Method of determination of resonance fraction

It is important to determine the exact contribution of resonance production which occupies considerable portion in the cross section of inelastic scattering in several GeV region. In this paper, the standard methods of analysis are introduced, and the example of application to anti pp → 2π-2π+π0 reaction at o.7 GeV/C is presented. The first method is as follows. Background is expressed by a polynomial, and the structure of effective mass distribution is shown by a Breit - Wigner term. The mass and width of resonance and its ratio to the background are obtained by chi2 fitting. Then, the contribution of resonance is obtained by numerical integration. The method was applied to the anti pp → 2π-2π+π0 reaction. This method is not effective on the problems of the overlapping, kinematical reflection and cascade decay of resonance. The second method is called maximum likelihood method. This method can give the distribution which cannot be deduced from the first method. Associated production and cascade decay can also be analyzed. (Kato, T.)