pythiaeRHIC/pythia/pygrvl.f

0001
0002 C*********************************************************************
0003
0004 C...PYGRVL
0005 C...Gives the GRV 94 L (leading order) parton distribution function set
0006 C...in parametrized form.
0007 C...Authors: M. Glueck, E. Reya and A. Vogt.
0008
0009       SUBROUTINE PYGRVL (X, Q2, UV, DV, DEL, UDB, SB, CHM, BOT, GL)
0010
0011 C...Double precision declaration.
0012       IMPLICIT DOUBLE PRECISION (A - Z)
0013
0014 C...Common expressions.
0015       MU2  = 0.23D0
0016       LAM2 = 0.2322D0 * 0.2322D0
0017       S  = LOG (LOG(Q2/LAM2) / LOG(MU2/LAM2))
0018       DS = SQRT (S)
0019       S2 = S * S
0020       S3 = S2 * S
0021
0022 C...uv :
0023       NU  =  2.284D0 + 0.802D0 * S + 0.055D0 * S2
0024       AKU =  0.590D0 - 0.024D0 * S
0025       BKU =  0.131D0 + 0.063D0 * S
0026       AU  = -0.449D0 - 0.138D0 * S - 0.076D0 * S2
0027       BU  =  0.213D0 + 2.669D0 * S - 0.728D0 * S2
0028       CU  =  8.854D0 - 9.135D0 * S + 1.979D0 * S2
0029       DU  =  2.997D0 + 0.753D0 * S - 0.076D0 * S2
0030       UV  = PYGRVV (X, NU, AKU, BKU, AU, BU, CU, DU)
0031
0032 C...dv :
0033       ND  =  0.371D0 + 0.083D0 * S + 0.039D0 * S2
0034       AKD =  0.376D0
0035       BKD =  0.486D0 + 0.062D0 * S
0036       AD  = -0.509D0 + 3.310D0 * S - 1.248D0 * S2
0037       BD  =  12.41D0 - 10.52D0 * S + 2.267D0 * S2
0038       CD  =  6.373D0 - 6.208D0 * S + 1.418D0 * S2
0039       DD  =  3.691D0 + 0.799D0 * S - 0.071D0 * S2
0040       DV  = PYGRVV (X, ND, AKD, BKD, AD, BD, CD, DD)
0041
0042 C...del :
0043       NE  =  0.082D0 + 0.014D0 * S + 0.008D0 * S2
0044       AKE =  0.409D0 - 0.005D0 * S
0045       BKE =  0.799D0 + 0.071D0 * S
0046       AE  = -38.07D0 + 36.13D0 * S - 0.656D0 * S2
0047       BE  =  90.31D0 - 74.15D0 * S + 7.645D0 * S2
0048       CE  =  0.0D0
0049       DE  =  7.486D0 + 1.217D0 * S - 0.159D0 * S2
0050       DEL = PYGRVV (X, NE, AKE, BKE, AE, BE, CE, DE)
0051
0052 C...udb :
0053       ALX =  1.451D0
0054       BEX =  0.271D0
0055       AKX =  0.410D0 - 0.232D0 * S
0056       BKX =  0.534D0 - 0.457D0 * S
0057       AGX =  0.890D0 - 0.140D0 * S
0058       BGX = -0.981D0
0059       CX  =  0.320D0 + 0.683D0 * S
0060       DX  =  4.752D0 + 1.164D0 * S + 0.286D0 * S2
0061       EX  =  4.119D0 + 1.713D0 * S
0062       ESX =  0.682D0 + 2.978D0 * S
0063       UDB = PYGRVW (X, S, ALX, BEX, AKX, BKX, AGX, BGX, CX,
0064      & DX, EX, ESX)
0065
0066 C...sb :
0067       STS =  0D0
0068       ALS =  0.914D0
0069       BES =  0.577D0
0070       AKS =  1.798D0 - 0.596D0 * S
0071       AS  = -5.548D0 + 3.669D0 * DS - 0.616D0 * S
0072       BS  =  18.92D0 - 16.73D0 * DS + 5.168D0 * S
0073       DST =  6.379D0 - 0.350D0 * S  + 0.142D0 * S2
0074       EST =  3.981D0 + 1.638D0 * S
0075       ESS =  6.402D0
0076       SB  = PYGRVS (X, S, STS, ALS, BES, AKS, AS, BS, DST, EST, ESS)
0077
0078 C...cb :
0079       STC =  0.888D0
0080       ALC =  1.01D0
0081       BEC =  0.37D0
0082       AKC =  0D0
0083       AC  =  0D0
0084       BC  =  4.24D0  - 0.804D0 * S
0085       DCT =  3.46D0  - 1.076D0 * S
0086       ECT =  4.61D0  + 1.49D0  * S
0087       ESC =  2.555D0 + 1.961D0 * S
0088       CHM = PYGRVS (X, S, STC, ALC, BEC, AKC, AC, BC, DCT, ECT, ESC)
0089
0090 C...bb :
0091       STB =  1.351D0
0092       ALB =  1.00D0
0093       BEB =  0.51D0
0094       AKB =  0D0
0095       AB  =  0D0
0096       BB  =  1.848D0
0097       DBT =  2.929D0 + 1.396D0 * S
0098       EBT =  4.71D0  + 1.514D0 * S
0099       ESB =  4.02D0  + 1.239D0 * S
0100       BOT = PYGRVS (X, S, STB, ALB, BEB, AKB, AB, BB, DBT, EBT, ESB)
0101
0102 C...gl :
0103       ALG =  0.524D0
0104       BEG =  1.088D0
0105       AKG =  1.742D0 - 0.930D0 * S
0106       BKG =                         - 0.399D0 * S2
0107       AG  =  7.486D0 - 2.185D0 * S
0108       BG  =  16.69D0 - 22.74D0 * S  + 5.779D0 * S2
0109       CG  = -25.59D0 + 29.71D0 * S  - 7.296D0 * S2
0110       DG  =  2.792D0 + 2.215D0 * S  + 0.422D0 * S2 - 0.104D0 * S3
0111       EG  =  0.807D0 + 2.005D0 * S
0112       ESG =  3.841D0 + 0.316D0 * S
0113       GL  = PYGRVW (X, S, ALG, BEG, AKG, BKG, AG, BG, CG,
0114      & DG, EG, ESG)
0115
0116       RETURN
0117       END