Higher Threshold Parameters in ππ Scattering
نویسنده
چکیده
A family of threshold parameters which probe the stability of chiral predictions is considered. The relevant criteria for the choice of threshold parameters are discussed. Sum rules for these quantities are derived from dispersion relations and evaluated from effective range formulae. Good agreement with two-loop chiral estimates for many of these quantities is found and interesting discrepancies are discussed.
منابع مشابه
Low energy parameters of the KK and ππ scalar - isoscalar interactions
Low energy parameters of the KK and ππ scalar-isoscalar interactions Abstract Threshold expansions of the ππ and KK spin 0 and isospin 0 scattering amplitudes are performed. Scattering lengths, effective ranges and so–called volume parameters are evaluated. Good agreement with the existing experimental data for the ππ scalar–isoscalar amplitude is found. An importance of future accurate measure...
متن کاملThe pion - pion scattering amplitude . II : Improved analysis above K̄K threshold
We improve, in the energy region between K̄K threshold and ∼ 1.4 GeV, the energy-dependent phase shift analysis of ππ scattering presented in a previous paper. For the S0 wave we have included more data above K̄K threshold and we have taken into account systematically the elasticity data on the reaction ππ → K̄K. We here made a coupled channel fit. For the D0 wave we have considered information on...
متن کاملRigorous pion - pion scattering lengths from threshold πN → ππN data
A new evaluation of the universal ππ scattering length relation is used to extract the ππ s-wave scattering lengths from threshold pion production data. Previous work has shown that the chiral perturbation series relating threshold pion production to ππ scattering lengths appears to converge well only for the isospin-2 case, giving a2 = −0.031±0.007m−1 π . A model-independent and data-insensiti...
متن کامل5 v 1 1 S ep 2 00 0 1 π − π interaction amplitudes with chiral constraints
The ππ interactions are one of the main sources of information on low energy physics. Their knowledge in scalar-isoscalar channel allows us to investigate scalar meson spectroscopy and to test the predictions of many theoretical models. Amplitudes of the ππ interactions should fulfill some basic conditions like unitarity and crossing symmetry. Described in 1) three-coupled channel amplitudes fo...
متن کاملProbing the quark condensate by means of ππ scattering
The available experimental information is consistent with the Weinberg predictions for the threshold parameters of ππ-scattering. The data, however, only test those relations that are insensitive to the quark masses mu and md. Recent theoretical progress leads to remarkably sharp predictions for the behaviour of the Sand P-wave phase shifts in the elastic region – one of the very few low energy...
متن کامل