Probability distribution function f vs. angle Ψ for various values of ﹩( \xi ,\,\zeta ) ﹩ as well as the dependence of mean values ﹩\langle \Psi \rangle ﹩ and ﹩\langle q\rangle ﹩ on ζ for individual values of ξ; (a) f vs. Ψ for ﹩\xi =0.1﹩ and ﹩\zeta =0.1﹩, 0.5, and 0.9; (b) ﹩\langle \Psi \rangle ﹩ (solid line) and ﹩\langle q\rangle ﹩ (dashed line) vs. ζ for ﹩\xi =0.1﹩. (c) Same as (a), but ﹩\xi =0.3﹩ and ﹩\zeta =0.3﹩, 0.6, and 0.9. (d) Same as (b), but ﹩\xi =0.3﹩. (e) Same as (a), but ﹩\xi =0.5﹩ and ﹩\zeta =0.5﹩, 0.7, and 0.9. (f) Same as (b), but ﹩\xi =0.5﹩. In (b), (d), and (f), the crosses highlight the region in which ﹩\langle q\rangle =0.5{\mbox{--}} 0.65﹩, consistent with observations.