437 research outputs found
Existence of Fermion Zero Modes and Deconfinement of Spinons in Quantum Antiferromagnetism resulting from Algebraic Spin Liquid
We investigate the quantum antiferromagnetism arising from algebraic spin
liquid via spontaneous chiral symmetry breaking. We claim that in the
antiferromagnet massive Dirac spinons can appear to make broad continuum
spectrum at high energies in inelastic neutron scattering. The mechanism of
spinon deconfinement results from the existence of fermion zero modes in single
monopole potentials. Neel vectors can make a skyrmion configuration around a
magnetic monopole of compact U(1) gauge fields. Remarkably, in the
monopole-skyrmion composite potential the Dirac fermion is shown to have a zero
mode. The emergence of the fermion zero mode forbids the condensation of
monopoles, resulting in deconfinement of Dirac spinons in the quantum
antiferromagnet.Comment: K. -S. Kim is much indebted to Dr. A. Tanaka who pointed out a
mistake in association with the gradient expansion in Eq. (C3) and Eq. (C4
Clinical assessment of gestational age in the newborn
The scoring method of Dubowitz et al. was used for the assessment of gestational age in 100 newborn Cape Colored infants. The accuracy of prediction of gestational age by this method was confirmed.Publishers' Versio
A Pixel Vertex Tracker for the TESLA Detector
In order to fully exploit the physics potential of a e+e- linear collider,
such as TESLA, a Vertex Tracker providing high resolution track reconstruction
is required. Hybrid Silicon pixel sensors are an attractive sensor technology
option due to their read-out speed and radiation hardness, favoured in the high
rate TESLA environment, but have been so far limited by the achievable single
point space resolution. A novel layout of pixel detectors with interleaved
cells to improve their spatial resolution is introduced and the results of the
characterisation of a first set of test structures are discussed. In this note,
a conceptual design of the TESLA Vertex Tracker, based on hybrid pixel sensors
is presentedComment: 20 pages, 11 figure
High resolution pixel detectors for e+e- linear colliders
The physics goals at the future e+e- linear collider require high performance
vertexing and impact parameter resolution. Two possible technologies for the
vertex detector of an experimental apparatus are outlined in the paper: an
evolution of the Hybrid Pixel Sensors already used in high energy physics
experiments and a new detector concept based on the monolithic CMOS sensors.Comment: 8 pages, to appear on the Proceedings of the International Workshop
on Linear Colliders LCWS99, Sitges (Spain), April 28 - May 5, 199
AGK Cutting Rules and Multiple Scattering in Hadronic Collisions
We discuss the AGK rules for the exchange of an arbitrary number of reggeized
gluons in perturbative QCD in the high energy limit. Results include the
cancellation of corrections to single jet and double jet inclusive cross
sections, both for hard and soft rescattering contributions.Comment: 31 pages, latex, 20 figure
Inclusive 1-jet Production Cross Section at Small x in QCD: Multiple Interactions
We study corrections due to two Pomeron exchanges to the inclusive 1-jet
production cross section in the Regge limit of perturbative QCD for a finite
number of colors. By considering deep inelastic scattering on a weakly bound
two-nucleon system, we carefully follow the logic of the AGK cutting rules and
show, for the single inclusive cross section, that, due to the reggeization of
the gluon, modifications of the AGK cutting rules appear. As our main result,
we investigate and calculate the jet production vertex in the presence of a
two-Pomeron cut correction. Compared to previous studies, we find a novel
structure of the jet vertex which has not been considered before. We discuss a
few implications of this new piece.Comment: 42 pages, 22 figures, few references and comments added, to appear on
JHE
A Large Area Fiber Optic Gyroscope on multiplexed fiber network
We describe a fiber optical gyroscope based on the Sagnac effect realized on a multiplexed telecom fiber network. Our loop encloses an area of 20 km2 and coexists with Internet data traffic. This Sagnac interferometer achieves a sensitivity of about (10-8 rad/s)/sqrt(Hz), thus approaching ring laser gyroscopes without using narrow linewidth laser nor sophisticated optics. The proposed gyroscope is sensitive enough for seismic applications, opening new possibilities for this kind of optical fiber sensors
Quantization of the Chern-Simons Coupling Constant
We investigate the quantum consistency of p-form Maxwell-Chern-Simons
electrodynamics in 3p+2 spacetime dimensions (for p odd). These are the
dimensions where the Chern--Simons term is cubic, i.e., of the form FFA. For
the theory to be consistent at the quantum level in the presence of magnetic
and electric sources, we find that the Chern--Simons coupling constant must be
quantized. We compare our results with the bosonic sector of eleven dimensional
supergravity and find that the Chern--Simons coupling constant in that case
takes its corresponding minimal allowed value.Comment: 15 pages, 1 figure, JHEP3.cls. Equation (8.6) corrected and perfect
agreement with previous results is obtaine
Microcrystalline Bi2ZnB2O7-polymer composites with silver nanoparticles as materials for laser operated devices
A novel type of composite for optoelectronic which is operated by second harmonic generation in the Bi2ZnB2O7 crystallites (with sizes varying within 1â30 Όm) and Ag nanoparticles (NP) embedded in PMMA polymer composites is proposed. The substantial influence of the Ag NP on the bicolor induced second harmonic generation was established. The phototreatment was performed by bicolor beams of nanosecond Nd:YAG laser (1,064/532 nm) at angles between the fundamental and photoinducing beams varying within the 19°â21° range. The studies of the corresponding dependences of the SHG during illumination by the two coherent beams at 1,064/532 nm showed a maximal enhancement of the output SHG for the Ag NP average sizes equal to about 40 nm. The role of the excited plasmons may be here crucial. Additionally the time shift between the fundamental and the doubled frequency beam maxima was found, which shows strong sensitivity to illumination. The established time shift is sensitive to the pumping power
- âŠ