Pion–nucleon sigma term σπNand deeply bound pionic atoms

Abstract

AbstractWe investigate the possibility of determining the value of the pion–nucleon sigma term σπN precisely by the experimental observables of deeply bound pionic atoms. We discuss the sensitivity of the observables to σπN and take into account the typical errors of up-to-date experiments on deeply bound pionic atoms. We find that the gap in the binding energies and the width of the deeply bound pionic states are good observables for σπN value determination with experimental data. We also discuss the expected difficulties for the accurate determination of the value of σπN due to the correlation between the σ term and the potential parameter in the pion–nucleus optical potential.