Transverse-Momentum—Correlation Features in Multipion Annihilations at 5.7 GeV/c

Abstract

A study of the two-particle correlation in the $\overline{p}p\to 3{\pi }^{+}3{\pi }^{-}$, $\overline{p}p\to 3{\pi }^{+}3{\pi }^{-}{\pi }^0$, $\overline{p}p\to 4{\pi }^{+}4{\pi }^{-}$, and $\overline{p}p\to 4{\pi }^{+}4{\pi }^{-}{\pi }^0$ reactions was carried out by means of variables constructed from ${\overrightarrow{\mathrm{r}}}_1$ and ${\overrightarrow{\mathrm{r}}}_2$, the transverse momenta of the particles entering in each considered pair of pions. We show that transverse-momentum-correlation information can be obtained by using the convenient variables $P^2={|{\overrightarrow{\mathrm{r}}}_1+{\overrightarrow{\mathrm{r}}}_2|}^2$ and $Q^2={|{\overrightarrow{\mathrm{r}}}_1-{\overrightarrow{\mathrm{r}}}_2|}^2$. The fourth differential distribution $\frac{d^{4}N}{\left(d{\overrightarrow{\mathrm{r}}}_{1}d{\overrightarrow{\mathrm{r}}}_2\right)}$. was described by a simple parametrization allowing a direct measurement of the transverse-momentum correlation for the ${\pi }^{\pm }{\pi }^{\pm }$ and ${\pi }^{+}{\pi }^{-}$ pairs.