[u/mrichter/AliRoot.git] / PYTHIA / pythia / pygdir.F

 
C*********************************************************************
 
       SUBROUTINE PYGDIR(X,Q2,P2,AK0,XPGA)
C...Purpose: to evaluate the direct contribution, i.e. the C^gamma term,
C...as needed in MSbar parametrizations.
      DIMENSION XPGA(-6:6)
      DATA PMC/1.3/, PMB/4.6/, AEM2PI/0.0011614/
 
C...Reset output.
      DO 100 KFL=-6,6
      XPGA(KFL)=0.
  100 CONTINUE
 
C...Evaluate common x-dependent expression.
      XTMP = (X**2+(1.-X)**2) * (-LOG(X)) - 1.
      CGAM = 3.*AEM2PI*X * (XTMP*(1.+P2/(P2+AK0**2)) + 6.*X*(1.-X))
 
C...d, u, s part by simple charge factor.
      XPGA(1)=(1./9.)*CGAM
      XPGA(2)=(4./9.)*CGAM
      XPGA(3)=(1./9.)*CGAM
 
C...Also fill for antiquarks.
      DO 110 KF=1,5
      XPGA(-KF)=XPGA(KF)
  110 CONTINUE
 
      RETURN
      END
Commit	Line	Data
fe4da5cc	1
	2	C*********************************************************************
	3
	4	SUBROUTINE PYGDIR(X,Q2,P2,AK0,XPGA)
	5	C...Purpose: to evaluate the direct contribution, i.e. the C^gamma term,
	6	C...as needed in MSbar parametrizations.
	7	DIMENSION XPGA(-6:6)
	8	DATA PMC/1.3/, PMB/4.6/, AEM2PI/0.0011614/
	9
	10	C...Reset output.
	11	DO 100 KFL=-6,6
	12	XPGA(KFL)=0.
	13	100 CONTINUE
	14
	15	C...Evaluate common x-dependent expression.
	16	XTMP = (X2+(1.-X)2) * (-LOG(X)) - 1.
	17	CGAM = 3.AEM2PIX * (XTMP(1.+P2/(P2+AK02)) + 6.X*(1.-X))
	18
	19	C...d, u, s part by simple charge factor.
	20	XPGA(1)=(1./9.)*CGAM
	21	XPGA(2)=(4./9.)*CGAM
	22	XPGA(3)=(1./9.)*CGAM
	23
	24	C...Also fill for antiquarks.
	25	DO 110 KF=1,5
	26	XPGA(-KF)=XPGA(KF)
	27	110 CONTINUE
	28
	29	RETURN
	30	END