Showing papers by "Zhengguo Zhao published in 1995"

Strong interaction shift and width of the 1s level in pionic hydrogen.

Abstract: The $3p\ensuremath{-}1s$ x-ray line of pionic hydrogen was measured with a reflecting bent crystal spectrometer. The strong interaction energy level shift and the total decay width of the $1s$ state, obtained from the transition energy and the linewidth, are ${\ensuremath{\varepsilon}}_{1s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}7.127\ifmmode\pm\else\textpm\fi{}0.028\left(\mathrm{stat}\right)\ifmmode\pm\else\textpm\fi{}0.036(\mathrm{syst})\phantom{\rule{0ex}{0ex}}\mathrm{eV}$ (attractive) and ${\ensuremath{\gamma}}_{1s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.97\ifmmode\pm\else\textpm\fi{}0.10\left(\mathrm{stat}\right)\ifmmode\pm\else\textpm\fi{}0.05\left(\mathrm{syst}\right)\phantom{\rule{0ex}{0ex}}\mathrm{eV}$. The corresponding hadronic $\ensuremath{\pi}N$ s-wave scattering lengths for elastic scattering and single charge exchange are ${a}_{{\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p}^{h}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.0885\ifmmode\pm\else\textpm\fi{}{0.0009m}_{\ensuremath{\pi}}^{\ensuremath{-}1}$ and ${a}_{{\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}n}^{h}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.136\ifmmode\pm\else\textpm\fi{}{0.010m}_{\ensuremath{\pi}}^{\ensuremath{-}1}$.

Determination of the S-wave scattering length in pionic deuterium with a high resolution crystal spectrometer.

Abstract: The pionic deuterium 3{ital P}{minus}1{ital S} x-ray transition was measured with a quartz crystal spectrometer in combination with a cyclotron trap and charge coupled device detectors. The strong interaction shift and total decay width of the 1{ital S} level are {epsilon}{sub 1{ital S}}(shift)=2.48{plus_minus}0.10 eV (repulsive), {Gamma}{sub 1{ital S}}(width)=1.02{plus_minus}0.21 eV, where the statistical and systematic errors were added linearly. They yield the total pionic deuterium {ital S}-wave scattering length: {ital a}{sub {pi}{sup {minus}}{ital d}}= {minus}0.0264({plus_minus}0.0011)+{ital i}0.0054({plus_minus}0.0011){ital m}{sub {pi}}{sup {minus}1}.