In these models, is
massless. The new gauge interaction coupling is constrained
to be . b) Models with broken
and the breaking scale is not related to electroweak
symmetry breaking scale. The gauge boson is massive. The allowed range of
the coupling and the mass are constrained, but mass can be large; And
c) The is broken and the breaking scale is related to the
electroweak scale. In this case the mass is constrained to be
GeV. We find that there are interesting experimental signatures in
in these models.Comment: 13 pages, 9 figure
Sound propagation in density wave conductors and the effect of long-range Coulomb interaction
We study theoretically the sound propagation in charge- and spin-density
waves in the hydrodynamic regime. First, making use of the method of comoving
frame, we construct the stress tensor appropriate for quasi-one dimensional
systems within tight-binding approximation. Taking into account the screening
effect of the long-range Coulomb interaction, we find that the increase of the
sound velocity below the critical temperature is about two orders of magnitude
less for longitudinal sound than for transverse one. It is shown that only the
transverse sound wave with displacement vector parallel to the chain direction
couples to the phason of the density wave, therefore we expect significant
electromechanical effect only in this case.Comment: revtex, 14 pages (in preprint form), submitted to PR
Kaon differential flow in relativistic heavy-ion collisions
Using a relativistic transport model, we study the azimuthal momentum
asymmetry of kaons with fixed transverse momentum, i.e., the differential flow,
in heavy-ion collisions at beam momentum of 6 GeV/c per nucleon, available from
the Alternating Gradient Synchrotron (AGS) at the Brookhaven National
Laboratory (BNL). We find that in the absence of kaon potential the kaon
differential flow is positive and increases with transverse momentum as that of
nucleons. The repulsive kaon potential as predicted by theoretical models,
however, reduces the kaon differetnial flow, changing it to negative for kaons
with low momenta. Cancellation between the negative differential flow at low
mementa and the positive one at high momenta is then responsible for the
experimentally observed nearly vanishing in-plane transverse flow of kaons in
heavy ion experiments.Comment: Phys. Rev. C in pres
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