HIJING/hipyset1_35/ulmass_hijing.F

   1 * $Id$
   2
   3 C*********************************************************************
   4
   5       FUNCTION ULMASS_HIJING(KF)
   6
   7 C...Purpose: to give the mass of a particle/parton.
   8 #include "ludat1_hijing.inc"
   9 #include "ludat2_hijing.inc"
  10
  11 C...Reset variables. Compressed code.
  12       ULMASS_HIJING=0.
  13       KFA=IABS(KF)
  14       KC=LUCOMP_HIJING(KF)
  15       IF(KC.EQ.0) RETURN
  16       PARF(106)=PMAS(6,1)
  17       PARF(107)=PMAS(7,1)
  18       PARF(108)=PMAS(8,1)
  19
  20 C...Guarantee use of constituent masses for internal checks.
  21       IF((MSTJ(93).EQ.1.OR.MSTJ(93).EQ.2).AND.KFA.LE.10) THEN
  22         ULMASS_HIJING=PARF(100+KFA)
  23         IF(MSTJ(93).EQ.2) ULMASS_HIJING=MAX(0.,ULMASS_HIJING-PARF(121))
  24
  25 C...Masses that can be read directly off table.
  26       ELSEIF(KFA.LE.100.OR.KC.LE.80.OR.KC.GT.100) THEN
  27         ULMASS_HIJING=PMAS(KC,1)
  28
  29 C...Find constituent partons and their masses.
  30       ELSE
  31         KFLA=MOD(KFA/1000,10)
  32         KFLB=MOD(KFA/100,10)
  33         KFLC=MOD(KFA/10,10)
  34         KFLS=MOD(KFA,10)
  35         KFLR=MOD(KFA/10000,10)
  36         PMA=PARF(100+KFLA)
  37         PMB=PARF(100+KFLB)
  38         PMC=PARF(100+KFLC)
  39
  40 C...Construct masses for various meson, diquark and baryon cases.
  41         IF(KFLA.EQ.0.AND.KFLR.EQ.0.AND.KFLS.LE.3) THEN
  42           IF(KFLS.EQ.1) PMSPL=-3./(PMB*PMC)
  43           IF(KFLS.GE.3) PMSPL=1./(PMB*PMC)
  44           ULMASS_HIJING=PARF(111)+PMB+PMC+PARF(113)*PARF(101)**2*PMSPL
  45         ELSEIF(KFLA.EQ.0) THEN
  46           KMUL=2
  47           IF(KFLS.EQ.1) KMUL=3
  48           IF(KFLR.EQ.2) KMUL=4
  49           IF(KFLS.EQ.5) KMUL=5
  50           ULMASS_HIJING=PARF(113+KMUL)+PMB+PMC
  51         ELSEIF(KFLC.EQ.0) THEN
  52           IF(KFLS.EQ.1) PMSPL=-3./(PMA*PMB)
  53           IF(KFLS.EQ.3) PMSPL=1./(PMA*PMB)
  54           ULMASS_HIJING=2.*PARF(112)/3.+PMA+PMB+PARF(114)*PARF(101)**2
  55      $         *PMSPL
  56           IF(MSTJ(93).EQ.1) ULMASS_HIJING=PMA+PMB
  57           IF(MSTJ(93).EQ.2) ULMASS_HIJING=MAX(0.,ULMASS_HIJING-PARF(122)
  58      $         -2.*PARF(112)/3.)
  59         ELSE
  60           IF(KFLS.EQ.2.AND.KFLA.EQ.KFLB) THEN
  61             PMSPL=1./(PMA*PMB)-2./(PMA*PMC)-2./(PMB*PMC)
  62           ELSEIF(KFLS.EQ.2.AND.KFLB.GE.KFLC) THEN
  63             PMSPL=-2./(PMA*PMB)-2./(PMA*PMC)+1./(PMB*PMC)
  64           ELSEIF(KFLS.EQ.2) THEN
  65             PMSPL=-3./(PMB*PMC)
  66           ELSE
  67             PMSPL=1./(PMA*PMB)+1./(PMA*PMC)+1./(PMB*PMC)
  68           ENDIF
  69           ULMASS_HIJING=PARF(112)+PMA+PMB+PMC+PARF(114)*PARF(101)**2
  70      $         *PMSPL
  71         ENDIF
  72       ENDIF
  73
  74 C...Optional mass broadening according to truncated Breit-Wigner
  75 C...(either in m or in m^2).
  76       IF(MSTJ(24).GE.1.AND.PMAS(KC,2).GT.1E-4) THEN
  77         IF(MSTJ(24).EQ.1.OR.(MSTJ(24).EQ.2.AND.KFA.GT.100)) THEN
  78            ULMASS_HIJING=ULMASS_HIJING+0.5*PMAS(KC,2)*TAN((2.
  79      $          *RLU_HIJING(0)-1.)*ATAN(2.*PMAS(KC,3)/PMAS(KC,2)))
  80         ELSE
  81           PM0=ULMASS_HIJING
  82           PMLOW=ATAN((MAX(0.,PM0-PMAS(KC,3))**2-PM0**2)/
  83      &    (PM0*PMAS(KC,2)))
  84           PMUPP=ATAN((PM0+PMAS(KC,3))**2-PM0**2)/(PM0*PMAS(KC,2))
  85           ULMASS_HIJING=SQRT(MAX(0.,PM0**2+PM0*PMAS(KC,2)*TAN(PMLOW+
  86      &    (PMUPP-PMLOW)*RLU_HIJING(0))))
  87         ENDIF
  88       ENDIF
  89       MSTJ(93)=0
  90
  91       RETURN
  92       END