96 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.
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.
Duality violations in tau hadronic spectral moments
Evidence is presented for the necessity of including duality violations in a
consistent description of spectral function moments employed in the precision
determination of from decay. A physically motivated ansatz
for duality violations in the spectral functions enables us to perform fits to
spectral moments employing both pinched and unpinched weights. We describe our
analysis strategy and provide some preliminary findings. Final numerical
results await completion of an ongoing re-determination of the ALEPH covariance
matrices incorporating correlations due to the unfolding procedure which are
absent from the currently posted versions. To what extent this issue affects
existing analyses and our own work will require further study.Comment: 6 pages, 3 figures. Talk given at 11th International Workshop on Tau
Lepton Physics, Manchester, UK, 13-17 September 201
RFX-1, a putative alpha Adducin interacting protein in a human kidney library
Adducin regulates tubular absorption of sodium by modulating the expression levels of the sodium-potassium-ATPase in renal tubular cells. Adducin is a candidate gene in the pathogenesis of hypertension. Yeast two hybrid screen showed a specific interaction between human alpha Adducin and the regulatory factor for X box (RFX-1), a nuclear protein that down regulates the expression of several proteins in non neuronal cells. The interaction was confirmed in cells through co-immunoprecipitation and colocalization experiments. The binding of alpha Adducin to RFX-I and their nuclear co-localization suggests that Adducin can have a role in modulating the transcriptional regulating activity of RFX-I
K pi vector form factor constrained by tau ---> K pi nu_tau and K_l3 decays
Dispersive representations of the Kpi vector and scalar form factors are used
to fit the spectrum of tau ---> K pi nu_tau obtained by the Belle collaboration
incorporating constraints from results for K_l3 decays. The slope and curvature
of the vector form factor are obtained directly from the data through the use
of a three-times-subtracted dispersion relation. We find and . From
the pole position on the second Riemann sheet the mass and width of the
are found to be ~MeV and
~MeV. The phase-space integrals needed for
K_l3 decays are calculated as well. Furthermore, the Kpi isospin-1/2 P-wave
threshold parameters are derived from the phase of the vector form factor. For
the scattering length and the effective range we find respectively
and .Comment: 22 pages, 4 figure
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