text: The Higgs ﬁelds φ and ψ are obtained by expanding Φ and Ψ as 
  
  0 
  (5) 
  
  1 
  √2 
  
   
  1 
  √2 
  
  around the true vacuum with the vacuum expectation values v and v′. These are related 
  
  with the mass eigenstates h and H through 
  
  h  cos θ  sin θ  φ 
  
  − 
  cos θ 
  , 
  =  
  (7) 
           
  H  sin θ  ψ 
  
   
   
  with θ being the mixing angle. Their masses are given by 
  
         
  
  M 2 
  h = 2λ1v2 cos2 θ + 2λ2v′ 
  2 sin2 θ  2λ3vv′ sin θ cos θ,  (8) 
  − 
  
  M 2 
  H = 2λ1v2 sin2 θ + 2λ2v′  2 cos2 θ + 2λ3vv′ sin θ cos θ.  (9) 