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ENERGY DEPENDENCE OF ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}}$ DALITZ PLOTS

$\alpha $ PARAMETER FOR ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$

INSPIRE   PDGID:

S014A0

See the “Note on ${{\mathit \eta}}$ Decay Parameters” in our 1994 edition, Phys.Rev.$\mathbf {D50}$, 1 August 1994, Part$~$I, p.$~$1454. The value here is of $\alpha $ in $\vert $matrix element$\vert ^2$ = 1 + 2${}\alpha {}\mathit z$.

VALUE EVTS DOCUMENT ID TECN  COMMENT $\bf{ -0.0288 \pm0.0012}$ OUR AVERAGE  Error includes scale factor of 1.1. $-0.0265$ $\pm0.0010$ $\pm0.0009$ 7M PRAKHOV 2018 CRYB ${{\mathit \gamma}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \eta}}$ $-0.055$ $\pm0.014$ $\pm0.004$ 33k ABLIKIM 2015 G BES3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}}$ $-0.0301$ $\pm0.0035$ ${}^{+0.0022}_{-0.0035}$ 512k AMBROSINO 2010 A KLOE ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \phi}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \gamma}}$ $-0.027$ $\pm0.008$ $\pm0.005$ 120k 1 ADOLPH 2009 WASA ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit p}}{{\mathit \eta}}$ $-0.0322$ $\pm0.0012$ $\pm0.0022$ 3M 2 PRAKHOV 2009 CRYB ${{\mathit \gamma}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \eta}}$ $-0.032$ $\pm0.002$ $\pm0.002$ 1.8M 2 UNVERZAGT 2009 CRYB ${{\mathit \gamma}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \eta}}$ $-0.026$ $\pm0.010$ $\pm0.010$ 75k BASHKANOV 2007 WASA ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit p}}{{\mathit \eta}}$ $-0.010$ $\pm0.021$ $\pm0.010$ 12k ACHASOV 2001 C SND ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \phi}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \gamma}}$ $-0.031$ $\pm0.004$ 1M TIPPENS 2001 CRYB ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit n}}{{\mathit \eta}}$ , 720 MeV $-0.052$ $\pm0.017$ $\pm0.010$ 98k ABELE 1998 C CBAR ${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ 5 ${{\mathit \pi}^{0}}$ $-0.022$ $\pm0.023$ 50k ALDE 1984 GAM2 • • We do not use the following data for averages, fits, limits, etc. • • $-0.038$ $\pm0.003$ ${}^{+0.012}_{-0.008}$ 1.34M 3 AMBROSINO 2008 D KLOE $-0.32$ $\pm0.37$ 192 BAGLIN 1970 HLBC 1  This ADOLPH 2009 result is independent of the BASHKANOV 2007 result. 2  The PRAKHOV 2009 and UNVERZAGT 2009 results are independent. 3  This AMBROSINO 2008D value is an indirect result using ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{0}}{{\mathit \pi}^{-}}$ events and a$~$rescattering matrix that mixes isospin decay amplitudes.

References:

PRAKHOV 2018 PR C97 065203 High-statistics measurement of the $\eta \to 3\pi^0$ decay at the Mainz Microtron ABLIKIM 2015G PR D92 012014 Measurement of the Matrix Elements for the Decays ${{\mathit \eta}}$ $\rightarrow$ ${+}$ ${{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ and ${{\mathit \eta}}$ $/$ ${{\mathit \eta}^{\,'}}$ $\rightarrow$ ${{\mathit \pi}^{0}}{{\mathit \pi}^{0}}{{\mathit \pi}^{0}}$ AMBROSINO 2010A PL B694 16 Measurement of the ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ Slope Parameter $\alpha $ with the KLOE Detector ADOLPH 2009 PL B677 24 Measurement of the ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ Dalitz Plot Distribution with the WASA Detector at COSY PRAKHOV 2009 PR C79 035204 Measurement of the Slope Parameter $\alpha $ for the ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ Decay with the Crystal Ball Detector at the Mainz Microtron (MAMI-C) UNVERZAGT 2009 EPJ A39 169 Determination of the Dalitz Plot Parameter $\alpha $ for the Decay ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ with the Crystal Ball at MAMI-B AMBROSINO 2008D JHEP 0805 006 Determination of ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ Dalitz Plot Slopes and Asymmetries with the KLOE Detector BASHKANOV 2007 PR C76 048201 Measurement of the Slope Parameter for the ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ Decay in the ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit p}}{{\mathit \eta}}$ Reaction ACHASOV 2001C JETPL 73 451 Dynamics of ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ Decay TIPPENS 2001 PRL 87 192001 Determination of the Quadratic Slope Parameter in ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ Decay ABELE 1998C PL B417 193 Decay Dynamics of the Process ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ ALDE 1984 ZPHY C25 225 Neutral Decays of ${{\mathit \eta}}$ Meson Also SJNP 40 918 Neutral Decays of ${{\mathit \eta}}$ Meson BAGLIN 1970 NP B22 66 Heavy Liquid Bubble Chamber Analysis of ${{\mathit \eta}}$ Neutral Decay Modes ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ and ${{\mathit \eta}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$

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