[u/mrichter/AliRoot.git] / PDF / spdf / grv94lo.F

*
* $Id$
*
* $Log$
* Revision 1.4  2000/09/18 10:02:35  hristov
* Makefile added to PDF8
*
* Revision 1.1.1.2  1996/10/30 08:28:36  cernlib
* Version 7.04
*
* Revision 1.1.1.1  1996/04/12 15:29:22  plothow
* Version 7.01
*
*
#include "pdf/pilot.h"
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*                                                                 *
*    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     *
*                                                                 *
*                         1994 UPDATE                             *
*                                                                 *
*                 FOR A DETAILED EXPLANATION SEE                  *
*                   M. GLUECK, E.REYA, A.VOGT :                   *
*                   DO-TH 94/24  =  DESY 94-206                   *
*                    (TO APPEAR IN Z. PHYS. C)                    *
*                                                                 *
*   THE PARAMETRIZATIONS ARE FITTED TO THE EVOLVED PARTONS FOR    *
*        Q**2 / GEV**2  BETWEEN   0.4   AND  1.E6                 *
*             X         BETWEEN  1.E-5  AND   1.                  *
*   LARGE-X REGIONS, WHERE THE DISTRIBUTION UNDER CONSIDERATION   *
*   IS NEGLIGIBLY SMALL, WERE EXCLUDED FROM THE FIT.              *
*                                                                 *
*   HEAVY QUARK THRESHOLDS  Q(H) = M(H)  IN THE BETA FUNCTION :   *
*                   M(C)  =  1.5,  M(B)  =  4.5                   *
*   CORRESPONDING LAMBDA(F) VALUES IN GEV FOR  Q**2 > M(H)**2 :   *
*      LO :   LAMBDA(3)  =  0.232,   LAMBDA(4)  =  0.200,         *
*             LAMBDA(5)  =  0.153,                                *
*      NLO :  LAMBDA(3)  =  0.248,   LAMBDA(4)  =  0.200,         *
*             LAMBDA(5)  =  0.131.                                *
*   THE NUMBER OF ACTIVE QUARK FLAVOURS IS  NF = 3  EVERYWHERE    *
*   EXCEPT IN THE BETA FUNCTION, I.E. THE HEAVY QUARKS C,B,...    *
*   ARE NOT PRESENT AS PARTONS IN THE Q2-EVOLUTION.               *
*   IF NEEDED, HEAVY QUARK DENSITIES CAN BE TAKEN FROM THE 1991   *
*   GRV PARAMETRIZATION.                                          *
*                                                                 *
*   NLO DISTRIBUTIONS ARE GIVEN IN MS-BAR FACTORIZATION SCHEME    *
*   (SUBROUTINE GRV94HO) AS WELL AS IN THE DIS SCHEME (GRV94DI),  *
*   THE LEADING ORDER PARAMETRIZATION IS PROVIDED BY "GRV94LO".   *
*                                                                 *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
*...INPUT PARAMETERS :
*
*    X   = MOMENTUM FRACTION
*    Q2  = SCALE Q**2 IN GEV**2
*
*...OUTPUT (ALWAYS X TIMES THE DISTRIBUTION) :
*
*    UV  = U(VAL) = U - U(BAR)
*    DV  = D(VAL) = D - D(BAR)
*    DEL = D(BAR) - U(BAR)
*    UDB = U(BAR) + D(BAR)
*    SB  = S = S(BAR)
*    GL  = GLUON
*
*...LO PARAMETRIZATION :
*
       SUBROUTINE GRV94LO (ZX,ZQ,ZUV,ZDV,ZUB,ZDB,ZSB,ZCB,ZBB,ZTB,ZGL)
       IMPLICIT REAL (A - Y)
C+SEQ, IMPDP.
#if defined(CERNLIB_DOUBLE)
      DOUBLE PRECISION
#endif
#if defined(CERNLIB_SINGLE)
      REAL
#endif
     +      ZX,ZQ,ZUV,ZDV,ZDEL,ZUDB,ZUB,ZDB,ZSB,ZCB,ZBB,ZTB,ZGL
       REAL X, Q
       X = ZX
       Q = ZQ
       MU2  = 0.23
       LAM2 = 0.2322   * 0.2322
       Q2 = Q*Q
       ARG1 = MAX(MU2,Q2)/LAM2
       ARG2 = MU2/LAM2
       S  =  LOG ( LOG( ARG1  ) /  LOG( ARG2   ))
       DS =  SQRT (S)
       S2 = S * S
       S3 = S2 * S
*...UV :
       NU  =  2.284 + 0.802 * S + 0.055 * S2
       AKU =  0.590 - 0.024 * S
       BKU =  0.131 + 0.063 * S
       AU  = -0.449 - 0.138 * S - 0.076 * S2
       BU  =  0.213 + 2.669 * S - 0.728 * S2
       CU  =  8.854 - 9.135 * S + 1.979 * S2
       DU  =  2.997 + 0.753 * S - 0.076 * S2
       UV  = GR94FV (X, NU, AKU, BKU, AU, BU, CU, DU)
       ZUV = UV
*...DV :
       ND  =  0.371 + 0.083 * S + 0.039 * S2
       AKD =  0.376
       BKD =  0.486 + 0.062 * S
       AD  = -0.509 + 3.310 * S - 1.248 * S2
       BD  =  12.41 - 10.52 * S + 2.267 * S2
       CD  =  6.373 - 6.208 * S + 1.418 * S2
       DD  =  3.691 + 0.799 * S - 0.071 * S2
       DV  = GR94FV (X, ND, AKD, BKD, AD, BD, CD, DD)
       ZDV = DV
*...DEL :
       NE  =  0.082 + 0.014 * S + 0.008 * S2
       AKE =  0.409 - 0.005 * S
       BKE =  0.799 + 0.071 * S
       AE  = -38.07 + 36.13 * S - 0.656 * S2
       BE  =  90.31 - 74.15 * S + 7.645 * S2
       CE  =  0.0
       DE  =  7.486 + 1.217 * S - 0.159 * S2
       DEL = GR94FV (X, NE, AKE, BKE, AE, BE, CE, DE)
       ZDEL= DEL
*...UDB :
       ALX =  1.451
       BEX =  0.271
       AKX =  0.410 - 0.232 * S
       BKX =  0.534 - 0.457 * S
       AGX =  0.890 - 0.140 * S
       BGX = -0.981
       CX  =  0.320 + 0.683 * S
       DX  =  4.752 + 1.164 * S + 0.286 * S2
       EX  =  4.119 + 1.713 * S
       ESX =  0.682 + 2.978 * S
       UDB = GR94FW(X, S, ALX, BEX, AKX, BKX, AGX, BGX, CX, DX, EX, ESX)
       ZUDB= UDB
*...UB
       ZUB = (ZUDB - ZDEL)/2.D0
*...DB
       ZDB = (ZUDB + ZDEL)/2.D0
*...SB :
       ALS =  0.914
       BES =  0.577
       AKS =  1.798 - 0.596 * S
       AS  = -5.548 + 3.669 * DS - 0.616 * S
       BS  =  18.92 - 16.73 * DS + 5.168 * S
       DST =  6.379 - 0.350 * S  + 0.142 * S2
       EST =  3.981 + 1.638 * S
       ESS =  6.402
       SB  = GR94FWS (X, S, ALS, BES, AKS, AS, BS, DST, EST, ESS)
       ZSB = SB
*...GL :
       ALG =  0.524
       BEG =  1.088
       AKG =  1.742 - 0.930 * S
       BKG =        - 0.399 * S2
       AG  =  7.486 - 2.185 * S
       BG  =  16.69 - 22.74 * S  + 5.779 * S2
       CG  = -25.59 + 29.71 * S  - 7.296 * S2
       DG  =  2.792 + 2.215 * S  + 0.422 * S2 - 0.104 * S3
       EG  =  0.807 + 2.005 * S
       ESG =  3.841 + 0.316 * S
       GL  = GR94FW (X, S, ALG, BEG, AKG, BKG, AG, BG, CG, DG, EG, ESG)
       ZGL = GL
*...
       ZCB = 0.D0
       ZBB = 0.D0
       ZTB = 0.D0
*...
       RETURN
       END
Commit	Line	Data
21886bb6	1	*
	2	* $Id$
	3	*
	4	* $Log$
7ef50f50	5	* Revision 1.4 2000/09/18 10:02:35 hristov
	6	* Makefile added to PDF8
	7	*
21886bb6	8	* Revision 1.1.1.2 1996/10/30 08:28:36 cernlib
	9	* Version 7.04
	10	*
	11	* Revision 1.1.1.1 1996/04/12 15:29:22 plothow
	12	* Version 7.01
	13	*
	14	*
	15	#include "pdf/pilot.h"
	16	* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
	17	* *
	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 *
	19	* *
	20	* 1994 UPDATE *
	21	* *
	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) *
	26	* *
	27	* THE PARAMETRIZATIONS ARE FITTED TO THE EVOLVED PARTONS FOR *
	28	* Q2 / GEV2 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. *
	32	* *
	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 Q2 > 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. *
	45	* *
	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". *
	49	* *
	50	* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
	51	*
	52	*...INPUT PARAMETERS :
	53	*
	54	* X = MOMENTUM FRACTION
	55	* Q2 = SCALE Q2 IN GEV2
	56	*
	57	*...OUTPUT (ALWAYS X TIMES THE DISTRIBUTION) :
	58	*
	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)
	63	* SB = S = S(BAR)
	64	* GL = GLUON
	65	*
	66	*...LO PARAMETRIZATION :
	67	*
	68	SUBROUTINE GRV94LO (ZX,ZQ,ZUV,ZDV,ZUB,ZDB,ZSB,ZCB,ZBB,ZTB,ZGL)
	69	IMPLICIT REAL (A - Y)
	70	C+SEQ, IMPDP.
7ef50f50	71	#if defined(CERNLIB_DOUBLE)
	72	DOUBLE PRECISION
	73	#endif
	74	#if defined(CERNLIB_SINGLE)
	75	REAL
	76	#endif
21886bb6	77	+ ZX,ZQ,ZUV,ZDV,ZDEL,ZUDB,ZUB,ZDB,ZSB,ZCB,ZBB,ZTB,ZGL
	78	REAL X, Q
	79	X = ZX
	80	Q = ZQ
	81	MU2 = 0.23
	82	LAM2 = 0.2322 * 0.2322
	83	Q2 = Q*Q
	84	ARG1 = MAX(MU2,Q2)/LAM2
	85	ARG2 = MU2/LAM2
	86	S = LOG ( LOG( ARG1 ) / LOG( ARG2 ))
	87	DS = SQRT (S)
	88	S2 = S * S
	89	S3 = S2 * S
	90	*...UV :
	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)
	99	ZUV = UV
	100	*...DV :
	101	ND = 0.371 + 0.083 * S + 0.039 * S2
	102	AKD = 0.376
	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)
	109	ZDV = DV
	110	*...DEL :
	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
	116	CE = 0.0
	117	DE = 7.486 + 1.217 * S - 0.159 * S2
	118	DEL = GR94FV (X, NE, AKE, BKE, AE, BE, CE, DE)
	119	ZDEL= DEL
	120	*...UDB :
	121	ALX = 1.451
	122	BEX = 0.271
	123	AKX = 0.410 - 0.232 * S
	124	BKX = 0.534 - 0.457 * S
	125	AGX = 0.890 - 0.140 * S
	126	BGX = -0.981
	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)
	132	ZUDB= UDB
	133	*...UB
	134	ZUB = (ZUDB - ZDEL)/2.D0
	135	*...DB
	136	ZDB = (ZUDB + ZDEL)/2.D0
	137	*...SB :
	138	ALS = 0.914
	139	BES = 0.577
	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
145	ESS = 6.402
146	SB = GR94FWS (X, S, ALS, BES, AKS, AS, BS, DST, EST, ESS)
147	ZSB = SB
148	*...GL :
149	ALG = 0.524
150	BEG = 1.088
151	AKG = 1.742 - 0.930 * S
152	BKG = - 0.399 * S2
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)
160	ZGL = GL
161	*...
162	ZCB = 0.D0
163	ZBB = 0.D0
164	ZTB = 0.D0
165	*...
166	RETURN
167	END