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Extracting PHOS and EMCAL trackers from the correspondig reconstructors (Yu.Belikov)
[u/mrichter/AliRoot.git] / PDF / spdf / alphas2.F
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21886bb6 1*
2* $Id$
3*
4* $Log$
5* Revision 1.3 1996/10/30 11:05:22 cernlib
6* Conflicts resolved
7*
8* Revision 1.1.1.2 1996/10/30 08:32:07 cernlib
9* Version 7.04
10*
11* Revision 1.2 1996/05/31 13:57:48 pdflib
12* replace # by +
13*
14* Revision 1.1.1.1 1996/04/12 15:29:01 plothow
15* Version 7.01
16*
17*
18#include "pdf/pilot.h"
19C-----------------------------------------------------------------------
20#if defined(CERNLIB_SINGLE)
21 FUNCTION ALPHAS2(SCALE)
22#endif
23#if defined(CERNLIB_DOUBLE)
24 DOUBLE PRECISION FUNCTION ALPHAS2(SCALE)
25
26#endif
27C
28C **********************************************************************
29C * *
30C * Program to calculate alfa strong to second order *
31C * as a function of lambda of 5 flavours *
32C * and the desired number of flavours (NFL) *
33C * for the selected set of structure functions which fixes lambda. *
34C * NFL is limited to max. of 6 flavours. *
35C * The value of alfa is matched at the thresholds q = mq. *
36C * When invoked with NFL < 0, it chooses NFL *
37C * as the number of flavours with mass less then q. *
38C * (mc = 1.5 GeV, mb = 4.75 GeV, mt = 100 GeV) *
39C * *
40C * Input: SCALE = QCD scale in GeV *
41C * *
42C * Output: ALPHAS2 = alpha strong to second order, *
43C * if not LO = 1 *
44C * *
45C * The variables NPTYPE,NGROUP,NSET,NFL,LO,TMAS,QCDL4,QCDL5 *
46C * should be provided by the user via a call to the *
47C * subroutine PDFSET at the initialization phase. *
48C * *
49C * Author: H. Plothow-Besch (CERN-PPE) *
50C * *
51C **********************************************************************
52C
53#include "pdf/impdp.inc"
54C
55#include "pdf/w5051p1.inc"
56#include "pdf/w5051p2.inc"
57#include "pdf/w5051p7.inc"
58#include "pdf/w50510.inc"
59#include "pdf/w50511.inc"
60#include "pdf/w50512.inc"
61#include "pdf/w50513.inc"
62#include "pdf/w50515.inc"
63#include "pdf/w50516.inc"
64#include "pdf/w50517.inc"
65#include "pdf/w50519.inc"
66#include "pdf/w505120.inc"
67#include "pdf/w505121.inc"
68C
69#include "pdf/expdp.inc"
70 + NF,KNF
71 CHARACTER*20 PARM(NCHDIM)
72#include "pdf/expdp.inc"
73 + VAL(NCHDIM)
74 DATA XMC/1.5D0/,XMB/4.75D0/,XMT/100.D0/
75 DATA ZEROD/0.D0/,PONED/0.001D0/,ONED/1.D0/,TWOD/2.D0/
76C.
77C. initialization of the parameters for the coupling constant
78C.
79C. QCDL4 : QCD scale, which is matched to the scale used in the
80C. parton distribution function chosen above for 4 flavours.
81C.
82C. QCDL5 : QCD scale, which is matched to the scale used in the
83C. parton distribution function chosen above.
84C.
85C. be aware, this lambda is given for 5 flavours (mb = 4.75 GeV/c**2) !!
86C.
87C
88C set the default values
89C
90 ALPHAS2 = ZEROD
91C
92 IF(N6.LE.0) N6 = L6
93C.
94#include "pdf/w50511c.inc"
95C.
96C User wants new version (4.0 or bigger) of PDFLIB format
97 IF (IFLSET.NE.1) THEN
98 IF(FIRST) THEN
99 WRITE(N6,*) ' Warning : NO initialisation via PDFSET made !!'
100 WRITE(N6,*)
101 + ' ALL Parameters set to default (Nucleon PDFs) !!'
102 ENDIF
103 NPTYPE = LPTYPE
104 NGROUP = LGROUP
105 NSET = LNSET
106C
107 PARM(1) = 'NPTYPE'
108 VAL(1) = NPTYPE
109 PARM(2) = 'NGROUP'
110 VAL(2) = NGROUP
111 PARM(3) = 'NSET'
112 VAL(3) = NSET
113C
114 CALL PDFSET(PARM,VAL)
115 ENDIF
116C.
117C User wants old version (3.0 or less) of PDFLIB format
118 IF(.NOT.NEWVER) THEN
119 IF (MODE .GE.0 .AND. MODE .LE.MODEMX) THEN
120 IF(MODE.EQ.0) THEN
121 NPTYPE = LPTYPO
122 NGROUP = LGROPO
123 NSET = LNSETO
124 ELSE
125 NPTYPE = NPTYCR(MODE)
126 NGROUP = NGROCR(MODE)
127 NSET = NSETCR(MODE)
128C Check on validity of parameter values
129 IF (NPTYPE.LT.0 .OR. NGROUP.LT.0 .OR. NSET.LT.0) THEN
130 IF(FIRST) THEN
131 WRITE(N6,*) ' PDFLIB : MODE value INCORRECT, MODE = ',
132 + MODE
133 WRITE(N6,*) ' Warning : MODE value set to OLD default !!'
134 ENDIF
135 NPTYPE = LPTYPO
136 NGROUP = LGROPO
137 NSET = LNSETO
138 ENDIF
139 ENDIF
140 ENDIF
141 ENDIF
142C.
143 IF (QCDL5 .LE. PONED) THEN
144 IF(FIRST) THEN
145 WRITE (N6,*) ' PDFLIB: QCD-Lambda5 is not defined !! '
146 ENDIF
147 ALPHAS2 = ZEROD
148 RETURN
149 ENDIF
150C.
151 PI=4.0D0*ATAN(ONED)
152 B6 = (33.D0-2.D0*6.D0)/PI/12.D0
153 BP6 = (153.D0 - 19.D0*6.D0) / PI / TWOD / (33.D0 - 2.D0*6.D0)
154 B5 = (33.D0-2.D0*5.D0)/PI/12.D0
155 BP5 = (153.D0 - 19.D0*5.D0) / PI / TWOD / (33.D0 - 2.D0*5.D0)
156 B4 = (33.D0-2.D0*4.D0)/PI/12.D0
157 BP4 = (153.D0 - 19.D0*4.D0) / PI / TWOD / (33.D0 - 2.D0*4.D0)
158 B3 = (33.D0-2.D0*3.D0)/PI/12.D0
159 BP3 = (153.D0 - 19.D0*3.D0) / PI / TWOD / (33.D0 - 2.D0*3.D0)
160 XLC = TWOD * LOG( XMC/QCDL5)
161 XLB = TWOD * LOG( XMB/QCDL5)
162 XLT = TWOD * LOG( XMT/QCDL5 * TMAS/XMT)
163 XLLC = LOG( XLC)
164 XLLB = LOG( XLB)
165 XLLT = LOG( XLT)
166 C65 = ONED/( ONED/(B5 * XLT) - XLLT*BP5/(B5 * XLT)**2 )
167 + - ONED/( ONED/(B6 * XLT) - XLLT*BP6/(B6 * XLT)**2 )
168 C45 = ONED/( ONED/(B5 * XLB) - XLLB*BP5/(B5 * XLB)**2 )
169 + - ONED/( ONED/(B4 * XLB) - XLLB*BP4/(B4 * XLB)**2 )
170 C35 = ONED/( ONED/(B4 * XLC) - XLLC*BP4/(B4 * XLC)**2 )
171 + - ONED/( ONED/(B3 * XLC) - XLLC*BP3/(B3 * XLC)**2 ) + C45
172C
173 Q = SCALE
174 XLQ = TWOD * LOG( Q/QCDL5 )
175 XLLQ = LOG( XLQ )
176 KNF = NFL
177 NF = KNF
178 IF ( NF .LT. ZEROD) THEN
179 IF ( Q .GT. XMT * TMAS/XMT) THEN
180 NF = 6.D0
181 ELSEIF ( Q .GT. XMB ) THEN
182 NF = 5.D0
183 ELSEIF ( Q .GT. XMC ) THEN
184 NF = 4.D0
185 ELSE
186 NF = 3.D0
187 ENDIF
188 ENDIF
189 IF(NF .GT. 6.D0) NF = 6.D0
190 IF ( NF .EQ. 6.D0 ) THEN
191 ALF = ONED/(ONED/(ONED/(B6*XLQ)- BP6/(B6*XLQ)**2*XLLQ) + C65)
192 IF (LO.EQ.1) ALF = ONED/B6/XLQ
193 ELSEIF ( NF .EQ. 5.D0 ) THEN
194 ALF = ONED/(B5 * XLQ) - BP5/(B5 * XLQ)**2 * XLLQ
195 IF (LO.EQ.1) ALF = ONED/B5/XLQ
196 ELSEIF ( NF .EQ. 4.D0 ) THEN
197 ALF = ONED/(ONED/(ONED/(B4*XLQ)- BP4/(B4*XLQ)**2*XLLQ) + C45)
198 IF (LO.EQ.1) ALF = ONED/B4/XLQ
199 ELSEIF ( NF .EQ. 3.D0 ) THEN
200 ALF = ONED/(ONED/(ONED/(B3*XLQ)- BP3/(B3*XLQ)**2*XLLQ) + C35)
201 IF (LO.EQ.1) ALF = ONED/B3/XLQ
202 ELSE
203 WRITE(N6,*)'Error in Alphas2: unimplemented # of light flavours',
204 + NFL
205 STOP
206 ENDIF
207 ALPHAS2 = ALF
208 RETURN
209 END