Summary
For the lower-energy π+N→N *+π reaction, it is shown that the exchange of two-pion system (or the system of evenG parity) with isotopic spin 2 and angular momentum 0 might become important. It is also shown that, if this is actually the case, then the reaction occurs predominantly from theT=1/2,d 3/2 state of the initial πN system. Therefore, in connection with the problem of the second πN resonance, the above possibility is very interesting. Some possible experimental tests of this possibility are suggested.
Riassunto
Si dimostra, per la reazione π+N→N *+π di più bassa energia, che lo scambio del sistema di due pioni (o sistema di paritàG pari) con spin isotopico 2 e momento angolare 0 può diventare importante. Si dimostra anche che, se questo è il caso, allora la reazione avviene principalmente a partire dallo statoT=1/2,d 3/2 del sistema π-N iniziale. Quindi, in relazione al problema della seconda risonanza πN, la suddetta possibilità è molto interessante. Si suggeriscono alcune possibili verifiche sperimentali di questa ipotesi.
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References
K. Itabashi, M. Kato, K. Nakagawa andG. Takeda:Progr. Theor. Phys. (Kyoto),24, 529 (1960).
P. Carruthers andH. A. Bethe:Phys. Rev. Lett.,4, 536 (1960).
J. S. Ball andW. R. Frazer:Phys. Rev. Lett.,7, 204 (1961).
R. F. Peierls:Phys. Rev.,118, 325 (1960). See alsoW. N. Wong andM. Ross:Phys. Rev. Lett.,3, 398 (1959).
K. Itabashi andT. Ebata:Prog. Theor. Phys. (Kyoto),30, 505 (1963). For detailed discussions of the method, seeK. Itabashi andT. Ebata:Progr. Theor. Phys. (Kyoto),28, 915 (1962).
L. Stodolsky andJ. J. Sakurai:Phys. Rev. Lett.,11, 90 (1963).
S. B. Treiman andC. N. Yang:Phys. Rev. Lett.,8, 140 (1962).
If we rely upon the dispersion theory of the virtual photon reactions, we can calculateA, B andC in terms of only one parameter λ, the effective coupling strength of thet=j=l π-π system. See ref. (5). andS. Fubini, Y. Nambu andV. Wataghin:Phys. Rev.,111, 529 (1958). However, for convenience, all three of the quantitiesA, B andC are also left as unknown parameters.
J. Kirz, J. Schwartz andR. D. Tripp:Phys. Rev.,130, 2481 (1963). They reported also that, if one selects only the events with 1188⩽M π − n⩽1288 MeV, the angular distribution of the (nπ−) pair shows a significant fore-aft asymmetry whose degree varies with energy. However, this does not necessarily mean the breakdown of the present model. Note that theN * production predicted from eq. (3) is notpure S and also that there should be another angle-dependent factor such as (a 1+X 2)−1, which has not been written explicitly in eq. (3).
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Work performed under the auspices of the U.S. Atomic Energy Commission.
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Itabashi, K. Two-pion-exchange model for π+N→N *+π and the second π-N resonance. Nuovo Cim 34, 93–100 (1964). https://doi.org/10.1007/BF02725872
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DOI: https://doi.org/10.1007/BF02725872