12,977 research outputs found
Asymptotic deconfinement in high-density QCD
We discuss QCD with two light flavors at large baryon chemical potential mu.
Color superconductivity leads to partial breaking of the color SU(3) group. We
show that the infrared physics is governed by the gluodynamics of the remaining
SU(2) group with an exponentially soft confinement scale Lambda_QCD'
Delta*exp[-a*mu/(g*Delta)], where Delta<<mu is the superconducting gap, g is
the strong coupling, and a=0.81... We estimate that at moderate baryon
densities Lambda_QCD' is O(10 MeV) or smaller. The confinement radius increases
exponentially with density, leading to "asymptotic deconfinement." The velocity
of the SU(2) gluons is small due to the large dielectric constant of the
medium.Comment: 4 pages; restructured, published versio
Low-power and high-detectivity Ge photodiodes by in-situ heavy As doping during Ge-on-Si seed layer growth
Germanium (Ge)-based photodetectors have become one of the mainstream components in photonic-integrated circuits (PICs). Many emerging PIC applications require the photodetectors to have high detectivity and low power consumption. Herein, we demonstrate high-detectivity Ge vertical p-i-n photodiodes on an in-situ heavily arsenic (As)-doped Ge-on-Si platform. The As doping was incorporated during the initial Ge-on-Si seed layer growth. The grown film exhibits an insignificant up-diffusion of the As dopants. The design results in a âŒ45Ă reduction on the dark current and consequently a âŒ5Ă enhancement on the specific detectivity (D*) at low reverse bias. The improvements are mainly attributed to the improved epi-Ge crystal quality and the narrowing of the device junction depletion width. Furthermore, a significant deviation on the AsH3 flow finds a negligible effect on the D* enhancement. This unconventional but low-cost approach provides an alternative solution for future high-detectivity and low-power photodiodes in PICs. This method can be extended to the use of other n-type dopants (e.g., phosphorus (P) and antimony (Sb)) as well as to the design of other types of photodiodes (e.g., waveguide-integrated)
Global Strings in High Density QCD
We show that several types of global strings occur in colour superconducting
quark matter due to the spontaneous violation of relevant U(1) symmetries.
These include the baryon U(1)_B, and approximate axial U(1)_A symmetries as
well as an approximate U(1)_S arising from kaon condensation. We discuss some
general properties of these strings and their interactions. In particular, we
demonstrate that the U(1)_A strings behave as superconducting strings. We draw
some parallels between these strings and global cosmological strings and
discuss some possible implications of these strings to the physics in neutron
star cores.Comment: LaTeX JHEP-format (26 pages) Option in source for REVTeX4 forma
Persistence of insecticidal activity of novel bio-encapsulated formulations of Bacillus thuringiensis var. kurstaki against Choristoneura rosaceana [Lepidoptera: Tortricidae]
Le DiPelTM, une formulation commerciale du Bacillus thuringiensis var. kurstaki (Btk), et des formulations bio-encapsulĂ©es du Btk ont Ă©tĂ© pulvĂ©risĂ©es dans un verger de pommiers. Pendant trois annĂ©es consĂ©cutives, leur persistance a Ă©tĂ© Ă©valuĂ©e en laboratoire sur des larves de tordeuse Ă bandes obliques (Choristoneura rosaceana). En 1995, le DiPel et la formulation bio-encapsulĂ©e ont causĂ© une mortalitĂ© larvaire significativement plus grande que celle du tĂ©moin, au moins 1 jour et jusquâĂ 27 jours aprĂšs les traitements, respectivement. En 1996, bien que 6 mm de pluie soient tombĂ©s la journĂ©e des traitements, le DiPel et la formulation bio-encapsulĂ©e ont causĂ© respectivement 21 et 33 % de mortalitĂ© larvaire immĂ©diatement aprĂšs les traitements. Le DiPel a causĂ© une mortalitĂ© significativement plus grande que celle du tĂ©moin pour une pĂ©riode de trois jours aprĂšs les traitements alors que la formulation bio-encapsulĂ©e a causĂ© une mortalitĂ© plus grande pendant 14 jours. En 1997, deux souches de Btk (HD-1 et BMP123) ont Ă©tĂ© pulvĂ©risĂ©es Ă des concentrations diffĂ©rentes en matiĂšre active (3 et 8 %) et en doses (30 et 240 g 15 L-1). Des concentrations Ă©levĂ©es en matiĂšre active et des doses Ă©levĂ©es ont accru la persistance de lâactivitĂ© insecticide des formulations de Btk. Parmi les facteurs mĂ©tĂ©orologiques mesurĂ©s (prĂ©cipitations, tempĂ©rature et radiations solaires), les prĂ©cipitations ont rĂ©duit la persistance de lâactivitĂ© insecticide. Les radiations solaires peuvent Ă©galement avoir contribuĂ© Ă moduler la persistance des formulations.DiPelTM, a registered Bacillus thuringiensis var. kurstaki (Btk)-based formulation, and experimental bio-encapsulated Btk formulations were sprayed in an apple orchard. Their persistence was assessed in the laboratory against obliquebanded leafroller (Choristoneura rosaceana) larvae for three consecutive years. In 1995, DiPel and the bio-encapsulated formulation caused significantly higher larval mortality than the control at least 1 day, and up to 27 days after treatments, respectively. In 1996, although 6.4 mm of rain fell during the day of treatments, DiPel and the bio-encapsulated formulation caused respectively 21 and 33% larval mortality immediately after treatments. DiPel caused significantly higher mortality than the control for up to 3 days while the bio-encapsulated formulation caused significantly higher mortality for up to 14 days. In 1997, two Btk strains (HD-1 and BMP123) were sprayed at different concentrations in a.i. (3 and 8%) and doses (30 and 240 g 15 L-1 applied). Higher concentrations of a.i. in the Btk formulations and higher doses sprayed increased the persistence of the insecticidal activity. Among the meteorological factors that were measured (i.e. precipitations, temperature and solar radiations), precipitations reduced the persistence of the insecticidal activity. Solar radiations may have modulated the persistence of the formulations
Pion Propagation near the QCD Chiral Phase Transition
We point out that, in analogy with spin waves in antiferromagnets, all
parameters describing the real-time propagation of soft pions at temperatures
below the QCD chiral phase transition can be expressed in terms of static
correlators. This allows, in principle, the determination of the soft pion
dispersion relation on the lattice. Using scaling and universality arguments,
we determine the critical behavior of the parameters of pion propagation. We
predict that when the critical temperature is approached from below, the pole
mass of the pion drops despite the growth of the pion screening mass. This fact
is attributed to the decrease of the pion velocity near the phase transition.Comment: 8 pages (single column), RevTeX; added references, version to be
published in PR
A Static Optimality Transformation with Applications to Planar Point Location
Over the last decade, there have been several data structures that, given a
planar subdivision and a probability distribution over the plane, provide a way
for answering point location queries that is fine-tuned for the distribution.
All these methods suffer from the requirement that the query distribution must
be known in advance.
We present a new data structure for point location queries in planar
triangulations. Our structure is asymptotically as fast as the optimal
structures, but it requires no prior information about the queries. This is a
2D analogue of the jump from Knuth's optimum binary search trees (discovered in
1971) to the splay trees of Sleator and Tarjan in 1985. While the former need
to know the query distribution, the latter are statically optimal. This means
that we can adapt to the query sequence and achieve the same asymptotic
performance as an optimum static structure, without needing any additional
information.Comment: 13 pages, 1 figure, a preliminary version appeared at SoCG 201
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