MULTIPOLE AMPLITUDES IN ${{\mathit \chi}_{{{c1}}}{(1P)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit J / \psi}{(1S)}}$

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

INSPIRE   PDGID:
M055A1
VALUE ($ 10^{-2} $) EVTS DOCUMENT ID TECN  COMMENT
$\bf{ -6.7 \pm0.9}$ OUR AVERAGE  Error includes scale factor of 2.6.  See the ideogram below.
$-7.40$ $\pm0.33$ $\pm0.34$ 164k 1
ABLIKIM
2017N
 BES3 ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$
$-6.26$ $\pm0.63$ $\pm0.24$ 39k
ARTUSO
2009
CLEO ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \ell}^{+}}{{\mathit \ell}^{-}}$
$0.2$ $\pm3.2$ $\pm0.4$ 2090
AMBROGIANI
2002
E835 ${{\mathit p}}$ ${{\overline{\mathit p}}}$ $\rightarrow$ ${{\mathit \chi}_{{{c1}}}}$ $\rightarrow$ ${{\mathit J / \psi}}{{\mathit \gamma}}$
$-0.2$ ${}^{+0.8}_{-2.0}$ 921
OREGLIA
1982
CBAL ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit \chi}_{{{c1}}}}{{\mathit \gamma}}$ $\rightarrow$ ${{\mathit J / \psi}}{{\mathit \gamma}}{{\mathit \gamma}}$
1  Correlated with ${{\mathit b}_{{{2}}}}$ with correlation coefficient $\rho _{{{\mathit a}_{{{2}}}} {{\mathit b}_{{{2}}}}}$ = 0.133.

           $\mathit a_{2}$ = $\mathit M2/\sqrt {\mathit E1{}^{2}+\mathit M2{}^{2} }$
References