Investigation of the conjectured nucleon deformation at low momentum transfer.
We report new precise H(e,e(')p)pi(0) measurements at the Delta(1232) resonance at Q(2)=0.127 (GeV/c)(2) obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the gamma(*)N-->Delta transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: Re(E(3/2)(1+)/M(3/2)(1+))=(-2.3+/-0.3(stat+syst)+/-0.6(model))% and Re(S(3/2)(1+)/M(3/2)(1+))=(-6.1+/-0.2(stat+syst)+/-0.5(model))% for M(3/2)(1+)=(41.4+/-0.3(stat+syst)+/-0.4(model))(10(-3)/m(pi(+))). The derived amplitudes give credence to the conjecture of deformation in hadrons favoring, at low Q2, the dominance of mesonic effects.
Sparveris
N F
NF
Institute of Accelerating Systems and Applications and Department of Physics, University of Athens, Athens, Greece.
Alarcon
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Bernstein
A M
AM
Bertozzi
W
W
Botto
T
T
Bourgeois
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Calarco
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Casagrande
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Distler
M O
MO
Dow
K
K
Farkondeh
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M
Georgakopoulos
S
S
Gilad
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S
Hicks
R
R
Holtrop
M
M
Hotta
A
A
Jiang
X
X
Karabarbounis
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Kirkpatrick
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Kowalski
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Milner
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Miskimen
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Nakagawa
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Papanicolas
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Sarty
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Sato
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Y
Sirca
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S
Shaw
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Six
E
E
Stave
S
S
Stiliaris
E
E
Tamae
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T
Tsentalovich
G
G
Tschalaer
C
C
Turchinetz
W
W
Zhou
Z-L
ZL
Zwart
T
T