5 * Revision 1.4 2000/09/18 10:02:35 hristov
6 * Makefile added to PDF8
8 * Revision 1.1.1.2 1996/10/30 08:28:36 cernlib
11 * Revision 1.1.1.1 1996/04/12 15:29:22 plothow
15 #include "pdf/pilot.h"
16 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
18 * G R V - P R O T O N - P A R A M E T R I Z A T I O N S *
22 * FOR A DETAILED EXPLANATION SEE *
23 * M. GLUECK, E.REYA, A.VOGT : *
24 * DO-TH 94/24 = DESY 94-206 *
25 * (TO APPEAR IN Z. PHYS. C) *
27 * THE PARAMETRIZATIONS ARE FITTED TO THE EVOLVED PARTONS FOR *
28 * Q**2 / GEV**2 BETWEEN 0.4 AND 1.E6 *
29 * X BETWEEN 1.E-5 AND 1. *
30 * LARGE-X REGIONS, WHERE THE DISTRIBUTION UNDER CONSIDERATION *
31 * IS NEGLIGIBLY SMALL, WERE EXCLUDED FROM THE FIT. *
33 * HEAVY QUARK THRESHOLDS Q(H) = M(H) IN THE BETA FUNCTION : *
34 * M(C) = 1.5, M(B) = 4.5 *
35 * CORRESPONDING LAMBDA(F) VALUES IN GEV FOR Q**2 > M(H)**2 : *
36 * LO : LAMBDA(3) = 0.232, LAMBDA(4) = 0.200, *
37 * LAMBDA(5) = 0.153, *
38 * NLO : LAMBDA(3) = 0.248, LAMBDA(4) = 0.200, *
39 * LAMBDA(5) = 0.131. *
40 * THE NUMBER OF ACTIVE QUARK FLAVOURS IS NF = 3 EVERYWHERE *
41 * EXCEPT IN THE BETA FUNCTION, I.E. THE HEAVY QUARKS C,B,... *
42 * ARE NOT PRESENT AS PARTONS IN THE Q2-EVOLUTION. *
43 * IF NEEDED, HEAVY QUARK DENSITIES CAN BE TAKEN FROM THE 1991 *
44 * GRV PARAMETRIZATION. *
46 * NLO DISTRIBUTIONS ARE GIVEN IN MS-BAR FACTORIZATION SCHEME *
47 * (SUBROUTINE GRV94HO) AS WELL AS IN THE DIS SCHEME (GRV94DI), *
48 * THE LEADING ORDER PARAMETRIZATION IS PROVIDED BY "GRV94LO". *
50 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
52 *...INPUT PARAMETERS :
54 * X = MOMENTUM FRACTION
55 * Q2 = SCALE Q**2 IN GEV**2
57 *...OUTPUT (ALWAYS X TIMES THE DISTRIBUTION) :
59 * UV = U(VAL) = U - U(BAR)
60 * DV = D(VAL) = D - D(BAR)
61 * DEL = D(BAR) - U(BAR)
62 * UDB = U(BAR) + D(BAR)
66 *...LO PARAMETRIZATION :
68 SUBROUTINE GRV94LO (ZX,ZQ,ZUV,ZDV,ZUB,ZDB,ZSB,ZCB,ZBB,ZTB,ZGL)
71 #if defined(CERNLIB_DOUBLE)
74 #if defined(CERNLIB_SINGLE)
77 + ZX,ZQ,ZUV,ZDV,ZDEL,ZUDB,ZUB,ZDB,ZSB,ZCB,ZBB,ZTB,ZGL
82 LAM2 = 0.2322 * 0.2322
84 ARG1 = MAX(MU2,Q2)/LAM2
86 S = LOG ( LOG( ARG1 ) / LOG( ARG2 ))
91 NU = 2.284 + 0.802 * S + 0.055 * S2
92 AKU = 0.590 - 0.024 * S
93 BKU = 0.131 + 0.063 * S
94 AU = -0.449 - 0.138 * S - 0.076 * S2
95 BU = 0.213 + 2.669 * S - 0.728 * S2
96 CU = 8.854 - 9.135 * S + 1.979 * S2
97 DU = 2.997 + 0.753 * S - 0.076 * S2
98 UV = GR94FV (X, NU, AKU, BKU, AU, BU, CU, DU)
101 ND = 0.371 + 0.083 * S + 0.039 * S2
103 BKD = 0.486 + 0.062 * S
104 AD = -0.509 + 3.310 * S - 1.248 * S2
105 BD = 12.41 - 10.52 * S + 2.267 * S2
106 CD = 6.373 - 6.208 * S + 1.418 * S2
107 DD = 3.691 + 0.799 * S - 0.071 * S2
108 DV = GR94FV (X, ND, AKD, BKD, AD, BD, CD, DD)
111 NE = 0.082 + 0.014 * S + 0.008 * S2
112 AKE = 0.409 - 0.005 * S
113 BKE = 0.799 + 0.071 * S
114 AE = -38.07 + 36.13 * S - 0.656 * S2
115 BE = 90.31 - 74.15 * S + 7.645 * S2
117 DE = 7.486 + 1.217 * S - 0.159 * S2
118 DEL = GR94FV (X, NE, AKE, BKE, AE, BE, CE, DE)
123 AKX = 0.410 - 0.232 * S
124 BKX = 0.534 - 0.457 * S
125 AGX = 0.890 - 0.140 * S
127 CX = 0.320 + 0.683 * S
128 DX = 4.752 + 1.164 * S + 0.286 * S2
129 EX = 4.119 + 1.713 * S
130 ESX = 0.682 + 2.978 * S
131 UDB = GR94FW(X, S, ALX, BEX, AKX, BKX, AGX, BGX, CX, DX, EX, ESX)
134 ZUB = (ZUDB - ZDEL)/2.D0
136 ZDB = (ZUDB + ZDEL)/2.D0
140 AKS = 1.798 - 0.596 * S
141 AS = -5.548 + 3.669 * DS - 0.616 * S
142 BS = 18.92 - 16.73 * DS + 5.168 * S
143 DST = 6.379 - 0.350 * S + 0.142 * S2
144 EST = 3.981 + 1.638 * S
146 SB = GR94FWS (X, S, ALS, BES, AKS, AS, BS, DST, EST, ESS)
151 AKG = 1.742 - 0.930 * S
153 AG = 7.486 - 2.185 * S
154 BG = 16.69 - 22.74 * S + 5.779 * S2
155 CG = -25.59 + 29.71 * S - 7.296 * S2
156 DG = 2.792 + 2.215 * S + 0.422 * S2 - 0.104 * S3
157 EG = 0.807 + 2.005 * S
158 ESG = 3.841 + 0.316 * S
159 GL = GR94FW (X, S, ALG, BEG, AKG, BKG, AG, BG, CG, DG, EG, ESG)