1,828 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.
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 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
Profitable Unproductive Innovations
The present paper studies resource allocation in an expanding product variety framework à la Romer (1990). We consider the limiting case where net returns to specialization are zero and, therefore, R&D is completely useless, socially. Nevertheless, the market equilibrium involves allocation of ressources to R&D, and this wasteful allocation may take place even in a steady state.Research and development (R&D); Expanding product variety; Creative destruction.
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