Measurement of the transverse–longitudinal cross sections in the π reaction in the Δ region

Kunz, C. L.; Kaloskamis, N. I.; Distler, M. O.; Zhou, Zhengfang; Alarcón, R.; Barkhuff, D.; Bernstein, A. M.; Bertozzi, W.; Calarco, J. R.; Casagrande, F.; Chen, J.; Comfort, J. R.; Dodson, G.; Dooley, A.; Farkhondeh, M.; Georgakopoulos, Stavros V.; Gilad, S.; Hicks, R. S.; Hotta, A.; Jiang, X.; Karabarbounis, A.; Kowalski, S.; Margaziotis, D. J.; Mertz, C.; Miskimen, R.; Nakagawa, I.; Papanicolas, C. N.; Pavan, M. M.; Peterson, G. A.; Ramirez, A. F.; Rowntree, D.; Sarty, A. J.; Shaw, J.; Six, E.; Sparveris, N.; Soong, S.; Stiliaris, S.; Tamae, T.; Tieger, D.; Tschalaer, C.; Tsentalovich, G.; Turchinetz, W.; Vellidis, C.; Warren, G.; Williamson, S. E.; Young, A. T.; Zhao, J.; Zwart, T.

doi:10.1016/s0370-2693(03)00675-0

Cited by 43 publications

(22 citation statements)

References 24 publications

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“…Measurements of the E2 amplitude from photopion reaction experiments with polarized photons have been reported [4,5]. Electroproduction experiments at JLab [6,7] for Q 2 from 0.4 to 4.0 (GeV/c) 2 , at Bates [8][9][10][11] at Q 2 = 0.127 (GeV/c) 2 and Mainz [12][13][14] at Q 2 = 0.127, 0.20 (GeV/c) 2 have been published. The present result at Q 2 = 0.060 (GeV/c) 2 is the lowest-Q 2 value probed to date in modern, precision electroproduction.…”

Section: Pacs 1360le Meson Production -1340gp Electromagnetic Fomentioning

confidence: 99%

Lowest- Q2 measurement of the γp → Δ reaction: Probing the pionic contribution

et al. 2006

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Abstract. To determine nonspherical angular-momentum amplitudes in hadrons at long ranges (low Q 2 ), data were taken for the p( e, e p)π 0 reaction in the ∆ region at Q 2 = 0.060 (GeV/c) 2 utilizing the magnetic spectrometers of the A1 Collaboration at MAMI. The results for the dominant transition magnetic dipole amplitude and the quadrupole to dipole ratios at W = 1232 MeV are M Experimental confirmation of the presence of nonspherical hadron amplitudes (i.e. d states in quark models or p-wave π-N states) is fundamental and has been the subject of intense experimental and theoretical interest (for reviews see [1][2][3]). This effort has focused on the measurement of the electric and Coulomb quadrupole amplitudes (E2, C2) in the predominantly M 1 (maga Current address:

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Section: Pacs 1360le Meson Production -1340gp Electromagnetic Fomentioning

confidence: 99%

Lowest- Q2 measurement of the γp → Δ reaction: Probing the pionic contribution

et al. 2006

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“…This work represents the initial phase of the isospin decomposition of the γ * p → reaction at low Q 2 . The data, which exhibit a higher sensitivity to the background amplitude terms compared to our previously explored 1 H(e,e p)π 0 channel studies in the small Q 2 region [6][7][8][9][10][11], provide strong constraints to the most recent theoretical calculations. We find that the DMT [30] and MAID [32] models are in reasonable agreement with the data but that the Sato-Lee model [29] and the chiral effective field theory calculations [35] are not.…”

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confidence: 80%

“…At long ranges the dominant contribution originates in the spontaneous breaking of chiral symmetry, which leads to a spherically asymmetric virtual pion cloud [3]. With this in mind our group has focused on the γ * p → reaction at low Q 2 [ 0.2 (GeV/c) 2 ] [6][7][8][9][10][11][12] with precise measurements at Bates and Mainz. Other experiments at low Q 2 have also been performed at Mainz and Brookhaven [13][14][15][16].…”

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confidence: 99%

Measurement of the partial cross sectionsσTT,σLT, and(

Kirkpatrick¹,

Sparveris²,

Nakagawa³

et al. 2011

Phys. Rev. C

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Measurement of the partial cross sections σ T T , σ LT , and (σ T + εσ L ) of the 1 H(e,e π + )n reaction in the (1232) resonance We report precision 1 H(e,e π + )n measurements in the (1232) resonance at Q 2 = 0.127(GeV/c) 2 obtained at the MIT-Bates out-of-plane scattering facility. These are the lowest, but nonzero, Q 2 measurements in the π + channel. The data offer tests of the theoretical calculations, particularly of the background amplitude contributions. The chiral effective field theory and Sato-Lee model calculations are not in agreement with this experiment.

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“…In the whole region up to ∼ 4 GeV 2 the ratios E2/M1 and C2/M1 are found to be small and negative, especially |E2/M1| is smaller than 5% [3,4,5,6,7]. In the case of real photons, which is relevant for this work, the Coulomb quadrupole is known to vanish.…”

Section: Introductionmentioning

confidence: 99%

Light-cone sum rules for theNγΔtransitions for real photons

Rohrwild

2007

Phys. Rev. D

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Abstract:We examine the radiative ∆ → γN transition at the real photon point Q 2 = 0 using the framework of light-cone QCD sum rules. In particular, the sum rules for the transition form factors G M (0) and R EM are determined up to twist 4. The result for G M (0) agrees with experiment within 10% accuracy. The agreement for R EM is also reasonable. In addition, we derive new light-cone sum rules for the magnetic moments of nucleons, with a complete account of twist-4 corrections based on a recent reanalysis of photon distribution amplitudes.

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Measurement of the transverse–longitudinal cross sections in the π reaction in the Δ region

Cited by 43 publications

References 24 publications

Lowest- Q2 measurement of the γp → Δ reaction: Probing the pionic contribution

Lowest- Q2 measurement of the γp → Δ reaction: Probing the pionic contribution

Measurement of the partial cross sectionsσTT,σLT, and(

Light-cone sum rules for theNγΔtransitions for real photons

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