| 1 | SUBROUTINE ISOBAR( E,KIND,AMASS,ASMASS,NOPI )
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| 2 |
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| 3 | C-----------------------------------------------------------------------
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| 4 | C ISOBAR
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| 5 | C
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| 6 | C THREE AND FOUR PION DECAY OF HEAVY ISOBAR, DECAY IS PICKED AT
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| 7 | C RANDOM FROM A UNIFORM DISTRIBUTION WITH EQUAL PROBABILITY
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| 8 | C CHARGE IS DISTRIBUTED AT RANDOM WITH EQUAL PROBABILITY
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| 9 | C DECAYS ARE COMPUTED VIA MOMENTA, HAVING UNIFORM DISTRIBUTION
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| 10 | C UPPER LIMIT OF MOMENTUM DISTRIBUTIONS ARE SPECIFIED BY INPUT DATA
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| 11 | C ENERGY IS STRICTLY CONSERVED, MOMENTA ONLY ON AVERAGE
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| 12 | C THIS SUBROUTINE IS CALLED FROM MANY BOX ROUTINES
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| 13 | C ARGUMENTS:
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| 14 | C E = AVAILABLE ENERGY IN CM
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| 15 | C KIND = 1 BACKWARD ISOBAR
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| 16 | C = 0 FORWARD ISOBAR
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| 17 | C AMASS = MASS OF HEAVY MESON
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| 18 | C ASMASS = MASS TO BE LEFT OVER FOR OTHER PARTICLES
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| 19 | C NOPI = NUMBER OF PIONS TO BE GENERATED
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| 20 | C-----------------------------------------------------------------------
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| 21 |
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| 22 | IMPLICIT DOUBLE PRECISION (A-H,O-Z)
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| 23 | *KEEP,BAL.
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| 24 | COMMON /BAL/ EBAL
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| 25 | DOUBLE PRECISION EBAL(10)
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| 26 | *KEEP,CONST.
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| 27 | COMMON /CONST/ PI,PI2,OB3,TB3,ENEPER
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| 28 | DOUBLE PRECISION PI,PI2,OB3,TB3,ENEPER
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| 29 | *KEEP,ELASTY.
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| 30 | COMMON /ELASTY/ ELAST,IELIS,IELHM,IELNU,IELPI
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| 31 | DOUBLE PRECISION ELAST
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| 32 | INTEGER IELIS(20),IELHM(20),IELNU(20),IELPI(20)
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| 33 | *KEEP,MULT.
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| 34 | COMMON /MULT/ EKINL,MSMM,MULTMA,MULTOT
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| 35 | DOUBLE PRECISION EKINL
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| 36 | INTEGER MSMM,MULTMA(37,13),MULTOT(37,13)
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| 37 | *KEEP,PAM.
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| 38 | COMMON /PAM/ PAMA,SIGNUM
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| 39 | DOUBLE PRECISION PAMA(6000),SIGNUM(6000)
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| 40 | *KEEP,PARPAR.
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| 41 | COMMON /PARPAR/ CURPAR,SECPAR,PRMPAR,OUTPAR,C,
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| 42 | * E00,E00PN,PTOT0,PTOT0N,THICKH,ITYPE,LEVL
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| 43 | DOUBLE PRECISION CURPAR(14),SECPAR(14),PRMPAR(14),OUTPAR(14),
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| 44 | * C(50),E00,E00PN,PTOT0,PTOT0N,THICKH
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| 45 | INTEGER ITYPE,LEVL
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| 46 | *KEEP,PARPAE.
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| 47 | DOUBLE PRECISION GAMMA,COSTHE,PHI,H,T,X,Y,CHI,BETA,GCM,ECM
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| 48 | EQUIVALENCE (CURPAR(2),GAMMA), (CURPAR(3),COSTHE),
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| 49 | * (CURPAR(4), PHI ), (CURPAR(5), H ),
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| 50 | * (CURPAR(6), T ), (CURPAR(7), X ),
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| 51 | * (CURPAR(8), Y ), (CURPAR(9), CHI ),
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| 52 | * (CURPAR(10),BETA), (CURPAR(11),GCM ),
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| 53 | * (CURPAR(12),ECM )
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| 54 | *KEEP,RANDPA.
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| 55 | COMMON /RANDPA/ FAC,U1,U2,RD,NSEQ,ISEED,KNOR
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| 56 | DOUBLE PRECISION FAC,U1,U2
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| 57 | REAL RD(3000)
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| 58 | INTEGER ISEED(103,10),NSEQ
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| 59 | LOGICAL KNOR
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| 60 | *KEEP,RUNPAR.
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| 61 | COMMON /RUNPAR/ FIXHEI,THICK0,HILOECM,HILOELB,
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| 62 | * STEPFC,NRRUN,NSHOW,PATAPE,MONIIN,
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| 63 | * MONIOU,MDEBUG,NUCNUC,
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| 64 | * CETAPE,
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| 65 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 66 | * N1STTR,MDBASE,
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| 67 | * DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 68 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 69 | * ,GHEISH,GHESIG
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| 70 | COMMON /RUNPAC/ DSN,HOST,USER
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| 71 | DOUBLE PRECISION FIXHEI,THICK0,HILOECM,HILOELB
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| 72 | REAL STEPFC
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| 73 | INTEGER NRRUN,NSHOW,PATAPE,MONIIN,MONIOU,MDEBUG,NUCNUC,
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| 74 | * SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
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| 75 | * N1STTR,MDBASE
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| 76 | INTEGER CETAPE
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| 77 | CHARACTER*79 DSN
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| 78 | CHARACTER*20 HOST,USER
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| 79 |
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| 80 | LOGICAL DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
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| 81 | * FIX1I,FMUADD,FNKG,FPRINT,FDBASE
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| 82 | * ,GHEISH,GHESIG
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| 83 | *KEEP,VKIN.
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| 84 | COMMON /VKIN/ BETACM
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| 85 | DOUBLE PRECISION BETACM
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| 86 | *KEND.
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| 87 |
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| 88 | C-----------------------------------------------------------------------
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| 89 |
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| 90 | IF ( DEBUG ) WRITE(MDEBUG,201)E,KIND,AMASS,ASMASS,NOPI
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| 91 | 201 FORMAT(' ISOBAR: E,KIND,AMASS,ASMASS,NOPI=',1P,E10.4,I3,2E10.4,I3)
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| 92 |
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| 93 | C RETURN 1 KILLS PARTICLE
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| 94 |
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| 95 | ISET = 1
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| 96 | EDI = 0.D0
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| 97 | PACC = 0.D0
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| 98 | RESTE = AMASS
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| 99 |
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| 100 | IF ( KIND .NE. 0 ) GOTO 100
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| 101 |
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| 102 | C-----------------------------------------------------------------------
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| 103 | C FORWARD ISOBAR
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| 104 | C PIONS FROM FORWARD ISOBAR
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| 105 | IF ( NOPI .EQ. 1 ) THEN
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| 106 | INOPI = NOPI
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| 107 | A = C(36)
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| 108 | W = 0.38D0
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| 109 | ELSE
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| 110 | W = 1.5D0
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| 111 | CALL RMMAR( RD,1,1 )
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| 112 | IF ( RD(1) .LE. 0.5 ) THEN
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| 113 | INOPI = 3
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| 114 | A = C(36)
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| 115 | ELSE
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| 116 | INOPI = 4
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| 117 | A = C(35)
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| 118 | ENDIF
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| 119 | ENDIF
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| 120 |
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| 121 | GIFCM = (E**2+AMASS**2-ASMASS**2) * 0.5D0 /(E*AMASS)
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| 122 | BEIFCM = SQRT(GIFCM**2 - 1.D0) / GIFCM
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| 123 | GIFLAB = GCM * GIFCM * (1.D0+BETACM*BEIFCM)
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| 124 | BEIFL = SQRT(GIFLAB**2 - 1.D0) / GIFLAB
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| 125 |
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| 126 | C PION LOOP FOR FORWARD ISOBAR DECAY
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| 127 | 13 CONTINUE
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| 128 | P = PCL(A,W)
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| 129 | PT = PTRANS(DUMMY)
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| 130 | GPIIF = SQRT( P**2 / PAMA(8)**2 + 1.D0 )
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| 131 | BEPIIF = SQRT(GPIIF**2 - 1.D0) / GPIIF
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| 132 | EDI = EDI + SQRT( PAMA(8)**2 + P**2 + PT**2 )
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| 133 | RESTE = RESTE - EDI
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| 134 |
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| 135 | CALL RMMAR( RD,3,1 )
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| 136 | IF ( RD(1) .GT. 0.5 ) THEN
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| 137 | GPILAB = GPIIF*GIFLAB*(1.D0-BEIFL*BEPIIF)
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| 138 | PACC = PACC - P
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| 139 | ELSE
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| 140 | GPILAB = GPIIF*GIFLAB*(1.D0+BEIFL*BEPIIF)
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| 141 | PACC = PACC + P
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| 142 | ENDIF
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| 143 |
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| 144 | C CORRECTIVE ACTION IF PLLAB2 LE 1.E-6
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| 145 | PLLAB2 = PAMA(8)**2 *(GPILAB**2 - 1.D0)
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| 146 | PLLAB2 = MAX( 1.D-6, PLLAB2 )
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| 147 | CTHETA = SQRT( PLLAB2 / (PT**2+PLLAB2) )
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| 148 | IF ( CTHETA .GE. C(27) ) THEN
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| 149 | CALL ADDANG( COSTHE,PHI, CTHETA,RD(2)*PI2, SECPAR(3),SECPAR(4) )
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| 150 | IF ( SECPAR(3) .GE. C(29) ) THEN
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| 151 | SECPAR(2) = GPILAB
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| 152 | C CHARGE ASSIGNMENT
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| 153 | IF ( RD(3) .LE. OB3 ) THEN
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| 154 | SECPAR(1) = 7.D0
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| 155 | ELSEIF ( RD(3) .LE. TB3 ) THEN
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| 156 | SECPAR(1) = 8.D0
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| 157 | ELSE
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| 158 | SECPAR(1) = 9.D0
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| 159 | ENDIF
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| 160 | DO 5 J = 5,8
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| 161 | SECPAR(J) = CURPAR(J)
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| 162 | 5 CONTINUE
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| 163 |
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| 164 | CALL TSTACK
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| 165 | ENDIF
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| 166 | ENDIF
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| 167 | IF ( RESTE .LE. PAMA(14) .OR. ISET .EQ. INOPI ) GOTO 14
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| 168 | ISET = ISET + 1
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| 169 | GOTO 13
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| 170 |
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| 171 | C NUCLEON FROM FORWARD ISOBAR
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| 172 | 14 CONTINUE
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| 173 | PT = PTRANS(DUMMY)
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| 174 | MSMM = MSMM + ISET
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| 175 | EPT = SQRT( PAMA(14)**2 + PT**2 )
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| 176 | RESTE = RESTE - EPT
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| 177 |
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| 178 | IF ( RESTE .LE. 0.D0 ) THEN
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| 179 | GNFLAB = GIFLAB
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| 180 | EBAL(1) = EBAL(1) + RESTE
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| 181 | ELSE
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| 182 | GNIF = (RESTE+PAMA(14)) / PAMA(14)
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| 183 | BENIF = SQRT(GNIF**2 - 1.D0) / GNIF
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| 184 | IF ( PACC .LE. 0.D0 ) THEN
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| 185 | GNFLAB = GIFLAB * GNIF * (1.D0 + BENIF*BEIFL)
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| 186 | ELSE
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| 187 | GNFLAB = GIFLAB * GNIF * (1.D0 - BENIF*BEIFL)
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| 188 | ENDIF
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| 189 | ENDIF
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| 190 |
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| 191 | PLLAB2 = PAMA(14)**2 * (GNFLAB**2 - 1.D0)
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| 192 | PLLAB2 = MAX( 1.D-6, PLLAB2 )
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| 193 | CTHETA = SQRT( PLLAB2 / (PT**2+PLLAB2) )
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| 194 | IF ( CTHETA .LT. C(27) ) RETURN
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| 195 | CALL RMMAR( RD,2,1 )
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| 196 | CALL ADDANG( COSTHE,PHI, CTHETA,RD(1)*PI2, SECPAR(3),SECPAR(4) )
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| 197 | IF ( SECPAR(3) .LT. C(29) ) RETURN
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| 198 | SECPAR(2) = GNFLAB
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| 199 |
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| 200 | IF ( RD(2) .LT. 0.5 ) THEN
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| 201 | IADD = 1
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| 202 | ELSE
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| 203 | IADD = 0
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| 204 | ENDIF
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| 205 |
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| 206 | IF ( ITYPE .EQ. 13 .OR. ITYPE .EQ. 14 ) THEN
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| 207 | SECPAR(1) = 14 - IADD
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| 208 | ELSE
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| 209 | SECPAR(1) = 15 + 10*IADD
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| 210 | ENDIF
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| 211 |
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| 212 | C CHARGE ASSIGNMENT
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| 213 | DO 9 J = 5,8
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| 214 | SECPAR(J) = CURPAR(J)
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| 215 | 9 CONTINUE
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| 216 | CALL TSTACK
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| 217 |
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| 218 | C FILL HISTOGRAM
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| 219 | IN = 1.D0 + SECPAR(2) / GAMMA * 20.D0
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| 220 | IN = MIN( IN, 20 )
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| 221 | IELIS(IN) = IELIS(IN) + 1
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| 222 |
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| 223 | RETURN
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| 224 |
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| 225 | C-----------------------------------------------------------------------
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| 226 | C BACKWARD ISOBAR
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| 227 | C PIONS FROM BACKWARD ISOBAR
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| 228 | 100 CONTINUE
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| 229 |
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| 230 | IF ( NOPI .EQ. 1 ) THEN
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| 231 | INOPI = NOPI
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| 232 | ELSE
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| 233 | CALL RMMAR( RD,1,1 )
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| 234 | IF ( RD(1) .LE. 0.5 ) THEN
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| 235 | INOPI = 3
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| 236 | ELSE
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| 237 | INOPI = 4
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| 238 | ENDIF
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| 239 | ENDIF
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| 240 | WORK = MIN( C(11), GAMMA*0.5D0 )
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| 241 | MSMM = MSMM + INOPI
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| 242 | DO 101 J = 1,INOPI
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| 243 | CALL RMMAR( RD,3,1 )
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| 244 | GPI = RD(1)*(WORK-1.D0) + 1.D0
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| 245 | PT = PTRANS(DUMMY)
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| 246 | EDI = EDI+SQRT( PAMA(8)**2+PAMA(8)**2*(GPI**2-1.D0)+PT**2 )
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| 247 | RESTE = ASMASS - EDI
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| 248 | PLLAB2 = PAMA(8)**2 * (GPI**2 - 1.D0)
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| 249 | PLLAB2 = MAX( 1.D-6, PLLAB2 )
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| 250 | CTHETA = SQRT( PLLAB2 / (PT**2+PLLAB2) )
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| 251 | IF ( CTHETA .GE. C(27) ) THEN
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| 252 | CALL ADDANG( COSTHE,PHI, CTHETA,RD(2)*PI2,
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| 253 | * SECPAR(3),SECPAR(4) )
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| 254 | IF ( SECPAR(3) .GE. C(29) ) THEN
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| 255 | SECPAR(2) = GPI
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| 256 | C CHARGE ASSIGNMENT
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| 257 | RR = RD(3)
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| 258 | IF ( RR .LE. OB3 ) THEN
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| 259 | SECPAR(1) = 7.D0
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| 260 | ELSEIF ( RR .LE. TB3 ) THEN
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| 261 | SECPAR(1) = 8.D0
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| 262 | ELSE
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| 263 | SECPAR(1) = 9.D0
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| 264 | ENDIF
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| 265 | DO 104 I = 5,8
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| 266 | SECPAR(I) = CURPAR(I)
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| 267 | 104 CONTINUE
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| 268 |
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| 269 | CALL TSTACK
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| 270 | ENDIF
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| 271 | ENDIF
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| 272 | IF ( RESTE .LE. PAMA(14) ) GOTO 110
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| 273 | 101 CONTINUE
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| 274 |
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| 275 | C NUCLEON FROM BACKWARD ISOBAR
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| 276 |
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| 277 | 110 CONTINUE
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| 278 | WORK = MIN( C(10), GAMMA*0.5D0 )
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| 279 | CALL RMMAR( RD,3,1 )
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| 280 | GNRLAB = RD(1) * (WORK-1.D0) + 1.D0
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| 281 | PT = PTRANS(DUMMY)
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| 282 | EDI = EDI+SQRT( PAMA(14)**2 + PAMA(14)**2*(GNRLAB**2-1.D0)+PT**2)
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| 283 | RESTE = ASMASS - EDI
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| 284 | EBAL(2) = EBAL(2) + RESTE
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| 285 | PLLAB2 = PAMA(14)**2 * (GNRLAB**2 - 1.D0)
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| 286 | PLLAB2 = MAX( 1.D-6, PLLAB2 )
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| 287 | CTHETA = SQRT( PLLAB2 / (PT**2+PLLAB2) )
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| 288 | IF ( CTHETA .LT. C(27) ) RETURN
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| 289 | CALL ADDANG( COSTHE,PHI, CTHETA,RD(2)*PI2, SECPAR(3),SECPAR(4) )
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| 290 | IF ( SECPAR(3) .LT. C(29) ) RETURN
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| 291 | SECPAR(2) = GNRLAB
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| 292 | C CHARGE ASSIGNMENT
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| 293 | IF ( RD(3) .LT. 0.5 ) THEN
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| 294 | SECPAR(1) = 13.D0
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| 295 | ELSE
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| 296 | SECPAR(1) = 14.D0
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| 297 | ENDIF
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| 298 | DO 113 J = 5,8
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| 299 | SECPAR(J) = CURPAR(J)
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| 300 | 113 CONTINUE
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| 301 | CALL TSTACK
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| 302 |
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| 303 | RETURN
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| 304 | END
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