HIJING/hipyset1_35/luxtot_hijing.F

   1 * $Id$
   2
   3 C*********************************************************************
   4
   5       SUBROUTINE LUXTOT_HIJING(KFL,ECM,XTOT)
   6
   7 C...Purpose: to calculate total cross-section, including initial
   8 C...state radiation effects.
   9 #include "ludat1_hijing.inc"
  10 #include "ludat2_hijing.inc"
  11
  12 C...Status, (optimized) Q^2 scale, alpha_strong.
  13       PARJ(151)=ECM
  14       MSTJ(119)=10*MSTJ(102)+KFL
  15       IF(MSTJ(111).EQ.0) THEN
  16         Q2R=ECM**2
  17       ELSEIF(MSTU(111).EQ.0) THEN
  18         PARJ(168)=MIN(1.,MAX(PARJ(128),EXP(-12.*PARU(1)/
  19      &  ((33.-2.*MSTU(112))*PARU(111)))))
  20         Q2R=PARJ(168)*ECM**2
  21       ELSE
  22         PARJ(168)=MIN(1.,MAX(PARJ(128),PARU(112)/ECM,
  23      &  (2.*PARU(112)/ECM)**2))
  24         Q2R=PARJ(168)*ECM**2
  25       ENDIF
  26       ALSPI=ULALPS_HIJING(Q2R)/PARU(1)
  27
  28 C...QCD corrections factor in R.
  29       IF(MSTJ(101).EQ.0.OR.MSTJ(109).EQ.1) THEN
  30         RQCD=1.
  31       ELSEIF(IABS(MSTJ(101)).EQ.1.AND.MSTJ(109).EQ.0) THEN
  32         RQCD=1.+ALSPI
  33       ELSEIF(MSTJ(109).EQ.0) THEN
  34         RQCD=1.+ALSPI+(1.986-0.115*MSTU(118))*ALSPI**2
  35         IF(MSTJ(111).EQ.1) RQCD=MAX(1.,RQCD+(33.-2.*MSTU(112))/12.*
  36      &  LOG(PARJ(168))*ALSPI**2)
  37       ELSEIF(IABS(MSTJ(101)).EQ.1) THEN
  38         RQCD=1.+(3./4.)*ALSPI
  39       ELSE
  40         RQCD=1.+(3./4.)*ALSPI-(3./32.+0.519*MSTU(118))*ALSPI**2
  41       ENDIF
  42
  43 C...Calculate Z0 width if default value not acceptable.
  44       IF(MSTJ(102).GE.3) THEN
  45         RVA=3.*(3.+(4.*PARU(102)-1.)**2)+6.*RQCD*(2.+(1.-8.*PARU(102)/
  46      &  3.)**2+(4.*PARU(102)/3.-1.)**2)
  47         DO 100 KFLC=5,6
  48         VQ=1.
  49         IF(MOD(MSTJ(103),2).EQ.1) VQ=SQRT(MAX(0.,1.-(2.
  50      $       *ULMASS_HIJING(KFLC)/ECM)**2))
  51         IF(KFLC.EQ.5) VF=4.*PARU(102)/3.-1.
  52         IF(KFLC.EQ.6) VF=1.-8.*PARU(102)/3.
  53   100   RVA=RVA+3.*RQCD*(0.5*VQ*(3.-VQ**2)*VF**2+VQ**3)
  54         PARJ(124)=PARU(101)*PARJ(123)*RVA/(48.*PARU(102)*(1.-PARU(102)))
  55       ENDIF
  56
  57 C...Calculate propagator and related constants for QFD case.
  58       POLL=1.-PARJ(131)*PARJ(132)
  59       IF(MSTJ(102).GE.2) THEN
  60         SFF=1./(16.*PARU(102)*(1.-PARU(102)))
  61         SFW=ECM**4/((ECM**2-PARJ(123)**2)**2+(PARJ(123)*PARJ(124))**2)
  62         SFI=SFW*(1.-(PARJ(123)/ECM)**2)
  63         VE=4.*PARU(102)-1.
  64         SF1I=SFF*(VE*POLL+PARJ(132)-PARJ(131))
  65         SF1W=SFF**2*((VE**2+1.)*POLL+2.*VE*(PARJ(132)-PARJ(131)))
  66         HF1I=SFI*SF1I
  67         HF1W=SFW*SF1W
  68       ENDIF
  69
  70 C...Loop over different flavours: charge, velocity.
  71       RTOT=0.
  72       RQQ=0.
  73       RQV=0.
  74       RVA=0.
  75       DO 110 KFLC=1,MAX(MSTJ(104),KFL)
  76       IF(KFL.GT.0.AND.KFLC.NE.KFL) GOTO 110
  77       MSTJ(93)=1
  78       PMQ=ULMASS_HIJING(KFLC)
  79       IF(ECM.LT.2.*PMQ+PARJ(127)) GOTO 110
  80       QF=KCHG(KFLC,1)/3.
  81       VQ=1.
  82       IF(MOD(MSTJ(103),2).EQ.1) VQ=SQRT(1.-(2.*PMQ/ECM)**2)
  83
  84 C...Calculate R and sum of charges for QED or QFD case.
  85       RQQ=RQQ+3.*QF**2*POLL
  86       IF(MSTJ(102).LE.1) THEN
  87         RTOT=RTOT+3.*0.5*VQ*(3.-VQ**2)*QF**2*POLL
  88       ELSE
  89         VF=SIGN(1.,QF)-4.*QF*PARU(102)
  90         RQV=RQV-6.*QF*VF*SF1I
  91         RVA=RVA+3.*(VF**2+1.)*SF1W
  92         RTOT=RTOT+3.*(0.5*VQ*(3.-VQ**2)*(QF**2*POLL-2.*QF*VF*HF1I+
  93      &  VF**2*HF1W)+VQ**3*HF1W)
  94       ENDIF
  95   110 CONTINUE
  96       RSUM=RQQ
  97       IF(MSTJ(102).GE.2) RSUM=RQQ+SFI*RQV+SFW*RVA
  98
  99 C...Calculate cross-section, including QCD corrections.
 100       PARJ(141)=RQQ
 101       PARJ(142)=RTOT
 102       PARJ(143)=RTOT*RQCD
 103       PARJ(144)=PARJ(143)
 104       PARJ(145)=PARJ(141)*86.8/ECM**2
 105       PARJ(146)=PARJ(142)*86.8/ECM**2
 106       PARJ(147)=PARJ(143)*86.8/ECM**2
 107       PARJ(148)=PARJ(147)
 108       PARJ(157)=RSUM*RQCD
 109       PARJ(158)=0.
 110       PARJ(159)=0.
 111       XTOT=PARJ(147)
 112       IF(MSTJ(107).LE.0) RETURN
 113
 114 C...Virtual cross-section.
 115       XKL=PARJ(135)
 116       XKU=MIN(PARJ(136),1.-(2.*PARJ(127)/ECM)**2)
 117       ALE=2.*LOG(ECM/ULMASS_HIJING(11))-1.
 118       SIGV=ALE/3.+2.*LOG(ECM**2/(ULMASS_HIJING(13)*ULMASS_HIJING(15)))/3
 119      $     .-4./3.+1.526*LOG(ECM**2/0.932)
 120
 121 C...Soft and hard radiative cross-section in QED case.
 122       IF(MSTJ(102).LE.1) THEN
 123         SIGV=1.5*ALE-0.5+PARU(1)**2/3.+2.*SIGV
 124         SIGS=ALE*(2.*LOG(XKL)-LOG(1.-XKL)-XKL)
 125         SIGH=ALE*(2.*LOG(XKU/XKL)-LOG((1.-XKU)/(1.-XKL))-(XKU-XKL))
 126
 127 C...Soft and hard radiative cross-section in QFD case.
 128       ELSE
 129         SZM=1.-(PARJ(123)/ECM)**2
 130         SZW=PARJ(123)*PARJ(124)/ECM**2
 131         PARJ(161)=-RQQ/RSUM
 132         PARJ(162)=-(RQQ+RQV+RVA)/RSUM
 133         PARJ(163)=(RQV*(1.-0.5*SZM-SFI)+RVA*(1.5-SZM-SFW))/RSUM
 134         PARJ(164)=(RQV*SZW**2*(1.-2.*SFW)+RVA*(2.*SFI+SZW**2-4.+3.*SZM-
 135      &  SZM**2))/(SZW*RSUM)
 136         SIGV=1.5*ALE-0.5+PARU(1)**2/3.+((2.*RQQ+SFI*RQV)/RSUM)*SIGV+
 137      &  (SZW*SFW*RQV/RSUM)*PARU(1)*20./9.
 138         SIGS=ALE*(2.*LOG(XKL)+PARJ(161)*LOG(1.-XKL)+PARJ(162)*XKL+
 139      &  PARJ(163)*LOG(((XKL-SZM)**2+SZW**2)/(SZM**2+SZW**2))+
 140      &  PARJ(164)*(ATAN((XKL-SZM)/SZW)-ATAN(-SZM/SZW)))
 141         SIGH=ALE*(2.*LOG(XKU/XKL)+PARJ(161)*LOG((1.-XKU)/(1.-XKL))+
 142      &  PARJ(162)*(XKU-XKL)+PARJ(163)*LOG(((XKU-SZM)**2+SZW**2)/
 143      &  ((XKL-SZM)**2+SZW**2))+PARJ(164)*(ATAN((XKU-SZM)/SZW)-
 144      &  ATAN((XKL-SZM)/SZW)))
 145       ENDIF
 146
 147 C...Total cross-section and fraction of hard photon events.
 148       PARJ(160)=SIGH/(PARU(1)/PARU(101)+SIGV+SIGS+SIGH)
 149       PARJ(157)=RSUM*(1.+(PARU(101)/PARU(1))*(SIGV+SIGS+SIGH))*RQCD
 150       PARJ(144)=PARJ(157)
 151       PARJ(148)=PARJ(144)*86.8/ECM**2
 152       XTOT=PARJ(148)
 153
 154       RETURN
 155       END