| fe4da5cc |
1 | *CMZ : 17/07/98 15.44.35 by Federico Carminati |
| 2 | *-- Author : |
| 3 | C********************************************************************* |
| 4 | |
| 5 | SUBROUTINE LUXKFL(KFL,ECM,ECMC,KFLC) |
| 6 | |
| 7 | C...Purpose: to select flavour for produced qqbar pair. |
| 8 | *KEEP,LUDAT1. |
| 9 | COMMON /LUDAT1/ MSTU(200),PARU(200),MSTJ(200),PARJ(200) |
| 10 | SAVE /LUDAT1/ |
| 11 | *KEEP,LUDAT2. |
| 12 | COMMON /LUDAT2/ KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4) |
| 13 | SAVE /LUDAT2/ |
| 14 | *KEND. |
| 15 | |
| 16 | C...Calculate maximum weight in QED or QFD case. |
| 17 | IF(MSTJ(102).LE.1) THEN |
| 18 | RFMAX=4./9. |
| 19 | ELSE |
| 20 | POLL=1.-PARJ(131)*PARJ(132) |
| 21 | SFF=1./(16.*PARU(102)*(1.-PARU(102))) |
| 22 | SFW=ECMC**4/((ECMC**2-PARJ(123)**2)**2+(PARJ(123)*PARJ(124))**2) |
| 23 | SFI=SFW*(1.-(PARJ(123)/ECMC)**2) |
| 24 | VE=4.*PARU(102)-1. |
| 25 | HF1I=SFI*SFF*(VE*POLL+PARJ(132)-PARJ(131)) |
| 26 | HF1W=SFW*SFF**2*((VE**2+1.)*POLL+2.*VE*(PARJ(132)-PARJ(131))) |
| 27 | RFMAX=MAX(4./9.*POLL-4./3.*(1.-8.*PARU(102)/3.)*HF1I+ |
| 28 | & ((1.-8.*PARU(102)/3.)**2+1.)*HF1W,1./9.*POLL+2./3.* |
| 29 | & (-1.+4.*PARU(102)/3.)*HF1I+((-1.+4.*PARU(102)/3.)**2+1.)*HF1W) |
| 30 | ENDIF |
| 31 | |
| 32 | C...Choose flavour. Gives charge and velocity. |
| 33 | NTRY=0 |
| 34 | 100 NTRY=NTRY+1 |
| 35 | IF(NTRY.GT.100) THEN |
| 36 | CALL LUERRM(14,'(LUXKFL:) caught in an infinite loop') |
| 37 | KFLC=0 |
| 38 | RETURN |
| 39 | ENDIF |
| 40 | KFLC=KFL |
| 41 | IF(KFL.LE.0) KFLC=1+INT(MSTJ(104)*RLU(0)) |
| 42 | MSTJ(93)=1 |
| 43 | PMQ=ULMASS(KFLC) |
| 44 | IF(ECM.LT.2.*PMQ+PARJ(127)) GOTO 100 |
| 45 | QF=KCHG(KFLC,1)/3. |
| 46 | VQ=1. |
| 47 | IF(MOD(MSTJ(103),2).EQ.1) VQ=SQRT(MAX(0.,1.-(2.*PMQ/ECMC)**2)) |
| 48 | |
| 49 | C...Calculate weight in QED or QFD case. |
| 50 | IF(MSTJ(102).LE.1) THEN |
| 51 | RF=QF**2 |
| 52 | RFV=0.5*VQ*(3.-VQ**2)*QF**2 |
| 53 | ELSE |
| 54 | VF=SIGN(1.,QF)-4.*QF*PARU(102) |
| 55 | RF=QF**2*POLL-2.*QF*VF*HF1I+(VF**2+1.)*HF1W |
| 56 | RFV=0.5*VQ*(3.-VQ**2)*(QF**2*POLL-2.*QF*VF*HF1I+VF**2*HF1W)+ |
| 57 | & VQ**3*HF1W |
| 58 | ENDIF |
| 59 | |
| 60 | C...Weighting or new event (radiative photon). Cross-section update. |
| 61 | IF(KFL.LE.0.AND.RF.LT.RLU(0)*RFMAX) GOTO 100 |
| 62 | PARJ(158)=PARJ(158)+1. |
| 63 | IF(ECMC.LT.2.*PMQ+PARJ(127).OR.RFV.LT.RLU(0)*RF) KFLC=0 |
| 64 | IF(MSTJ(107).LE.0.AND.KFLC.EQ.0) GOTO 100 |
| 65 | IF(KFLC.NE.0) PARJ(159)=PARJ(159)+1. |
| 66 | PARJ(144)=PARJ(157)*PARJ(159)/PARJ(158) |
| 67 | PARJ(148)=PARJ(144)*86.8/ECM**2 |
| 68 | |
| 69 | RETURN |
| 70 | END |
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