[u/mrichter/AliRoot.git] / PDF / spdf / dopho1.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.2  1996/10/30 08:28:06  cernlib
* Version 7.04
*
* Revision 1.2  1996/10/28 14:59:08  pdflib
* PDFLIB new version 7.04
*
* Revision 1.1.1.1  1996/04/12 15:29:17  plothow
* Version 7.01
*
*
#include "pdf/pilot.h"
       SUBROUTINE DOPHO1(DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL)
C********************************************************************
C*                                                                  *
C*    Parametrization of parton distribution functions              *
C*    in the photon (LO analysis) - asymptotic solution of AP eq.!  *
C*                                                                  *
C* authors:  D.Duke and H.Owens (DO)                                *
C*           /Phys.Rev. D26 (1982) 1600/                            *
C*                                                                  *
C* Prepared by:                                                     *
C*             Krzysztof Charchula, DESY                            *
C*             bitnet: F1PCHA@DHHDESY3                              *
C*             decnet: 13313::CHARCHULA                             *
C*                                                                  *
C* Modified by:                                                     *
C*             H. Plothow-Besch/CERN-PPE                            *
C*                                                                  *
C********************************************************************
C
#include "pdf/impdp.inc"
#include "pdf/expdp.inc"
     +        CQ(5),
     +        DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL
      PARAMETER (ALPEM=7.29927D-3, PI=3.141592D0)
      PARAMETER (ALAM=0.2D0)
      DATA CQ/0.33333D0,0.66666D0,0.33333D0,0.66666D0,0.33333D0/
C
       Q2 = DQ*DQ
       ALAM2=ALAM**2
       FQ=ALPEM/(2.*PI)*LOG(Q2/ALAM2)
C
C...gluons
       POMG=0.194*(1.-DX)**1.03/(DX**0.97)
       DGL=POMG*FQ
C
C...quarks
        POM1=(1.81-1.67*DX+2.16*DX**2)
        POM2=DX**0.7/(1.-0.4*LOG(1.-DX))
        POM3=38.D-4*(1.-DX)**1.82/(DX**1.18)
          DDB=(CQ(1)**2*POM1*POM2+POM3)*FQ
          DDV=DDB
          DUB=(CQ(2)**2*POM1*POM2+POM3)*FQ
          DUV=DUB
          DSB=(CQ(3)**2*POM1*POM2+POM3)*FQ
          DCB=(CQ(4)**2*POM1*POM2+POM3)*FQ
          DBB=(CQ(5)**2*POM1*POM2+POM3)*FQ
       RETURN
       END
Commit	Line	Data
21886bb6	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.2 1996/10/30 08:28:06 cernlib
	6	* Version 7.04
	7	*
	8	* Revision 1.2 1996/10/28 14:59:08 pdflib
	9	* PDFLIB new version 7.04
	10	*
	11	* Revision 1.1.1.1 1996/04/12 15:29:17 plothow
	12	* Version 7.01
	13	*
	14	*
	15	#include "pdf/pilot.h"
	16	SUBROUTINE DOPHO1(DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL)
	17	C********************************************************************
	18	C* *
	19	C* Parametrization of parton distribution functions *
	20	C* in the photon (LO analysis) - asymptotic solution of AP eq.! *
	21	C* *
	22	C* authors: D.Duke and H.Owens (DO) *
	23	C* /Phys.Rev. D26 (1982) 1600/ *
	24	C* *
	25	C* Prepared by: *
	26	C* Krzysztof Charchula, DESY *
	27	C* bitnet: F1PCHA@DHHDESY3 *
	28	C* decnet: 13313::CHARCHULA *
	29	C* *
	30	C* Modified by: *
	31	C* H. Plothow-Besch/CERN-PPE *
	32	C* *
	33	C********************************************************************
	34	C
	35	#include "pdf/impdp.inc"
	36	#include "pdf/expdp.inc"
	37	+ CQ(5),
	38	+ DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL
	39	PARAMETER (ALPEM=7.29927D-3, PI=3.141592D0)
	40	PARAMETER (ALAM=0.2D0)
	41	DATA CQ/0.33333D0,0.66666D0,0.33333D0,0.66666D0,0.33333D0/
	42	C
	43	Q2 = DQ*DQ
	44	ALAM2=ALAM**2
	45	FQ=ALPEM/(2.PI)LOG(Q2/ALAM2)
	46	C
	47	C...gluons
	48	POMG=0.194(1.-DX)1.03/(DX*0.97)
	49	DGL=POMG*FQ
	50	C
	51	C...quarks
	52	POM1=(1.81-1.67DX+2.16DX**2)
	53	POM2=DX*0.7/(1.-0.4LOG(1.-DX))
	54	POM3=38.D-4(1.-DX)1.82/(DX*1.18)
	55	DDB=(CQ(1)*2POM1POM2+POM3)FQ
	56	DDV=DDB
	57	DUB=(CQ(2)*2POM1POM2+POM3)FQ
	58	DUV=DUB
	59	DSB=(CQ(3)*2POM1POM2+POM3)FQ
	60	DCB=(CQ(4)*2POM1POM2+POM3)FQ
	61	DBB=(CQ(5)*2POM1POM2+POM3)FQ
	62	RETURN
	63	END