On the Determination of πN Phase Shifts from Isospin Constraints and Fixed t Analyticity
This seminar deals with the problem of the determination of the phase of the πN scattering amplitudes from observable quantities (differential cross-sections and polarizations). Its aim is to present, following Ref., conditions on the amplitudes under which a unique construction of the phase can be achieved in some neighbourhood of the forward direction, using constraints coming from analyticity at fixed momentum transfer (t), isospin invariance and unitarity.
KeywordsAnalytic Continuation Meromorphic Function Positivity Property Physical Region Observable Quantity
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