hiboost.f

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C
C
C
C
  SUBROUTINE hiboost
        IMPLICIT DOUBLE PRECISION(d)  
        common/lujets/n,k(9000,5),p(9000,5),v(9000,5) 
        SAVE /lujets/ 
        common/ludat1/mstu(200),paru(200),mstj(200),parj(200) 
        SAVE /ludat1/ 
  common/hiparnt/hipr1(100),ihpr2(50),hint1(100),ihnt2(50)
  SAVE  /hiparnt/
  DO 100 i=1,n
     dbeta=p(i,3)/p(i,4)
     IF(abs(dbeta).GE.1.d0) THEN
        db=hint1(2)
        IF(db.GT.0.99999999d0) THEN 
C   ********Rescale boost vector if too close to unity. 
     WRITE(6,*) '(HIBOOT:) boost vector too large' 
     db=0.99999999d0
        ENDIF 
        dga=1d0/sqrt(1d0-db**2)
        dp3=p(i,3)
        dp4=p(i,4)
        p(i,3)=(dp3+db*dp4)*dga  
        p(i,4)=(dp4+db*dp3)*dga  
        go to 100
     ENDIF
     y=0.5*dlog((1.d0+dbeta)/(1.d0-dbeta))
     amt=sqrt(p(i,1)**2+p(i,2)**2+p(i,5)**2)
     p(i,3)=amt*sinh(y+hint1(3))
     p(i,4)=amt*cosh(y+hint1(3))
100 CONTINUE
  RETURN
  END