5,487 research outputs found
Relative categories: Another model for the homotopy theory of homotopy theories
We lift Charles Rezk's complete Segal space model structure on the category
of simplicial spaces to a Quillen equivalent one on the category of relative
categories.Comment: 27 pages. Updated to correct typographical error
A characterization of simplicial localization functors
We characterize simplicial localization functors among relative functors from
relative categories to simplicial categories as any choice of homotopy inverse
to the delocalization functor of Dwyer and the second author.Comment: 7 pages. Typographical errors correcte
n-relative categories: a model for the homotopy theory of n-fold homotopy theories
We introduce, for every integer n ≥ 1, the notion of an n-relative category and show that the category of the small n-relative categories is a model for the homotopy theory of n-fold homotopy theories, i.e., homotopy theories of… homotopy theories
A 3-D Track-Finding Processor for the CMS Level-1 Muon Trigger
We report on the design and test results of a prototype processor for the CMS
Level-1 trigger that performs 3-D track reconstruction and measurement from
data recorded by the cathode strip chambers of the endcap muon system. The
tracking algorithms are written in C++ using a class library we developed that
facilitates automatic conversion to Verilog. The code is synthesized into
firmware for field-programmable gate-arrays from the Xilinx Virtex-II series. A
second-generation prototype has been developed and is currently under test. It
performs regional track-finding in a 60 degree azimuthal sector and accepts 3
GB/s of input data synchronously with the 40 MHz beam crossing frequency. The
latency of the track-finding algorithms is expected to be 250 ns, including
geometrical alignment correction of incoming track segments and a final
momentum assignment based on the muon trajectory in the non-uniform magnetic
field in the CMS endcaps.Comment: 7 pages, 5 figures, proceedings for the conference on Computing in
High Energy and Nuclear Physics, March 24-28 2003, La Jolla, Californi
Kondo Effect in Fermi Systems with a Gap: A Renormalization Group Study
We present the results of a Wilson Renormalization Group study of the
single-impurity Kondo and Anderson models in a system with a gap in the
conduction electron spectrum. The behavior of the impurity susceptibility and
the zero-frequency response function, are discussed in the
cases with and without particle-hole symmetry. In addition, for the asymmetric
Anderson model the correlation functions, , are computed.Comment: 10 pages, 10 figure
X-ray Dichroism and the Pseudogap Phase of Cuprates
A recent polarized x-ray absorption experiment on the high temperature
cuprate superconductor Bi2Sr2CaCu2O8 indicates the presence of broken parity
symmetry below the temperature, T*, where a pseudogap appears in photoemission.
We critically analyze the x-ray data, and conclude that a parity-breaking
signal of the kind suggested is unlikely based on the crystal structures
reported in the literature. Possible other origins of the observed dichroism
signal are discussed. We propose x-ray scattering experiments that can be done
in order to determine whether such alternative interpretations are valid or
not.Comment: final version to be published in Phys Rev B: some calculational
details added, clarification of XNLD contamination and biaxiality, more
discussion on possible space groups and previous optics result
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