Moved GetGoodParticles to alimacros

[u/mrichter/AliRoot.git] / PYTHIA / jetset / ulmass.F

 
C********************************************************************* 
 
      FUNCTION ULMASS(KF) 
 
C...Purpose: to give the mass of a particle/parton. 
      COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200) 
      COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4) 
      SAVE /LUDAT1/,/LUDAT2/ 
 
C...Reset variables. Compressed code. 
      ULMASS=0. 
      KFA=IABS(KF) 
      KC=LUCOMP(KF) 
      IF(KC.EQ.0) RETURN 
      PARF(106)=PMAS(6,1) 
      PARF(107)=PMAS(7,1) 
      PARF(108)=PMAS(8,1) 
 
C...Guarantee use of constituent masses for internal checks. 
      IF((MSTJ(93).EQ.1.OR.MSTJ(93).EQ.2).AND.KFA.LE.10) THEN 
        ULMASS=PARF(100+KFA) 
        IF(MSTJ(93).EQ.2) ULMASS=MAX(0.,ULMASS-PARF(121)) 
 
C...Masses that can be read directly off table. 
      ELSEIF(KFA.LE.100.OR.KC.LE.80.OR.KC.GT.100) THEN 
        ULMASS=PMAS(KC,1) 
 
C...Find constituent partons and their masses. 
      ELSE 
        KFLA=MOD(KFA/1000,10) 
        KFLB=MOD(KFA/100,10) 
        KFLC=MOD(KFA/10,10) 
        KFLS=MOD(KFA,10) 
        KFLR=MOD(KFA/10000,10) 
        PMA=PARF(100+KFLA) 
        PMB=PARF(100+KFLB) 
        PMC=PARF(100+KFLC) 
 
C...Construct masses for various meson, diquark and baryon cases. 
        IF(KFLA.EQ.0.AND.KFLR.EQ.0.AND.KFLS.LE.3) THEN 
          IF(KFLS.EQ.1) PMSPL=-3./(PMB*PMC) 
          IF(KFLS.GE.3) PMSPL=1./(PMB*PMC) 
          ULMASS=PARF(111)+PMB+PMC+PARF(113)*PARF(101)**2*PMSPL 
        ELSEIF(KFLA.EQ.0) THEN 
          KMUL=2 
          IF(KFLS.EQ.1) KMUL=3 
          IF(KFLR.EQ.2) KMUL=4 
          IF(KFLS.EQ.5) KMUL=5 
          ULMASS=PARF(113+KMUL)+PMB+PMC 
        ELSEIF(KFLC.EQ.0) THEN 
          IF(KFLS.EQ.1) PMSPL=-3./(PMA*PMB) 
          IF(KFLS.EQ.3) PMSPL=1./(PMA*PMB) 
          ULMASS=2.*PARF(112)/3.+PMA+PMB+PARF(114)*PARF(101)**2*PMSPL 
          IF(MSTJ(93).EQ.1) ULMASS=PMA+PMB 
          IF(MSTJ(93).EQ.2) ULMASS=MAX(0.,ULMASS-PARF(122)- 
     &    2.*PARF(112)/3.) 
        ELSE 
          IF(KFLS.EQ.2.AND.KFLA.EQ.KFLB) THEN 
            PMSPL=1./(PMA*PMB)-2./(PMA*PMC)-2./(PMB*PMC) 
          ELSEIF(KFLS.EQ.2.AND.KFLB.GE.KFLC) THEN 
            PMSPL=-2./(PMA*PMB)-2./(PMA*PMC)+1./(PMB*PMC) 
          ELSEIF(KFLS.EQ.2) THEN 
            PMSPL=-3./(PMB*PMC) 
          ELSE 
            PMSPL=1./(PMA*PMB)+1./(PMA*PMC)+1./(PMB*PMC) 
          ENDIF 
          ULMASS=PARF(112)+PMA+PMB+PMC+PARF(114)*PARF(101)**2*PMSPL 
        ENDIF 
      ENDIF 
 
C...Optional mass broadening according to truncated Breit-Wigner 
C...(either in m or in m^2). 
      IF(MSTJ(24).GE.1.AND.PMAS(KC,2).GT.1E-4) THEN 
        IF(MSTJ(24).EQ.1.OR.(MSTJ(24).EQ.2.AND.KFA.GT.100)) THEN 
          ULMASS=ULMASS+0.5*PMAS(KC,2)*TAN((2.*RLU(0)-1.)* 
     &    ATAN(2.*PMAS(KC,3)/PMAS(KC,2))) 
        ELSE 
          PM0=ULMASS 
          PMLOW=ATAN((MAX(0.,PM0-PMAS(KC,3))**2-PM0**2)/ 
     &    (PM0*PMAS(KC,2))) 
          PMUPP=ATAN(((PM0+PMAS(KC,3))**2-PM0**2)/(PM0*PMAS(KC,2))) 
          ULMASS=SQRT(MAX(0.,PM0**2+PM0*PMAS(KC,2)*TAN(PMLOW+ 
     &    (PMUPP-PMLOW)*RLU(0)))) 
        ENDIF 
      ENDIF 
      MSTJ(93)=0 
 
      RETURN 
      END