pytbhb.f

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C------------------------------------------------------------------
      SUBROUTINE pytbhb(MT,MB,MHP,BR,GAMT)
C  WIDTH AND BRANCHING RATIO FOR (ON-SHELL) T-> B W+, T->B H+
      IMPLICIT DOUBLE PRECISION(a-h, o-z)
      IMPLICIT INTEGER(i-n)
      DOUBLE PRECISION mw2,mt,mb,mhp,mw,kfun
      common/pyctbh/ alpha,alphas,sw2,mw2,tanb,vtb,v,a
      SAVE /pyctbh/
 
C   TOP WIDTH CALCULATION
C       VTB  = 0.99
      mw=dsqrt(mw2)
      xb=(mb/mt)**2
      xw=(mw/mt)**2
      xh =(mhp/mt)**2
      gamtbh = 0d0
      IF (mt .LT. (mhp+mb)) THEN
C  T ->B W ONLY
         betw = dsqrt(1.d0-2*(xb+xw)+(xw-xb)**2)
         gamtbw = vtb**2*alpha/(16*sw2)*mt/xw*betw*
     &        (2*(1.d0-xb-xw)-(1.d0+xb-xw)*(1.d0-xb -2*xw) )
         gamt  = gamtbw
      ELSE
C T ->BW +T ->B H^+
         betw = dsqrt(1.d0-2*(xb+xw)+(xw-xb)**2)
         gamtbw = vtb**2*alpha/(16*sw2)*mt/xw*betw*
     &        (2*(1.d0-xb-xw)-(1.d0+xb-xw)*(1.d0-xb -2*xw) )
C
         kfun = dsqrt( (1.d0-(mhp/mt)**2-(mb/mt)**2)**2
     &        -4.d0*(mhp*mb/mt**2)**2 )
         gamtbh= alpha/sw2/8.d0*vtb**2*kfun/mt *
     &        (v**2*((mt+mb)**2-mhp**2)+a**2*((mt-mb)**2-mhp**2))
         gamt  = gamtbw+gamtbh
      ENDIF
C THUS BR IS
      br=gamtbh/gamt
      RETURN
      END