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تسجيل مستخدم جديدExtracting the sigma-term from low-energy pion-nucleon scattering
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We present an extraction of the pion-nucleon ($pi N$) scattering lengths from low-energy $pi N$ scattering, by fitting a representation based on Roy-Steiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large $pi N$ $sigma$-term, $sigma_{pi N}=58(5)$ MeV, in agreement with, albeit less precise than, the determination from pionic atoms.
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We have reanalyzed the $pi ^{pm} p$ scattering data at low energy in the Coulomb-nuclear interference region as measured by the CHAOS group at TRIUMF with the aim to determine the pion-nucleon $sigma$ term. The resulting value $sigma=(44pm 12)$ MeV,
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