15,840 research outputs found
Light meson resonances from unitarized Chiral Perturbation Theory
We report on our recent progress in the generation of resonant behavior in
unitarized meson-meson scattering amplitudes obtained from Chiral Perturbation
Theory. These amplitudes provide simultaneously a remarkable description of the
resonance region up to 1.2 GeV as well as the low energy region, since they
respect the chiral symmetry expansion. By studying the position of the poles in
these amplitudes it is possible to determine the mass and width of the
associated resonances, as well as to get a hint on possible classification
schemes, that could be of interest for the spectroscopy of the scalar sector.Comment: Invited talk to the II International Workshop on Hadron Physics &
Effective Theories of Low Energy QCD. 25-29 September 2002. Coimbra. Portuga
Meson resonances from unitarized meson scattering at one loop in Chiral Perturbation Theory
We show the results for the scattering poles associated to the rho, f0, a0,
K*, sigma and kappa resonances in meson-meson scattering. Our amplitudes are
obtained from the complete one-loop meson-meson scattering amplitudes from
Chiral Perturbation Theory. Once unitarized with the Inverse Amplitude Method,
they describe remarkably well the data simultaneously in the low energy and
resonance regions up to 1.2 GeV, using low energy parameters compatible with
present determinations.Comment: To appear in the proceedings of the 5th International Conference on
``Quark confinement and the hadron spectrum'', held in Gargnano, Garda Lake,
Italy. 10-14th September 2002. 3 page
Unitarization of the complete meson-meson scattering at one loop in Chiral Perturbation Theory
We report on our one-loop calculation of all the two meson scattering
amplitudes within SU(3) Chiral Perturbation Theory, i.e. with pions, kaons and
etas. Once the amplitudes are unitarized with the coupled channel Inverse
Amplitude Method, they satisfy simultaneously the correct low-energy chiral
constraints and unitarity. We obtain a remarkable description of meson-meson
scattering data up to 1.2 GeV including the scattering lengths and seven light
resonances.Comment: To appear in the proceedings of QCD@work: International Workshop on
QCD: Theory and Experiment. Martina Franca (Italy) June 16-20. 200
Complete meson-meson scattering within one loop in Chiral Perturbation Theory: Unitarization and resonances
We review our recent one-loop calculation of all the two meson scattering
amplitudes within SU(3) Chiral Perturbation Theory, i.e. with pions, kaons and
etas. By unitarizing these amplitudes we are able to generate dynamically the
lightest resonances in meson-meson scattering. We thus obtain a remarkable
description of the meson-meson scattering data right from threshold up to 1.2
GeV, in terms of chiral parameters in good agreement with previous
determinations.Comment: 4 pages, To appear in the Proceedings of the IX International
Conference on Hadron Spectroscopy, HADRON2001, IHEP, Protvino, Russia, August
200
Photoactivatable metal complexes : from theory to applications in biotechnology and medicine
This short review highlights some of the exciting new experimental and theoretical developments in the field of photoactivatable metal complexes and their applications in biotechnology and medicine. The examples chosen are based on some of the presentations at the Royal Society Discussion Meeting in June 2012, many of which are featured in more detail in other articles in this issue. This is a young field. Even the photochemistry of well-known systems such as metalâcarbonyl complexes is still being elucidated. Striking are the recent developments in theory and computation (e.g. time-dependent density functional theory) and in ultrafast-pulsed radiation techniques which allow photochemical reactions to be followed and their mechanisms to be revealed on picosecond/nanosecond time scales. Not only do some metal complexes (e.g. those of Ru and Ir) possess favourable emission properties which allow functional imaging of cells and tissues (e.g. DNA interactions), but metal complexes can also provide spatially controlled photorelease of bioactive small molecules (e.g. CO and NO)âa novel strategy for site-directed therapy. This extends to cancer therapy, where metal-based precursors offer the prospect of generating excited-state drugs with new mechanisms of action that complement and augment those of current organic photosensitizers
Tri-layer superlattices: A route to magnetoelectric multiferroics?
We explore computationally the formation of tri-layer superlattices as an
alternative approach for combining ferroelectricity with magnetism to form
magnetoelectric multiferroics. We find that the contribution to the
superlattice polarization from tri-layering is small compared to typical
polarizations in conventionalferroelectrics, and the switchable ferroelectric
component is negligible. In contrast, we show that epitaxial strain and
``negative pressure'' can yield large, switchable polarizations that are
compatible with the coexistence of magnetism, even in materials with no active
ferroelectric ions.Comment: 10 pages, 3 figures; references added, and minor editorial changes
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