[u/mrichter/AliRoot.git] / PDF / spdf / ctq1opf.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.4  1997/07/13 13:22:34  cernlib
* Import version 7.09
*
* Revision 1.1.1.1  1996/04/12 15:29:07  plothow
* Version 7.01
*
*
#include "pdf/pilot.h"
      FUNCTION Ctq1OPf (Iset, Iparton, X, Q, Irt)

C     CTEQ distribution function in a parametrized form.
C     (No data tables are needed.)

C    The returned function value is the PROBABILITY density for a given FLAVOR.

C  !!   A companion function Ctq1Pd (Iset, Iparton, X, Q, Irt) gives the
C  !!   VALENCE and SEA MOMENTUM FRACTION distributions.  See next module.

C     Ref.: "CTEQ Parton Distributions and Flavor Dependence of the Sea Quarks"
C         by: J. Botts, J.G. Morfin, J.F. Owens, J. Qiu, W.K. Tung & H. Weerts
C             MSUHEP-92-27, Fermilab-Pub-92/371, FSU-HEP-92-1225, ISU-NP-92-17

C     Since this is an initial distribution, and there may be updates, it is
C     useful for the authors to maintain a record of the distribution list.
C     Please do not freely distribute this program package; instead, refer any
C     interested colleague to direct their request for a copy to:
C     Botts@msupa.pa.msu.edu  or  Botts@msupa (bitnet)  or  MSUHEP::Botts

C     If you have any questions concerning these distributions, direct inquires
C     to Jim Botts or Wu-Ki Tung (username Tung at same E-mail nodes as above).

C $Header$
C $Log$
C Revision 1.1.1.4  1997/07/13 13:22:34  cernlib
C Import version 7.09
C
C Revision 1.1.1.1  1996/04/12 15:29:07  plothow
C Version 7.01
C
C Revision 1.1  93/02/08  18:35:25  wkt
C Initial revision
C
C
C     This function returns the CTEQ parton distributions f^Iset_Lp/proton
C     where Iset (= 1, 2, ..., 5) is the set label;
C       Name convention for CTEQ distributions:  CTEQnSx  where
C            n : version number                      (currently n = 1)
C            S : factorization scheme label: = [M D L] for [MS-bar DIS LO] resp.
C            x : special characteristics, if any
C                        (e.g. S for singular gluon, L for "LEP lambda value")

C     Lp  is the parton label (6, 5, 4, 3, 2, 1, 0, -1, ......, -6)
C                         for (t, b, c, s, d, u, g, u_bar, ..., t_bar)

C     X, Q are the usual x, Q; Irt is a return error code (not implemented yet).

C --> Iset = 1, 2, 3, 4, 5 correspond to the following CTEQ global fits:
C     cteq1M, cteq1MS, cteq1ML, cteq1D, cteq1L  respectively.

C --> QCD parameters for parton distribution set Iset can be obtained inside
C         the user's program by:
C     Call ParCtqO
C    >        (Iset, Iord, Ischeme, MxFlv,
C    >         Alam4, Alam5, Alam6, Amas4, Amas5, Amas6,
C    >         Xmin, Qini, Qmax, ExpNor)
C     where the arguments are self-explanary -- see details in next module.

C     The range of (x, Q) used in this round of global analysis is, approxi-
C     mately,  0.01 < x < 0.75 ; and 4 GeV^2 < Q^2 < 400 GeV^2.

C      The range of (x, Q) used in the reparametrization of the QCD evolved
C      parton distributions is 10E-5 < x < 1 ; 2 GeV < Q < 1 TeV.  The
C      functional form of this parametrization is:

C      A0 * x^A1 * (1-x)^A2 * (1 + A3 * x^A4) * [log(1+1/x)]^A5

C      with the A'coefficients being smooth functions of Q.
C      Since this function is positive definite and smooth, it provides sensible
C      extrapolations of the parton distributions if they are called beyond
C      the original range in an application.   There is no artificial boundaries
C      or sharp cutoff's.

C     IMPLICIT DOUBLE PRECISION (A-H, O-Z)
C+SEQ, IMPDP.
      REAL Ctq1OPd,X,Q
C
      Ifl = Iparton
      JFL = ABS(Ifl)
C                                                                       Valence
      IF (Ifl .LE. 0) THEN
        VL = 0.
      ELSEIF (Ifl .LE. 2) THEN
        VL = Ctq1OPd (Iset, Ifl, X, Q, Irt)
      ELSE
        VL = 0.
      ENDIF
C                                                                         Sea
      SEA = Ctq1OPd (Iset, -JFL, X, Q, Irt)
C                                               Full (probability) Distribution
      Ctq1OPf = (VL + SEA) / X

      Return
C                         *************************
      END
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.4 1997/07/13 13:22:34 cernlib
	6	* Import version 7.09
	7	*
	8	* Revision 1.1.1.1 1996/04/12 15:29:07 plothow
	9	* Version 7.01
	10	*
	11	*
	12	#include "pdf/pilot.h"
	13	FUNCTION Ctq1OPf (Iset, Iparton, X, Q, Irt)
	14
	15	C CTEQ distribution function in a parametrized form.
	16	C (No data tables are needed.)
	17
	18	C The returned function value is the PROBABILITY density for a given FLAVOR.
	19
	20	C !! A companion function Ctq1Pd (Iset, Iparton, X, Q, Irt) gives the
	21	C !! VALENCE and SEA MOMENTUM FRACTION distributions. See next module.
	22
	23	C Ref.: "CTEQ Parton Distributions and Flavor Dependence of the Sea Quarks"
	24	C by: J. Botts, J.G. Morfin, J.F. Owens, J. Qiu, W.K. Tung & H. Weerts
	25	C MSUHEP-92-27, Fermilab-Pub-92/371, FSU-HEP-92-1225, ISU-NP-92-17
	26
	27	C Since this is an initial distribution, and there may be updates, it is
	28	C useful for the authors to maintain a record of the distribution list.
	29	C Please do not freely distribute this program package; instead, refer any
	30	C interested colleague to direct their request for a copy to:
	31	C Botts@msupa.pa.msu.edu or Botts@msupa (bitnet) or MSUHEP::Botts
	32
	33	C If you have any questions concerning these distributions, direct inquires
	34	C to Jim Botts or Wu-Ki Tung (username Tung at same E-mail nodes as above).
	35
	36	C $Header$
	37	C $Log$
	38	C Revision 1.1.1.4 1997/07/13 13:22:34 cernlib
	39	C Import version 7.09
	40	C
	41	C Revision 1.1.1.1 1996/04/12 15:29:07 plothow
	42	C Version 7.01
	43	C
	44	C Revision 1.1 93/02/08 18:35:25 wkt
	45	C Initial revision
	46	C
	47	C
	48	C This function returns the CTEQ parton distributions f^Iset_Lp/proton
	49	C where Iset (= 1, 2, ..., 5) is the set label;
	50	C Name convention for CTEQ distributions: CTEQnSx where
	51	C n : version number (currently n = 1)
	52	C S : factorization scheme label: = [M D L] for [MS-bar DIS LO] resp.
	53	C x : special characteristics, if any
	54	C (e.g. S for singular gluon, L for "LEP lambda value")
	55
	56	C Lp is the parton label (6, 5, 4, 3, 2, 1, 0, -1, ......, -6)
	57	C for (t, b, c, s, d, u, g, u_bar, ..., t_bar)
	58
	59	C X, Q are the usual x, Q; Irt is a return error code (not implemented yet).
	60
	61	C --> Iset = 1, 2, 3, 4, 5 correspond to the following CTEQ global fits:
	62	C cteq1M, cteq1MS, cteq1ML, cteq1D, cteq1L respectively.
	63
	64	C --> QCD parameters for parton distribution set Iset can be obtained inside
65	C the user's program by:
66	C Call ParCtqO
67	C > (Iset, Iord, Ischeme, MxFlv,
68	C > Alam4, Alam5, Alam6, Amas4, Amas5, Amas6,
69	C > Xmin, Qini, Qmax, ExpNor)
70	C where the arguments are self-explanary -- see details in next module.
71
72	C The range of (x, Q) used in this round of global analysis is, approxi-
73	C mately, 0.01 < x < 0.75 ; and 4 GeV^2 < Q^2 < 400 GeV^2.
74
75	C The range of (x, Q) used in the reparametrization of the QCD evolved
76	C parton distributions is 10E-5 < x < 1 ; 2 GeV < Q < 1 TeV. The
77	C functional form of this parametrization is:
78
79	C A0 * x^A1 * (1-x)^A2 * (1 + A3 * x^A4) * [log(1+1/x)]^A5
80
81	C with the A'coefficients being smooth functions of Q.
82	C Since this function is positive definite and smooth, it provides sensible
83	C extrapolations of the parton distributions if they are called beyond
84	C the original range in an application. There is no artificial boundaries
85	C or sharp cutoff's.
86
87	C IMPLICIT DOUBLE PRECISION (A-H, O-Z)
88	C+SEQ, IMPDP.
89	REAL Ctq1OPd,X,Q
90	C
91	Ifl = Iparton
92	JFL = ABS(Ifl)
93	C Valence
94	IF (Ifl .LE. 0) THEN
95	VL = 0.
96	ELSEIF (Ifl .LE. 2) THEN
97	VL = Ctq1OPd (Iset, Ifl, X, Q, Irt)
98	ELSE
99	VL = 0.
100	ENDIF
101	C Sea
102	SEA = Ctq1OPd (Iset, -JFL, X, Q, Irt)
103	C Full (probability) Distribution
104	Ctq1OPf = (VL + SEA) / X
105
106	Return
107	C *************************
108	END