MULTIPOLE AMPLITUDES IN ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \chi}_{{c1}}{(1S)}}$ RADIATIVE DECAY

$\mathit b_{2}$ = $\mathit M2/\sqrt {\mathit E1{}^{2}+\mathit M2{}^{2} }$ Magnetic quadrupole fractional transition amplitude

INSPIRE   PDGID:
M055QB2
VALUE ($ 10^{-2} $) EVTS DOCUMENT ID TECN  COMMENT
$\bf{ 2.5 \pm0.4}$ OUR AVERAGE
$2.29$ $\pm0.39$ $\pm0.27$ 164k 1
ABLIKIM
2017N
 BES3 ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$
$2.76$ $\pm0.73$ $\pm0.23$ 39k
ARTUSO
2009
CLEO ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$
$7.7$ ${}^{+5.0}_{-4.5}$ 921
OREGLIA
1982
CBAL ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$
1  Correlated with ${{\mathit a}_{{2}}}$ with correlation coefficient $\rho _{ {{\mathit a}_{{2}}} {{\mathit b}_{{2}}} }$ = 0.133.
References:
ABLIKIM 2017N
PR D95 072004 Measurement of Higher-Order Multipole Amplitudes in ${{\mathit \psi}{(3686)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \chi}_{{c1,2}}}$ with ${{\mathit \chi}_{{c1,2}}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit J / \psi}}$ and Search for the Transition ${{\mathit \eta}_{{c}}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit J / \psi}}$
ARTUSO 2009
PR D80 112003 Higher-Order Multipole Amplitudes in Charmonium Radiative Transitions
OREGLIA 1982
PR D25 2259 Study of the Reaction ${{\mathit \psi}^{\,'}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit J / \psi}}$
Also
Private Comm. Private Communication