Summary
A model-independent analysis is made to determine the relative contribution of natural and unnatural parity exchange in the reactions (1) π+p→ρ0Δ++ at 11.7 GeV/c and (2) π−p→ρ0n at 11 GeV/c. A simple evasive Regge-pole model with only π-trajectory exchange has been applied to the data of reaction (1) and then to the combined data of reactions (1) and (2). A satisfactory fit to the data is obtained. The parameters determined in fitting reaction (1) have been used to make predictions for the same reaction at 8, 13.1 and 18.5 GeV/c. A comparison with experimental data at these momenta has been made. Considering the severe nature of this test for the evasive model there is altogether satisfactory agreement between the predictions and the data.
Riassunto
Un’analisi che prescinde da ogni modello specifico permette di separare il contributo relativo degli scambi di parità naturale e non naturale nelle reazioni (1) π+p → ρ0Δ++ a 11.7 GeV/c e (2) π−p → ρ0n a 11.2 GeV/c. In base ai risultati di tale analisi, dapprima si interpreta la reazione (1) mediante un semplice modello di Regge con scambio di un π di tipo evasivo; poi si interpretano i dati di entrambe le reazioni (1) e (2) congiuntamente, ottenendo risultati soddisfacenti. I parametri così determinati si usano quindi per ottenere le dovute previsioni sull’andamento della sezione d’urto differenziale dσ/d|t| per la reazione (1) da confrontare con dati esistenti a 8, 13.1 e 18.5 GeV/c. Considerato il carattere particolarmente severo della verifica cui il modello di Regge di tipo evasivo è qui sottoposto, l’accordo tra dati sperimentali e previsioni teoriche può ritenersi soddisfacente. Tuttavia il modello evasivo non è in grado di riprodurre il persistente picco in avanti presentato a tutte le energie dai dati sperimentali.
Реэюме
Проводится аналиэ, не эависяший от модели, для определения относительного вклада обмена с естественной и неестественной четностью в реакциях (1) π+p → ρ0Δ++ при 11.7 ГзВ/с и (2) π−p → ρ0n при 11 ГзВ/с. Была применена простая модель « неуловимых » полюсов Редже с обменом единственной π-траекторией к данным реакции (1), а эатем к комбинированным данным реакций (1) и (2). Получается удовлетворительное соответствие. Параметры, полученные иэ подгонки первой реакции, были испольэованы для получения предскаэаний для той же реакции при начальных импульсах 8, 13.1 и 18.5 ГзВ/с. Было проведено сравнение с зкспериментальными данными при зтих импульсах. Учитывая строгий характер зтой проверки модели « неуловимых » полюсов, получается удовлетворительное согласие между предскаэаниями и полученными данными.
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Supported by the Science Research Council.
Supported in part by the Ministerium für Bildung and Wissenschaft.
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Maddock, R.O., Pinter, G.F., Caso, C. et al. Analysis of the reaction π+p → ρ0Δ++ at 11.7 GeV/c incident momentum. Nuov Cim A 5, 457–477 (1971). https://doi.org/10.1007/BF02723467
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DOI: https://doi.org/10.1007/BF02723467