levinson bromberg 2008 eqn 11 asymptotic validation

import sympy
sympy.init_printing()
xi = sympy.Symbol('xi')
b = sympy.Symbol('beta')
J = sympy.Symbol('J')
g = sympy.Symbol('Gamma')
m_e = sympy.Symbol('m_e')
c = sympy.Symbol('c')
npm = sympy.Symbol('n_{\pm}')
C1 = sympy.Symbol('C_1')
C2 = sympy.Symbol('C_2')
m_p = sympy.Symbol('m_p')
ntb = sympy.Symbol("{n'}_b")
ux = sympy.Symbol('u^x')
u0 = sympy.Symbol('u^0')
Tb0x = sympy.Symbol('T_b^{0x}')
Tpm0x = sympy.Symbol('T_{\pm}^{0x}')
Tbxx = sympy.Symbol('T_b^{xx}')
Tpmxx = sympy.Symbol('T_{\pm}^{xx}')
eqn11_rhs = -(1+xi)/(1+xi-3*b**2)*(J/g+m_e*c**2*npm*b-C1*(1+xi+3*b**2)/(1+xi)+C2*(1+xi+3)*b/(1+xi))
temp = eqn11_rhs
temp = temp.subs(J,m_p*c**2*ntb*ux)
temp = temp.subs(C1,Tb0x+Tpm0x)
temp = temp.subs(C2,Tbxx+Tpmxx)
temp = temp.subs(Tb0x,m_p*c**2*ntb*u0*ux)
temp = temp.subs(Tbxx,m_p*c**2*ntb*ux*ux)
temp = temp.subs(Tpm0x,m_e*c**2*npm*u0*ux)
temp = temp.subs(Tpmxx,m_e*c**2*npm*ux*ux)
temp = temp.subs(u0,g)
temp = temp.subs(ux,g*b)
temp = temp.subs(g,1/sympy.sqrt(1-b**2))
temp = temp.subs(xi,0)
temp.simplify()