In:
The European Physical Journal A, Springer Science and Business Media LLC, Vol. 55, No. 10 ( 2019-10)
Abstract:
We report on new measurements of the electric Generalized Polarizability (GP) of the proton $ \alpha_{E}$ α E in a kinematic region where a puzzling dependence on momentum transfer has been observed, and we have found that $ \alpha_E = (5.3 \pm 0.6_{stat} \pm 1.3_{sys}) 10^{-4}$ α E = ( 5 . 3 ± 0 . 6 s t a t ± 1 . 3 s y s ) 10 - 4 fm 3 at $ Q^{2}=0.20$ Q 2 = 0 . 20 (GeV/ c ) 2 . The new measurements, when considered along with the rest of the world data, suggest that $ \alpha_E$ α E can be described by either a local plateau or by an enhancement in the region $ Q^2=0.20$ Q 2 = 0 . 20 (GeV/ c ) 2 to 0.33 (GeV/ c ) 2 . The experiment also provides the first measurement of the Coulomb quadrupole amplitude in the $ N \rightarrow \Delta$ N → Δ transition through the exploration of the $ p(e,e'p)\gamma$ p ( e , e p ) γ reaction. The new measurement gives $ CMR = (-4.4 \pm 0.8_{stat} \pm 0.6_{sys})\%$ C M R = ( - 4 . 4 ± 0 . 8 s t a t ± 0 . 6 s y s ) % at $ Q^2=0.20$ Q 2 = 0 . 20 (GeV/ c ) 2 and is consistent with the results from the pion electroproduction world data. It has been obtained using a completely different extraction method, and therefore represents a strong validation test of the world data model uncertainties.
Type of Medium:
Online Resource
ISSN:
1434-6001
,
1434-601X
DOI:
10.1140/epja/i2019-12877-0
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2019
detail.hit.zdb_id:
1413603-X
detail.hit.zdb_id:
1459066-9
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