Measurement of the N * − − N * + + Mass Difference
1966; American Institute of Physics; Volume: 141; Issue: 4 Linguagem: Inglês
10.1103/physrev.141.1261
ISSN1536-6065
AutoresG. Gidal, A. Kernan, Sedong Kim,
Tópico(s)High-Energy Particle Collisions Research
ResumoA measurement of the ${N}^{*\ensuremath{-}}\ensuremath{-}{N}^{*++}$ mass and width differences is described, where ${N}^{*}$ is the nucleon resonance with $I({J}^{P})=\frac{3}{2}({\frac{3}{2}}^{+})$ and mass approximately 1240 MeV. The resonances were produced in the inelastic reactions $\mathrm{nn}\ensuremath{\rightarrow}\mathrm{pn}{\ensuremath{\pi}}^{\ensuremath{-}}$ and $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{np}{\ensuremath{\pi}}^{+}$, which are known to proceed almost entirely via ${N}^{*\ensuremath{-}}$ and ${N}^{*++}$ production, respectively, in the observed energy region. A comparison of the ($n{\ensuremath{\pi}}^{\ensuremath{-}}$) and ($p{\ensuremath{\pi}}^{+}$) effective-mass distributions gives a mass difference of 7.9\ifmmode\pm\else\textpm\fi{}6.8 MeV and a width difference of 25\ifmmode\pm\else\textpm\fi{}23 MeV for ${N}^{*}\ensuremath{-}{N}^{*++}$. This result agrees with predictions based on the $\mathrm{SU}(3)$ and $\mathrm{SU}(6)$ symmetry schemes.
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