[u/mrichter/AliRoot.git] / HIJING / hipyset1_35 / lux3jt_hijing.F

* $Id$
    
C*********************************************************************  
    
      SUBROUTINE LUX3JT_HIJING(NJET,CUT,KFL,ECM,X1,X2) 
    
C...Purpose: to select the kinematical variables of three-jet events.   
#include "ludat1_hijing.inc"
      DIMENSION ZHUP(5,12)  
    
C...Coefficients of Zhu second order parametrization.   
      DATA ((ZHUP(IC1,IC2),IC2=1,12),IC1=1,5)/  
     &    18.29,    89.56,    4.541,   -52.09,   -109.8,    24.90,  
     &    11.63,    3.683,    17.50, 0.002440,   -1.362,  -0.3537,  
     &    11.42,    6.299,   -22.55,   -8.915,    59.25,   -5.855,  
     &   -32.85,   -1.054,   -16.90, 0.006489,  -0.8156,  0.01095,  
     &    7.847,   -3.964,   -35.83,    1.178,    29.39,   0.2806,  
     &    47.82,   -12.36,   -56.72,  0.04054,  -0.4365,   0.6062,  
     &    5.441,   -56.89,   -50.27,    15.13,    114.3,   -18.19,  
     &    97.05,   -1.890,   -139.9,  0.08153,  -0.4984,   0.9439,  
     &   -17.65,    51.44,   -58.32,    70.95,   -255.7,   -78.99,  
     &    476.9,    29.65,   -239.3,   0.4745,   -1.174,    6.081/  
    
C...Dilogarithm of x for x<0.5 (x>0.5 obtained by analytic trick).  
      DILOG(X)=X+X**2/4.+X**3/9.+X**4/16.+X**5/25.+X**6/36.+X**7/49.    
    
C...Event type. Mass effect factors and other common constants. 
      MSTJ(120)=2   
      MSTJ(121)=0   
      PMQ=ULMASS_HIJING(KFL)   
      QME=(2.*PMQ/ECM)**2   
      IF(MSTJ(109).NE.1) THEN   
        CUTL=LOG(CUT)   
        CUTD=LOG(1./CUT-2.) 
        IF(MSTJ(109).EQ.0) THEN 
          CF=4./3.  
          CN=3. 
          TR=2. 
          WTMX=MIN(20.,37.-6.*CUTD) 
          IF(MSTJ(110).EQ.2) WTMX=2.*(7.5+80.*CUT)  
        ELSE    
          CF=1. 
          CN=0. 
          TR=12.    
          WTMX=0.   
        ENDIF   
    
C...Alpha_strong and effects of optimized Q^2 scale. Maximum weight.    
        ALS2PI=PARU(118)/PARU(2)    
        WTOPT=0.    
        IF(MSTJ(111).EQ.1) WTOPT=(33.-2.*MSTU(112))/6.*LOG(PARJ(169))*  
     &  ALS2PI  
        WTMAX=MAX(0.,1.+WTOPT+ALS2PI*WTMX)  
    
C...Choose three-jet events in allowed region.  
  100   NJET=3  
  110   Y13L=CUTL+CUTD*RLU_HIJING(0)   
        Y23L=CUTL+CUTD*RLU_HIJING(0)   
        Y13=EXP(Y13L)   
        Y23=EXP(Y23L)   
        Y12=1.-Y13-Y23  
        IF(Y12.LE.CUT) GOTO 110 
        IF(Y13**2+Y23**2+2.*Y12.LE.2.*RLU_HIJING(0)) GOTO 110  
    
C...Second order corrections.   
        IF(MSTJ(101).EQ.2.AND.MSTJ(110).LE.1) THEN  
          Y12L=LOG(Y12) 
          Y13M=LOG(1.-Y13)  
          Y23M=LOG(1.-Y23)  
          Y12M=LOG(1.-Y12)  
          IF(Y13.LE.0.5) Y13I=DILOG(Y13)    
          IF(Y13.GE.0.5) Y13I=1.644934-Y13L*Y13M-DILOG(1.-Y13)  
          IF(Y23.LE.0.5) Y23I=DILOG(Y23)    
          IF(Y23.GE.0.5) Y23I=1.644934-Y23L*Y23M-DILOG(1.-Y23)  
          IF(Y12.LE.0.5) Y12I=DILOG(Y12)    
          IF(Y12.GE.0.5) Y12I=1.644934-Y12L*Y12M-DILOG(1.-Y12)  
          WT1=(Y13**2+Y23**2+2.*Y12)/(Y13*Y23)  
          WT2=CF*(-2.*(CUTL-Y12L)**2-3.*CUTL-1.+3.289868+   
     &    2.*(2.*CUTL-Y12L)*CUT/Y12)+   
     &    CN*((CUTL-Y12L)**2-(CUTL-Y13L)**2-(CUTL-Y23L)**2-11.*CUTL/6.+ 
     &    67./18.+1.644934-(2.*CUTL-Y12L)*CUT/Y12+(2.*CUTL-Y13L)*   
     &    CUT/Y13+(2.*CUTL-Y23L)*CUT/Y23)+  
     &    TR*(2.*CUTL/3.-10./9.)+   
     &    CF*(Y12/(Y12+Y13)+Y12/(Y12+Y23)+(Y12+Y23)/Y13+(Y12+Y13)/Y23+  
     &    Y13L*(4.*Y12**2+2.*Y12*Y13+4.*Y12*Y23+Y13*Y23)/(Y12+Y23)**2+  
     &    Y23L*(4.*Y12**2+2.*Y12*Y23+4.*Y12*Y13+Y13*Y23)/(Y12+Y13)**2)/ 
     &    WT1+  
     &    CN*(Y13L*Y13/(Y12+Y23)+Y23L*Y23/(Y12+Y13))/WT1+   
     &    (CN-2.*CF)*((Y12**2+(Y12+Y13)**2)*(Y12L*Y23L-Y12L*Y12M-Y23L*  
     &    Y23M+1.644934-Y12I-Y23I)/(Y13*Y23)+(Y12**2+(Y12+Y23)**2)* 
     &    (Y12L*Y13L-Y12L*Y12M-Y13L*Y13M+1.644934-Y12I-Y13I)/   
     &    (Y13*Y23)+(Y13**2+Y23**2)/(Y13*Y23*(Y13+Y23))-    
     &    2.*Y12L*Y12**2/(Y13+Y23)**2-4.*Y12L*Y12/(Y13+Y23))/WT1-   
     &    CN*(Y13L*Y23L-Y13L*Y13M-Y23L*Y23M+1.644934-Y13I-Y23I) 
          IF(1.+WTOPT+ALS2PI*WT2.LE.0.) MSTJ(121)=1 
          IF(1.+WTOPT+ALS2PI*WT2.LE.WTMAX*RLU_HIJING(0)) GOTO 110  
          PARJ(156)=(WTOPT+ALS2PI*WT2)/(1.+WTOPT+ALS2PI*WT2)    
    
        ELSEIF(MSTJ(101).EQ.2.AND.MSTJ(110).EQ.2) THEN  
C...Second order corrections; Zhu parametrization of ERT.   
          ZX=(Y23-Y13)**2   
          ZY=1.-Y12 
          IZA=0 
          DO 120 IY=1,5 
  120     IF(ABS(CUT-0.01*IY).LT.0.0001) IZA=IY 
          IF(IZA.NE.0) THEN 
            IZ=IZA  
            WT2=ZHUP(IZ,1)+ZHUP(IZ,2)*ZX+ZHUP(IZ,3)*ZX**2+(ZHUP(IZ,4)+  
     &      ZHUP(IZ,5)*ZX)*ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)*ZX)*ZY**2+ 
     &      (ZHUP(IZ,8)+ZHUP(IZ,9)*ZX)*ZY**3+ZHUP(IZ,10)/(ZX-ZY**2)+    
     &      ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY  
          ELSE  
            IZ=100.*CUT 
            WTL=ZHUP(IZ,1)+ZHUP(IZ,2)*ZX+ZHUP(IZ,3)*ZX**2+(ZHUP(IZ,4)+  
     &      ZHUP(IZ,5)*ZX)*ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)*ZX)*ZY**2+ 
     &      (ZHUP(IZ,8)+ZHUP(IZ,9)*ZX)*ZY**3+ZHUP(IZ,10)/(ZX-ZY**2)+    
     &      ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY  
            IZ=IZ+1 
            WTU=ZHUP(IZ,1)+ZHUP(IZ,2)*ZX+ZHUP(IZ,3)*ZX**2+(ZHUP(IZ,4)+  
     &      ZHUP(IZ,5)*ZX)*ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)*ZX)*ZY**2+ 
     &      (ZHUP(IZ,8)+ZHUP(IZ,9)*ZX)*ZY**3+ZHUP(IZ,10)/(ZX-ZY**2)+    
     &      ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY  
            WT2=WTL+(WTU-WTL)*(100.*CUT+1.-IZ)  
          ENDIF 
          IF(1.+WTOPT+2.*ALS2PI*WT2.LE.0.) MSTJ(121)=1  
          IF(1.+WTOPT+2.*ALS2PI*WT2.LE.WTMAX*RLU_HIJING(0)) GOTO 110   
          PARJ(156)=(WTOPT+2.*ALS2PI*WT2)/(1.+WTOPT+2.*ALS2PI*WT2)  
        ENDIF   
    
C...Impose mass cuts (gives two jets). For fixed jet number new try.    
        X1=1.-Y23   
        X2=1.-Y13   
        X3=1.-Y12   
        IF(4.*Y23*Y13*Y12/X3**2.LE.QME) NJET=2  
        IF(MOD(MSTJ(103),4).GE.2.AND.IABS(MSTJ(101)).LE.1.AND.QME*X3+   
     &  0.5*QME**2+(0.5*QME+0.25*QME**2)*((1.-X2)/(1.-X1)+  
     &  (1.-X1)/(1.-X2)).GT.(X1**2+X2**2)*RLU_HIJING(0)) NJET=2    
        IF(MSTJ(101).EQ.-1.AND.NJET.EQ.2) GOTO 100  
    
C...Scalar gluon model (first order only, no mass effects). 
      ELSE  
  130   NJET=3  
  140   Y12=SQRT(4.*CUT**2+RLU_HIJING(0)*((1.-CUT)**2-4.*CUT**2))  
        IF(LOG((Y12-CUT)/CUT).LE.RLU_HIJING(0)*LOG((1.-2.*CUT)/CUT))
     $       GOTO 140  
        YD=SIGN(2.*CUT*((Y12-CUT)/CUT)**RLU_HIJING(0)-Y12,RLU_HIJING(0)
     $       -0.5)  
        X1=1.-0.5*(Y12+YD)  
        X2=1.-0.5*(Y12-YD)  
        IF(4.*(1.-X1)*(1.-X2)*Y12/(1.-Y12)**2.LE.QME) NJET=2    
        IF(MSTJ(101).EQ.-1.AND.NJET.EQ.2) GOTO 130  
      ENDIF 
    
      RETURN    
      END
Commit	Line	Data
e74335a4	1	* $Id$
	2
	3	C*********************************************************************
	4
	5	SUBROUTINE LUX3JT_HIJING(NJET,CUT,KFL,ECM,X1,X2)
	6
	7	C...Purpose: to select the kinematical variables of three-jet events.
	8	#include "ludat1_hijing.inc"
	9	DIMENSION ZHUP(5,12)
	10
	11	C...Coefficients of Zhu second order parametrization.
	12	DATA ((ZHUP(IC1,IC2),IC2=1,12),IC1=1,5)/
	13	& 18.29, 89.56, 4.541, -52.09, -109.8, 24.90,
	14	& 11.63, 3.683, 17.50, 0.002440, -1.362, -0.3537,
	15	& 11.42, 6.299, -22.55, -8.915, 59.25, -5.855,
	16	& -32.85, -1.054, -16.90, 0.006489, -0.8156, 0.01095,
	17	& 7.847, -3.964, -35.83, 1.178, 29.39, 0.2806,
	18	& 47.82, -12.36, -56.72, 0.04054, -0.4365, 0.6062,
	19	& 5.441, -56.89, -50.27, 15.13, 114.3, -18.19,
	20	& 97.05, -1.890, -139.9, 0.08153, -0.4984, 0.9439,
	21	& -17.65, 51.44, -58.32, 70.95, -255.7, -78.99,
	22	& 476.9, 29.65, -239.3, 0.4745, -1.174, 6.081/
	23
	24	C...Dilogarithm of x for x<0.5 (x>0.5 obtained by analytic trick).
	25	DILOG(X)=X+X2/4.+X3/9.+X4/16.+X5/25.+X6/36.+X7/49.
	26
	27	C...Event type. Mass effect factors and other common constants.
	28	MSTJ(120)=2
	29	MSTJ(121)=0
	30	PMQ=ULMASS_HIJING(KFL)
	31	QME=(2.PMQ/ECM)*2
	32	IF(MSTJ(109).NE.1) THEN
	33	CUTL=LOG(CUT)
	34	CUTD=LOG(1./CUT-2.)
	35	IF(MSTJ(109).EQ.0) THEN
	36	CF=4./3.
	37	CN=3.
	38	TR=2.
	39	WTMX=MIN(20.,37.-6.*CUTD)
	40	IF(MSTJ(110).EQ.2) WTMX=2.(7.5+80.CUT)
	41	ELSE
	42	CF=1.
	43	CN=0.
	44	TR=12.
	45	WTMX=0.
	46	ENDIF
	47
	48	C...Alpha_strong and effects of optimized Q^2 scale. Maximum weight.
	49	ALS2PI=PARU(118)/PARU(2)
	50	WTOPT=0.
	51	IF(MSTJ(111).EQ.1) WTOPT=(33.-2.MSTU(112))/6.LOG(PARJ(169))*
	52	& ALS2PI
	53	WTMAX=MAX(0.,1.+WTOPT+ALS2PI*WTMX)
	54
	55	C...Choose three-jet events in allowed region.
	56	100 NJET=3
	57	110 Y13L=CUTL+CUTD*RLU_HIJING(0)
	58	Y23L=CUTL+CUTD*RLU_HIJING(0)
	59	Y13=EXP(Y13L)
	60	Y23=EXP(Y23L)
	61	Y12=1.-Y13-Y23
	62	IF(Y12.LE.CUT) GOTO 110
	63	IF(Y132+Y232+2.Y12.LE.2.RLU_HIJING(0)) GOTO 110
	64
65	C...Second order corrections.
66	IF(MSTJ(101).EQ.2.AND.MSTJ(110).LE.1) THEN
67	Y12L=LOG(Y12)
68	Y13M=LOG(1.-Y13)
69	Y23M=LOG(1.-Y23)
70	Y12M=LOG(1.-Y12)
71	IF(Y13.LE.0.5) Y13I=DILOG(Y13)
72	IF(Y13.GE.0.5) Y13I=1.644934-Y13L*Y13M-DILOG(1.-Y13)
73	IF(Y23.LE.0.5) Y23I=DILOG(Y23)
74	IF(Y23.GE.0.5) Y23I=1.644934-Y23L*Y23M-DILOG(1.-Y23)
75	IF(Y12.LE.0.5) Y12I=DILOG(Y12)
76	IF(Y12.GE.0.5) Y12I=1.644934-Y12L*Y12M-DILOG(1.-Y12)
77	WT1=(Y132+Y232+2.Y12)/(Y13Y23)
78	WT2=CF(-2.(CUTL-Y12L)*2-3.CUTL-1.+3.289868+
79	& 2.(2.CUTL-Y12L)*CUT/Y12)+
80	& CN((CUTL-Y12L)2-(CUTL-Y13L)2-(CUTL-Y23L)2-11.CUTL/6.+
81	& 67./18.+1.644934-(2.CUTL-Y12L)CUT/Y12+(2.CUTL-Y13L)
82	& CUT/Y13+(2.CUTL-Y23L)CUT/Y23)+
83	& TR(2.CUTL/3.-10./9.)+
84	& CF*(Y12/(Y12+Y13)+Y12/(Y12+Y23)+(Y12+Y23)/Y13+(Y12+Y13)/Y23+
85	& Y13L(4.Y12*2+2.Y12Y13+4.Y12Y23+Y13Y23)/(Y12+Y23)**2+
86	& Y23L(4.Y12*2+2.Y12Y23+4.Y12Y13+Y13Y23)/(Y12+Y13)**2)/
87	& WT1+
88	& CN(Y13LY13/(Y12+Y23)+Y23L*Y23/(Y12+Y13))/WT1+
89	& (CN-2.CF)((Y122+(Y12+Y13)2)(Y12LY23L-Y12LY12M-Y23L
90	& Y23M+1.644934-Y12I-Y23I)/(Y13Y23)+(Y122+(Y12+Y23)2)
91	& (Y12LY13L-Y12LY12M-Y13L*Y13M+1.644934-Y12I-Y13I)/
92	& (Y13Y23)+(Y132+Y232)/(Y13Y23*(Y13+Y23))-
93	& 2.Y12LY122/(Y13+Y23)2-4.Y12LY12/(Y13+Y23))/WT1-
94	& CN(Y13LY23L-Y13LY13M-Y23LY23M+1.644934-Y13I-Y23I)
95	IF(1.+WTOPT+ALS2PI*WT2.LE.0.) MSTJ(121)=1
96	IF(1.+WTOPT+ALS2PIWT2.LE.WTMAXRLU_HIJING(0)) GOTO 110
97	PARJ(156)=(WTOPT+ALS2PIWT2)/(1.+WTOPT+ALS2PIWT2)
98
99	ELSEIF(MSTJ(101).EQ.2.AND.MSTJ(110).EQ.2) THEN
100	C...Second order corrections; Zhu parametrization of ERT.
101	ZX=(Y23-Y13)**2
102	ZY=1.-Y12
103	IZA=0
104	DO 120 IY=1,5
105	120 IF(ABS(CUT-0.01*IY).LT.0.0001) IZA=IY
106	IF(IZA.NE.0) THEN
107	IZ=IZA
108	WT2=ZHUP(IZ,1)+ZHUP(IZ,2)ZX+ZHUP(IZ,3)ZX**2+(ZHUP(IZ,4)+
109	& ZHUP(IZ,5)ZX)ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)ZX)ZY**2+
110	& (ZHUP(IZ,8)+ZHUP(IZ,9)ZX)ZY3+ZHUP(IZ,10)/(ZX-ZY2)+
111	& ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY
112	ELSE
113	IZ=100.*CUT
114	WTL=ZHUP(IZ,1)+ZHUP(IZ,2)ZX+ZHUP(IZ,3)ZX**2+(ZHUP(IZ,4)+
115	& ZHUP(IZ,5)ZX)ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)ZX)ZY**2+
116	& (ZHUP(IZ,8)+ZHUP(IZ,9)ZX)ZY3+ZHUP(IZ,10)/(ZX-ZY2)+
117	& ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY
118	IZ=IZ+1
119	WTU=ZHUP(IZ,1)+ZHUP(IZ,2)ZX+ZHUP(IZ,3)ZX**2+(ZHUP(IZ,4)+
120	& ZHUP(IZ,5)ZX)ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)ZX)ZY**2+
121	& (ZHUP(IZ,8)+ZHUP(IZ,9)ZX)ZY3+ZHUP(IZ,10)/(ZX-ZY2)+
122	& ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY
123	WT2=WTL+(WTU-WTL)(100.CUT+1.-IZ)
124	ENDIF
125	IF(1.+WTOPT+2.ALS2PIWT2.LE.0.) MSTJ(121)=1
126	IF(1.+WTOPT+2.ALS2PIWT2.LE.WTMAX*RLU_HIJING(0)) GOTO 110
127	PARJ(156)=(WTOPT+2.ALS2PIWT2)/(1.+WTOPT+2.ALS2PIWT2)
128	ENDIF
129
130	C...Impose mass cuts (gives two jets). For fixed jet number new try.
131	X1=1.-Y23
132	X2=1.-Y13
133	X3=1.-Y12
134	IF(4.Y23Y13Y12/X3*2.LE.QME) NJET=2
135	IF(MOD(MSTJ(103),4).GE.2.AND.IABS(MSTJ(101)).LE.1.AND.QME*X3+
136	& 0.5QME2+(0.5QME+0.25QME2)((1.-X2)/(1.-X1)+
137	& (1.-X1)/(1.-X2)).GT.(X12+X22)*RLU_HIJING(0)) NJET=2
138	IF(MSTJ(101).EQ.-1.AND.NJET.EQ.2) GOTO 100
139
140	C...Scalar gluon model (first order only, no mass effects).
141	ELSE
142	130 NJET=3
143	140 Y12=SQRT(4.CUT2+RLU_HIJING(0)((1.-CUT)*2-4.CUT**2))
144	IF(LOG((Y12-CUT)/CUT).LE.RLU_HIJING(0)LOG((1.-2.CUT)/CUT))
145	$ GOTO 140
146	YD=SIGN(2.CUT((Y12-CUT)/CUT)**RLU_HIJING(0)-Y12,RLU_HIJING(0)
147	$ -0.5)
148	X1=1.-0.5*(Y12+YD)
149	X2=1.-0.5*(Y12-YD)
150	IF(4.(1.-X1)(1.-X2)Y12/(1.-Y12)*2.LE.QME) NJET=2
151	IF(MSTJ(101).EQ.-1.AND.NJET.EQ.2) GOTO 130
152	ENDIF
153
154	RETURN
155	END