Incompressible Quantum Hall fluids (QHF's) can be described in the scaling
limit by three-dimensional topological field theories. Thanks to the
correspondence between three-dimensional topological ...field theories and two
dimensional chiral conformal field theories (CCFT's), we propose to study QHF's
from the point of view of CCFT's.
We derive consistency conditions and stability criteria for those CCFT's that
can be expected to describe a QHF. A general algorithm is presented which uses
simple currents to construct interesting examples of such CCFT's. It
generalizes the description of QHF's in terms of Quantum Hall lattices.
Explicit examples, based on the coset construction, provide candidates for the
description of Quantum Hall fluids with Hall conductivity s_H=1/2 e^2/h, 1/4
e^2/h, 3/5 e^2/h, e^2/h,...
Nucl.Instrum.Meth.A578:253-260,2007 One contribution to the time resolution of a scintillation detector is the
signal time spread due to path length variations of the detected photons from a
point ...source. In an experimental study a rectangular scintillator was excited
by means of a fast pulsed ultraviolet laser at different positions along its
longitudinal axis. Timing measurements with a photomultiplier tube in a
detection plane displaced from the scintillator end face showed a correlation
between signal time and tube position indicating only a small distortion of
photon angles during transmission. The data is in good agreement with a Monte
Carlo simulation used to compute the average photon angle with respect to the
detection plane and the average propagation time. Limitations on timing
performance that arise from propagation time dispersion are expected for long
and thin scintillators used in future particle identification systems.
Nucl.Phys.B582:203-215,2000 B-type D-branes are constructed on two different K3-fibrations over IP_1
using boundary conformal field theory at the rational Gepner points of these
models. The ...microscopic CFT charges are compared with the Ramond charges of
D-branes wrapped on holomorphic cycles of the corresponding Calabi-Yau
manifold. We study in particular D4-branes and bundles localized on the K3
fibers, and find from CFT that each irreducible component of a bundle on K3
gains one modulus upon fibration over IP_1. This is in agreement with
expectations and so provides a further test of the boundary CFT.
We present new examples of maverick coset conformal field theories. They are closely related to conformal embeddings and exceptional modular invariants.
Experimental results obtained at the CERN Super Proton Synchrotron on the structure-function ratio {ital F}{sub 2}{sup {ital n}}/{ital F}{sub 2}{sup {ital p}} in the kinematic range 0.004{lt}{ital ...x}{lt}0.8 and 0.4{lt}{ital Q}{sup 2}{lt}190 GeV{sup 2}, together with the structure function {ital F}{sub 2}{sup {ital d}} determined from a fit to published data, are used to derive the difference {ital F}{sub 2}{sup {ital p}}({ital x}){minus}{ital F}{sub 2}{sup {ital n}}({ital x}). The value of the Gottfried sum {integral}({ital F}{sub 2}{sup {ital p}}{minus}{ital F}{sub 2}{sup {ital n}}){ital dx}/{ital x}=0.240{plus minus}0.016 is below the quark-parton-model expectation of 1/3.
Phys.Rev.C78:018201,2008 We report on new H$(e,e^\prime p)\gamma$ measurements in the $\Delta(1232)$
resonance at $Q^2=0.06$ (GeV/c) carried out simultaneously with H$(e,e^\prime
p)\pi^0$. It is the ...lowest $Q^2$ for which the virtual Compton scattering (VCS)
reaction has been studied in the first resonance region. The VCS measured cross
sections are well described by dispersion-relation calculations in which the
multipole amplitudes derived from H$(e,e^\prime p)\pi^0$ data are used as
input, thus confirming the compatibility of the results. The derived resonant
magnetic dipole amplitude $M^{3/2}_{1+} = (40.60 \pm
0.70_{stat+sys})(10^{-3}/m_{\pi^+})$ at $W=$ 1232 MeV is in excellent agreement
with the value extracted from H$(e,e^\prime p)\pi^0$ measurements.
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