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0795afa3 | 1 | #include "isajet/pilot.h" |
2 | DOUBLE PRECISION FUNCTION SSMQCD(DM,DQ) | |
3 | C----------------------------------------------------------------------- | |
4 | C Calculate leading-log running mass for quark with mass DM at | |
5 | C scale Q, using alpha_s which is continuous across thresholds. | |
6 | C See Drees and Hikasa, Phys. Lett. B240: 455-464, Eq. 4.5. | |
7 | C | |
8 | C Note the threshold is at Q = 2 m, not at Q = m as in MSbar. | |
9 | C | |
10 | C Bisset's QCDRAD, WDHFFC | |
11 | C----------------------------------------------------------------------- | |
12 | #if defined(CERNLIB_IMPNONE) | |
13 | IMPLICIT NONE | |
14 | #endif | |
15 | #include "isajet/sssm.inc" | |
16 | C | |
17 | DOUBLE PRECISION DM,DQ,DLAM4,DLAM5,DLAM6,DNEFF,POW,RENORM | |
18 | $,DQBT,DQTP | |
19 | C | |
20 | C Do nothing for light quarks | |
21 | C | |
22 | IF(DM.LT.1.0) THEN | |
23 | SSMQCD=DM | |
24 | RETURN | |
25 | ENDIF | |
26 | C | |
27 | C Calculate running mass | |
28 | C | |
29 | DLAM4=DBLE(ALQCD4) | |
30 | DQBT=2*DBLE(AMBT) | |
31 | DQTP=2*DBLE(AMTP) | |
32 | SSMQCD=0 | |
33 | C Q < 2 m(b) | |
34 | DNEFF=4 | |
35 | POW=12.D0/(33.D0-2.*DNEFF) | |
36 | IF(DQ.LT.DQBT) THEN | |
37 | RENORM=(LOG(2*DM/DLAM4)/LOG(DQ/DLAM4))**POW | |
38 | SSMQCD=RENORM*DM | |
39 | RETURN | |
40 | ELSE | |
41 | RENORM=(LOG(2*DM/DLAM4)/LOG(DQBT/DLAM4))**POW | |
42 | ENDIF | |
43 | C 2 m(b) < Q < 2 m(t) | |
44 | DNEFF=5 | |
45 | POW=12.D0/(33.D0-2.*DNEFF) | |
46 | DLAM5=DEXP((25.D0*LOG(DLAM4)-LOG(DQBT**2))/23.D0) | |
47 | IF(DQ.GE.DQBT.AND.DQ.LT.DQTP) THEN | |
48 | RENORM=RENORM | |
49 | $ *(LOG(DQBT/DLAM5)/LOG(DQ/DLAM5))**POW | |
50 | SSMQCD=RENORM*DM | |
51 | RETURN | |
52 | ELSE | |
53 | RENORM=RENORM | |
54 | $ *(LOG(DQBT/DLAM5)/LOG(DQTP/DLAM5))**POW | |
55 | ENDIF | |
56 | C 2 m(t) < Q | |
57 | DNEFF=6 | |
58 | POW=12.D0/(33.D0-2.*DNEFF) | |
59 | DLAM6=DEXP((25.D0*LOG(DLAM4)-LOG(DQBT**2) | |
60 | $-LOG(4*AMTP**2))/21.D0) | |
61 | RENORM=RENORM | |
62 | $*(LOG(DQTP/DLAM6)/LOG(DQ/DLAM6))**POW | |
63 | SSMQCD=RENORM*DM | |
64 | RETURN | |
65 | END |