6,045 research outputs found
Operator product expansion and the short distance behavior of 3-flavor baryon potentials
The short distance behavior of baryon-baryon potentials defined through
Nambu-Bethe-Salpeter wave functions is investigated using the operator product
expansion. In a previous analysis of the nucleon-nucleon case, corresponding to
the SU(3) channels and , we argued that the potentials
have a repulsive core. A new feature occurs for the case of baryons made up of
three flavors: manifestly asymptotically attractive potentials appear in the
singlet and octet channels. Attraction in the singlet channel was first
indicated by quark model considerations, and recently been found in numerical
lattice simulations. The latter have however not yet revealed asymptotic
attraction in the octet channels; we give a speculative explanation for this
apparent discrepancy.Comment: 11 pages, 2 figure
Ground-State Decay Rate for the Zener Breakdown in Band and Mott Insulators
Non-linear transport of electrons in strong electric fields, as typified by
dielectric breakdown, is re-formulated in terms of the ground-state decay rate
originally studied by Schwinger in non-linear QED. We discuss the effect of
electron interaction on Zener tunneling by comparing the dielectric breakdown
of the band insulator and the Mott insulator, where the latter is studied by
the time-dependent density-matrix renormalization group (DMRG). The relation
with the Berry's phase theory of polarization is also established.Comment: 5 pages 2 figures, revised text, version to appear in Phys. Rev. Let
A narrow quasi-bound state
The energies and widths of quasi-bound states with isospin I=1/2 are
evaluated in two methods, the fixed center approximation to the Faddeev
equation and the variational method approach to the effective one-channel
Hamiltonian. The interactions are constructed so that they dynamically
generate the (I=0, ) resonance state. We find
that the system is bound by about 250 MeV from the threshold, MeV. Its width including both the mesonic decay and the
absorption, is estimated to be about 20-40 MeV. The I=0 pair in the
system is found to form a cluster that is similar to the .Comment: 17 pages, 18 figures, 3 table
A Chandra Proper Motion for PSR J1809-2332
We report on a new Chandra exposure of PSR J1809-2332, the recently
discovered pulsar powering the bright EGRET source 3EG J1809-2328. By
registration of field X-ray sources in an archival exposure, we measure a
significant proper motion for the pulsar point source over an ~11 year
baseline. The shift of 0.30+/-0.06" (at PA= 153.3+/-18.4) supports an
association with proposed SNR parent G7.5-1.7. Spectral analysis of diffuse
emission in the region also supports the interpretation as a hard wind nebula
trail pointing back toward the SNR.Comment: To Appear in the Astrophysical Journal, Sept 1 (v. 756
Breakdown of an Electric-Field Driven System: a Mapping to a Quantum Walk
Quantum transport properties of electron systems driven by strong electric
fields are studied by mapping the Landau-Zener transition dynamics to a quantum
walk on a semi-infinite one-dimensional lattice with a reflecting boundary,
where the sites correspond to energy levels and the boundary the ground state.
Quantum interference induces a distribution localized around the ground state,
and when the electric field is strengthened, a delocalization transition occurs
describing breakdown of the original electron system.Comment: 4 pages, 3 figures, Journal-ref adde
KN and KbarN Elastic Scattering in the Quark Potential Model
The KN and KbarN low-energy elastic scattering is consistently studied in the
framework of the QCD-inspired quark potential model. The model is composed of
the t-channel one-gluon exchange potential, the s-channel one-gluon exchange
potential and the harmonic oscillator confinement potential. By means of the
resonating group method, nonlocal effective interaction potentials for the KN
and KbarN systems are derived and used to calculate the KN and KbarN elastic
scattering phase shifts. By considering the effect of QCD renormalization, the
contribution of the color octet of the clusters (qqbar) and (qqq) and the
suppression of the spin-orbital coupling, the numerical results are in fairly
good agreement with the experimental data.Comment: 20 pages, 8 figure
Cattle ticks population and prevalence of Babesia spp amongst it vector: Rhipicephalus (Boophilus) microplus in a zone of Ivory Coast
The aim of this survey is to evaluate prevalence of Babesia spp in Rhipicephalus (Boophilus) microplus and the importance of ticks species existing in Bingerville area. In this cross sectional study, thirty six cattlefrom 6 farms have been sampled in Bingerville area (Ivory coast Southeast). From 511 ticks collected, 102 Ambyomma spp (19.97%) and 409 Rhipicephalus (Boophilus) microplus (80.03%) were identified. Then, theprevalence of Babesia spp parasites amongst Rhipicephalus (Boophilus) microplus was focused. With 120 engorged females of Rhipicephalus (Boophilus) microplus, 24 pools of 5 ticks each were done. The Giemsastain test had shown prevalences of 8.33% and 1.73% of Babesia spp respectively in pool and individual levels
Parametric amplification with a friction in heavy ion collisions
We study the effects of the expansion of the system and the friction on the
parametric amplification of mesonic fields in high energy heavy ion collisions
within the linear model . The equation of motion which is similar to
Mathieu equation is derived to describe the time development of classical
fields in the last stage of a heavy ion collision after the freezeout time. The
enhanced mode is extracted analytically by comparison with Mathieu equation and
the equation of motion is solved numerically to examine whether soft modes will
be enhanced or not. It is found that the strong peak appears around 267 MeV in
the pion transverse momentum distribution in cases with weak friction and high
maximum temperature. This enhancement can be extracted by taking the ratio
between different modes in the pion transverse momentum distribution.Comment: 10 pages, 9 figures LaTeX: appendix adde
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