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pyhiinki.f
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1 
2 C*********************************************************************
3 
4  SUBROUTINE pyhiinki(CHFRAM,CHBEAM,CHTARG,WIN)
5 
6 C...Identifies the two incoming particles and sets up kinematics,
7 C...including rotations and boosts to/from CM frame.
8  common/lujets/n,k(9000,5),p(9000,5),v(9000,5)
9  SAVE /lujets/
10  common/ludat1/mstu(200),paru(200),mstj(200),parj(200)
11  SAVE /ludat1/
12  common/pyhisubs/msel,msub(200),kfin(2,-40:40),ckin(200)
13  SAVE /pyhisubs/
14  common/pyhipars/mstp(200),parp(200),msti(200),pari(200)
15  SAVE /pyhipars/
16  common/pyhiint1/mint(400),vint(400)
17  SAVE /pyhiint1/
18  CHARACTER chfram*8,chbeam*8,chtarg*8,chcom(3)*8,chalp(2)*26,
19  &chidnt(3)*8,chtemp*8,chcde(18)*8,chinit*76
20  dimension len(3),kcde(18)
21  DATA chalp/'abcdefghijklmnopqrstuvwxyz',
22  &'ABCDEFGHIJKLMNOPQRSTUVWXYZ'/
23  DATA chcde/'e- ','e+ ','nue ','nue~ ',
24  &'mu- ','mu+ ','numu ','numu~ ','tau- ',
25  &'tau+ ','nutau ','nutau~ ','pi+ ','pi- ',
26  &'n ','n~ ','p ','p~ '/
27  DATA kcde/11,-11,12,-12,13,-13,14,-14,15,-15,16,-16,
28  &211,-211,2112,-2112,2212,-2212/
29 
30 C...Convert character variables to lowercase and find their length.
31  chcom(1)=chfram
32  chcom(2)=chbeam
33  chcom(3)=chtarg
34  DO 120 i=1,3
35  len(i)=8
36  DO 100 ll=8,1,-1
37  IF(len(i).EQ.ll.AND.chcom(i)(ll:ll).EQ.' ') len(i)=ll-1
38  DO 100 la=1,26
39  100 IF(chcom(i)(ll:ll).EQ.chalp(2)(la:la)) chcom(i)(ll:ll)=
40  &chalp(1)(la:la)
41  chidnt(i)=chcom(i)
42  DO 110 ll=1,6
43  IF(chidnt(i)(ll:ll+2).EQ.'bar') THEN
44  chtemp=chidnt(i)
45  chidnt(i)=chtemp(1:ll-1)//'~'//chtemp(ll+3:8)//' '
46  ENDIF
47  110 CONTINUE
48  DO 120 ll=1,8
49  IF(chidnt(i)(ll:ll).EQ.'_') THEN
50  chtemp=chidnt(i)
51  chidnt(i)=chtemp(1:ll-1)//chtemp(ll+1:8)//' '
52  ENDIF
53  120 CONTINUE
54 
55 C...Set initial state. Error for unknown codes. Reset variables.
56  n=2
57  DO 140 i=1,2
58  k(i,2)=0
59  DO 130 j=1,18
60  130 IF(chidnt(i+1).EQ.chcde(j)) k(i,2)=kcde(j)
61  p(i,5)=ulmass(k(i,2))
62  mint(40+i)=1
63  IF(iabs(k(i,2)).GT.100) mint(40+i)=2
64  DO 140 j=1,5
65  140 v(i,j)=0.
66  IF(k(1,2).EQ.0) WRITE(mstu(11),1000) chbeam(1:len(2))
67  IF(k(2,2).EQ.0) WRITE(mstu(11),1100) chtarg(1:len(3))
68  IF(k(1,2).EQ.0.OR.k(2,2).EQ.0) stop
69  DO 150 j=6,10
70  150 vint(j)=0.
71  chinit=' '
72 
73 C...Set up kinematics for events defined in CM frame.
74  IF(chcom(1)(1:2).EQ.'cm') THEN
75  IF(chcom(2)(1:1).NE.'e') THEN
76  loffs=(34-(len(2)+len(3)))/2
77  chinit(loffs+1:76)='PYTHIA will be initialized for a '//
78  & chcom(2)(1:len(2))//'-'//chcom(3)(1:len(3))//' collider'//' '
79  ELSE
80  loffs=(33-(len(2)+len(3)))/2
81  chinit(loffs+1:76)='PYTHIA will be initialized for an '//
82  & chcom(2)(1:len(2))//'-'//chcom(3)(1:len(3))//' collider'//' '
83  ENDIF
84 C WRITE(MSTU(11),1200) CHINIT
85 C WRITE(MSTU(11),1300) WIN
86  s=win**2
87  p(1,1)=0.
88  p(1,2)=0.
89  p(2,1)=0.
90  p(2,2)=0.
91  p(1,3)=sqrt(((s-p(1,5)**2-p(2,5)**2)**2-(2.*p(1,5)*p(2,5))**2)/
92  & (4.*s))
93  p(2,3)=-p(1,3)
94  p(1,4)=sqrt(p(1,3)**2+p(1,5)**2)
95  p(2,4)=sqrt(p(2,3)**2+p(2,5)**2)
96 
97 C...Set up kinematics for fixed target events.
98  ELSEIF(chcom(1)(1:3).EQ.'fix') THEN
99  loffs=(29-(len(2)+len(3)))/2
100  chinit(loffs+1:76)='PYTHIA will be initialized for '//
101  & chcom(2)(1:len(2))//' on '//chcom(3)(1:len(3))//
102  & ' fixed target'//' '
103 C WRITE(MSTU(11),1200) CHINIT
104 C WRITE(MSTU(11),1400) WIN
105  p(1,1)=0.
106  p(1,2)=0.
107  p(2,1)=0.
108  p(2,2)=0.
109  p(1,3)=win
110  p(1,4)=sqrt(p(1,3)**2+p(1,5)**2)
111  p(2,3)=0.
112  p(2,4)=p(2,5)
113  s=p(1,5)**2+p(2,5)**2+2.*p(2,4)*p(1,4)
114  vint(10)=p(1,3)/(p(1,4)+p(2,4))
115  CALL lurobo(0.,0.,0.,0.,-vint(10))
116 C WRITE(MSTU(11),1500) SQRT(S)
117 
118 C...Set up kinematics for events in user-defined frame.
119  ELSEIF(chcom(1)(1:3).EQ.'use') THEN
120  loffs=(13-(len(1)+len(2)))/2
121  chinit(loffs+1:76)='PYTHIA will be initialized for '//
122  & chcom(2)(1:len(2))//' on '//chcom(3)(1:len(3))//
123  & 'user-specified configuration'//' '
124 C WRITE(MSTU(11),1200) CHINIT
125 C WRITE(MSTU(11),1600)
126 C WRITE(MSTU(11),1700) CHCOM(2),P(1,1),P(1,2),P(1,3)
127 C WRITE(MSTU(11),1700) CHCOM(3),P(2,1),P(2,2),P(2,3)
128  p(1,4)=sqrt(p(1,1)**2+p(1,2)**2+p(1,3)**2+p(1,5)**2)
129  p(2,4)=sqrt(p(2,1)**2+p(2,2)**2+p(2,3)**2+p(2,5)**2)
130  DO 160 j=1,3
131  160 vint(7+j)=(dble(p(1,j))+dble(p(2,j)))/dble(p(1,4)+p(2,4))
132  CALL lurobo(0.,0.,-vint(8),-vint(9),-vint(10))
133  vint(7)=ulangl(p(1,1),p(1,2))
134  CALL lurobo(0.,-vint(7),0.,0.,0.)
135  vint(6)=ulangl(p(1,3),p(1,1))
136  CALL lurobo(-vint(6),0.,0.,0.,0.)
137  s=p(1,5)**2+p(2,5)**2+2.*(p(1,4)*p(2,4)-p(1,3)*p(2,3))
138 C WRITE(MSTU(11),1500) SQRT(S)
139 
140 C...Unknown frame. Error for too low CM energy.
141  ELSE
142  WRITE(mstu(11),1800) chfram(1:len(1))
143  stop
144  ENDIF
145  IF(s.LT.parp(2)**2) THEN
146  WRITE(mstu(11),1900) sqrt(s)
147  stop
148  ENDIF
149 
150 C...Save information on incoming particles.
151  mint(11)=k(1,2)
152  mint(12)=k(2,2)
153  mint(43)=2*mint(41)+mint(42)-2
154  vint(1)=sqrt(s)
155  vint(2)=s
156  vint(3)=p(1,5)
157  vint(4)=p(2,5)
158  vint(5)=p(1,3)
159 
160 C...Store constants to be used in generation.
161  IF(mstp(82).LE.1) vint(149)=4.*parp(81)**2/s
162  IF(mstp(82).GE.2) vint(149)=4.*parp(82)**2/s
163 
164 C...Formats for initialization and error information.
165  1000 FORMAT(1x,'Error: unrecognized beam particle ''',a,'''.'/
166  &1x,'Execution stopped!')
167  1100 FORMAT(1x,'Error: unrecognized target particle ''',a,'''.'/
168  &1x,'Execution stopped!')
169  1200 FORMAT(/1x,78('=')/1x,'I',76x,'I'/1x,'I',a76,'I')
170  1300 FORMAT(1x,'I',18x,'at',1x,f10.3,1x,'GeV center-of-mass energy',
171  &19x,'I'/1x,'I',76x,'I'/1x,78('='))
172  1400 FORMAT(1x,'I',22x,'at',1x,f10.3,1x,'GeV/c lab-momentum',22x,'I')
173  1500 FORMAT(1x,'I',76x,'I'/1x,'I',11x,'corresponding to',1x,f10.3,1x,
174  &'GeV center-of-mass energy',12x,'I'/1x,'I',76x,'I'/1x,78('='))
175  1600 FORMAT(1x,'I',76x,'I'/1x,'I',24x,'px (GeV/c)',3x,'py (GeV/c)',3x,
176  &'pz (GeV/c)',16x,'I')
177  1700 FORMAT(1x,'I',15x,a8,3(2x,f10.3,1x),15x,'I')
178  1800 FORMAT(1x,'Error: unrecognized coordinate frame ''',a,'''.'/
179  &1x,'Execution stopped!')
180  1900 FORMAT(1x,'Error: too low CM energy,',f8.3,' GeV for event ',
181  &'generation.'/1x,'Execution stopped!')
182 
183  RETURN
184  END