| 1 | SUBROUTINE VHMESO( E,AMASS,ASMASS )
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| 2 |
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| 3 | C-----------------------------------------------------------------------
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| 4 | C (STRANGE) H(EAVY) MESO(N)
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| 5 | C
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| 6 | C HANDLES KAON INITIATED HEAVY MESON AND ITS DECAY INTO 1 KAON AND 2 PI
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| 7 | C STRANGE HEAVY MESON EMITTED FORWARD
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| 8 | C THIS SUBROUTINE IS CALLED FROM BOX72 AND BOX74
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| 9 | C ARGUMENTS:
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| 10 | C E = AVAILABLE ENERGY IN CM
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| 11 | C AMASS = MASS OF STRANGE MESON
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| 12 | C ASMASS = MASS TO BE LEFT OVER FOR OTHER PARTICLES
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| 13 | C-----------------------------------------------------------------------
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| 14 |
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| 15 | IMPLICIT DOUBLE PRECISION (A-H,O-Z)
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| 16 | *KEEP,BAL.
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| 17 | COMMON /BAL/ EBAL
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| 18 | DOUBLE PRECISION EBAL(10)
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| 19 | *KEEP,CONST.
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| 20 | COMMON /CONST/ PI,PI2,OB3,TB3,ENEPER
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| 21 | DOUBLE PRECISION PI,PI2,OB3,TB3,ENEPER
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| 22 | *KEEP,KAONS.
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| 23 | COMMON /KAONS/ CKA
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| 24 | DOUBLE PRECISION CKA(80)
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| 25 | *KEEP,MULT.
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| 26 | COMMON /MULT/ EKINL,MSMM,MULTMA,MULTOT
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| 27 | DOUBLE PRECISION EKINL
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| 28 | INTEGER MSMM,MULTMA(37,13),MULTOT(37,13)
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| 29 | *KEEP,PAM.
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| 30 | COMMON /PAM/ PAMA,SIGNUM
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| 31 | DOUBLE PRECISION PAMA(6000),SIGNUM(6000)
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| 32 | *KEEP,PARPAR.
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| 33 | COMMON /PARPAR/ CURPAR,SECPAR,PRMPAR,OUTPAR,C,
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| 34 | * E00,E00PN,PTOT0,PTOT0N,THICKH,ITYPE,LEVL
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| 35 | DOUBLE PRECISION CURPAR(14),SECPAR(14),PRMPAR(14),OUTPAR(14),
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| 36 | * C(50),E00,E00PN,PTOT0,PTOT0N,THICKH
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| 37 | INTEGER ITYPE,LEVL
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| 38 | *KEEP,PARPAE.
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| 39 | DOUBLE PRECISION GAMMA,COSTHE,PHI,H,T,X,Y,CHI,BETA,GCM,ECM
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| 40 | EQUIVALENCE (CURPAR(2),GAMMA), (CURPAR(3),COSTHE),
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| 41 | * (CURPAR(4), PHI ), (CURPAR(5), H ),
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| 42 | * (CURPAR(6), T ), (CURPAR(7), X ),
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| 43 | * (CURPAR(8), Y ), (CURPAR(9), CHI ),
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| 44 | * (CURPAR(10),BETA), (CURPAR(11),GCM ),
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| 45 | * (CURPAR(12),ECM )
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| 46 | *KEEP,RANDPA.
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| 47 | COMMON /RANDPA/ FAC,U1,U2,RD,NSEQ,ISEED,KNOR
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| 48 | DOUBLE PRECISION FAC,U1,U2
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| 49 | REAL RD(3000)
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| 50 | INTEGER ISEED(103,10),NSEQ
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| 51 | LOGICAL KNOR
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| 52 | *KEEP,RUNPAR.
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| 53 | COMMON /RUNPAR/ FIXHEI,THICK0,HILOECM,HILOELB,
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| 54 | * STEPFC,NRRUN,NSHOW,PATAPE,MONIIN,
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| 55 | * MONIOU,MDEBUG,NUCNUC,
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| 56 | * CETAPE,
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| 57 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 58 | * N1STTR,MDBASE,
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| 59 | * DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 60 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 61 | * ,GHEISH,GHESIG
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| 62 | COMMON /RUNPAC/ DSN,HOST,USER
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| 63 | DOUBLE PRECISION FIXHEI,THICK0,HILOECM,HILOELB
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| 64 | REAL STEPFC
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| 65 | INTEGER NRRUN,NSHOW,PATAPE,MONIIN,MONIOU,MDEBUG,NUCNUC,
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| 66 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 67 | * N1STTR,MDBASE
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| 68 | INTEGER CETAPE
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| 69 | CHARACTER*79 DSN
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| 70 | CHARACTER*20 HOST,USER
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| 71 |
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| 72 | LOGICAL DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 73 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 74 | * ,GHEISH,GHESIG
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| 75 | *KEEP,VKIN.
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| 76 | COMMON /VKIN/ BETACM
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| 77 | DOUBLE PRECISION BETACM
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| 78 | *KEND.
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| 79 |
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| 80 | C-----------------------------------------------------------------------
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| 81 |
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| 82 | IF ( DEBUG ) WRITE(MDEBUG,201) E,AMASS,ASMASS
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| 83 | 201 FORMAT(' VHMESO: E,AMASS,ASMASS=',1P,3E10.4)
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| 84 |
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| 85 | EDVH = 0.D0
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| 86 | W = 0.6D0
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| 87 |
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| 88 | C GAMMA AND BETA OF HEAVY MESON IN CM AND LAB
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| 89 | C E > AMASS + ASMASS TO KEEP GHMCM > 1.
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| 90 | GVHCM = (E**2 + AMASS**2 - ASMASS**2) / (2.D0 * E * AMASS)
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| 91 | BVHCM = SQRT(GVHCM**2 - 1.D0) / GVHCM
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| 92 | GVHLAB = GCM * GVHCM * (1.D0+BETACM*BVHCM)
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| 93 | BVHLAB = SQRT(GVHLAB**2 - 1.D0) / GVHLAB
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| 94 |
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| 95 | C DECAY OF HEAVY MESON
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| 96 |
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| 97 | C KAON PART
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| 98 | C CHOSE LONGITUDINAL MOMENTUM RANDOMLY FROM EXPONENTIAL DISTRIBUTION
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| 99 | P = PCL(CKA(2),W)
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| 100 | PT = PTRANS(DUMMY)
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| 101 | C CALCULATE REST OF ENERGY FOR OTHER PARTICLES
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| 102 | EDVH = SQRT( PAMA(ITYPE)**2 + P**2 + PT**2 )
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| 103 | RESTE = AMASS - EDVH
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| 104 | C GAMMA AND BETA OF KAON
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| 105 | GKAVH = SQRT( P**2 / PAMA(ITYPE)**2 + 1.D0 )
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| 106 | BKAVH = SQRT(GKAVH**2 - 1.D0) / GKAVH
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| 107 | C KAON FORWARD OR BACKWARD ?
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| 108 | CALL RMMAR( RD,1,1 )
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| 109 | IF ( RD(1) .LT. 0.5 ) THEN
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| 110 | GKALAB = GVHLAB * GKAVH * (1.D0+BKAVH*BVHLAB)
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| 111 | PACC = P
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| 112 | ELSE
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| 113 | GKALAB = GVHLAB * GKAVH * (1.D0-BKAVH*BVHLAB)
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| 114 | PACC = -P
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| 115 | ENDIF
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| 116 | C GET NEW DIRECTION
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| 117 | PLLAB2 = PAMA(ITYPE)**2 * (GKALAB**2 - 1.D0)
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| 118 | PLLAB2 = MAX( 1.D-6, PLLAB2 )
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| 119 | CTHETA = SQRT( PLLAB2 / (PT**2+PLLAB2) )
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| 120 | IF ( CTHETA .GE. C(27) ) THEN
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| 121 | CALL RMMAR( RD,1,1 )
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| 122 | CALL ADDANG( COSTHE,PHI, CTHETA,RD(1)*PI2, SECPAR(3),SECPAR(4) )
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| 123 | IF ( SECPAR(3) .GE. C(29) ) THEN
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| 124 | SECPAR(2) = GKALAB
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| 125 | C CHARGE ASSIGNMENT
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| 126 | SECPAR(1) = CURPAR(1)
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| 127 | DO 8 J = 5,8
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| 128 | SECPAR(J) = CURPAR(J)
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| 129 | 8 CONTINUE
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| 130 | CALL TSTACK
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| 131 | ENDIF
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| 132 | ENDIF
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| 133 |
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| 134 | C PION PART
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| 135 |
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| 136 | C WHAT DECAY MODE ?
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| 137 | C NDEC=1 : K,PI0,PI0
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| 138 | C NDEC=2 : K,PI+,PI-
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| 139 | C NDEC=3 : K,PI-,PI+
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| 140 | CALL RMMAR( RD,2,1 )
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| 141 | IF ( RD(1) .LT. 0.5 ) THEN
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| 142 | NDEC = 1
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| 143 | ELSE
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| 144 | IF ( RD(2) .LT. 0.5 ) THEN
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| 145 | NDEC = 2
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| 146 | ELSE
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| 147 | NDEC = 3
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| 148 | ENDIF
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| 149 | ENDIF
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| 150 |
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| 151 | IPI = 0
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| 152 | 2 CONTINUE
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| 153 | IPI = IPI + 1
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| 154 |
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| 155 | C TRANSVERS MOMENTUM
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| 156 | PT = PTRANS(DUMMY)
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| 157 | IF ( IPI .EQ. 1 ) THEN
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| 158 | C LONGITUDINAL MOMENTUM IS SELECTED FROM EXPONENTIAL DISTRIBUTION
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| 159 | P = PCL(C(42),W)
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| 160 | C CHARGE ASSIGNMENT
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| 161 | IF ( NDEC .EQ. 1 ) THEN
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| 162 | SECPAR(1) = 7.D0
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| 163 | PMA = PAMA(7)
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| 164 | ELSEIF ( NDEC .EQ. 2 ) THEN
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| 165 | PMA = PAMA(8)
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| 166 | SECPAR(1) = 8.D0
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| 167 | ELSE
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| 168 | PMA = PAMA(9)
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| 169 | SECPAR(1) = 9.D0
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| 170 | ENDIF
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| 171 | ELSE
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| 172 | C LONGITUDINAL MOMENTUM AS ENERGY IS LEFT
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| 173 | P2 = RESTE**2 - PMA**2 - PT**2
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| 174 | P = SQRT(MAX( P2, 0.D0 ))
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| 175 | IF ( NDEC .EQ. 1 ) THEN
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| 176 | SECPAR(1) = 7.D0
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| 177 | ELSEIF ( NDEC .EQ. 2 ) THEN
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| 178 | SECPAR(1) = 9.D0
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| 179 | ELSE
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| 180 | SECPAR(1) = 8.D0
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| 181 | ENDIF
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| 182 | ENDIF
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| 183 | C REST OF ENERGY FOR OTHER PARTICLES
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| 184 | EDVH = EDVH + SQRT( PMA**2 + P**2 + PT**2 )
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| 185 | RESTE = AMASS - EDVH
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| 186 |
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| 187 | C GAMMA AND BETA OF PION
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| 188 | GPIVH = SQRT(P**2/PMA**2 + 1.D0)
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| 189 | BEPIVH = SQRT(GPIVH**2 - 1.D0) / GPIVH
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| 190 | C FOR FIRST PION CHOSE RANDOMLY WHETHER FORWARD OR BACKWARD
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| 191 | C FOR SECOND PION DECIDE ACCORDING TO ACCUMULATED P
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| 192 | CALL RMMAR( RD,2,1 )
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| 193 | IF ( IPI .EQ. 2 ) THEN
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| 194 | IF ( PACC .LT. 0.D0 ) THEN
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| 195 | RD(1) = 0.
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| 196 | ELSE
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| 197 | RD(1) = 1.
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| 198 | ENDIF
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| 199 | ENDIF
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| 200 | IF ( RD(1) .LT. 0.5 ) THEN
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| 201 | C BACKWARD PION
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| 202 | GPILAB = GVHLAB * GPIVH * (1.D0-BEPIVH*BVHLAB)
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| 203 | PACC = PACC - P
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| 204 | ELSE
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| 205 | C FORWARD PION
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| 206 | GPILAB = GVHLAB * GPIVH * (1.D0+BEPIVH*BVHLAB)
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| 207 | PACC = PACC + P
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| 208 | ENDIF
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| 209 |
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| 210 | PLLAB2 = PMA**2 * (GPILAB**2 - 1.D0)
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| 211 | PLLAB2 = MAX( 1.D-6, PLLAB2 )
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| 212 | CTHETA = SQRT( PLLAB2 / (PT**2+PLLAB2) )
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| 213 | IF ( CTHETA .GE. C(27) ) THEN
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| 214 | CALL ADDANG( COSTHE,PHI, CTHETA,RD(2)*PI2, SECPAR(3),SECPAR(4) )
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| 215 | IF ( SECPAR(3) .GE. C(29) ) THEN
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| 216 | SECPAR(2) = GPILAB
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| 217 | DO 11 J = 5,8
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| 218 | SECPAR(J) = CURPAR(J)
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| 219 | 11 CONTINUE
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| 220 | CALL TSTACK
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| 221 | ENDIF
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| 222 | ENDIF
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| 223 |
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| 224 | IF ( IPI .LT. 2 .AND. RESTE .GT. PMA ) GOTO 2
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| 225 |
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| 226 | EBAL(5) = EBAL(5) + RESTE
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| 227 | MSMM = MSMM + IPI
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| 228 |
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| 229 | RETURN
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| 230 | END
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| 231 |
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