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Commit | Line | Data |
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0795afa3 | 1 | #include "isajet/pilot.h" |
2 | C---------------------------------------------------------------------- | |
3 | FUNCTION SUALFE(QS) | |
4 | C---------------------------------------------------------------------- | |
5 | C | |
6 | C Returns the running EM coupling alpha_em(q**2) | |
7 | C | |
8 | C-----SEE BARGER/PHILLIPS, P. 202 --------------------------- | |
9 | #if defined(CERNLIB_IMPNONE) | |
10 | IMPLICIT NONE | |
11 | #endif | |
12 | #include "isajet/sslun.inc" | |
13 | REAL SUALFE | |
14 | REAL PI,MB,SUM,A0,QD,QU,MS,ME,QS,MM,MD,MU,MTAU,MC | |
15 | DATA ME/.0005/,MM/.105/,MTAU/1.784/,MU/.01/,MD/.01/ | |
16 | DATA MS/.5/,MC/1.6/,MB/5.0/,PI/3.1415926/ | |
17 | C | |
18 | SUM=0. | |
19 | QU=2./3. | |
20 | QD=-1./3. | |
21 | IF (QS.GT.4*ME**2) SUM=SUM+LOG(QS/4./ME**2) | |
22 | IF (QS.GT.4*MM**2) SUM=SUM+LOG(QS/4./MM**2) | |
23 | IF (QS.GT.4*MTAU**2) SUM=SUM+LOG(QS/4./MTAU**2) | |
24 | IF (QS.GT.4*MU**2) SUM=SUM+3*QU**2*LOG(QS/4./MU**2) | |
25 | IF (QS.GT.4*MD**2) SUM=SUM+3*QD**2*LOG(QS/4./MD**2) | |
26 | IF (QS.GT.4*MS**2) SUM=SUM+3*QD**2*LOG(QS/4./MS**2) | |
27 | IF (QS.GT.4*MC**2) SUM=SUM+3*QU**2*LOG(QS/4./MC**2) | |
28 | IF (QS.GT.4*MB**2) SUM=SUM+3*QD**2*LOG(QS/4./MB**2) | |
29 | A0=1./137. | |
30 | SUALFE=A0/(1.-A0/3./PI*SUM) | |
31 | RETURN | |
32 | END |