Determination of resonance couplings and high energy amplitudes in γN → πN using fixed-t dispersion relations

Devenish, R.C.E.; Lyth, David H.; Rankin, W.A.

doi:10.1016/0370-2693(74)90097-5

Cited by 45 publications

(10 citation statements)

References 65 publications

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“…Fixed-t dispersion relations were also used in the past to determine the baryon spectrum in Refs. [32][33][34][35] but to the best of our knowledge, FESR in photoproduction have not been implemented in constraining the low-energy models. This is important because in the last decades high quality data in the low energy region have been collected and new partial wave analyses have been performed.…”

Section: Introductionmentioning

confidence: 99%

Structure of pion photoproduction amplitudes

et al. 2018

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We derive and apply the finite energy sum rules to pion photoproduction. We evaluate the low-energy part of the sum rules using several state-of-the-art models. We show how the differences in the low-energy side of the sum rules might originate from different quantum number assignments of baryon resonances. We interpret the observed features in the low-energy side of the sum rules with the expectation from Regge theory. Finally, we present a model, in terms of a Regge-pole expansion, that matches the sum rules and the high-energy observables.

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Section: Introductionmentioning

confidence: 99%

Structure of pion photoproduction amplitudes

et al. 2018

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“…(3.16) we have calculated r' from numbers quoted in various photoproduction fits [22,28,29]. In particular in the case of the F 15 the value of (I + i) and thereby s 3 _ may go down by a factor of 3 , depending on what fit is taken.…”

Section: Comparison With Datamentioning

confidence: 99%

“…We define the relevant ratio of coupling strengthsas KHORR [29] DLR [22] HH [28] KHORR [29] DLR [22] I!W [28] 0 Hith the large theoretical uncertainty go~ng into a multipole analysis one should avoid a literal interpretation of the quoted errors and rather take the for both abnormal and normal parity transitions (replacing r + r').…”

Section: Comparison With Datamentioning

confidence: 99%

ElectromagneticN−N*transition form factors

1976

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Namely, the qualitative features of the multipole structure of each resonance are governed by one coupling ratio each. The results of recent multipole analyses indicate that these coupling ratios are approximately the same 1n all three cases. Our analysis supports the contention made by some authors that the N -6 form factor falls with one power faster asymptotically than that corresponding to canonical dipole behaviour.

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“…We have also directly estimated the high-energy tail with the parameters given by the Regge models of the 1970's [20,21], which were constructed to fit the data in the 5-20 GeV region. Since these models include the exchange of axial vector mesons and Regge cuts corresponding to many-particle exchange, they also contribute to the crossing-odd amplitude A 3 .…”

Section: Resultsmentioning

confidence: 99%

“…(48) fitted as above, and (III) phenomenological parameterizations of Regge trajectories and cuts fitted directly to older high-energy data [20,21].…”

Section: Vector Mesons and Regge Tailsmentioning

confidence: 99%

Dispersion theory and the low-energy constants for neutral-pion photoproduction

2006

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The relativistic amplitudes of pion photoproduction are evaluated by dispersion relations at t = const. The imaginary parts of the amplitudes are taken from the MAID model covering the absorption spectrum up to center-of-mass energies W = 2.2 GeV. For sub-threshold kinematics the amplitudes are expanded in powers of the two independent variables ν and t related to energy and momentum transfer. Subtracting the loop corrections from this power series allows one to determine the counter terms of covariant baryon chiral perturbation theory. The proposed continuation of the amplitudes into the unphysical region provides a unique framework to derive the low-energy constants to any given order as well as an estimate of the higher order terms by global properties of the absorption spectrum.

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Determination of resonance couplings and high energy amplitudes in γN → πN using fixed-t dispersion relations

Cited by 45 publications

References 65 publications

Structure of pion photoproduction amplitudes

Structure of pion photoproduction amplitudes

ElectromagneticN−N*transition form factors

Dispersion theory and the low-energy constants for neutral-pion photoproduction

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