Higher threshold parameters in ππ scattering
نویسندگان
چکیده
منابع مشابه
Higher Threshold Parameters in ππ Scattering
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 discrepanci...
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Using the analysis of ChPT to two loops, we perform an error analysis of the threshold and low energy parameters, based on the uncertainties for the one loop low energy parameters and the resonance saturation mechanism. Different sets of one loop low energy constants have been considered. Thus, the predictive power of the effective field theory is quantified on the basis of the present experime...
متن کاملΠπ Scattering
We demonstrate that, together with the available experimental information , chiral symmetry determines the low energy behaviour of the ππ scattering amplitude to within very small uncertainties. In particular, the threshold parameters of the S–, P –, D– and F –waves are predicted, as well as the mass and width of the ρ and of the broad bump in the S–wave. The implications for the coupling const...
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The chiral expansion of the ππ amplitude to the order of two loops was expressed in terms of six independent parameters in a previous paper: four of these are shown here to satisfy sum rules. Their derivation, where crossing symmetry plays a key role, is explained. Their convergence properties are studied and their practical evaluation, in terms of the available data on ππ phase shifts above 0....
متن کاملTheory of Ππ Scattering
The study of ππ scattering is a classical subject in the field of strong interactions: it is a scattering process that may occur at very low energy, far away from the resonance region, and it only involves the quasi–Goldstone bosons of the chiral symmetry of strong interactions. If we stay at low energy, we could expect its dynamics to be strongly constrained by chiral symmetry: as Weinberg sho...
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ژورنال
عنوان ژورنال: Physics Letters B
سال: 1997
ISSN: 0370-2693
DOI: 10.1016/s0370-2693(97)01231-8