Summary
We estimate low-energy photoproduction and electro-production of pions by using equal-time commutators between current densities and divergences and by including low-lying intermediate states. Predictions are presented for charged photoproductions- andp-wave multipoles, in agreement with experiments and dispersion theory, and for transversal and longitudinal electroproduction cross-sections near threshold. The dependence of the results on the axial vector form factorG A(t) is discussed.
Riassunto
Si stimano la fotoproduzione e l'elettroproduzione di un pione lento, usando commutatori a tempi uguali di densità di corrente e divergenze, e includendo gli stati intermedi più bassi. Si danno predizioni per i multipoli di ondas ep in fotoproduzione di pioni carichi, in accordo con i dati sperimentali e con la teoria delle relazioni di dispersione, e per le sezioni d'urto di elettroproduzione (trasversale e longitudinale) in prossimità della soglia. Si discute la dipendenza dei risultati del fattore di forma assialeG A(t).
Резюме
Мы оцениваем фоторождение и электророЗдение пионов при низких энергиях, используя коммутаторы при равных временах между плотностями токов и дивергенциями и включая низко лежащие промежуточные состояния. Предлагаются предсказания для заряженного фоторожденияs- иp-волновых мультиполей, в соответствии с экспериментами и дисперсионной теорией, и для поперечных сечений поперечного и продольного электророждения вблизи порога. Обсуждается зависимость полученных результатов от аксиально-векторной формы фактораG A(t).
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This work has been partially supported by the Istituto Nazionale di Fisica Nucleare, Sottosezione di Trieste.
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Furlan, G., Paver, N. & Verzegnassi, C. Low-energy electroproduction and equal-time commutators. Nuovo Cimento A (1965-1970) 70, 247–265 (1970). https://doi.org/10.1007/BF02758982
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DOI: https://doi.org/10.1007/BF02758982