90 research outputs found
Decay and Scattering
Using chiral low energy theorems and elastic unitarity assumption, the
decay is investigated. The vector and scalar form
factors are calculated. It is found that the spectrum is dominated by
the resonance. By measuring the forward-backward asymmetry, it is shown
that the S wave phase shift can be determined near the
resonance region. The calculated branching ratio and resonance parameters are
in good agreement with experiments.Comment: 15 pages, Tex, 6 included figure
decays in Chiral Perturbation Theory
The process is calculated to two-loop order () in Chiral
Perturbation Theory (ChPT) in the isospin conserved case. We present
expressions suitable for use with previous work in two-loop CHPT where the
order parameters () were determined from experiment.
We point out that all the order parameters () that appear in the
value of relevant for the determination of can be
determined from measurements via the slope and the curvature of the
scalar form-factor. As a by product we update the value of the CKM matrix
element .Comment: 23 pages, changes: comparison with work of Post-Schilcher extended,
comparison with KEK PS E246 added and a value for V_us included, discussion
of Ref. [9] changed. Some misprints correcte
Search for Tensor Interactions in Kaon Decays at DANE
The semileptonic kaon decays and are considered. We
use the most general forms of the matrix elements for these decays. Additional
terms could arise as a result of new tensor interactions between quarks and
leptons. Such terms have been detected in a recent experiments. The high
precision experiments at DANE may be ideal to confirm these results.Comment: 8 LaTeX pages, no figure
Unitarity, Chiral Perturbation Theory, and Meson Form Factors
The inverse-amplitude method is applied to the one-loop chiral expansion of
the pion, kaon, and form factors. Since these form factors are
determined by the same chiral low-energy constants, it is possible to obtain
finite predictions for the inverse-amplitude method. It is shown that this
method clearly improves one-loop chiral perturbation theory, and a very good
agreement between the inverse-amplitude method and the experimental information
is obtained. This suggests that the inverse-amplitude method is a rather
systematic way of improving chiral perturbation theory.Comment: 15 pages, 5 figs, uses REVTeX and epsfig.st
Measurement of K^0_e3 form factors
The semileptonic decay of the neutral K meson, KL -> pi e nu (Ke3), was used
to study the strangeness-changing weak interaction of hadrons. A sample of 5.6
million reconstructed events recorded by the NA48 experiment was used to
measure the Dalitz plot density. Admitting all possible Lorentz-covariant
couplings, the form factors for vector (f_+(q^2)), scalar (f_S) and tensor
(f_T) interactions were measured. The linear slope of the vector form factor
lambda_+ = 0.0284+-0.0007+-0.0013 and values for the ratios |f_S/f_+(0)| =
0.015^{+0.007}_{-0.010}+-0.012 and |f_T/f_+(0)| = 0.05^{+0.03}_{-0.04}+-0.03
were obtained. The values for f_S and f_T are consistent with zero. Assuming
only Vector-Axial vector couplings, lambda_+ = 0.0288+-0.0004+-0.0011 and a
good fit consistent with pure V-A couplings were obtained. Alternatively, a fit
to a dipole form factor yields a pole mass of M = 859+-18 MeV, consistent with
the K^*(892) mass.Comment: 16 pages, 7 figures. submitted to Phys. Lett.
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