π-N charge exchange and π+-π0 scattering at low energies
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文摘
π-N and π-π interactions near threshold are uniquely sensitive to the chiral symmetry breaking part of the strong interaction. The π-N σ-term value with its implications for nucleon quark structure and the recent controversy concerning the size of the scalar quark condensate have renewed the experimental interest in these two fundamental systems. We report new differential cross sections for the reaction π−p→π0n at 27.5 MeV pion incident kinetic energy, measured between θCM = 0° and 55°. Our results are in excellent agreement with the existing comprehensive πN phase shift analysis. We also report on a Chew-Low analysis of exclusive π+p→π+π0p data at 260 MeV pion incident energy.