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Commit | Line | Data |
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fe4da5cc | 1 | |
2 | C********************************************************************* | |
3 | ||
4 | SUBROUTINE LUXKFL(KFL,ECM,ECMC,KFLC) | |
5 | ||
6 | C...Purpose: to select flavour for produced qqbar pair. | |
7 | COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200) | |
8 | COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4) | |
9 | SAVE /LUDAT1/,/LUDAT2/ | |
10 | ||
11 | C...Calculate maximum weight in QED or QFD case. | |
12 | IF(MSTJ(102).LE.1) THEN | |
13 | RFMAX=4./9. | |
14 | ELSE | |
15 | POLL=1.-PARJ(131)*PARJ(132) | |
16 | SFF=1./(16.*PARU(102)*(1.-PARU(102))) | |
17 | SFW=ECMC**4/((ECMC**2-PARJ(123)**2)**2+(PARJ(123)*PARJ(124))**2) | |
18 | SFI=SFW*(1.-(PARJ(123)/ECMC)**2) | |
19 | VE=4.*PARU(102)-1. | |
20 | HF1I=SFI*SFF*(VE*POLL+PARJ(132)-PARJ(131)) | |
21 | HF1W=SFW*SFF**2*((VE**2+1.)*POLL+2.*VE*(PARJ(132)-PARJ(131))) | |
22 | RFMAX=MAX(4./9.*POLL-4./3.*(1.-8.*PARU(102)/3.)*HF1I+ | |
23 | & ((1.-8.*PARU(102)/3.)**2+1.)*HF1W,1./9.*POLL+2./3.* | |
24 | & (-1.+4.*PARU(102)/3.)*HF1I+((-1.+4.*PARU(102)/3.)**2+1.)*HF1W) | |
25 | ENDIF | |
26 | ||
27 | C...Choose flavour. Gives charge and velocity. | |
28 | NTRY=0 | |
29 | 100 NTRY=NTRY+1 | |
30 | IF(NTRY.GT.100) THEN | |
31 | CALL LUERRM(14,'(LUXKFL:) caught in an infinite loop') | |
32 | KFLC=0 | |
33 | RETURN | |
34 | ENDIF | |
35 | KFLC=KFL | |
36 | IF(KFL.LE.0) KFLC=1+INT(MSTJ(104)*RLU(0)) | |
37 | MSTJ(93)=1 | |
38 | PMQ=ULMASS(KFLC) | |
39 | IF(ECM.LT.2.*PMQ+PARJ(127)) GOTO 100 | |
40 | QF=KCHG(KFLC,1)/3. | |
41 | VQ=1. | |
42 | IF(MOD(MSTJ(103),2).EQ.1) VQ=SQRT(MAX(0.,1.-(2.*PMQ/ECMC)**2)) | |
43 | ||
44 | C...Calculate weight in QED or QFD case. | |
45 | IF(MSTJ(102).LE.1) THEN | |
46 | RF=QF**2 | |
47 | RFV=0.5*VQ*(3.-VQ**2)*QF**2 | |
48 | ELSE | |
49 | VF=SIGN(1.,QF)-4.*QF*PARU(102) | |
50 | RF=QF**2*POLL-2.*QF*VF*HF1I+(VF**2+1.)*HF1W | |
51 | RFV=0.5*VQ*(3.-VQ**2)*(QF**2*POLL-2.*QF*VF*HF1I+VF**2*HF1W)+ | |
52 | & VQ**3*HF1W | |
53 | IF(RFV.GT.0.) PARJ(171)=MIN(1.,VQ**3*HF1W/RFV) | |
54 | ENDIF | |
55 | ||
56 | C...Weighting or new event (radiative photon). Cross-section update. | |
57 | IF(KFL.LE.0.AND.RF.LT.RLU(0)*RFMAX) GOTO 100 | |
58 | PARJ(158)=PARJ(158)+1. | |
59 | IF(ECMC.LT.2.*PMQ+PARJ(127).OR.RFV.LT.RLU(0)*RF) KFLC=0 | |
60 | IF(MSTJ(107).LE.0.AND.KFLC.EQ.0) GOTO 100 | |
61 | IF(KFLC.NE.0) PARJ(159)=PARJ(159)+1. | |
62 | PARJ(144)=PARJ(157)*PARJ(159)/PARJ(158) | |
63 | PARJ(148)=PARJ(144)*86.8/ECM**2 | |
64 | ||
65 | RETURN | |
66 | END |