801 research outputs found
The semileptonic baryonic decay
The decay with a proton-antiproton pair in the
final state is unique in the sense that it is the only semileptonic baryonic
decay which is physically allowed in the charmed meson sector. Its measurement
will test our basic knowledge on semileptonic decays and the low-energy
interactions. Taking into account the major intermediate state
contributions from and , we find that its
branching fraction is at the level of . The location and
the nature of state are crucial for the precise determination of the
branching fraction. We wish to trigger a new round of a careful study with the
upcoming more data in BESIII as well as the future super tau-charm factory.Comment: final version, accepted for publication in Phys. Lett.
Branching fractions of semileptonic and decays from the covariant light-front quark model
Based on the predictions of the relevant form factors from the covariant
light-front quark model, we show the branching fractions for the ( or ) decays, where denotes
the pseudoscalar meson, the scalar meson with a mass above 1 GeV, the
vector meson and the axial-vector one. Comparison with the available
experimental results are made, and we find an excellent agreement. The
predictions for other decay modes can be tested in a charm factory, e.g., the
BESIII detector. The future measurements will definitely further enrich our
knowledge on the hadronic transition form factor as well as the inner structure
of the even-parity mesons ( and ).Comment: Predictions on D-> K1(1270), K1(1400) l nu rates correcte
Antinucleon-nucleon interaction in chiral effective field theory
Results of an exploratory study of the antinucleon-nucleon interaction within
chiral effective field theory are reported. The antinucleon-nucleon potential
is derived up to next-to-next-to-leading order, based on a modified Weinberg
power counting, in close analogy to pertinent studies of the nucleon-nucleon
interaction. The low-energy constants associated with the arising contact
interactions are fixed by a fit to phase shifts and inelasticities provided by
a recently published phase-shift analysis of antiproton-proton scattering data.
The overall quality of the achieved description of the antinucleon-nucleon
amplitudes is comparable to the one found in case of the nucleon-nucleon
interaction at the same order. For most S-waves and several P-waves good
agreement with the antinucleon-nucleon phase shifts and inelasticities is
obtained up to laboratory energies of around 200 MeV.Comment: 24 pp, uses JHEP styl
On the near-threshold invariant mass spectrum measured in and decays
A systematic analysis of the near-threshold enhancement in the
invariant mass spectrum seen in the decay reactions and
is
presented. The enhancement is assumed to be due to the final-state
interaction (FSI) and the pertinent FSI effects are evaluated in an approach
that is based on the distorted-wave Born approximation. For the
interaction a recent potential derived within chiral effective field theory and
fitted to results of a partial-wave analysis of scattering data is
considered and, in addition, an older phenomenological model constructed by the
J\"ulich group. It is shown that the near-threshold spectrum observed in
various decay reactions can be reproduced simultaneously and consistently by
our treatment of the FSI. It turns out that the interaction in the
isospin-1 channel required for the description of the decay predicts a bound state.Comment: 13 pages, 12 figure
Antinucleon-nucleon interaction in chiral effective field theory
Results of an exploratory study of the antinucleon-nucleon interaction within
chiral effective field theory are reported. The antinucleon-nucleon potential
is derived up to next-to-next-to-leading order, based on a modified Weinberg
power counting, in close analogy to pertinent studies of the nucleon-nucleon
interaction. The low-energy constants associated with the arising contact
interactions are fixed by a fit to phase shifts and inelasticities provided by
a recently published phase-shift analysis of antiproton-proton scattering data.
The overall quality of the achieved description of the antinucleon-nucleon
amplitudes is comparable to the one found in case of the nucleon-nucleon
interaction at the same order. For most S-waves and several P-waves good
agreement with the antinucleon-nucleon phase shifts and inelasticities is
obtained up to laboratory energies of around 200 MeV.Comment: 24 pp, uses JHEP styl
Test of semi-local duality in a large framework
In this paper we test the semi-local duality based on the method of Ref.[1]
for calculating final-state interactions at varying number of colors ().
We compute the amplitudes by dispersion relations that respect analyticity and
coupled channel unitarity, as well as accurately describing experiment. The
dependence of the scattering amplitudes is obtained by
comparing these amplitudes to the one of chiral perturbation theory. The
semi-local duality is investigated by varying . Our results show that the
semi-local duality is not violated when is large. At large , the
contributions of the , the and the cancel
that of the in the finite energy sum rules, while the
has almost no effect. This gives further credit to the method developed in
Ref.[1] for investigating the dependence of hadron-hadron scattering with
final-state interactions. This study is also helpful to understand the
structure of the scalar mesons.Comment: 8 pages, 5 figures, several comments are adde
B_l4 decays and the extraction of |V_ub|
The Cabibbo-Kobayashi-Maskawa matrix element |V_ub| is not well determined
yet. It can be extracted from both inclusive or exclusive decays, like B --> pi
(rho) l nu-bar_l. However, the exclusive determination from B --> rho l
nu-bar_l, in particular, suffers from a large model dependence. In this paper,
we propose to extract |V_ub| from the four-body semileptonic decay B --> pi pi
l nu-bar_l, where the form factors for the pion-pion system are treated in
dispersion theory. This is a model-independent approach that takes into account
the pi-pi rescattering effects, as well as the effect of the rho meson. We
demonstrate that both finite-width effects of the rho meson as well as scalar
pi-pi contributions can be considered completely in this way.Comment: 12 pages, 4 figures; v2: Appendix C removed, version published in
Phys. Rev.
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