Pomeranchuk's theorem
Pomeranchuk's theorem, named after Soviet physicist Isaak Pomeranchuk, states that difference of cross sections of interactions of elementary particles 
  
    
      
        
          κ
          
            1
          
        
        +
        
          κ
          
            2
          
        
      
    
    {\displaystyle \kappa _{1}+\kappa _{2}}
  
 and 
  
    
      
        
          κ
          
            1
          
        
        +
        
          
            
              
                κ
                
                  2
                
              
              ¯
            
          
        
      
    
    {\displaystyle \kappa _{1}+{\bar {\kappa _{2}}}}
  
 (i. e. particle 
  
    
      
        
          
            κ
            
              1
            
          
        
      
    
    {\displaystyle {\kappa _{1}}}
  
 with particle 
  
    
      
        
          κ
          
            2
          
        
      
    
    {\displaystyle \kappa _{2}}
  
, and with its antiparticle 
  
    
      
        
          
            
              
                κ
                
                  2
                
              
              ¯
            
          
        
      
    
    {\displaystyle {\bar {\kappa _{2}}}}
  
) approach 0 when 
  
    
      
        s
        →
        ∞
      
    
    {\displaystyle s\to \infty }
  
, where 
  
    
      
        s
      
    
    {\displaystyle s}
  
 is the energy in center of mass system.