217,873 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
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
Quantum phase transition in an atomic Bose gas near a Feshbach resonance
We study the quantum phase transition in an atomic Bose gas near a Feshbach
resonance in terms of the renormalization group. This quantum phase transition
is characterized by an Ising order parameter. We show that in the low
temperature regime where the quantum fluctuations dominate the low-energy
physics this phase transition is of first order because of the coupling between
the Ising order parameter and the Goldstone mode existing in the bosonic
superfluid. However, when the thermal fluctuations become important, the phase
transition turns into the second order one, which belongs to the
three-dimensional Ising universality class. We also calculate the damping rate
of the collective mode in the phase with only a molecular Bose-Einstein
condensate near the second-order transition line, which can serve as an
experimental signature of the second-order transition.Comment: 8 pages, 2 figures, published version in Phys. Rev.
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