33,616 research outputs found
Chiral Unitary approach to meson-meson and meson-baryon interactions and nuclear applications
We report on recent nonperturbative techniques that combine the information
of chiral Lagrangians (with and without resonances) with unitarity in coupled
channels and other requirements of the S-matrix theory of the strong
interactions. As a result, the region of applicability of such techniques is
much larger than the one of Chiral Perturbation Theory allowing one to study
also resonance physics. Applications to meson-meson and meson-baryon
scattering, as well as to problems where pairs of mesons or a meson and a
baryon appear in the initial or final state are shown. Implications in several
nuclear problems are also discussed.Comment: 85 pages, Latex, Review paper to appear in Prog. Part. Nucl. Phys.,
vol. 4
Triangle singularities in and
We study the appearance of structures in the decay of the into and final states by forming
invariant mass distributions of and pairs,
respectively. The structure in the distribution is associated to the
kinematical triangle singularity that appears when the () decay process is followed by the decay
of the into and the subsequent rescattering of the () pair forming the ()
resonance. We find this type of non-resonant peaks at 2850 MeV in the invariant
mass of pairs from decays and
around 3000 MeV in the invariant mass of pairs from decays. By employing the measured branching ratios of
the and decays, we
predict the branching ratios for the processes into and , in the vicinity of the
triangle singularity peak, to be about and ,
respectively. The observation of this reaction would also give extra support to
the molecular picture of the and .Comment: 18 pages, 15 figures, accepted version for publication in Eur. Phys.
J.
Microscopic approach to the proton asymmetry in the non-mesonic weak decay of Lambda-hypernuclei
The non--mesonic weak decay of polarized -hypernuclei is studied
with a microscopic diagrammatic formalism in which one- and two-nucleon induced
decay mechanisms, and , are
considered together with (and on the same ground of) nucleon final state
interactions. We adopt a nuclear matter formalism extended to finite nuclei via
the local density approximation. Our approach adopts different
one-meson-exchange weak transition potentials, while the strong interaction
effects are accounted for by a Bonn nucleon-nucleon interaction. We also
consider the two-pion-exchange effect in the weak transition potential. Both
the two-nucleon induced decay mechanism and the final state interactions reduce
the magnitude of the asymmetry. The quantum interference terms considered in
the present microscopic approach give rise to an opposite behavior of the
asymmetry with increasing energy cuts to that observed in models describing the
nucleon final state interactions semi-classically via the intranuclear cascade
code. Our results for the asymmetry parameter in C obtained
with different potential models are consistent with the asymmetry measured at
KEK
An analysis of the Lattice QCD spectra for and
In this talk I present the results obtained using effective field theories in
a finite volume from a reanalysis of lattice data on the systems,
where bound states of and are found and associated with the states
and , respectively. We confirm the presence of
such states on the lattice data and determine the weight of the channel in
the wave function of and that of in the wave function
of . Our results indicate a large meson-meson component in both
cases.Comment: Conference Proceedings, Hadron 2017, Salamanca, Spai
- …