Il Nuovo Cimento A (1965-1970)

, Volume 4, Issue 1, pp 156–181 | Cite as

Photoproduction of charged pions in the veneziano model

  • E. N. Argyres
  • A. P. Contogouris
  • C. S. Lam
  • S. Ray


Photoproduction of charged pions on nucleons is studied in the framework of the Veneziano representation. General conditions for the elimination of parity doublets are derived. A model with a small number of beta-function terms provides a very satisfactory (and essentially parameter-free) description of differential cross-sections and asymmetry ratios of forward γp→π+n and γn→πp in a wide energy range; it also correctly predicts a significant number of residues of higher baryon resonances. However, it leads to backward cross-sections for γp→π+n significantly larger than the data. Introduction of satellite terms provides a relatively simple parametrization which correctly accounts for all the differential backward cross-sections and for all the known baryon residues.

Фоторождение эаряженных пионов в модели Венециано


В рамках представления Венециано исследуется фоторождение эаряженных пионов на нуклонах. Выводятся обшие условия для исключения дублетов по четности. Модель с небольщим числом бета-функциональных членов обеспечивает очень удовлетворительное (и, по сушеству, свободное от параметров) описание дифференциальных поперечных сечений и асиммеричные отнощения рассеяния вперед γр → π+n и γn → πр в щирокой области знергий. Эта модель также правильно предскаэывает эначительное число вычетов для более высоких барионных реэо-нансов. Однако, зто приводит к эначительно больщим поперечным сечениям рассеяния наэад для γр → π+n, чем зкспериментальные данные. Введение сопутствуюших членов обеспечивает относительно простую параметриэацию, которая правильно общясняет все дифференциальные поперечные сечения рассеяния наэад и все иэвестные барионные вычеты.


Si studia, nel quadro della rappresentazione di Veneziano, la fotoproduzione di pioni carichi su nucleoni. Si deducono le condizioni generali per l’eliminazione dei doppietti di parità. Un modello con un piccolo numero di termini di funzioni beta fornisce una descrizione molto soddisfacente (ed essenzialmente libera da parametri) delle sezioni d’urto differenziali e dei rapporti di asimmetria delle reazioni in avanti γp → π+n e γn → πp in un ampio intervallo di energie; esso anche predice correttamente un significativo numero di residui di risonanze barioniche superiori. Però esso porta a sezioni d’urto all’indietro per γp → π+n significativamente maggiori dei dati. L’introduzione dei termini satellite fornisce una parametrizzazione relativamente semplice che tiene conto correttamente di tutte le sezioni d’urto differenziali all’indietro e di tutti i residui barionici noti.


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Copyright information

© Società Italiana di Fisica 1971

Authors and Affiliations

  • E. N. Argyres
    • 1
  • A. P. Contogouris
    • 2
  • C. S. Lam
    • 2
  • S. Ray
    • 2
  1. 1.Physics DepartmentState University CollegePlattsburgh
  2. 2.Institute of Theoretical PhysicsMcGill UniversityMontreal

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