985 research outputs found
Regge description of high energy pion pion total cross sections
We have recently presented a Regge description of pion-pion total cross
sections valid above 1.4 GeV, consistent with the few existing experiments,
factorization and crossing symmetry. In this note we show how it also describes
a further large data sample obtained from an analysis of experiments on
and .Comment: 3 pages. To appear in the proceedings of the MESON 2004 workshop,
Krakow, July 2004, to be published in Int. J. Mod. Phys.
The pion-pion scattering amplitude. II: Improved analysis above threshold
We improve, in the energy region between threshold and
GeV, the energy-dependent phase shift analysis of scattering presented
in a previous paper. For the S0 wave we have included more data above
threshold and we have taken into account systematically the
elasticity data on the reaction . We here made a coupled
channel fit. For the D0 wave we have considered information on low energy
parameters, and imposed a better fit to the resonance. For both waves the
expressions we now find are substantially more precise than the previous ones.
We also provide slightly improved D2 and P waves, including the estimated
inelasticity for the first, and a more flexible parametrization between 1 and
1.42 GeV for the second. The accuracy of our amplitudes is now such that it
requires a refinement of the Regge analysis, for GeV, which
we also carry out. We show that this more realistic input produces
scattering amplitudes that satisfy better forward dispersion relations,
particularly for scattering.Comment: Plain TeX. 12 figures. Minor anomaly in the K-matrix fit corrected by
moving matching point to 932 MeV, and pole to 910.6 MeV. Results
unaltere
Forward dispersion relations and Roy equations in pi-pi scattering
We review results of an analysis of pipi interactions in S, P and D waves for
two-pion effective mass from threshold to about 1.4 GeV. In particular we show
a recent improvement of this analysis above the K anti-K threshold using more
data for phase shifts and including the S0 wave inelasticity from pipi -> K
anti-K. In addition, we have improved the fit to the f2(1270) resonance and
used a more flexible P wave parametrization above the K anti-K threshold and
included an estimation of the D2 wave inelasticity. The better accuracy thus
achieved also required a refinement of the Regge analysis above 1.42 GeV. We
have checked that the pipi scattering amplitudes obtained in this approach
satisfy remarkably well forward dispersion relations and Roy's equations.Comment: 6 pages, invited talk to the IV International Conference on Quarks
and Nuclear Physics QNP06, Madrid 5th-10th June 200
Strange resonance poles from scattering below 1.8 GeV
In this work we present a determination of the mass, width and coupling of
the resonances that appear in kaon-pion scattering below 1.8 GeV. These are:
the much debated scalar -meson, nowdays known as , the
scalar , the and vectors, the spin-two
as well as the spin-three . The parameters will be
determined from the pole associated to each resonance by means of an analytic
continuation of the scattering amplitudes obtained in a recent and
precise data analysis constrained with dispersion relations, which were not
well satisfied in previous analyses. This analytic continuation will be
performed by means of Pad\'e approximants, thus avoiding a particular model for
the pole parameterization. We also pay particular attention to the evaluation
of uncertainties.Comment: 13 pages, 12 figures. Accepted version to appear in Eur. Phys. J. C.
Clarifications and references added, minor typos correcte
The Inverse Amplitude Method and Adler Zeros
The Inverse Amplitude Method is a powerful unitarization technique to enlarge
the energy applicability region of Effective Lagrangians. It has been widely
used to describe resonances from Chiral Perturbation Theory as well as for the
Strongly Interacting Symmetry Breaking Sector. In this work we show how it can
be slightly modified to account also for the sub-threshold region,
incorporating correctly the Adler zeros required by chiral symmetry and
eliminating spurious poles. These improvements produce negligible effects on
the physical region.Comment: 17 pages, 4 figure
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