Improvements in Tests of Long-Range Charge Independence
AUTOR(ES)
Breit, G.
RESUMO
The procedure used to determine the pionnucleon coupling constant g2 from multi-energy fits to nucleon-nucleon (N-N) scattering data has been shortened without a material loss of accuracy. The g2 presetting effect is discussed in connection with the limited accuracy of g2 determinations in general and the possibilities of the “optimized polynomial expansions”. The desirability of the Yale graded introduction of one-pion exchange (OPE)-to-“searched” transition energies (Etr) is brought out. Corrections for virtual discontinuities in phase-shift-energy dependence at the Etr decreased the violation of long-range charge independence (LRCI). The effect of two-pion exchange (TPE) has been calculated on the ps theory as ≈ 1 for go2(p-p) - go2(n-p), go2 = g2/[unk]c; a result consistent with LRCI. Searching all phase parameters including g2 for both isospin values I in g2 determinations from n-p data, but with fixed I = 1 non-OPE phases as deduced from p-p data in the base search with frozen g2, the OPE effect of the neutral pion, π°, was separated from that of the charged pion, πc. The g2 for πc in n-p scattering is determined with much better statistical accuracy than that for π°. The overall n-p value of g2 is nearly equal to that for πc. The results suggest that the distinction between p-p and n-p values of g2, if present, is in first approximation that arising from the difference between π°-N and πc-N couplings. Some limitations on the validity of the conclusions are mentioned.
