Angle and energy dependence of the superratio forπ+andπ−

Abstract

Data are presented on the energy and angle dependence of the charge-symmetry superratio R and simple ratios r I and r2 for~-elastic scattering from H and He. r i and r2 were normalized with respect to~+ d and m d elastic scattering, which is assumed to have the ratio 1.0. The beam energies are T =142, 180, and 220 MeV, and the scattering angle, |9L, ranges from 40' to 110. In all cases measured it is found that R ) 1, r', =1, and r2) 1. These results provide substantial evidence for charge-symmetry violation. The angular distributions for a -H and m -He elastic scattering also have been measured and comparisons are made with various model calculations. R:cr(0)[sr+ H]o'(0)[tr 3H]/cr(0)[n He]o'(8)[sr+ He], r', =o(0)[~+ 'H]cr(0)[vr d]/o(0)[m. 'He]cr(0)[vr+d], r'2 =o{0)[n H]cr(0)[m+d]/o. (0)[m+ 3He]cr(0)[vr d].

Measurement of theH3(π+

“…Observation of 7r+p elastic scattering also served to establish the momentum acceptance of the spectrometer. The tritium content of the tritiated foils was determined by comparing measured H yields from sr+ H elastic scattering with known values [17]. The uncertainty in the tritium content of the targets was less than 8'%%uo.…”

Charge-symmetry violation in pion scattering from three-body nuclei

“…This WF was successfully used by Foursat et al [22] for the description of the differential cross sections for the reaction 4 He(p, d) 3 He at 770 MeV for a wide range of scattering angles. The WF (8) reproduces the minimum of the 3 He charge form factor at Q = 670 MeV /c, but shows an enhancement at momentum transfer Q ≈ 300 − 400 MeV /c.…”

“…The effect seems to peak near 80 • in the CM frame (e.g., r 2 ≃ R ≃ 1.2 at 180 MeV [7]). The experiment was repeated with better statistics and systematics for approximately the same range of scattering angles at energies spanning the ∆ 33 [8] and beyond [9]. These measurements also were extended to backward angles from 120 • to 170 • [19] and are reported in the previous paper [10].…”

“…The experimental study of these ratios has been concentrated on large-angle scattering because the Coulomb interaction, which intrinsically violates charge symmetry, makes a significant contribution in the forward-scattering region. In a series of LAMPF experiments [7][8][9][10], the ratios (1) were measured in the range of the ∆ 33 (1232) πN resonance. Significant deviation (several standard deviations) from unity (up to ∼20%) was observed for r 2 and R in the angular range outside of the Coulomb cone, θ ≥ 30 • .…”

“…[6]. We then take CSV effects into account to obtain expressions for the ratios (1), which then are compared with the experimental data [7][8][9][10].…”