# ${{\boldsymbol a}_{{4}}{(1970)}}$ MASS INSPIRE search

VALUE (MeV) EVTS DOCUMENT ID TECN CHG  COMMENT
$\bf{ 1967 \pm16}$ OUR AVERAGE  Error includes scale factor of 2.1.
$1935$ ${}^{+11}_{-13}$ 46M 1
 2018 B
COMP 190 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \pi}^{-}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit p}}$
$1900$ ${}^{+80}_{-20}$
 2015
COMP 191 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}^{(')}}{{\mathit \pi}^{-}}{{\mathit p}}$
$1985$ $\pm10$ $\pm13$ 145k
 2005
B852 18 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \omega}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}{{\mathit p}}$
$1996$ $\pm25$ $\pm43$
 2002
B852 18.3 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ 3 ${{\mathit \pi}}{{\mathit p}}$
$2000$ $\pm40$ ${}^{+60}_{-20}$
 2001
B852 18 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}^{\,'}}{{\mathit \pi}^{-}}{{\mathit p}}$
$2010$ $\pm20$ 2
 1996
GAM2 0 38 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \pi}^{0}}{{\mathit n}}$
$2040$ $\pm30$ 3
 1982 B
SPEC $\pm{}$ 50 ${{\mathit \pi}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit K}_S^0}$ ${{\mathit K}^{\pm}}{{\mathit p}}$
• • • We do not use the following data for averages, fits, limits, etc. • • •
$1885$ $\pm13$ ${}^{+50}_{-2}$ 420k 4
 2010
COMP 190 ${{\mathit \pi}^{-}}$ $\rightarrow$ ${{\mathit \pi}^{-}}{{\mathit \pi}^{-}}{{\mathit \pi}^{+}}{{\mathit P}}{{\mathit b}^{\,'}}$
$2004$ $\pm6$ 80k 5
 2006
E835 5.2 ${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \eta}}{{\mathit \pi}^{0}}$
$2005$ ${}^{+25}_{-45}$ 6
 2001 F
SPEC 2.0 ${{\overline{\mathit p}}}$ ${{\mathit p}}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ , ${{\mathit \pi}^{0}}{{\mathit \eta}}$ , ${{\mathit \pi}^{0}}{{\mathit \eta}^{\,'}}$
$1944$ $\pm8$ $\pm50$ 7
 1999
VES 37 ${{\mathit \pi}^{-}}$ ${{\mathit A}}$ $\rightarrow$ ${{\mathit \omega}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}{{\mathit A}^{*}}$
$1903$ $\pm10$ 8
 1978
SPEC - 10 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit K}_S^0}$ ${{\mathit K}^{-}}$
$2030$ $\pm50$ 9
 1978 C
OMEG 0 15 ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ 3 ${{\mathit \pi}}{{\mathit n}}$
1  Statistical error negligible.
2  From a simultaneous fit to the $\mathit G_{+}$ and $\mathit G_{0}$ wave intensities.
3  From an amplitude analysis.
4  Superseded by AGHASYAN 2018B.
5  Statistical error only.
6  From the combined analysis of ANISOVICH 1999C, ANISOVICH 1999E, and ANISOVICH 2001F.
7  May be a different state.
8  From a fit to the $\mathit Y{}^{0}_{8}$ moment. Limited by phase space.
9  $\mathit J{}^{P} = 4{}^{+}$ is favored, though $\mathit J{}^{P} = 2{}^{+}$ cannot be excluded.

${{\mathit a}_{{4}}{(1970)}}$ MASS (MeV)
References:
 AGHASYAN 2018B
PR D98 092003 Light isovector resonances in $\pi^- p \to \pi^-\pi^-\pi^+ p$ at 190 GeV/${\it c}$
PL B740 303 Odd and Even Partial Waves of ${{\mathit \eta}}{{\mathit \pi}^{-}}$ and ${{\mathit \eta}^{\,'}}{{\mathit \pi}^{-}}$ in ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}^{{(')}}}{{\mathit \pi}^{-}}{{\mathit p}}$ at 191 GeV/$\mathit c$
 ALEKSEEV 2010
PRL 104 241803 Observation of a $\mathit J{}^{PC} = 1-+$ Exotic Resonance in Diffractive Dissociation of 190 GeV/$\mathit c$ ${{\mathit \pi}^{-}}$ into ${{\mathit \pi}^{-}}{{\mathit \pi}^{-}}{{\mathit \pi}^{+}}$
 UMAN 2006
PR D73 052009 Light Quark Resonances in ${{\overline{\mathit p}}}{{\mathit p}}$ Annihilations at 5.2 GeV/$\mathit c$
 LU 2005
PRL 94 032002 Exotic Meson Decay to ${{\mathit \omega}}{{\mathit \pi}^{0}}{{\mathit \pi}^{-}}$
 CHUNG 2002
PR D65 072001 Exotic and ${\mathit {\mathit q}}{\mathit {\overline{\mathit q}}}$ Resonances in the ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{-}}$ System Produced in ${{\mathit \pi}^{-}}{{\mathit p}}$ Collisions at 18-GeV/$\mathit c$
 ANISOVICH 2001F
PL B517 261 Partial Wave Analysis of ${{\overline{\mathit p}}}{{\mathit p}}$ Annihilation Channels in Flight with $\mathit I = 1,\mathit C$=+1
 IVANOV 2001
PRL 86 3977 Observation of Exotic Meson Production in the Reaction ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \eta}^{\,'}}{{\mathit \pi}^{-}}{{\mathit p}}$ at 18 ${\mathrm {GeV/}}\mathit c$
 AMELIN 1999
PAN 62 445 Investigation of the Reaction ${{\mathit \pi}^{-}}$ ${+}$ ${{\mathit A}}$ $\rightarrow$ ${{\mathit \omega}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}{+}$ ${{\mathit A}}$
 DONSKOV 1996
PAN 59 982 Observation of ${{\mathit a}_{{4}}{(2040)}^{0}}$ Meson in the ${{\mathit \eta}}{{\mathit \pi}^{0}}$ Decay Channel
 CLELAND 1982B
NP B208 228 Resonance Production in the Reaction ${{\mathit \pi}^{\pm}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit K}_S^0}$ ${{\mathit K}^{\pm}}{{\mathit p}}$ at 30 and 50 ${\mathrm {GeV/}}\mathit c$
 BALDI 1978
PL 74B 413 Observation of a Spin = 4, Isospin = 1, Meson Resonance
 CORDEN 1978C
NP B136 77 A Partial Wave Analysis of the Neutral 3${{\mathit \pi}}$ System Produced in the Reaction ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ( ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$) ${{\mathit n}}$ at 12 and 15 ${\mathrm {GeV/}}\mathit c$