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Commit | Line | Data |
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0795afa3 | 1 | #include "isajet/pilot.h" |
2 | FUNCTION ALQCD(Q2) | |
3 | C----------------------------------------------------------------------- | |
4 | C Strong coupling formula from page 201 of Barger and Phillips: | |
5 | C (using ALQCD4 for 4 flavor Lambda) | |
6 | C----------------------------------------------------------------------- | |
7 | REAL Q2,AS,TH5,TH6,PI,ALQCD4 | |
8 | LOGICAL FIRST | |
9 | SAVE FIRST,PI,TH5,TH6,ALQCD4 | |
10 | DATA FIRST/.TRUE./ | |
11 | C | |
12 | IF(FIRST) THEN | |
13 | PI=4.*ATAN(1.) | |
14 | TH5=4*AMASS(5)**2 | |
15 | TH6=4*AMASS(6)**2 | |
16 | ALQCD4=0.177 | |
17 | FIRST=.FALSE. | |
18 | ENDIF | |
19 | IF (Q2.LE.TH5)THEN | |
20 | AS=12*PI/(25*LOG(Q2/ALQCD4**2)) | |
21 | ELSE IF(Q2.GT.TH5.AND.Q2.LE.TH6) THEN | |
22 | AS=25*LOG(Q2/ALQCD4**2)-2*LOG(Q2/TH5) | |
23 | AS=12*PI/AS | |
24 | ELSEIF(Q2.GT.TH6)THEN | |
25 | AS=25*LOG(Q2/ALQCD4**2) | |
26 | AS=AS-2*(LOG(Q2/TH5)+LOG(Q2/TH6)) | |
27 | AS=12*PI/AS | |
28 | ENDIF | |
29 | ALQCD=AS | |
30 | RETURN | |
31 | END |