PYTHIA/pythia/pydocu.F

   1
   2 C*********************************************************************
   3
   4       SUBROUTINE PYDOCU
   5
   6 C...Handles the decumentation of the process in MSTI and PARI,
   7 C...and also computes cross-sections based on accumulated statistics.
   8       COMMON/LUJETS/N,K(4000,5),P(4000,5),V(4000,5)
   9       COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
  10       COMMON/PYPARS/MSTP(200),PARP(200),MSTI(200),PARI(200)
  11       COMMON/PYSUBS/MSEL,MSUB(200),KFIN(2,-40:40),CKIN(200)
  12       COMMON/PYINT1/MINT(400),VINT(400)
  13       COMMON/PYINT2/ISET(200),KFPR(200,2),COEF(200,20),ICOL(40,4,2)
  14       COMMON/PYINT5/NGEN(0:200,3),XSEC(0:200,3)
  15       COMMON/PYINT9/DXSEC(0:200)
  16       DOUBLE PRECISION DXSEC
  17       SAVE /LUJETS/,/LUDAT1/
  18       SAVE /PYSUBS/,/PYPARS/,/PYINT1/,/PYINT2/,/PYINT5/,/PYINT9/
  19
  20 C...Calculate Monte Carlo estimates of cross-sections.
  21       ISUB=MINT(1)
  22       IF(MSTP(111).NE.-1) NGEN(ISUB,3)=NGEN(ISUB,3)+1
  23       NGEN(0,3)=NGEN(0,3)+1
  24       XSEC(0,3)=0.
  25       DO 100 I=1,200
  26       IF(I.EQ.96.OR.I.EQ.97) THEN
  27         XSEC(I,3)=0.
  28       ELSEIF(MSUB(95).EQ.1.AND.(I.EQ.11.OR.I.EQ.12.OR.I.EQ.13.OR.
  29      &I.EQ.28.OR.I.EQ.53.OR.I.EQ.68)) THEN
  30         XSEC(I,3)=DXSEC(96)*NGEN(I,3)/MAX(1.,FLOAT(NGEN(96,1))*
  31      &  FLOAT(NGEN(96,2)))
  32       ELSEIF(MSUB(I).EQ.0.OR.NGEN(I,1).EQ.0) THEN
  33         XSEC(I,3)=0.
  34       ELSEIF(NGEN(I,2).EQ.0) THEN
  35         XSEC(I,3)=DXSEC(I)*NGEN(0,3)/(FLOAT(NGEN(I,1))*
  36      &  FLOAT(NGEN(0,2)))
  37       ELSE
  38         XSEC(I,3)=DXSEC(I)*NGEN(I,3)/(FLOAT(NGEN(I,1))*
  39      &  FLOAT(NGEN(I,2)))
  40       ENDIF
  41       XSEC(0,3)=XSEC(0,3)+XSEC(I,3)
  42   100 CONTINUE
  43
  44 C...Rescale to known low-pT cross-section for standard QCD processes.
  45       IF(MSUB(95).EQ.1) THEN
  46         XSECH=XSEC(11,3)+XSEC(12,3)+XSEC(13,3)+XSEC(28,3)+XSEC(53,3)+
  47      &  XSEC(68,3)+XSEC(95,3)
  48         XSECW=DXSEC(97)/MAX(1.,FLOAT(NGEN(97,1)))
  49         IF(XSECH.GT.1E-10.AND.XSECW.GT.1E-10) THEN
  50           FAC=XSECW/XSECH
  51           XSEC(11,3)=FAC*XSEC(11,3)
  52           XSEC(12,3)=FAC*XSEC(12,3)
  53           XSEC(13,3)=FAC*XSEC(13,3)
  54           XSEC(28,3)=FAC*XSEC(28,3)
  55           XSEC(53,3)=FAC*XSEC(53,3)
  56           XSEC(68,3)=FAC*XSEC(68,3)
  57           XSEC(95,3)=FAC*XSEC(95,3)
  58           XSEC(0,3)=XSEC(0,3)-XSECH+XSECW
  59         ENDIF
  60       ENDIF
  61
  62 C...Save information for gamma-p and gamma-gamma.
  63       IF(MINT(121).GT.1) THEN
  64         IGA=MINT(122)
  65         CALL PYSAVE(2,IGA)
  66         CALL PYSAVE(5,0)
  67       ENDIF
  68
  69 C...Reset information on hard interaction.
  70       DO 110 J=1,200
  71       MSTI(J)=0
  72       PARI(J)=0.
  73   110 CONTINUE
  74
  75 C...Copy integer valued information from MINT into MSTI.
  76       DO 120 J=1,31
  77       MSTI(J)=MINT(J)
  78   120 CONTINUE
  79       IF(MINT(121).GT.1) MSTI(9)=MINT(122)
  80
  81 C...Store cross-section variables in PARI.
  82       PARI(1)=XSEC(0,3)
  83       PARI(2)=XSEC(0,3)/MINT(5)
  84       PARI(9)=VINT(99)
  85       PARI(10)=VINT(100)
  86       VINT(98)=VINT(98)+VINT(100)
  87       IF(MSTP(142).EQ.1) PARI(2)=XSEC(0,3)/VINT(98)
  88
  89 C...Store kinematics variables in PARI.
  90       PARI(11)=VINT(1)
  91       PARI(12)=VINT(2)
  92       IF(ISUB.NE.95) THEN
  93         DO 130 J=13,26
  94         PARI(J)=VINT(30+J)
  95   130   CONTINUE
  96         PARI(31)=VINT(141)
  97         PARI(32)=VINT(142)
  98         PARI(33)=VINT(41)
  99         PARI(34)=VINT(42)
 100         PARI(35)=PARI(33)-PARI(34)
 101         PARI(36)=VINT(21)
 102         PARI(37)=VINT(22)
 103         PARI(38)=VINT(26)
 104         PARI(39)=VINT(157)
 105         PARI(40)=VINT(158)
 106         PARI(41)=VINT(23)
 107         PARI(42)=2.*VINT(47)/VINT(1)
 108       ENDIF
 109
 110 C...Store information on scattered partons in PARI.
 111       IF(ISUB.NE.95.AND.MINT(7)*MINT(8).NE.0) THEN
 112         DO 140 IS=7,8
 113         I=MINT(IS)
 114         PARI(36+IS)=P(I,3)/VINT(1)
 115         PARI(38+IS)=P(I,4)/VINT(1)
 116         PR=MAX(1E-20,P(I,5)**2+P(I,1)**2+P(I,2)**2)
 117         PARI(40+IS)=SIGN(LOG(MIN((SQRT(PR+P(I,3)**2)+ABS(P(I,3)))/
 118      &  SQRT(PR),1E20)),P(I,3))
 119         PR=MAX(1E-20,P(I,1)**2+P(I,2)**2)
 120         PARI(42+IS)=SIGN(LOG(MIN((SQRT(PR+P(I,3)**2)+ABS(P(I,3)))/
 121      &  SQRT(PR),1E20)),P(I,3))
 122         PARI(44+IS)=P(I,3)/SQRT(1E-20+P(I,1)**2+P(I,2)**2+P(I,3)**2)
 123         PARI(46+IS)=ULANGL(P(I,3),SQRT(P(I,1)**2+P(I,2)**2))
 124         PARI(48+IS)=ULANGL(P(I,1),P(I,2))
 125   140   CONTINUE
 126       ENDIF
 127
 128 C...Store sum up transverse and longitudinal momenta.
 129       PARI(65)=2.*PARI(17)
 130       IF(ISUB.LE.90.OR.ISUB.GE.95) THEN
 131         DO 150 I=MSTP(126)+1,N
 132         IF(K(I,1).LE.0.OR.K(I,1).GT.10) GOTO 150
 133         PT=SQRT(P(I,1)**2+P(I,2)**2)
 134         PARI(69)=PARI(69)+PT
 135         IF(I.LE.MINT(52)) PARI(66)=PARI(66)+PT
 136         IF(I.GT.MINT(52).AND.I.LE.MINT(53)) PARI(68)=PARI(68)+PT
 137   150   CONTINUE
 138         PARI(67)=PARI(68)
 139         PARI(71)=VINT(151)
 140         PARI(72)=VINT(152)
 141         PARI(73)=VINT(151)
 142         PARI(74)=VINT(152)
 143       ELSE
 144         PARI(66)=PARI(65)
 145         PARI(69)=PARI(65)
 146       ENDIF
 147
 148 C...Store various other pieces of information into PARI.
 149       PARI(61)=VINT(148)
 150       PARI(75)=VINT(155)
 151       PARI(76)=VINT(156)
 152       PARI(77)=VINT(159)
 153       PARI(78)=VINT(160)
 154       PARI(81)=VINT(138)
 155
 156 C...Set information for LUTABU.
 157       IF(ISET(ISUB).EQ.1.OR.ISET(ISUB).EQ.3) THEN
 158         MSTU(161)=MINT(21)
 159         MSTU(162)=0
 160       ELSEIF(ISET(ISUB).EQ.5) THEN
 161         MSTU(161)=MINT(23)
 162         MSTU(162)=0
 163       ELSE
 164         MSTU(161)=MINT(21)
 165         MSTU(162)=MINT(22)
 166       ENDIF
 167
 168       RETURN
 169       END