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Electron-positron model for the charged mesons and pion resonances

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Il Nuovo Cimento (1955-1965)

Summary

The relativistic electron-pair model for the neutral pion developed earlier is extended to arrive at models for the charged mesons. The addition of a third electron or positron to the singlet state of the π0 system results in a charged particle of spin 1/2 whose mass and magnetic moment agree closely with the observed μ±-meson properties. A calculation of the lifetime against the emission of two quanta of spin 1/2 by the neutral core of this system, taking account of the relativistically increased mass of the radiating pair, leads to agreement with the observed μ-meson lifetime. The excited states of this system are found to be quantized in units of (ħ/2), and the first of these is found to fit the observed properties of the π±, including its mass, spin, and lifetime for decay to the μ± state with the emission of a spin-1/2 quantum or neutrino. The electromagnetic interaction between any two pions is examined and found to have the observed strength and short range of nuclear forces, independent of the charge state of the meson. By contrast, the interaction of muons with pions is shown not to lead to strong binding, thus accounting for the observed difference in the interaction of these two particles with matter. An examination of simple multi-pion systems leads to 2π, 3π and 4π molecular-type structures whose ground states reproduce the observed spins and masses of the K and η mesons, while the excited rotational states account for the known masses and angular momenta of all the pion-resonance systems observed so far.

Riassunto

Si estende il modello del pione neutro a coppia di elettroni relativistici, sviluppato in precedenza, in modo da giungere a modelli dei mesoni carichi. Con l’aggiunta di un terzo elettrone o positrone allo stato di singoletto del sistema del π0 si ottiene una particella carica di spin 1/2, la cui massa e il cui momento magnetico concordano strettamente con le proprietà osservate del mesone μ±. Un calcolo della vita media per l’emissione di due quanti di spin 1/2 da parte del centro neutro del sistema, tenendo conto del fatto che la massa della coppia irradiante cresce relativisticamente, porta ad un accordo con la vita media osservata del mesone μ. Si trova che gli stati eccitati di questo sistema sono quantizzati in unità di (ħ/2), e che il primo di questi risponde alle proprietà osservate del π±, compresa la massa, lo spin, la vita media per il decadimento nello stato μ± con l’emissione di un quanto di spin 1/2ħ o di un neutrino. Si esamina l’interazione elettromagnetica fra due pioni qualsiasi e si trova che ha l’intensità osservata e il breve raggio d’azione delle forze nucleari, indipendenti dallo stato di carica del mesone. Per contrasto, si mostra che l’interazione dei muoni coi pioni non porta a legami forti, rendendo così conto della differenza delle interazioni di queste due particelle colla materia. L’esame dei semplici sistemi multipionici porta a strutture 2π, 3π e 4π di tipo molecolare, i cui stati fondamentali riproducono gli spin e le masse osservate dei mesoni K ed η, mentre gli stati rotazionali eccitati rendono conto delle masse note e dei momenti angolari di tutti i sistemi di risonanza pionica sinora osservati.

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Authors and Affiliations

  1. Westinghouse Research Laboratories, Pittsburgh, Pa.

    E. J. Sternglass

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Sternglass, E.J. Electron-positron model for the charged mesons and pion resonances. Nuovo Cim 35, 227–260 (1965). https://doi.org/10.1007/BF02734836

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