We discuss the attempts made at the end of the sixties and at the beginning of the seventies in order to get a consistent N -point amplitude involving the lightest hadrons, such as the pion, that then brought to string theory containing massless gluons and gravitons but not massless pions. This gives us the opportunity to remember the period in which I first met Peter Freund and also to summarise the results of a recent work where an N -point extension of the Lovelace–Shapiro model is constructed.

中文翻译：

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弦理论的早期以及Lovelace-Shapiro模型的N-pion扩展

我们讨论在六十年代末和七十年代初所做的尝试，以便获得涉及最轻质强子（例如介子）的一致的N点振幅，然后将其引入包含无质量胶子和引力子的弦论，但是不是无质量的介子。这使我们有机会记住我第一次见到Peter Freund的时期，并总结了最近工作的结果，其中构造了Lovelace-Shapiro模型的N点扩展。