Summary
The mechanism for the rare radiative decay mode K 01 →2γ is treated as the virtual disassociation of K 01 into a π+π− pair followed by internal annihilation of the pions into photons. Introducing a direct K 01 -2π interaction and using the techniques of dispersion theory, the branching ratioΓ(K 01 →2γ)/Γ(K 01 →π+π−) is expressed in terms of theI=0,s-wave pion-pion scattering phase shifts. With negative and small positive π-π scattering lengths, numerical estimates indicate no appreciable enhancement of the branching ratio from its perturbation-theory value: 0.24·10−5. Branching ratios of the order of 10−4 to 10−3 are obtained for large positive scattering lengths provided that the high-energy behaviour of the phase shifts has a specified character.
Riassunto
Si tratta il meccanismo del raro modo di decadimento radiativo K 01 2→γ come una dissociazione virtuale del K 01 in una coppia π+π− seguita da annichilazione interna dei pioni in fotoni. Introducendo un’interazione diretta K 01 -2π e facendo uso delle tecniche della teoria della dispersione, si esprime il rapporto di suddivisioneΓ(K 01 →2γ)/Γ(K 01 →π+π−) in funzione degli spostamenti di fase dello scattering pione-pione in ondas, conI=0. Per lunghezze dello scattering π-π negative e positive piccole, le stime numeriche indicano che non si ha un apprezzabile aumento del rapporto di suddivisione rispetto al suo valore in teoria delle perturbazioni: 0.24·10−5. Per grandi lunghezze di scattering positive si ottengono rapporti di suddivisione dell’ordine di 10−4 a 10−3, purchè il comportamento degli spostamenti di fase abbia alle alte energie un carattere specifico.
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Work supported in part by the U. S. Atomic Energy Commission.
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Barger, V. K 01 →γ+γ decay mode. Nuovo Cim 32, 127–135 (1964). https://doi.org/10.1007/BF02732596
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DOI: https://doi.org/10.1007/BF02732596