4.282 + 2.075 \eta - 0.8584 \chi_+ - 5.04 \eta \chi_- - 1.626 \chi_+ \chi_- - 4.319 \eta^2 \chi_+ + 21.01 \eta^2 \chi_- - 2.27 \eta \chi_+^2 + 5.414 \eta \chi_+ \chi_-