273,852 research outputs found
DIS Prospects at the Future Muon Collider Facility
We discuss prospects of deep inelastic scattering physics capabilities at the
future muon collider facility. In addition to mu^+ mu^- collider itself, the
facility provides other possibilities. Among the possibilities, we present
muon-proton collider and neutrino fixed target programs at the muon collider
facility. This mu-p collider program extends kinematic reach and luminosity by
an order of magnitude, increasing the possibility of search for new exotic
particles. Perhaps most intriguing DIS prospects come from utilizing high
intensity neutrino beam resulting from continuous decays of muons in various
sections of the muon collider facility. One of the most interesting findings is
a precision measurement of electroweak mixing angle, sin^2theta_W, which can be
achieved to the precision equivalent to delta M_W ~ 30 MeV.Comment: 8 pages, 4 figures, To be published in the proceedings of the 6th
international workshop on Deep Inelastic Scattering, Brussel, Belgium (1998
Alternative Derivation of the Hu-Paz-Zhang Master Equation for Quantum Brownian Motion
Hu, Paz and Zhang [ B.L. Hu, J.P. Paz and Y. Zhang, Phys. Rev. D {\bf 45}
(1992) 2843] have derived an exact master equation for quantum Brownian motion
in a general environment via path integral techniques. Their master equation
provides a very useful tool to study the decoherence of a quantum system due to
the interaction with its environment. In this paper, we give an alternative and
elementary derivation of the Hu-Paz-Zhang master equation, which involves
tracing the evolution equation for the Wigner function. We also discuss the
master equation in some special cases.Comment: 17 pages, Revte
Assessment criteria for 2D shape transformations in animation
The assessment of 2D shape transformations (or morphing) for animation is a difficult task because it is a multi-dimensional problem. Existing morphing techniques pay most attention to shape information interactive control and mathematical simplicity. This paper shows that it is not enough to use shape information alone, and we should consider other factors such as structure, dynamics, timing, etc. The paper also shows that an overall objective assessment of morphing is impossible because factors such as timing are related to subjective judgement, yet local objective assessment criteria, e.g. based on shape, are available. We propose using “area preservation” as the shape criterion for the 2D case as an acceptable approximation to “volume preservation” in reality, and use it to establish cases in which a number of existing techniques give clearly incorrect results. The possibility of deriving objective assessment criteria for dynamics simulations and timing under certain conditions is discussed
Bayesian analysis of a Tobit quantile regression model
This paper develops a Bayesian framework for Tobit quantile regression. Our approach
is organized around a likelihood function that is based on the asymmetric Laplace dis-
tribution, a choice that turns out to be natural in this context. We discuss families
of prior distribution on the quantile regression vector that lead to proper posterior
distributions with ÂŻnite moments. We show how the posterior distribution can be
sampled and summarized by Markov chain Monte Carlo methods. A method for com-
paring alternative quantile regression models is also developed and illustrated. The
techniques are illustrated with both simulated and real data. In particular, in an em-
pirical comparison, our approach out-performed two other common classical estimators
High quality graph-based similarity search
SimRank is an influential link-based similarity measure that has been used in many fields of Web search and sociometry. The best-of-breed method by Kusumoto et. al., however, does not always deliver high-quality results, since it fails to accurately obtain its diagonal correction matrix D. Besides, SimRank is also limited by an unwanted "connectivity trait": increasing the number of paths between nodes a and b often incurs a decrease in score s(a,b). The best-known solution, SimRank++, cannot resolve this problem, since a revised score will be zero if a and b have no common in-neighbors. In this paper, we consider high-quality similarity search. Our scheme, SR#, is efficient and semantically meaningful: (1) We first formulate the exact D, and devise a "varied-D" method to accurately compute SimRank in linear memory. Moreover, by grouping computation, we also reduce the time of from quadratic to linear in the number of iterations. (2) We design a "kernel-based" model to improve the quality of SimRank, and circumvent the "connectivity trait" issue. (3) We give mathematical insights to the semantic difference between SimRank and its variant, and correct an argument: "if D is replaced by a scaled identity matrix, top-K rankings will not be affected much". The experiments confirm that SR# can accurately extract high-quality scores, and is much faster than the state-of-the-art competitors
Coherent State Control of Non-Interacting Quantum Entanglement
We exploit a novel approximation scheme to obtain a new and compact formula
for the parameters underlying coherent-state control of the evolution of a pair
of entangled two-level systems. It is appropriate for long times and for
relatively strong external quantum control via coherent state irradiation. We
take account of both discrete-state and continuous-variable degrees of freedom.
The formula predicts the relative heights of entanglement revivals and their
timing and duration.Comment: Published in PRA, 10 pages, 7 figure
On Wilson Criterion
U(1) gauge theory with the Villain action on a cubic lattice approximation of
three- and four-dimensional torus is considered. The naturally chosen
correlation functions converge to the correlation functions of the R-gauge
electrodynamics on three- and four-dimensional torus as the lattice spacing
approaches zero only for the special scaling. This special scaling depends on a
choice of a correlation function system. Another scalings give the degenerate
continuum limits. The Wilson criterion for the confinement is ambiguous. The
asymptotics of the smeared Wilson loop integral for the large loop perimeters
is defined by the density of the loop smearing over a torus which is
transversal to the loop plane. When the initial torus radius tends to infinity
the correlation functions converge to the correlation functions of the R-gauge
Euclidean electrodynamics.Comment: latex, 6 page
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