Neutral-decay mode of η⁰ and ω⁰ mesons

Summary

A study of thenγ (n=3, 4, 5, 6) system in the reaction π⁺p→π⁺pnγ has been made using a hydrogen target inside the Ecole Polytechnique heavy-liquid bubble chamber. Directions and momenta of charged tracks and γ-rays are measured. Neutral-decay mode of ω⁰ and η⁰ have been studied with direct identification of secondaries (γ or π⁰). The following branching ratios and cross-sections have been determined:$\begin{gathered} \frac{{\omega ^0 \to \pi ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }} = 0.13 \pm 0.04; \hfill \\ \frac{{\omega ^0 \to \eta ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }}< 0.045 and \frac{{\omega ^0 \to \pi ^0 \pi ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }}< 0.08 \hfill \\ \end{gathered}$ with 95% of confidence.$\begin{gathered} \sigma (\pi ^ + p \to \pi ^ + p\pi ^0 \pi ^0 ) = (1.55 \pm 0.32)mb; \hfill \\ \sigma (\pi ^ + p \to \pi ^ + p\pi ^0 \pi ^0 \pi ^0 ) = (0.68 \pm 0.20)mb; \hfill \\ \end{gathered}$.

Riassunto

Si è studiato il sistemanγ (n=3, 4, 5, 6) nella reazione π⁺p→π⁺pnγ usando un bersaglio di idrogeno nella camera a bolle a liquido pesante della Ecole Polytechnique. Si sono misurate le direzioni e le quantità di moto delle tracce cariche e dei raggi γ. Si è studiato il modo di decadimento neutro di ω⁰ e η⁰ con identificazione diretta dei secondari (γ 0 π⁰). Si sono determinati i rapporti di diramazione e le sezioni d’urto seguenti:$\begin{gathered} \frac{{\omega ^0 \to \pi ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }} = 0.13 \pm 0.04; \hfill \\ \frac{{\omega ^0 \to \eta ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }}< 0.045 e\frac{{\omega ^0 \to \pi ^0 \pi ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }}< 0.08 \hfill \\ \end{gathered}$ col 95% di credibilità.$\begin{gathered} \sigma (\pi ^ + p \to \pi ^ + p\pi ^0 \pi ^0 ) = (1.55 \pm 0.32)mb; \hfill \\ \sigma (\pi ^ + p \to \pi ^ + p\pi ^0 \pi ^0 \pi ^0 ) = (0.68 \pm 0.20)mb; \hfill \\ \end{gathered}$.

Реэуме

Было проведено исследование системыnγ (n=3, 4, 5, 6) в реакции π⁺p→π⁺pnγ, исполяэуя водороднуу мищеня внутри пуэыряковои камеры с тязелои зидкостяу в Политехническои Щколе. Иэмеряутся направления и импулясы эарязенных треков и у-лучеи. Была исследована неитраляная мода распада γ 0 π⁰ с непосредственнои идентификациеи вторичных частиц (γ или π⁰). Были определены следуушие отнощения ветвеи и поперечные сечения:$\frac{{\omega ^0 \to \pi ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }} = 0.13 \pm 0.04;$ $\frac{{\omega ^0 \to \eta ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }}< 0.045$и$\frac{{\omega ^0 \to \pi ^0 \pi ^0 \gamma }}{{\omega ^0 \to \pi ^ + \pi ^ - \pi ^0 }}< 0.08$ с 95% уверенностяу.