11,241 research outputs found
Universal Properties of Two-Dimensional Boson Droplets
We consider a system of N nonrelativistic bosons in two dimensions,
interacting weakly via a short-range attractive potential. We show that for N
large, but below some critical value, the properties of the N-boson bound state
are universal. In particular, the ratio of the binding energies of (N+1)- and
N-boson systems, B_{N+1}/B_N, approaches a finite limit, approximately 8.567,
at large N. We also confirm previous results that the three-body system has
exactly two bound states. We find for the ground state B_3^(0) = 16.522688(1)
B_2 and for the excited state B_3^(1) = 1.2704091(1) B_2.Comment: 4 pages, 2 figures, final versio
Recommended from our members
Synthesis, structural characterisation and thermoelectric properties of Bi1−xPbxOCuSe
The effect of Pb2+ doping on the structure and thermoelectric properties of BiOCuSe (also known as BiCuSeO or BiCuOSe) is described. With increasing Pb2+ content, the expansion of the unit cell results in a weakening of the bonding between the [Bi2(1-x) Pb2xO2]2(1-x)+ and the [Cu2Se2]2(1-x)- layers. The electrical resistivity and Seebeck coefficient decrease in a systematic way with growing Pb2+ levels. The thermal conductivity rises due to the increase of the electronic contribution with doping. The power factor of materials with a 4-5% Pb2+ content takes values of ca. 8 W cm-1 K-2 over a wide temperature range. ZT at 673 K is enhanced by ca. 50% when compared to values found for other dopants, such as Sr2+ or Mg2+
Spontaneous Symmetry Breaking with Abnormal Number of Nambu-Goldstone Bosons and Kaon Condensate
We describe a class of relativistic models incorporating finite density of
matter in which spontaneous breakdown of continuous symmetries leads to a
lesser number of Nambu-Goldstone bosons than that required by the Goldstone
theorem. This class, in particular, describes the dynamics of the kaon
condensate in the color-flavor locked phase of high density QCD. We describe
the spectrum of low energy excitations in this dynamics and show that, despite
the presence of a condensate and gapless excitations, this system is not a
superfluid.Comment: 5 pages, 1 figure, REVTeX. Minor revisions made and 2 new references
added. To appear in Phys. Rev. Let
Inverse meson mass ordering in color-flavor-locking phase of high density QCD: erratum
We correct a mistake in the calculation of meson masses at large baryon
chemical potential made in hep-ph/9910491v2Comment: 2 pages, 1 figure, erratum to hep-ph/9910491v
Mercury and Water Quality Study. Impact of Gold Mining in Song Bung 4 Project Area, Central Vietnam
Årsliste 2006The aim of this study is to elucidate any impact that the mining activity in the catchment of Song Bung River has on the water quality, sediment quality, as well as for the fish and the fish flesh quality in the mainstream river and in some tributaries in the Song Bung 4 hydropower development project area. In Song Bung mainstream enhanced concentrations of mercury were found both in the water and in the sediments in the river stretch where gold dredging activity was carried out. The concentrations were however low, much lower than problem levels both in national and internationally recognized environmental quality guidelines. This also applied for the tributaries. For arsenic and all other heavy metals normally confined with mining activity, observed concentrations were all lower than levels known to give environmental or consumption concerns. In the downstream part of the tributaries no traces of cyanide pollution were detected. The concentrations of mercury and other heavy metals in fish flesh were all low, and well below the WHO standards for consumption. The sediment dredging had only moderate impact on river water turbidity. However, the dredging made large physical disturbances of river habitats in the dredged sections of the rivers. Otherwise the water quality of Song Bung River was good and was to a low degree impacted by human activities. The mercury pollution of river sediments from the gold mining was so small that it will not create problems in the planned reservoir of Song Bung 4 Hydropower plant.Asian Development Ban
Recommended from our members
The impact of the state of the troposphere on the response to stratospheric heating in a simplified GCM
Previous studies have made use of simplified general circulation models (sGCMs) to investigate the atmospheric response to various forcings. In particular, several studies have investigated the tropospheric response to changes in stratospheric temperature. This is potentially relevant for many climate forcings. Here the impact of changing the tropospheric climatology on the modeled response to perturbations in stratospheric temperature is investigated by the introduction of topography into the model and altering the tropospheric jet structure.
The results highlight the need for very long integrations so as to determine accurately the magnitude of response. It is found that introducing topography into the model and thus removing the zonally symmetric nature of the model’s boundary conditions reduces the magnitude of response to stratospheric heating. However, this reduction is of comparable size to the variability in the magnitude of response between different ensemble members of the same 5000-day experiment.
Investigations into the impact of varying tropospheric jet structure reveal a trend with lower-latitude/narrower jets having a much larger magnitude response to stratospheric heating than higher-latitude/wider jets. The jet structures that respond more strongly to stratospheric heating also exhibit longer time scale variability in their control run simulations, consistent with the idea that a feedback between the eddies and the mean flow is both responsible for the persistence of the control run variability and important in producing the tropospheric response to stratospheric temperature perturbations
Color Superconductivity from Supersymmetry
A supersymmetric composite model of color superconductivity is proposed.
Quarks and diquarks are dynamically generated as composite fields by a newly
introduced strong gauge dynamics. It is shown that the condensation of the
scalar component of the diquark supermultiplet occurs when the chemical
potential becomes larger than some critical value. We believe that the model
well captures aspects of the diquark condensate behavior and helps our
understanding of the diquark dynamics in real QCD. The results obtained here
might be useful when we consider a theory composed of quarks and diquarks.Comment: 4 pages, 2 figures, An error in Eq.(10) correcte
The shear viscosity of the non-commutative plasma
We compute the shear viscosity of the non-commutative N=4 super Yang-Mills
quantum field theory at strong coupling using the dual supergravity background.
Special interest derives from the fact that the background presents an
intrinsic anisotropy in space through the distinction of commutative and
non-commutative directions. Despite this anisotropy the analysis exhibits the
ubiquitous result \eta/s = 1/4\pi for two different shear channels. In order to
derive this result, we show that the boundary energy momentum tensor must
couple to the open string metric. As a byproduct we compute the renormalised
holographic energy momentum tensor and show that it coincides with one in the
commutative theory.Comment: 17 pages. v2: reference adde
Superconductivity from perturbative one-gluon exchange in high density quark matter
We study color superconductivity in QCD at asymptotically large chemical
potential. In this limit, pairing is dominated by perturbative one-gluon
exchange. We derive the Eliashberg equation for the pairing gap and solve this
equation numerically. Taking into account both magnetic and electric gluon
exchanges, we find with ,
verifying a recent result by Son. For chemical potentials that are of physical
interest, GeV, the calculation ceases to be reliable quantitatively,
but our results suggest that the gap can be as large as 100 MeV.Comment: 19 pages, 6 figures. I accidentally replaced the paper with an
outdated version. This version has typos corrected and will appear in PR
- …