3.918 + 30.68 \eta + 1.65 \chi_+ + 2.251 \chi_- - 196.8 \eta^2 - 15.94 \eta \chi_+ - 35.86 \eta \chi_- - 0.2809 \chi_+^2 - 2.797 \chi_+ \chi_- + 324.6 \eta^3 + 32.04 \eta^2 \chi_+ + 107 \eta^2 \chi_- + 11.19 \eta \chi_+ \chi_- - 0.2427 \chi_+^3