16,019 research outputs found
Fundamental Framework for Technical Analysis
Starting from the characterization of the past time evolution of market
prices in terms of two fundamental indicators, price velocity and price
acceleration, we construct a general classification of the possible patterns
characterizing the deviation or defects from the random walk market state and
its time-translational invariant properties. The classification relies on two
dimensionless parameters, the Froude number characterizing the relative
strength of the acceleration with respect to the velocity and the time horizon
forecast dimensionalized to the training period. Trend-following and contrarian
patterns are found to coexist and depend on the dimensionless time horizon. The
classification is based on the symmetry requirements of invariance with respect
to change of price units and of functional scale-invariance in the space of
scenarii. This ``renormalized scenario'' approach is fundamentally
probabilistic in nature and exemplifies the view that multiple competing
scenarii have to be taken into account for the same past history. Empirical
tests are performed on on about nine to thirty years of daily returns of twelve
data sets comprising some major indices (Dow Jones, SP500, Nasdaq, DAX, FTSE,
Nikkei), some major bonds (JGB, TYX) and some major currencies against the US
dollar (GBP, CHF, DEM, JPY). Our ``renormalized scenario'' exhibits
statistically significant predictive power in essentially all market phases. In
constrast, a trend following strategy and trend + acceleration following
strategy perform well only on different and specific market phases. The value
of the ``renormalized scenario'' approach lies in the fact that it always finds
the best of the two, based on a calculation of the stability of their predicted
market trajectories.Comment: Latex, 27 page
Architecture and noise analysis of continuous variable quantum gates using two-dimensional cluster states
Due to its unique scalability potential, continuous variable quantum optics
is a promising platform for large scale quantum computing and quantum
simulation. In particular, very large cluster states with a two-dimensional
topology that are suitable for universal quantum computing and quantum
simulation can be readily generated in a deterministic manner, and routes
towards fault-tolerance via bosonic quantum error-correction are known. In this
article we propose a complete measurement-based quantum computing architecture
for the implementation of a universal set of gates on the recently generated
two-dimensional cluster states [1,2]. We analyze the performance of the various
quantum gates that are executed in these cluster states as well as in other
two-dimensional cluster states (the bilayer-square lattice and quad-rail
lattice cluster states [3,4]) by estimating and minimizing the associated
stochastic noise addition as well as the resulting gate error probability. We
compare the four different states and find that, although they all allow for
universal computation, the quad-rail lattice cluster state performs better than
the other three states which all exhibit similar performance
Phase transition in a spring-block model of surface fracture
A simple and robust spring-block model obeying threshold dynamics is
introduced to study surface fracture of an overlayer subject to stress induced
by adhesion to a substrate. We find a novel phase transition in the crack
morphology and fragment-size statistics when the strain and the substrate
coupling are varied. Across the transition, the cracks display in succession
short-range, power-law and long-range correlations. The study of stress release
prior to cracking yields useful information on the cracking process.Comment: RevTeX, 4 pages, 4 Postscript figures included using epsfi
Cohomology for infinitesimal unipotent algebraic and quantum groups
In this paper we study the structure of cohomology spaces for the Frobenius
kernels of unipotent and parabolic algebraic group schemes and of their quantum
analogs. Given a simple algebraic group , a parabolic subgroup , and
its unipotent radical , we determine the ring structure of the cohomology
ring . We also obtain new results on computing
as an -module where is a
simple -module with high weight in the closure of the bottom
-alcove. Finally, we provide generalizations of all our results to the
quantum situation.Comment: 18 pages. Some proofs streamlined over previous version. Additional
details added to some proofs in Section
Forward jets and forward -boson production at hadron colliders
In this talk we give a short review of forward jets and forward -boson
production at hadron colliders, in view of the extraction of footprints of BFKL
physics. We argue that at Tevatron energies, dijet production at large rapidity
intervals is still subasymptotic with respect to the BFKL regime, thus the
cross section is strongly dependent on the various cuts applied in the
experimental setup. In addition, the choice of equal transverse momentum cuts
on the tagging jets makes the cross section dependent on large logarithms of
non-BFKL origin, and thus may spoil the BFKL analysis. For vector boson
production in association with two jets, we argue that the configurations that
are kinematically favoured tend to have the vector boson forward in rapidity.
Thus jet production lends itself naturally to extensions to the
high-energy limit.Comment: LaTeX, JHEP style, 10 pages, 3 figures. Based on a talk at EPS2001,
Budapest, Hungar
The Structure of Barium in the hcp Phase Under High Pressure
Recent experimental results on two hcp phases of barium under high pressure
show interesting variation of the lattice parameters. They are here interpreted
in terms of electronic structure calculation by using the LMTO method and
generalized pseudopotential theory (GPT) with a NFE-TBB approach. In phase II
the dramatic drop in c/a is an instability analogous to that in the group II
metals but with the transfer of s to d electrons playing a crucial role in Ba.
Meanwhile in phase V, the instability decrease a lot due to the core repulsion
at very high pressure. PACS numbers: 62.50+p, 61.66Bi, 71.15.Ap, 71.15Hx,
71.15LaComment: 29 pages, 8 figure
Electronic structure of spin 1/2 Heisenberg antiferromagnetic systems: Ba_2Cu(PO_4)_2 and Sr_2Cu(PO_4)_2
We have employed first principles calculations to study the electronic
structure and magnetic properties of the low-dimensional phosphates,
Ba2Cu(PO4)2 and Sr2Cu(PO4)2. Using the self-consistent tight-binding lin-
earized muffin-tin orbital method and the Nth order muffin-tin orbital method,
we have calculated the various intrachain as well as the interchain hopping
parameters between the magnetic ions Cu2+ for both the com- pounds. We find
that the nearest-neighbor intrachain hopping t is the dominant interaction
suggesting the compounds to be indeed one dimensional. Our analysis of the band
dispersion, orbital projected band struc- tures, and the hopping parameters
confirms that the Cu2+-Cu2+ super-super exchange interaction takes place along
the crystallographic b direction mediated by O-P-O. We have also analyzed in
detail the origin of short-range exchange interaction for these systems. Our ab
initio estimate of the ratio of the exchange inter- action of Sr2Cu(PO4)2 to
that of Ba2Cu(PO4)2 compares excellently with available experimental results.Comment: 6 pages, 4 figure
0-pi transitions in Josephson junctions with antiferromagnetic interlayers
We show that the dc Josephson current through
superconductor-antiferromagnet-superconductor (S/AF/S) junctions manifests a
remarkable atomic scale dependence on the interlayer thickness. At low
temperatures the junction is either a 0- or pi-junction depending on whether
the AF interlayer consists of an even or odd number of atomic layers. This is
associated with different symmetries of the AF interlayers in the two cases. In
the junction with odd AF interlayers an additional pi-0 transition can take
place as a function of temperature. This originates from the interplay of
spin-split Andreev bound states. Experimental implications of these theoretical
findings are discussed.Comment: 4 pages, 2 figure
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