157 research outputs found
Kpi form factors and final state interactions in D+ --> K- pi+ pi+ decays
We present a model for the decay D+ --> K- pi+ pi+. The weak interaction part
of this reaction is described using the effective weak Hamiltonian in the
factorisation approach. Hadronic final state interactions are taken into
account through the Kpi scalar and vector form factors fulfilling analyticity,
unitarity and chiral symmetry constraints. The model has only two free
parameters that are fixed from experimental branching ratios. We show that the
modulus and phase of the S wave thus obtained agree nicely with experiment up
to 1.55 GeV. We perform Monte Carlo simulations to compare the predicted Dalitz
plot with experimental analyses. Allowing for a global phase difference between
the S and P waves of -65 degrees, the Dalitz plot of the D+ --> K- pi+ pi+
decay, the Kpi invariant mass spectra and the total branching ratio due to
S-wave interactions are well reproduced.Comment: 24 pages, 4 figures, REVTeX style. A discussion on the isospin 2
component has been included. Two references added. Published in Phys. Rev.
Constraining the Kpi vector form factor by tau---> K pi nu_tau and K_l3 decay data
A subtracted dispersive representation of the vector form factor,
, is used to fit the Belle spectrum of \tauKpi decays
incorporating constraints from results on decays. Through the use of
three subtractions, the slope and curvature of are obtained
directly from the data yielding
and . The phase-space integrals
relevant for analyses are calculated. Additionally, from the pole
position on the second Riemann sheet the mass and width of the
are found to be MeV and
MeV. Finally, we study the -wave
isospin-1/2 phase-shift and its threshold parameters.Comment: Talk presented at 15th International QCD Conference, Montpellier,
France. Submitted to Nuc. Phys. (Proc. Suppl.), 4 pages, 1 figur
Dispersive representation of the K pi vector form factor and fits to tau -> K pi nu(tau) and Ke3 data
Recently, we introduced several dispersive representations for the vector
form factor and fitted them to the Belle spectrum of . Here, we briefly present the model and discuss the results for the
slope and curvature of arising from the best fit. Furthermore, we
compare the pole position of the charged computed from our model
with other results in the literature. Finally, we discuss the prospects of a
simultaneous fit to and spectra.Comment: Talk given at "International Workshop on Effective Field Theories:
from the pion to the upsilon", February 2009, Valencia, Spain. 7 pages, 2
figures. PoS style. Minor correction in figure
Improving the Kpi vector form factor through Kl3 constraints
The vector form factor, , used to reproduce the Belle
spectrum of \tauKpi decays is described by means of a three-times subtracted
dispersion relation also incorporating constraints from decays. The
slope and curvature of are fitted to the data yielding
and . The pole parameters of the are found to be
MeV and
MeV. The phase-space integrals relevant for analyses and the -wave
isospin-1/2 phase-shift threshold parameters are also calculated.Comment: 3 pages, uses aipproc style. Talk presented by R. Escribano at the IX
International Conference on Quark Confinement and Hadron Spectrum (QCHS09),
Madrid, Spain, 30.8-3.9.201
Scalar resonances: scattering and production amplitudes
Scattering and production amplitudes involving scalar resonances are known,
according to Watson's theorem, to share the same phase . We show
that, at low energies, the production amplitude is fully determined by the
combination of with another phase , which describes
intermediate two-meson propagation and is theoretically unambiguous. Our main
result is a simple and almost model independent expression, which generalizes
the usual -matrix unitarization procedure and is suited to be used in
analyses of production data involving scalar resonances.Comment: 10 pages, 4 figures. Minor changes, references added, version to
appear in Phys. Rev.
Resonances and weak interactions in decays
We describe the -wave in decays using
a unitary model for the Final State Interactions (FSI). The three body
decay is treated as a quasi two-body process where, at the weak vertex, the D
meson decays into a resonance and a pion. The weak part of the decay amplitude
is evaluated using the effective weak Hamiltonian within the factorization
approximation.Comment: 4 pages. Contribution to the X Hadron Physics, Florianopolis-Brazil,
March 26-31, 200
D^+ \to K^- \p^+ \p^+ : the low-energy sector
An effective chiral lagrangian, which includes scalar
resonances, is used to describe the process D^+ \rar K^- \p^+ \p^+ at
low-energies. Our main result is a set of five -wave amplitudes, suited to
be used in analyses of production data.Comment: Talk given at SCADRON 70 - Workshop on Scalar Mesons and Related
Topics - Lisbon - February 200
Scalar resonances in a unitary -wave model for
We propose a model for decays following
experimental results which indicate that the two-pion interaction in the
-wave is dominated by the scalar resonances and
. The weak decay amplitude for , where is a
resonance that subsequently decays into , is constructed in a
factorization approach. In the -wave, we implement the strong decay by means of a scalar form factor. This provides a unitary
description of the pion-pion interaction in the entire kinematically allowed
mass range from threshold to about 3 GeV. In order to
reproduce the experimental Dalitz plot for \Dppp, we include contributions
beyond the -wave. For the -wave, dominated by the , we use a
Breit-Wigner description. Higher waves are accounted for by using the usual
isobar prescription for the and . The major
achievement is a good reproduction of the experimental
distribution, and of the partial as well as the total \Dppp branching ratios.
Our values are generally smaller than the experimental ones. We discuss this
shortcoming and, as a byproduct, we predict a value for the poorly known transition form factor at .Comment: 23 pages, 2 figures. Two new equations. The value for the strength of
the contribution of the scalar form factor now agrees with other results in
the literature. Main results unchanged. Version to appear in Phys. Rev.
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