Breit-Wigner model

The explanation for both phenomena is based on the Breit-Wigner model for resonant tunneling. In the vicinity of a narrow isolated resonance (i.e. jn < jcn — en i )j the transition probability amplitude is given... 

The phase of the transition probability amplitude, arg(t(J5)), changes by 7T when t E) exhibits a maximum (see Fig. 9(a)). This well-known phenomenon can be explained by the Breit-Wigner model for resonant tunneling. 

The lithium plus proton reactions thus exhibit many characteristic features of nuclear reactions as a whole, namely the existence of sharply defined resonant states from which particle break-up is prohibited, the probable influence of direct transitions not involving a compound state, the existence of very broad states constituting a background with which interference can take place in many reactions, the description of the levels by the Breit-Wigner formula, and the implications of the principle of charge independence. The information obtainable on the reduced widths and quantum numbers of the states of Be is discussed in the light of nuclear models in Sect. 76. 

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