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Commit | Line | Data |
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0795afa3 | 1 | #include "isajet/pilot.h" |
2 | FUNCTION ESTRUC(X,QS) | |
3 | C | |
4 | C THIS IS ELECTRON PARTON DISTRIBUTION FUNCTION; | |
5 | C SAME AS USED IN PYTHIA; NOTE! ESTRUC=0 FOR X>.999999 | |
6 | C | |
7 | #if defined(CERNLIB_IMPNONE) | |
8 | IMPLICIT NONE | |
9 | #endif | |
10 | REAL ESTRUC,AL,PI,AME,QS,X,BT,XM,T,A,B | |
11 | C | |
12 | AL=1./128. | |
13 | PI=4*ATAN(1.) | |
14 | AME=.511E-3 | |
15 | BT=2*AL/PI*(LOG(QS/AME/AME)-1.) | |
16 | C KLEISS/SJOSTRAND PRESCRIPTION | |
17 | C IF (X.LE..9999) THEN | |
18 | C ESTRUC=BT/2.*(1.-X)**(BT/2.-1.) | |
19 | C ELSE IF (X.LE..999999.AND.X.GT..9999) THEN | |
20 | C ESTRUC=100.**(BT/2.)/(100.**(BT/2.)-1.)*BT/2.* | |
21 | C $ (1.-X)**(BT/2.-1.) | |
22 | C ELSE | |
23 | C ESTRUC=0. | |
24 | C END IF | |
25 | C FADIN-KURAEV/DREES PRESCRIPTION | |
26 | XM=.998 | |
27 | IF(X.GT.XM) THEN | |
28 | T = (1.+.375*BT)*(1.-XM)**(BT/2.) | |
29 | A = ((1.0-BT/2.)*T | |
30 | & -.25*BT*(1.5-XM*(1.+XM/2.)))/(1.-XM) | |
31 | & +.25*BT*(1.0+XM) | |
32 | A = 2*A/(1.-XM) | |
33 | B = .5*BT*T/(1.-XM) - .25*BT*(1.+XM) - A*XM | |
34 | ESTRUC = A*X+B | |
35 | ELSE | |
36 | ESTRUC = .5*BT*((1.-X)**(.5*BT-1.)) * (1.+.375*BT) | |
37 | & -.25*BT*(1.+X) | |
38 | ENDIF | |
39 | RETURN | |
40 | END |