684 research outputs found
The , interaction in finite volume and the resonance
In this work the interaction of the coupled channels and
in an SU(4) extrapolation of the chiral unitary theory, where the
resonance appears as dynamically generated from that
interaction, is extended to produce results in finite volume. Energy levels in
the finite box are evaluated and, assuming that they would correspond to
lattice results, the inverse problem of determining the phase shifts in the
infinite volume from the lattice results is solved. We observe that it is
possible to obtain accurate phase shifts and the position of the
resonance, but it requires the explicit consideration of the
two coupled channels. We also observe that some of the energy levels in the box
are attached to the closed channel, such that their use to induce the phase shifts via L\"uscher's formula leads to incorrect results.Comment: 10 pages, 13 figures, accepted for publication in Eur. Phys. J.
Magnetic moments of the low-lying , resonances within the framework of the chiral quark model
The magnetic moments of the low-lying spin-parity ,
resonances, like, for example, ,
, as well as their transition magnetic moments, are
calculated using the chiral quark model. The results found are compared with
those obtained from the nonrelativistic quark model and those of unitary chiral
theories, where some of these states are generated through the dynamics of two
hadron coupled channels and their unitarization
Photo- and Electron-Production of Mesons on Nucleons and Nuclei
In these lectures I will show some results obtained with the chiral unitary
approach applied to the photo and electroproduction of mesons. The results for
photoproduction of and , together with
related reactions will be shown, having with common denominator the excitation
of the resonance which is one of those dynamically generated in
the chiral unitary approach. Then I will show results obtained for the reaction which reproduce the bulk of the data except for a
pronounced peak, giving support to a new mesonic resonance, X(2175). Results
will also be shown for the electromagnetic form factors of the
resonance, also dynamically generated in this approach. Finally, I will show
some results on the photoproduction of the in nuclei, showing that
present experimental results claiming a shift of the mass in the
medium are tied to a particular choice of background and are not conclusive.
One the other hand, the same experimental results show unambiguously a huge
increase of the width in the nuclear medium.Comment: Lecture at the "International School of Nuclear Physics", 29th Course
Quarks in Hadrons and Nuclei, Erice, Italy, September 2007. Note added in
Proofs concerning the mixed events technique and other comments on omega
productio
Meeting Report: Hackathon-Workshop on Darwin Core and MIxS Standards Alignment
The Global Biodiversity Information Facility and the Genomic Standards Consortium convened a joint workshop at the University of Oxford, 27–29 February 2012, with a small group of experts from Europe, USA, China and Japan, to continue the alignment of the Darwin Core with the MIxS and related genomics standards. Several reference mappings were produced as well as test expressions of MIxS in RDF. The use and management of controlled vocabulary terms was considered in relation to both GBIF and the GSC, and tools for working with terms were reviewed. Extensions for publishing genomic biodiversity data to the GBIF network via a Darwin Core Archive were prototyped and work begun on preparing translations of the Darwin Core to Japanese and Chinese. Five genomic repositories were identified for engagement to begin the process of testing the publishing of genomic data to the GBIF network commencing with the SILVA rRNA database
Peptide transporter 2 (PEPT2) expression in brain protects against 5-aminolevulinic acid neurotoxicity
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65903/1/j.1471-4159.2007.04905.x.pd
Dynamically generated resonances
In this talk I report on recent work related to the dynamical generation of
baryonic resonances, some made up from pseudoscalar meson-baryon, others from
vector meson-baryon and a third type from two meson-one baryon systems. We can
establish a correspondence with known baryonic resonances, reinforcing
conclusions previously drawn and bringing new light on the nature of some
baryonic resonances of higher mass.Comment: Talk given at the Workshop on physics of the excited nucleon-NSTAR
2009, Beijing, april 200
The pd --> ^3He eta pi0 reaction at T_p = 1450 MeV
The cross section for the pd --> ^3He eta pi0 reaction has been measured at a
beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring and
detecting one ^3He and four photons from the decays of the two photons. The
data indicate that the production mechanism involves the formation of the
Delta(1232) isobar. Although the beam energy does not allow the full peak of
this resonance to be seen, the invariant masses of all three pairs of final
state particles are well reproduced by a phase space Monte Carlo simulation
weighted with the p-wave factor of the square of the pi^0 momentum in the
^3Hepi^0 system.Comment: 10 pages, 5 figure
Quantum Histories and Quantum Gravity
This paper reviews the histories approach to quantum mechanics. This
discussion is then applied to theories of quantum gravity. It is argued that
some of the quantum histories must approximate (in a suitable sense) to
classical histories, if the correct classical regime is to be recovered. This
observation has significance for the formulation of new theories (such as
quantum gravity theories) as it puts a constraint on the kinematics, if the
quantum/classical correspondence principle is to be preserved. Consequences for
quantum gravity, particularly for Lorentz symmetry and the idea of "emergent
geometry", are discussed.Comment: 35 pages (29 pages main body), two figure
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