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arXiv · hep-ph/0512364

Mass and width of the lowest resonance in QCD

Irinel Caprini·Gilberto Colangelo·Heinrich Leutwyler
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Abstract

We demonstrate that near the threshold, the pi pi scattering amplitude contains a pole with the quantum numbers of the vacuum - commonly referred to as the sigma - and determine its mass and width within small uncertainties. Our derivation does not involve models or parametrizations, but relies on a straightforward calculation based on the Roy equation for the isoscalar S-wave.

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Irinel Caprini, Gilberto Colangelo, Heinrich Leutwyler. 2006-04-07. Mass and width of the lowest resonance in QCD. https://doi.org/10.1103/physrevlett.96.132001

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