# ${{\boldsymbol \eta}}{{\boldsymbol \pi}^{+}}{{\boldsymbol \pi}^{-}}$ MODE INSPIRE search

(For difficulties with MMS experiments, see the ${{\mathit a}_{{2}}{(1320)}}$ mini-review in the 1973 edition.)
VALUE (MeV) DOCUMENT ID TECN CHG  COMMENT
$\bf{ 126 \pm40}$ OUR AVERAGE  Error includes scale factor of 1.8.
$220$ $\pm30$ $\pm50$
 2000
VES 37 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit n}}$
$106$ $\pm27$
 1988
SPEC 0 8.95 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit n}}$
• • • We do not use the following data for averages, fits, limits, etc. • • •
$195$ 1
 1969
MMS - 16 ${{\mathit \pi}^{-}}{{\mathit p}}$ backward
$<21$ 2, 1
 1966
MMS - 7$-$12 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}$ MM
$<30$ 2, 1
 1966
MMS - 7$-$12 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}$ MM
$<38$ 2, 1
 1966
MMS - 7$-$12 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}$ MM
1  Seen in 2.5$-$3 ${\mathrm {GeV/}}\mathit c$ ${{\overline{\mathit p}}}{{\mathit p}}$ . 2 ${{\mathit \pi}^{+}}$2 ${{\mathit \pi}^{-}}$ , with 0, 1, 2 ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ pairs in ${{\mathit \rho}^{0}}$ band not seen by OREN 1974 (2.3 ${\mathrm {GeV/}}\mathit c$ ${{\overline{\mathit p}}}{{\mathit p}}$ ) with more statistics. (Jan. 1979)
2  Not seen by BOWEN 1972 .
References:
 AMELIN 2000
NP A668 83 Natural Parity Resonances in ${{\mathit \eta}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$
 FUKUI 1988
PL B202 441 Vector Resonances Around 1.6 GeV of the ${{\mathit \eta}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ System in the ${{\mathit \pi}^{-}}{{\mathit p}}$ Charge Exchange Reaction at 8.95 ${\mathrm {GeV/}}\mathit c$
 ANDERSON 1969
PRL 22 1390 Observations of ${{\mathit A}_{{1}}^{-}}$, ${{\mathit A}_{{2}}^{-}}$ and Higher Mass Bosons Produced near 180$^\circ{}$ in ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}$ (Missing Mass)${}^{-}$ at 16 ${\mathrm {GeV/}}\mathit c$
 FOCACCI 1966
PRL 17 890 Mass Spectrum of Bosons from 500 to 2500 MeV in the Reaction ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit X}}$ Observed by a Missing Mass Spectrometer