#!/usr/bin/python
# following are in MeV
from math import sqrt

m_pi = 139.57018
m_mu = 105.658367
m_nu = 0.19

E_nu = (m_pi * m_pi + m_nu * m_nu - m_mu * m_mu)/(2*m_pi)
p_nu = sqrt(E_nu*E_nu-m_nu*m_nu)

print 'p_nu  = ',p_nu
print 'E_nu  = ',E_nu
print 'p/E   = ',p_nu/E_nu
print '1-p/E = ',1-(p_nu/E_nu)