5 * Revision 1.1.1.4 1997/07/13 13:22:34 cernlib
8 * Revision 1.1.1.1 1996/04/12 15:29:07 plothow
12 #include "pdf/pilot.h"
13 FUNCTION Ctq1OPf (Iset, Iparton, X, Q, Irt)
15 C CTEQ distribution function in a parametrized form.
16 C (No data tables are needed.)
18 C The returned function value is the PROBABILITY density for a given FLAVOR.
20 C !! A companion function Ctq1Pd (Iset, Iparton, X, Q, Irt) gives the
21 C !! VALENCE and SEA MOMENTUM FRACTION distributions. See next module.
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
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
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).
38 C Revision 1.1.1.4 1997/07/13 13:22:34 cernlib
41 C Revision 1.1.1.1 1996/04/12 15:29:07 plothow
44 C Revision 1.1 93/02/08 18:35:25 wkt
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")
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)
59 C X, Q are the usual x, Q; Irt is a return error code (not implemented yet).
61 C --> Iset = 1, 2, 3, 4, 5 correspond to the following CTEQ global fits:
62 C cteq1M, cteq1MS, cteq1ML, cteq1D, cteq1L respectively.
64 C --> QCD parameters for parton distribution set Iset can be obtained inside
65 C the user's program by:
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.
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.
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:
79 C A0 * x^A1 * (1-x)^A2 * (1 + A3 * x^A4) * [log(1+1/x)]^A5
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
87 C IMPLICIT DOUBLE PRECISION (A-H, O-Z)
96 ELSEIF (Ifl .LE. 2) THEN
97 VL = Ctq1OPd (Iset, Ifl, X, Q, Irt)
102 SEA = Ctq1OPd (Iset, -JFL, X, Q, Irt)
103 C Full (probability) Distribution
104 Ctq1OPf = (VL + SEA) / X
107 C *************************