Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">E</mml:mi><mml:mn>2</mml:mn><mml:mi>/</mml:mi><mml:mi mathvariant="italic">M</mml:mi><mml:mn>1</mml:mn></mml:math>Ratio in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">N</mml:mi><mml:mi /><mml:mo>→</mml:mo><mml:mi /><mml:mi mathvariant="italic">Δ</mml:mi></mml:math>Transition Using the Reaction<mml:math xmlns:mml="http://www.w3

Beck, R.; Krahn, H. P.; Ahrens, J.; Arends, H. J.; Audit, G.; Braghieri, A.; d’Hose, N.; Hall, S.J.; Isbert, V.; Kellie, J. D.; MacGregor, I. J. D.; Pedroni, P.; Pinelli, T.; Tamas, G.; Walcher, Th.; Wartenberg, S.A.

doi:10.1103/physrevlett.79.4515.2

Cited by 97 publications

(209 citation statements)

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“…Results of previous data analysis at Q 2 = 0 from Ref. [5], data at Q 2 =2.8 and 4.0 (GeV /c) 2 from Ref. [1] (stars).…”

Section: Figmentioning

confidence: 99%

“…On the other hand, in symmetric SU (6) quark models, the γN ∆ transition can proceed only via the flip of a single quark spin in the nucleon, leading to M 1+ dominance and E 1+ = S 1+ ≡ 0. Recent experiments give nonvanishing ratios R EM lying between −2.5% [5] and −3.0% [6] at Q 2 = 0. This has been widely taken as an indication of a deformed ∆, namely, an admixture of a D state in the ∆.…”

Section: +mentioning

confidence: 99%

See 1 more Smart Citation

<‘γN→Δtransition form factors: A new analysis of data on
Kamalov
¹
,
Yang
²
,
Drechsel
³

et al. 2001
Phys. Rev. C*
148
3
140
1
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Recent JLab data of the differential cross section for the reaction p(e, e ′ p)π 0 in the invariant mass region of 1.1 < W < 1.4 GeV at four-momentum transfer squared Q 2 = 2.8 and 4.0 (GeV/c) 2 are analyzed with two models, both of which give an excellent description of most of the existing pion electroproduction data below W < 1.5 GeV. We find that at up to Q 2 = 4.0(GeV/c) 2 , the extracted helicity amplitudes A 3/2 and A /2 remain comparable with each other, implying that hadronic helicity is not conserved at this range of Q 2 . The ratios E1+/M1+ obtained show, starting from a small and negative value at the real photon point, a clear tendency to cross zero, and to become positive with increasing Q 2 . This is a possible indication of a very slow approach toward the pQCD region. Furthermore, we find that the helicity amplitude A 1/2 and S 1/2 , but not A 3/2 , starts exhibiting the scaling behavior at about Q 2 ≥ 2.5(GeV/c) 2 .

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“…Results of previous data analysis at Q 2 = 0 from Ref. [5], data at Q 2 =2.8 and 4.0 (GeV /c) 2 from Ref. [1] (stars).…”

Section: Figmentioning

confidence: 99%

Section: +mentioning

confidence: 99%

<‘γN→Δtransition form factors: A new analysis of data on
Kamalov
¹
,
Yang
²
,
Drechsel
³

et al. 2001
Phys. Rev. C*
148
3
140
1
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show abstract

“…The Lagrangian for the spin-3/2 isospin-3/2 ∆-isobar can be written in terms of the Rarita-Schwinger (vector-spinor) isoquartet field 1 …”

Section: The Effective Chiral Lagrangianmentioning

confidence: 99%

“…High-precision measurements of the nucleon-to-∆ transition by means of electromagnetic probes became possible with the advent of the new generation of electron scattering facilities, such as BATES, MAMI, and JLab, many measurements being completed in recent years [1,2,3,4].…”

Section: Introductionmentioning

confidence: 99%

Chiral effective-field theory in theΔ(1232)region: Pion electroproduction on the nucleon

2006

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We develop an extension of chiral perturbation theory to the ∆(1232)-resonance energy region and apply it to investigate the pion electroproduction off the nucleon (e − N → e − N π). We present a complete calculation of this process, in the ∆-resonance region, up to next-to-leading order in the δ-expansion. At this order, the only free parameters are the three low-energy constants corresponding to the magnetic (M1), electric (E2), and Coulomb (C2) γN → ∆ transition strength. After fitting these parameters to a few well-known data, our calculation provides a prediction for observables and multipole amplitudes of pion electroproduction. These results compare favorably with the phenomenological multipole solutions and recent experimental results from MIT-Bates and MAMI. Our prediction for the pion-mass dependence of the γN ∆ form factors offers an explanation for the discrepancy between the recent lattice-QCD results and the experimental value for the "C2/M1 ratio" at low Q 2 .

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“…In the case of real photons, which is relevant for this work, the Coulomb quadrupole is known to vanish. Thus precision measurements are only available for the ratio E2/M1 [8,9,10,11].…”

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.

show abstract

Measurement of theE2/M1Ratio in theN→ΔTransition Using the Reaction
R. Beck¹,
H. P. Krahn²,
J. Ahrens³
et al.

Cited by 97 publications

References 0 publications

<‘γN→Δtransition form factors: A new analysis of data on
Kamalov
¹
,
Yang
²
,
Drechsel
³

et al. 2001
Phys. Rev. C*
148
3
140
1
View full text Add to dashboard Cite

<‘γN→Δtransition form factors: A new analysis of data on
Kamalov
¹
,
Yang
²
,
Drechsel
³

et al. 2001
Phys. Rev. C*
148
3
140
1
View full text Add to dashboard Cite

Chiral effective-field theory in theΔ(1232)region: Pion electroproduction on the nucleon

Light-cone sum rules for theNγΔtransitions for real photons

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Measurement of theE2/M1Ratio in theN→ΔTransition Using the ReactionR. Beck1, H. P. Krahn2, J. Ahrens3 et al.

Cited by 97 publications

References 0 publications

<‘γ*N→Δtransition form factors: A new analysis of data onKamalov1, Yang2, Drechsel3 et al. 2001Phys. Rev. C14831401View full textAdd to dashboardCite

<‘γ*N→Δtransition form factors: A new analysis of data onKamalov1, Yang2, Drechsel3 et al. 2001Phys. Rev. C14831401View full textAdd to dashboardCite

Chiral effective-field theory in theΔ(1232)region: Pion electroproduction on the nucleon

Light-cone sum rules for theNγΔtransitions for real photons

Contact Info

Product

Resources

About

Measurement of theE2/M1Ratio in theN→ΔTransition Using the Reaction
R. Beck¹,
H. P. Krahn²,
J. Ahrens³
et al.

<‘γN→Δtransition form factors: A new analysis of data on
Kamalov
¹
,
Yang
²
,
Drechsel
³

et al. 2001
Phys. Rev. C*
148
3
140
1
View full text Add to dashboard Cite

<‘γN→Δtransition form factors: A new analysis of data on
Kamalov
¹
,
Yang
²
,
Drechsel
³

et al. 2001
Phys. Rev. C*
148
3
140
1
View full text Add to dashboard Cite