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${{\mathit \eta}}$ $\mathit C$-NONCONSERVING DECAY PARAMETERS

${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ PARAMETER $\beta $ (${\mathit D}{\mathrm -wave}$)

INSPIRE   PDGID:

S014BET

Sensitive to a ${\mathit D}{\mathrm -wave}$ contribution: $\mathit dN/\mathit d$cos $\theta $ = sin$^2\theta $ ${}$ (1 + $\beta $ ${}$ cos $^2\theta $).

VALUE EVTS DOCUMENT ID TECN $\bf{ -0.02 \pm0.07}$ OUR AVERAGE  Error includes scale factor of 1.3. $0.11$ $\pm0.11$ 35k JANE 1974 B OSPK $-0.060$ $\pm0.065$ 7250 GORMLEY 1970 WIRE • • We do not use the following data for averages, fits, limits, etc. • • $0.12$ $\pm0.06$ 1 THALER 1972 ASPK 1  The authors don't believe this indicates ${\mathit D}{\mathrm -wave}$ because the dependence of $\beta $ on the ${{\mathit \gamma}}$ energy is inconsistent with the theoretical prediction. A cos $^2\theta $ dependence can also come from $\mathit P$- and ${\mathit F}{\mathrm -wave}$ interference.

Conservation Laws:

CHARGE CONJUGATION ($\mathit C$) INVARIANCE

References:

JANE 1974B PL 48B 265 Measurement of the Charge Asymmetry in the Decay ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ THALER 1972 PRL 29 313 Charge Asymmetry in the Decay ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ GORMLEY 1970 PR D2 501 Experimental Determination of the Dalitz-Plot Distribution of the Decays ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ and ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ , and the Branching ratio ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ $/$ ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ Also Thesis Nevis 181 Dalitz Plot Analysis of the Decays of ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ and ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ . The Branching Ratio ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ / ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$

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