19 void setP4(
const HepLorentzVector& aMomentum );
21 void recover()
const { m_p4 = m_p4_bakup; }
29 const HepLorentzVector&
p4()
const;
34 mutable HepLorentzVector m_p4;
36 void bakup() {
if(m_hasbeenbakup)
return; m_p4_bakup = m_p4; m_hasbeenbakup=
true; }
37 HepLorentzVector m_p4_bakup;