168,549 research outputs found
Plasma Lens Backgrounds at a Future Linear Collider
A 'plasma lens' might be used to enhance the luminosity of future linear
colliders. However, its utility for this purpose depends largely on the
potential backgrounds that may be induced by the insertion of such a device in
the interaction region of the detector. In this note we identify different
sources of such backgrounds, calculate their event rates from the elementary
interaction processes, and evaluate their effects on the major parts of a
hypothetical Next Linear Collider (NLC) detector. For plasma lens parameters
which give a factor of seven enhancement of the luminosity, and using the NLC
design for beam parameters as a reference, we find that the background yields
are fairly high, and require further study and improvements in detector
technology to avoid their impact.Comment: 14 pages incl. 3 figures; contributed to the 4th International
Workshop, Electron-Electron Interactions at TeV Energies, Santa Cruz,
California, Dec. 7 - 9, 2001. To be published in Int.Journ. Mod. Phys.
Magnetic correlations on the full chains of Ortho-II YBaCuO
We propose that the NMR line shape on the chain Cu in the stoichiometric
high- superconductor Ortho-II YBaCuO is determined by the
magnetization induced on Cu near O vacancies, due to strong magnetic
correlations in the chains. An unrestricted Hartree-Fock calculation of a
coupled chain-plane Hubbard model with nearest-neighbor d-wave pairing
interaction shows that the broadening of NMR lines is consistent with
disorder-induced magnetization at low temperatures. In addition, we give a
possible explanation of the anomalous bimodal line shape observed at high
temperatures in terms of nonuniform Cu valence in the chains. The proximity
between chains and CuO plane induces anisotropic magnetization on the planar
Cu, and broadens the plane NMR lines in accordance with that of the chain
lines, in agreement with experiment. We discuss implications of the model for
other experiments on underdoped YBCO.Comment: 8 pages, 8 figures, submitted to PR
A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics
Adherend surfaces and fractography were studied using electron spectroscopy for chemical analysis and scanning electron microscopy/energy dispersive analysis of X-rays. In addition, Auger Electron Spectroscopy with depth profiling capability was used. It is shown that contamination of adhesion systems plays an important role not only in determining initial bond strengths but also in the durability of adhesive bonds. It is concluded that the analytical techniques used to characterize and monitor such contamination
Existence of negative differential thermal conductance in one-dimensional diffusive thermal transport
We show that in a finite one-dimensional (1D) system with diffusive thermal
transport described by the Fourier's law, negative differential thermal
conductance (NDTC) cannot occur when the temperature at one end is fixed. We
demonstrate that NDTC in this case requires the presence of junction(s) with
temperature dependent thermal contact resistance (TCR). We derive a necessary
and sufficient condition for the existence of NDTC in terms of the properties
of the TCR for systems with a single junction. We show that under certain
circumstances we even could have infinite (negative or positive) differential
thermal conductance in the presence of the TCR. Our predictions provide
theoretical basis for constructing NDTC-based devices, such as thermal
amplifiers, oscillators and logic devices
Inconsistency of Naive Dimensional Regularizations and Quantum Correction to Non-Abelian Chern-Simons-Matter Theory Revisited
We find the inconsistency of dimensional reduction and naive dimensional
regularization in their applications to Chern-Simons type gauge theories.
Further we adopt a consistent dimensional regularization to investigate the
quantum correction to non-Abelian Chern-Simons term coupled with fermionic
matter. Contrary to previous results, we find that not only the Chern-Simons
coefficient receives quantum correction from spinor fields, but the spinor
field also gets a finite quantum correction.Comment: 19 pages, RevTex, Feynman diagrams drawn by FEYNMAN routin
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