564 research outputs found
3D printing of optical materials: an investigation of the microscopic properties
3D printing technologies are currently enabling the fabrication of objects
with complex architectures and tailored properties. In such framework, the
production of 3D optical structures, which are typically based on optical
transparent matrices, optionally doped with active molecular compounds and
nanoparticles, is still limited by the poor uniformity of the printed
structures. Both bulk inhomogeneities and surface roughness of the printed
structures can negatively affect the propagation of light in 3D printed optical
components. Here we investigate photopolymerization-based printing processes by
laser confocal microscopy. The experimental method we developed allows the
printing process to be investigated in-situ, with microscale spatial
resolution, and in real-time. The modelling of the photo-polymerization
kinetics allows the different polymerization regimes to be investigated and the
influence of process variables to be rationalized. In addition, the origin of
the factors limiting light propagation in printed materials are rationalized,
with the aim of envisaging effective experimental strategies to improve optical
properties of printed materials.Comment: 8 pages, 3 figure
Quantum Solitons in Affine Toda Field Theories
The spectra of affine Toda field theories with imaginary coupling
constant, are investigated. Soliton solutions are found, which, despite the
non-unitary form of the Lagrangian, have real classical masses and are stable
to small perturbations. The quantum corrections to the soliton masses are
determined, to lowest order in . The solitons have the same spectrum as
the fundamental Toda particles; a feature that is preserved in the quantum
theory.Comment: 21 page
Quantum Soliton Mass Corrections in SL(N) Affine Toda Theory
The first quantum mass corrections for the solitons of complex affine
Toda field theory are calculated. The corrections are real and preserve the
classical mass ratios. The formalism also proves that the solitons are
classically stable.Comment: 14 page
First Observation of the Hadronic Transition Υ(4S)→ηhb(1P)and New Measurement of the hb(1P) and ηb(1S) Parameters
Using a sample of 771.6×106 ΥΥ(4S) decays collected by the Belle experiment at the KEKB e+e− collider, we observe, for the first time, the transition Υ(4S)→ηhb(1P) with the branching fraction B[Υ(4S)→ηhb(1P)]=(2.18±0.11±0.18)×10−3 and we measure the hb(1P) mass Mhb(1P)=(9899.3±0.4±1.0) MeV/c2, corresponding to the hyperfine (HF) splitting ΔMHF(1P)=(0.6±0.4±1.0) MeV/c2. Using the transition hb(1P)→γηb(1S), we measure the ηb(1S) mass Mηb(1S)=(9400.7±1.7±1.6) MeV/c2, corresponding to ΔMHF(1S)=(59.6±1.7±1.6) MeV/c2, the ηb(1S) width Γηb(1S)=(8+6−5±5) MeV/c2and the branching fraction B[hb(1P)→γηb(1S)]=(56±8±4)%
Reflection Amplitudes of Boundary Toda Theories and Thermodynamic Bethe Ansatz
We study the ultraviolet asymptotics in affine Toda theories with
integrable boundary actions. The reflection amplitudes of non-affine Toda
theories in the presence of conformal boundary actions have been obtained from
the quantum mechanical reflections of the wave functional in the Weyl chamber
and used for the quantization conditions and ground-state energies. We compare
these results with the thermodynamic Bethe ansatz derived from both the bulk
and (conjectured) boundary scattering amplitudes. The two independent
approaches match very well and provide the non-perturbative checks of the
boundary scattering amplitudes for Neumann and boundary conditions. Our
results also confirm the conjectured boundary vacuum energies and the duality
conjecture between the two boundary conditions.Comment: 20 pages, 3 figures, LaTeX2
Reflection Amplitudes of ADE Toda Theories and Thermodynamic Bethe Ansatz
We study the ultraviolet asymptotics in affine Toda theories. These models
are considered as perturbed non-affine Toda theories. We calculate the
reflection amplitudes, which relate different exponential fields with the same
quantum numbers. Using these amplitudes we derive the quantization condition
for the vacuum wave function, describing zero-mode dynamics, and calculate the
UV asymptotics of the effective central charge. These asymptotics are in a good
agreement with thermodynamic Bethe ansatz results.Comment: 20 pages, 2 ps figures, LaTeX 2e. We added the last section,
"Concluding Remarks", in which the new result for the one point function <
\exp a\cdot\phi > in ADE affine Toda theories is given explicitly. Version to
appear in Nucl. Phys.
The Analytic Structure of Trigonometric S Matrices
-matrices associated to the vector representations of the quantum groups
for the classical Lie algebras are constructed. For the and
algebras the complete -matrix is found by an application of the bootstrap
equations. It is shown that the simplest form for the -matrix which
generalizes that of the Gross-Neveu model is not consistent for the
non-simply-laced algebras due to the existence of unexplained singularities on
the physical strip. However, a form which generalizes the -matrix of the
principal chiral model is shown to be consistent via an argument which uses a
novel application of the Coleman-Thun mechanism. The analysis also gives a
correct description of the analytic structure of the -matrix of the
principle chiral model for .Comment: 25 pages (macro included, 6 figures included as uuencoded compressed
tar file), CERN-TH.6888/93, (An important argument is corrected leading to a
novel application of the Coleman-Thun mechanism. Also decided to risk some
figures.
Anapole moment of an exotic nucleus
We demonstrate that there is no appreciable enhancement of the anapole moment
of Be. The effect of small energy intervals is compensated for by a
small overlap of the halo neutron wave function with core.Comment: 5 pages, LaTe
Non linear integral equation and excited--states scaling functions in the sine-Gordon model
The NLIE (the non-linear integral equation equivalent to the Bethe Ansatz
equations for finite size) is generalized to excited states, that is states
with holes and complex roots over the antiferromagnetic ground state. We
consider the sine-Gordon/massive Thirring model (sG/mT) in a periodic box of
length using the light-cone approach, in which the sG/mT model is obtained
as the continuum limit of an inhomogeneous six vertex model. This NLIE is an
useful starting point to compute the spectrum of excited states both
analytically in the large (perturbative) and small (conformal) regimes
as well as numerically.Comment: LaTeX file, 40 pages, 4 figures in a tar.Z file (3 figures added and
few misprints corrected w.r.t. previous version
Realization of Haldane's Exclusion Statistics in a Model of Electron-Phonon Interactions
We discuss an integrable model describing one-dimensional electrons
interacting with two-dimensional anharmonic phonons. In the low temperature
limit it is possible to decouple phonons and consider one-dimensional
excitations separately. They have a trivial two-body scattering matrix and obey
fractional statistics. As far as we know the original model presents the first
example of a model with local bare interactions generating purely statistical
interactions between renormalized particles. As a by-product we obtain
non-trivial thermodynamic equations for the interacting system of
two-dimensional phonons.Comment: 4 page
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