#### ${{\mathit \Delta}{(1232)}}$ BREIT-WIGNER PHOTON DECAY AMPLITUDES

Papers on ${{\mathit \gamma}}{{\mathit N}}$ amplitudes predating 1981 may be found in our 2006 edition, Journal of Physics G33 1 (2006).

#### ${{\mathit \Delta}{(1232)}}$ $\rightarrow$ ${{\mathit N}}{{\mathit \gamma}}$ , ${{\mathit E}_{{2}}}/{{\mathit M}_{{1}}}$ ratio

VALUE DOCUMENT ID TECN  COMMENT
 $\bf{ -0.030\text{ to }-0.020\text{ }(\approx-0.025) }$ OUR ESTIMATE
$-0.0274$ $\pm0.0003$ $\pm0.0030$
 2004 A
DPWA $\vec\gamma\vec {{\mathit p}}$ $\rightarrow$ ${{\mathit N}}{{\mathit \pi}}$
$-0.020$ $\pm0.002$
 2002
DPWA ${{\mathit \gamma}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit N}}{{\mathit \pi}}$
$-0.0307$ $\pm0.0026$ $\pm0.0024$
 2001
LEGS ${{\mathit \gamma}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \gamma}}$ , ${{\mathit p}}{{\mathit \pi}^{0}}$ , ${{\mathit n}}{{\mathit \pi}^{+}}$
$-0.016$ $\pm0.004$ $\pm0.002$
 2001
DPWA ${{\mathit \gamma}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit p}}$
$-0.025$ $\pm0.001$ $\pm0.002$
 2000
IPWA $\vec\gamma$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{0}}$ , ${{\mathit n}}{{\mathit \pi}^{+}}$
$-0.0233$ $\pm0.0017$
 1998
IPWA ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit N}}$
$-0.015$ $\pm0.005$ 1
 1997
IPWA ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit N}}$
$-0.0319$ $\pm0.0024$
 1997
DPWA ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit N}}$
• • We do not use the following data for averages, fits, limits, etc. • •
$-0.022$
 2007
DPWA ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit N}}$
$-0.026$
 2002 D
DPWA Multichannel
$-0.0254$ $\pm0.0010$
 1998
DPWA ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit N}}$
$-0.025$ $\pm0.002$ $\pm0.002$
 1997
IPWA ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit N}}$
$-0.030$ $\pm0.003$ $\pm0.002$
 1997
DPWA ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit N}}$ , ${{\mathit \gamma}}{{\mathit N}}$
 1 This ARNDT 1997 value is very sensitive to the database being fitted. The result is from a fit to the full pion photoproduction database, apart from the BLANPIED 1997 cross-section measurements.

${{\mathit \Delta}{(1232)}}$ $\rightarrow$ ${{\mathit N}}{{\mathit \gamma}}$ , ${{\mathit E}_{{2}}}/{{\mathit M}_{{1}}}$ ratio
References:
 DRECHSEL 2007
EPJ A34 69 Unitary Isobar Model $−$ MAID2007
 AHRENS 2004A
EPJ A21 323 Helicity Dependence of the ${{\mathit \gamma}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit N}}{{\mathit \pi}}$ Channels and Multipole Analysis in the ${{\mathit \Delta}}$ Region
 ARNDT 2002
PR C66 055213 Analysis of Pion Photoproduction Data
 PENNER 2002D
PR C66 055212 Vector Meson Production and Nucleon Resonance Analysis in a Coupled Channel Approach for Energies ${\mathit m}_{{{\mathit N}}}$ $<$ $\sqrt {s }$ $<$ 2 GeV. 2. Photon Induced Results
 BLANPIED 2001
PR C64 025203 ${{\mathit N}}$ $\rightarrow$ ${{\mathit \Delta}}$ Transition and Proton Polarizabilities from Measurements of ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit \gamma}}$), ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit \pi}^{0}}$), and ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit \pi}^{+}}$)
 GALLER 2001
PL B503 245 Compton Scattering by the Proton
 BECK 2000
PR C61 035204 Determination of the $\mathit E2/\mathit M$1 Ratio in the ${{\mathit \gamma}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit \Delta}{(1232)}}$ Transition from a Simultaneous Measurement of ${{\mathit p}}({{\mathit \gamma}}↑$, ${{\mathit p}}){{\mathit \pi}^{0}}$ and ${{\mathit p}}({{\mathit \gamma}}↑$, ${{\mathit \pi}^{+}}){{\mathit n}}$
 HANSTEIN 1998
NP A632 561 Multipole Analysis of Pion Photoproduction Based on Fixed $\mathit t$ Dispersion Relations and Unitarity
 ARNDT 1997
PR C56 577 Pion Photoproduction in the ${{\mathit \Delta}}$ Resonance Region
 BECK 1997
PRL 78 606 Measurement of the $\mathit E2/\mathit M$1 Ratio in the ${{\mathit N}}$ $\rightarrow$ ${{\mathit \Delta}}$ Transition using the Reaction ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit p}}$) ${{\mathit \pi}^{0}}$
 Also
PRL 79 4510 Replay on BECK 1997 Measurement of the $\mathit E2/\mathit M$1 Ratio in the ${{\mathit N}}$ $\rightarrow$ ${{\mathit \Delta}}$ Transition using the Reaction ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit p}}$) ${{\mathit \pi}^{0}}$
 Also
PRL 79 4512 Measurement of the $\mathit E2/\mathit M$1 Ratio in the ${{\mathit N}}$ $\rightarrow$ ${{\mathit \Delta}}$ Transition using the Reaction ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit p}}$) ${{\mathit \pi}^{0}}$
 Also
PRL 79 4515 (erratum) Erratum: (BECK 1997 ) Measurement of the $\mathit E2/\mathit M$1 Ratio in the ${{\mathit N}}$ $\rightarrow$ ${{\mathit \Delta}}$ Transition using the Reaction ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit p}}$) ${{\mathit \pi}^{0}}$
 BLANPIED 1997
PRL 79 4337 ${{\mathit n}}$ $\rightarrow$ ${{\mathit \Delta}}$ Transition from Simultaneous Measurements of ${{\mathit p}}$ (${{\mathit \gamma}}$, ${{\mathit \pi}}$) and ${{\mathit p}}$ (${{\mathit \gamma}}↑$, ${{\mathit \gamma}}$)
 DAVIDSON 1997
PRL 79 4509 Mainz Measurement of the $\mathit E2/\mathit M$1 Ratio in the ${{\mathit N}}$ $−$ ${{\mathit \Delta}}$ Transition. (A Comment on the Letter by R.Beck $\mathit et~al$, PRL 78, 606 (BECK 1997 ))