A2+Mass Spectrum inπ+pInteractions at3.7 GeVc

Abstract

A study of the ${A_2}^{+}$ mass spectrum in ${\pi }^{+}p$ interactions at $3.7 \frac{\mathrm{GeV}}{c}$ is presented. For a cut of $t^{\prime }=0.1\mathrm{}-2.0$ Ge${\mathrm{V}}^2$ and on eliminating the ${\Delta }^{++}$ we find that the three-pion mass spectrum in the ${A_2}^{+}$ region is fitted by the dipole formula with a confidence level of 53% and a single Breit-Wigner formula with a confidence level of 11%. Our result thus favors ${A_2}^{+}$ splitting although a single Breit-Wigner fit cannot be ruled out. We also report the ${A_2}^{+}$ decay branching fractions measured over all $t^{\prime }$ values. They are 0.78 ± 0.05, 0.15 ± 0.04, 0.06 ± 0.03, and < 0.02 for $\rho \pi$, $\eta \pi$, $K\overline{K}$, and ${\eta }^{\prime }\pi$, respectively, in good agreement with other experiments.