Abstract
Electromagneticp δ(1232) andp−S 11(1535) transition form factors in the momentum transfer range 3 ≲Q 2≲ 20 GeV2 are investigated within the scope of perturbative QCD. Thereby baryons are considered as built up by quarks and spatially extended diquarks. The diquark parameters and the quark-diquark distribution amplitude of the nucleon are adopted from a previous study which already led to a consistent description of electromagnetic nucleon form factors and Compton scattering off nucleons. Results are presented for several choices of the resonance distribution amplitudes and confronted with data. Most noteworthy, we find that the diquark model may account for the experimentally observed strong deviation ofp−δ electric and magnetic transition form factors from the asymptotic Q−4 behaviour.
Similar content being viewed by others
References
For a comprehensive survey, see: Adams, G., et al.: Proceedings of the Topical Workshop on Excited Baryons, Troy, NY, 1988. Singapore: World Scientific 1988
For a discussion of available data, see: Foster, F., Hughes, G.: Rep. Prog. Phys.46, 1445 (1983)
Warns, M., Schröder, H., Pfeil, W., Rollnik, H.: Z. Phys. C — Particles and Fields45, 627 (1990)
Gianini, M.M.: Electromagnetic excitations in the constituent quark model. (to be published)
Papanicolas, C.N.: see [1]For a comprehensive survey,
Li, Z., Close, F.E.: Phys. Rev. D42, 2207 (1990); Warns, M., Pfeil, W., Rollnik, H.: Phys. Rev. D42, 2215 (1990)
Lepage, G.P., Brodsky, S.J.: Phys. Rev. D22, 2165 (1977)
Chernyak, V.L., Zhitnitsky, I.R.: Nucl. Phys. B246, 52 (1984);
Chernyak, V.L., Ogloblin, A.A., Zhitnitsky, I.R.: Novosibirsk Preprint 87-136 (1987); King, I.D., Sachrajda, C.T.: Nucl. Phys. B279, 785 (1987)
Chernyak, V.L., Oglobin, A.A., Zhitnitsky, I.R.: Novosibirsk Preprint 87-134 (1987)
Farrar, G.R., Zhang, H., Ogloblin, A.A., Zhitnitsky, I.R.: Nucl. Phys. B311, 585 (1988)
Carlson, C.E., Poor, J.L.: Phys. Rev. D38, 2758 (1988)
Gari, M., Stefanis, N.G.: Phys. Lett. B175, 462 (1986); Phys. Rev. D35, 1074 (1987)
Martinelli, G., Sachrajda, C.T.: Phys. Lett. B217, 319 (1989)
Carlson, C.E.: see [1]
Stoler, P.: Phys. Rev. Lett.66, 1003 (1991); Phys. Rev. D44, 73 (1991)
Isgur, N., Llewellyn-Smith, C.: Phys. Lett. B217, 535 (1989)
Anselmino, M., Kroll, P., Pire, B.: Z. Phys. C — Particles and Fields36, 89 (1987)
Kroll, P., Schweiger, W.: Nucl. Phys. A474, 608 (1987)
Kroll, P., Quadder, B., Schweiger, W.: Nucl. Phys. B316, 373 (1989)
Anselmino, M., Caruso, F., Kroll, P., Schweiger, W.: Int. J. Mod. Phys. A4, 5213 (1989)
Kroll, P., Schürmann, M., Schweiger, W.: Z. Phys. A — Hadrons and Nuclei338, 339 (1991)
Kroll, P., Schürmann, M., Schweiger, W.: Int. J. Mod. Phys. A6, 4107 (1991)
Dziembowski, Z., Franklin, J.: Phys. Rev. D42, 905 (1990)
Kroll, P.: Proceedings of the Adriatico Research Conference on Spin and Polarization Dynamics in Nuclear and Particle Physics, Triest 1988
Huang, T.: Nucl. Phys. B [Proc. Suppl.]7, 320 (1989)
Aubert, J.J., et al.: Phys. Lett. B95, 306 (1980)
Jones, H.F., Scadron, M.D.: Ann. Phys. (N.Y.)81, 1 (1973)
Devenish, R.C.E., Eisenschitz, T.S., Körner, J.G.: Phys. Rev. D14, 3063 (1976)
Lyth, D.H.: Electromagnetic interactions of hadrons. Donnachie, A., Shaw, G. (eds.), vol. I. New York: Plenum Press 1978
Frequently inclusivee-p data are analyzed in terms of a quantityQM/*(Q2), originally introduced by Ash et al. [31], which differs from our definition (3.19) of 438-01(Q2) by a threshold factor. In order to elucidate the dynamical scaling behaviour of inelastice-p scattering we however find it more appropriate to present the data in terms of 438-02 (Q 2), which is free of kinematical factors
Ash, W.W. et al.: Phys. Lett. B24, 165 (1967)
Brasse, F.W. et al.: Nucl. Phys. B110, 413 (1976)
Warren, G.A., Carlson, C.E.: Phys. Rev. D42, 3020 (1990)
A factor (m p +m Δ )/m p seems to be missing in (35) of [11]
Davidson, R.M., Mukhopadhyay, N.C., Wittmann, R.S.: Phys. Rev. D43, 71 (1991)
Körner, J.G.: Z. Phys. C — Particles and Fields33, 529 (1987)
Haidan, R.: DESY Report F21-79/03 (1979)
Brasse, F.W. et al.: Z. Phys. C — Particles and Fields22, 33 (1984)
Schürmann, M.: (in preparation)
Author information
Authors and Affiliations
Additional information
Sponsored in part by the Bundesministerium für Forschung und Technologie under contract number 06 Wü 765
We would like to thank Prof. P. Stoler for providing us with the numerical values of his resonance analysis results. One of us (W.S.) would like to thank the Theory Group at the University of Wuppertal for the kind hospitality extended to him.