168,839 research outputs found
Spin and chiral stiffness of the XY spin glass in two dimensions
We analyze the zero-temperature behavior of the XY Edwards-Anderson spin
glass model on a square lattice. A newly developed algorithm combining exact
ground-state computations for Ising variables embedded into the planar spins
with a specially tailored evolutionary method, resulting in the genetic
embedded matching (GEM) approach, allows for the computation of numerically
exact ground states for relatively large systems. This enables a thorough
re-investigation of the long-standing questions of (i) extensive degeneracy of
the ground state and (ii) a possible decoupling of spin and chiral degrees of
freedom in such systems. The new algorithm together with appropriate choices
for the considered sets of boundary conditions and finite-size scaling
techniques allows for a consistent determination of the spin and chiral
stiffness scaling exponents.Comment: 6 pages, 2 figures, proceedings of the HFM2006 conference, to appear
in a special issue of J. Phys.: Condens. Matte
Measuring the Higgs to Photon-Photon Branching Ratio at the Next Linear Collider
We examine the prospects for measuring the photon-photon branching ratio of a
Standard-Model-like Higgs boson () at the Next Linear Collider when
the Higgs boson is produced via --fusion: .
In particular, we study the accuracy of such a measurement and the statistical
significance of the associated signal as a function of the electromagnetic
calorimeter resolution and the Higgs boson mass. We compare results for the
--fusion production/measurement mode with the results obtained for the
production/measurement mode in a
parallel earlier study.Comment: 5 pages, full postscript file also available via anonymous ftp at
ftp://ucdhep.ucdavis.edu/gunion/htogamgam_sm96.ps To appear in ``Proceedings
of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics'
Why Water Markets Are Not Quick Fixes for Droughts in the Western United States
Water in the western United States can be bought and sold, but the transactions will always be complicated. Transfers of water will always be expensive and time consuming because of the hydrologic and institutional interconnections inherent to water. Our data show that most of the water rights in the West are messy. Therefore, markets cannot be quick fixes, and using markets for future water allocation, even if it is economically efficient, will take time and resources to set up. Untangling serial uses and negotiating multiple ownership claims are hurdles, not barriers, and they can be overcome in time but will require both time and money. Buying existing water rights may be less costly than building infrastructure to transport available water from long distances or desalinating seawater, but the transactions will come at a price. Municipalities may purchase water from farmers and thus bear the transaction costs directly, or the private sector may purchase agricultural water (e.g., Two Rivers Water and Farming, Colorado (Landry 2012)), bear the associated risk and transaction costs, and sell it on to municipalities. In either case, the end users will inevitably pay higher prices for water. Markets can and will be part of western U.S. water allocation, but they do not provide quick solutions. Droughts can focus public attention on the value of water and potentially increase the willingness-to-pay prices that reflect the transaction costs of tangled western water markets
Unified life detection system: A concept
Systematic investigation of techniques and hardware which could be utilized in life detection system has resulted in identification of group of candidate concepts and selection of "unified system". Theme of concept permits greatest flexibility in procedural details for experiments which can be performed in individual ampules
Algebras in Higher Dimensional Statistical Mechanics - the Exceptional Partition (MEAN Field) Algebras
We determine the structure of the partition algebra (a generalized
Temperley-Lieb algebra) for specific values of Q \in \C, focusing on the
quotient which gives rise to the partition function of site -state Potts
models (in the continuous formulation) in arbitrarily high lattice
dimensions (the mean field case). The algebra is non-semi-simple iff is a
non-negative integer less than . We determine the dimension of the key
irreducible representation in every specialization.Comment: 4 page
Fisher Zeroes and Singular Behaviour of the Two Dimensional Potts Model in the Thermodynamic Limit
The duality transformation is applied to the Fisher zeroes near the
ferromagnetic critical point in the q>4 state two dimensional Potts model. A
requirement that the locus of the duals of the zeroes be identical to the dual
of the locus of zeroes in the thermodynamic limit (i) recovers the ratio of
specific heat to internal energy discontinuity at criticality and the
relationships between the discontinuities of higher cumulants and (ii)
identifies duality with complex conjugation. Conjecturing that all zeroes
governing ferromagnetic singular behaviour satisfy the latter requirement gives
the full locus of such Fisher zeroes to be a circle. This locus, together with
the density of zeroes is then shown to be sufficient to recover the singular
form of the thermodynamic functions in the thermodynamic limit.Comment: 10 pages, 0 figures, LaTeX. Paper expanded and 2 references added
clarifying duality relationships between discontinuities in higher cumulant
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