35,005 research outputs found
Mixing in the D0 system - Results from collider experiments
Mixing in the D0 system may provide a sensitive probe for new physics beyond
the Standard Model (SM) but has so far eluded experimental observation. The SM
predictions are typically small (< 10^{-3}) for the mixing parameters x, y
which, in the absence of charge-parity (CP) symmetry violation, measure the
mass (x= Delta(m)/Gamma) and lifetime (y= Delta(Gamma)/2Gamma) difference of
the CP eigenstates in the D0 system. The asymmetric B-factory experiments BABAR
and Belle open up the opportunity of measuring x, y with unprecedented
statistical precision and sample purities. Results from BABAR and Belle, and
from CLEO are reviewed.Comment: 28 pages, 7 figures, typos correcte
The planar spectrum in U(N)-invariant quantum mechanics by Fock space methods: I. The bosonic case
Prompted by recent results on Susy-U(N)-invariant quantum mechanics in the
large N limit by Veneziano and Wosiek, we have examined the planar spectrum in
the full Hilbert space of U(N)-invariant states built on the Fock vacuum by
applying any U(N)-invariant combinations of creation-operators. We present
results about 1) the supersymmetric model in the bosonic sector, 2) the
standard quartic Hamiltonian. This latter is useful to check our techniques
against the exact result of Brezin et al. The SuSy case is where Fock space
methods prove to be the most efficient: it turns out that the problem is
separable and the exact planar spectrum can be expressed in terms of the
single-trace spectrum. In the case of the anharmonic oscillator, on the other
hand, the Fock space analysis is quite cumbersome due to the presence of large
off-diagonal O(N) terms coupling subspaces with different number of traces;
these terms should be absorbed before taking the planar limit and recovering
the known planar spectrum. We give analytical and numerical evidence that good
qualitative information on the spectrum can be obtained this way.Comment: 17 pages, 4 figures, uses youngtab.sty. Final versio
A Model of Electrodiffusion and Osmotic Water Flow and its Energetic Structure
We introduce a model for ionic electrodiffusion and osmotic water flow
through cells and tissues. The model consists of a system of partial
differential equations for ionic concentration and fluid flow with interface
conditions at deforming membrane boundaries. The model satisfies a natural
energy equality, in which the sum of the entropic, elastic and electrostatic
free energies are dissipated through viscous, electrodiffusive and osmotic
flows. We discuss limiting models when certain dimensionless parameters are
small. Finally, we develop a numerical scheme for the one-dimensional case and
present some simple applications of our model to cell volume control
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