1 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
3 C AUXILIARY ROUTINES FOR Q-PYTHIA version 1.0.
7 C AUTHORS: N. Armesto, L. Cunqueiro and C. A. Salgado
8 C Departamento de Fisica de Particulas and IGFAE
9 C Universidade de Santiago de Compostela
10 C 15706 Santiago de Compostela, Spain
12 C EMAILS: nestor@fpaxp1.usc.es, leticia@fpaxp1.usc.es,
13 C Carlos.Salgado@cern.ch
15 C CONTENT: auxiliary files for modified PYSHOW, fixed to PYTHIA-6.4.18.
16 C NOT to be modified by user.
18 C WHEN USING Q-PYTHIA, PLEASE QUOTE:
20 C 1) N. Armesto, G. Corcella, L. Cunqueiro and C. A. Salgado,
22 C 2) T. Sjostrand, S. Mrenna and P. Skands,
23 C ``PYTHIA 6.4 physics and manual,''
24 C JHEP 0605 (2006) 026 [arXiv:hep-ph/0603175].
26 C DISCLAIMER: this program comes without any guarantees. Beware of
27 C errors and use common sense when interpreting results.
28 C Any modifications are done under exclusive
29 C maker's resposibility.
31 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
33 c VERSION WITH THE LARGE X BEHAVIOR OF THE MEDIUM PART INTRODUCED
34 C BY MULTIPLYING BY THE NUMERATOR OF THE COLLINEAR PART OF THE
35 C VACUUM SPLITTING FUNCTION
38 c to integrate, adding vaccum plus medium q -> qg
39 implicit double precision (a-h,o-z)
42 auxq=splitgq(z)+splitmedq1(z)
43 if (auxq .gt. 0.d0) then
52 c to integrate, adding vaccum plus medium g -> gg, and g -> qqbar
53 implicit double precision (a-h,o-z)
56 c argument of running coupling is taken as kt of emission
57 auxg=splitgg(z)+splitmedg1(z)
58 if (auxg .gt. 0.d0) then
59 splitg1=(auxg+splitqqbar(z))
67 c to integrate, adding vaccum plus medium q -> qg
68 implicit double precision (a-h,o-z)
70 auxq=splitgq(z)+splitmedq2(z)
71 if (auxq .gt. 0.d0) then
76 if(splitmedq2(z).eq.0.) then
82 c to integrate, adding vaccum plus medium g -> gg, and g -> qqbar
83 implicit double precision (a-h,o-z)
84 auxg=splitgg(z)+splitmedg2(z)
90 if(splitmedg2(z).eq.0.) then
96 c q -> qg splitting kernel at 1 loop for the vacuum
97 implicit double precision (a-h,o-z)
99 splitgq=(0.5d0*(xnc-1.d0/xnc))*(1.d0+z*z)/(1.d0-z)
104 c g -> gg splitting kernel at 1 loop for the vacuum
105 implicit double precision (a-h,o-z)
109 splitgg=xnc*auxz2*auxz2/auxz
113 function splitqqbar(z)
114 c g -> qqbar splitting kernel at 1 loop
115 implicit double precision (a-h,o-z)
118 splitqqbar=0.5d0*xnf*(z*z+auxz*auxz)
122 function splitmedg1(z)
123 c g -> gg splitting kernel at 1 loop for the medium
124 implicit double precision (a-h,o-z)
125 common/qpc1/eee,qhatl,omegac
129 if (qhatl .le. 0.d0 .or. omegac .le. 0.d0) then
132 c symmetrized by hand with respect to 1/2
133 if (z .ge. 0.5d0) then
142 xkappa2=auxz2*t/qhatl
143 fff=genspec(ome,xkappa2)
144 cc 1/2 to avoid double counting
145 c splitmedg=0.5d0*xnc*2.d0*pi*zz*t*fff/qhatl
146 c we multiply by max(z,1-z) to introduce the large z behavior from the
147 c numerator in the vacuum
149 c 1/2 to avoid double counting
150 splitmedg1=0.5*flx*xnc*2.d0*pi*zz*t*fff/qhatl
155 function splitmedq1(z)
156 c q -> qg splitting kernel at 1 loop for the medium
157 implicit double precision (a-h,o-z)
158 common/qpc1/eee,qhatl,omegac
162 if (qhatl .le. 0.d0 .or. omegac .le. 0.d0) then
169 xkappa2=auxz2*t/qhatl
170 fff=genspec(ome,xkappa2)
171 c splitmedq=(0.5d0*(xnc-1.d0/xnc))*2.d0*pi*z*t*fff/qhatl
172 c we multiply by 1+z**2 to introduce the large z behavior from the
173 c numerator in the vacuum
175 splitmedq1=flx*(0.5d0*(xnc-1.d0/xnc))*2.d0*pi*z*t*fff/qhatl
180 function splitmedg2(z)
181 c g -> gg splitting kernel at 1 loop for the medium
182 implicit double precision (a-h,o-z)
183 common/qpc1/eee,qhatl,omegac
187 if (qhatl .le. 0.d0 .or. omegac .le. 0.d0) then
190 c symmetrized by hand with respect to 1/2
191 if (z .ge. 0.5d0) then
200 xkappa2=auxz2*t/qhatl
201 fff=genspec(ome,xkappa2)
202 cc 1/2 to avoid double counting
203 c splitmedg=0.5d0*xnc*2.d0*pi*zz*t*fff/qhatl
204 c we multiply by max(z,1-z) to introduce the large z behavior from the
205 c numerator in the vacuum
207 c 1/2 to avoid double counting
208 splitmedg2=0.5*flx*xnc*2.d0*pi*zz*t*fff/qhatl
213 function splitmedq2(z)
214 c q -> qg splitting kernel at 1 loop for the medium
215 implicit double precision (a-h,o-z)
216 common/qpc1/eee,qhatl,omegac
220 if (qhatl .le. 0.d0 .or. omegac .le. 0.d0) then
227 xkappa2=auxz2*t/qhatl
228 fff=genspec(ome,xkappa2)
229 c splitmedq=(0.5d0*(xnc-1.d0/xnc))*2.d0*pi*z*t*fff/qhatl
230 c we multiply by 1+z**2 to introduce the large z behavior from the
231 c numerator in the vacuum
233 splitmedq2=flx*(0.5d0*(xnc-1.d0/xnc))*2.d0*pi*z*t*fff/qhatl
238 function genspec(ome,xk2)
239 C THIS FUNCTION GENERATES (omega/omegac) dI/d(omega/omegac) dkappa2,
240 C omegac=qhat L/2, kappa2=kt2/(qhat L), in the mss approximation for m=0,
241 c using interpolation and extrapolation. It reads file grid-qp.dat.
242 c ome=omega/omegac, xk2=kappa2.
243 C MAXIMUM GRID 101 TIMES 101, MODIFY ARRAY DIMENSIONS IF EXCEEDED.
245 implicit double precision (a-h,o-z)
246 dimension xkap2(101), xlkap2(101), xome(101), xlome(101)
247 dimension xspec(101,101)
248 dimension aux1(101), aux2(101)
249 character*1000 filnam
250 character*1000 chroot
251 save xkap2, xlkap2, xome, xlome, xspec, npkap, npome
253 c WE READ THE GRID ONLY THE FIRST TIME.
254 IF (IFLAG .EQ. 0) THEN
256 call getenvf('ALICE_ROOT',chroot)
257 lnroot= lnblnk(chroot)
258 filnam=chroot(1:lnroot)//'/PYTHIA6/QPYTHIA/qgrid'
259 write(6,*) "Opening file ", filnam
260 open(11,file=filnam, status='old')
266 read(11,*) xkap2(i), xlkap2(i)
269 read(11,*) xome(i), xlome(i)
273 read(11,*) xspec(i,j)
280 c for ome>largest value set to 0,
281 c for xk2< smallest value frozen,
282 c for xk2> largest value 1/kappa4 extrapolation.
283 if (ome .gt. xome(npome)) then
285 elseif (ome .lt. xome(1)) then
286 scal=.05648d0*dexp(1.674d0*ome)*dlog(.136d0/ome)/(ome**.5397d0)
287 scal=0.25d0*9.d0*scal/xspec(1,1)
288 if (xk2 .le. xkap2(1)) then
289 genspec=scal*xspec(1,1)
290 elseif (xk2 .eq. xkap2(npkap)) then
291 genspec=scal*xspec(npkap,1)
292 elseif (xk2 .gt. xkap2(npkap)) then
293 genspec=scal*xspec(npkap,1)*
294 > xkap2(npkap)*xkap2(npkap)/(xk2*xk2)
299 genspec=scal*ddivdif(aux1,xlkap2,npkap,dlog(xk2),4)
303 if (ome .eq. xome(1)) then
307 do 60 i=1, npome-1, 1
308 if (ome .eq. xome(i+1)) then
311 elseif (ome .lt. xome(i+1)) then
319 if (iexact .gt. 0) then
320 if (xk2 .le. xkap2(1)) then
321 genspec=xspec(1,iexact)
322 elseif (xk2 .eq. xkap2(npkap)) then
323 genspec=xspec(npkap,iexact)
324 elseif (xk2 .gt. xkap2(npkap)) then
325 genspec=xspec(npkap,iexact)*
326 > xkap2(npkap)*xkap2(npkap)/(xk2*xk2)
329 aux1(i)=xspec(i,iexact)
331 genspec=ddivdif(aux1,xlkap2,npkap,dlog(xk2),4)
334 if (xk2 .le. xkap2(1)) then
335 genprev=xspec(1,iprev)
336 genpost=xspec(1,ipost)
337 elseif (xk2 .eq. xkap2(npkap)) then
338 genprev=xspec(npkap,iprev)
339 genpost=xspec(npkap,ipost)
340 elseif (xk2 .gt. xkap2(npkap)) then
341 genprev=xspec(npkap,iprev)*
342 > xkap2(npkap)*xkap2(npkap)/(xk2*xk2)
343 genpost=xspec(npkap,ipost)*
344 > xkap2(npkap)*xkap2(npkap)/(xk2*xk2)
347 aux1(i)=xspec(i,iprev)
348 aux2(i)=xspec(i,ipost)
350 genprev=ddivdif(aux1,xlkap2,npkap,dlog(xk2),4)
351 genpost=ddivdif(aux2,xlkap2,npkap,dlog(xk2),4)
354 xl12=xlome(iprev)-xlome(ipost)
356 c2=genprev-c1*xlome(iprev)
357 genspec=c1*dlog(ome)+c2
365 * $Id: divdif.F,v 1.1.1.1 1996/02/15 17:48:36 mclareni Exp $
368 * Revision 1.1.1.1 1996/02/15 17:48:36 mclareni
372 FUNCTION DDIVDIF(F,A,NN,X,MM)
373 c copy of cernlib divdif in double precision.
374 implicit double precision (a-h,o-z)
375 DIMENSION A(NN),F(NN),T(20),D(20)
380 C TABULAR INTERPOLATION USING SYMMETRICALLY PLACED ARGUMENT POINTS.
382 C START. FIND SUBSCRIPT IX OF X IN ARRAY A.
383 IF( (NN.LT.2) .OR. (MM.LT.1) ) GO TO 601
389 IF(A(1).GT.A(N)) GO TO 4
390 C (SEARCH INCREASING ARGUMENTS.)
392 IF(X.GE.A(MID)) GO TO 2
397 3 IF(IY-IX.GT.1) GO TO 1
399 C (SEARCH DECREASING ARGUMENTS.)
401 IF(X.LE.A(MID)) GO TO 5
406 6 IF(IY-IX.GT.1) GO TO 4
408 C COPY REORDERED INTERPOLATION POINTS INTO (T(I),D(I)), SETTING
409 C *EXTRA* TO TRUE IF M+2 POINTS TO BE USED.
417 IF((1.LE.ISUB).AND.(ISUB.LE.N)) GO TO 501
425 11 IF(IP.LT.NPTS) GO TO 8
428 C REPLACE D BY THE LEADING DIAGONAL OF A DIVIDED-DIFFERENCE TABLE, SUP-
429 C PLEMENTED BY AN EXTRA LINE IF *EXTRA* IS TRUE.
431 IF(.NOT.EXTRA) GO TO 12
433 D(M+2)=(D(M+2)-D(M))/(T(M+2)-T(ISUB))
437 D(I)=(D(I)-D(I-1))/(T(I)-T(ISUB))
442 C EVALUATE THE NEWTON INTERPOLATION FORMULA AT X, AVERAGING TWO VALUES
443 C OF LAST DIFFERENCE IF *EXTRA* IS TRUE.
445 IF(EXTRA) SUM=0.5*(SUM+D(M+2))
448 SUM=D(J)+(X-T(J))*SUM
454 601 CALL KERMTR('E105.1',LGFILE,MFLAG,RFLAG)
458 IF(MM.LT.1) WRITE(*,101) MM
459 IF(NN.LT.2) WRITE(*,102) NN
461 IF(MM.LT.1) WRITE(LGFILE,101) MM
462 IF(NN.LT.2) WRITE(LGFILE,102) NN
465 IF(.NOT.RFLAG) CALL ABEND
467 101 FORMAT( 7X, 'FUNCTION DDIVDIF ... M =',I6,' IS LESS THAN 1')
468 102 FORMAT( 7X, 'FUNCTION DDIVDIF ... N =',I6,' IS LESS THAN 2')
471 C COPY OF CERN DGAUSS
473 FUNCTION DGAUSS1(F,A,B,EPS)
474 IMPLICIT DOUBLE PRECISION (A-H,O-Z)
475 DIMENSION W(12),X(12)
476 PARAMETER (Z1 = 1.D0, HF = Z1/2.D0, CST = 5.D0*Z1/1000.D0)
478 1 /0.96028 98564 97536 23168 35608 68569 47D0,
479 2 0.79666 64774 13626 73959 15539 36475 83D0,
480 3 0.52553 24099 16328 98581 77390 49189 25D0,
481 4 0.18343 46424 95649 80493 94761 42360 18D0,
482 5 0.98940 09349 91649 93259 61541 73450 33D0,
483 6 0.94457 50230 73232 57607 79884 15534 61D0,
484 7 0.86563 12023 87831 74388 04678 97712 39D0,
485 8 0.75540 44083 55003 03389 51011 94847 44D0,
486 9 0.61787 62444 02643 74844 66717 64048 79D0,
487 A 0.45801 67776 57227 38634 24194 42983 58D0,
488 B 0.28160 35507 79258 91323 04605 01460 50D0,
489 C 0.95012 50983 76374 40185 31933 54249 58D-1/
492 1 /0.10122 85362 90376 25915 25313 54309 96D0,
493 2 0.22238 10344 53374 47054 43559 94426 24D0,
494 3 0.31370 66458 77887 28733 79622 01986 60D0,
495 4 0.36268 37833 78361 98296 51504 49277 20D0,
496 5 0.27152 45941 17540 94851 78057 24560 18D-1,
497 6 0.62253 52393 86478 92862 84383 69943 78D-1,
498 7 0.95158 51168 24927 84809 92510 76022 46D-1,
499 8 0.12462 89712 55533 87205 24762 82192 02D0,
500 9 0.14959 59888 16576 73208 15017 30547 48D0,
501 A 0.16915 65193 95002 53818 93120 79030 36D0,
502 B 0.18260 34150 44923 58886 67636 67969 22D0,
503 C 0.18945 06104 55068 49628 53967 23208 28D0/
506 IF(B .EQ. A) GO TO 99
516 3 S8=S8+W(I)*(F(C1+U)+F(C1-U))
520 4 S16=S16+W(I)*(F(C1+U)+F(C1-U))
522 IF(ABS(S16-C2*S8) .LE. EPS*(1.D0+ABS(S16))) THEN
524 IF(BB .NE. B) GO TO 1
527 IF(1.D0+CONST*ABS(C2) .NE. 1.D0) GO TO 2
529 WRITE(6,*) 'DGAUSS1: TOO HIGH ACCURACY REQUIRED'
536 FUNCTION SIMDIS(Numb,zmin,nzur,RI)
537 C IT SIMULATES A RANDOM NUMBER ACCORDING TO A DISCRETE DISTRIBUTION GIVEN
538 C BY ARRAY YA AT POINTS XA. THOUGHT FOR PYTHIA (PYR(0)).
539 C N: NUMBER OF POINTS IN THE ARRAYS.
540 C XA: ARRAY OF X-VALUES.
541 C YA: ARRAY OF Y-VALUES.
542 c RI: VALUE OF THE INTEGRAL.
543 IMPLICIT DOUBLE PRECISION (A-H,O-Z)
544 DIMENSION XA(500), YA(500)
545 common/qpc1/eee,qhatl,omegac
546 dlz=(1.d0-2.d0*zmin)/500.d0
549 if(nzur.eq.1) ya(no)=splitq2(xa(no))
550 if(nzur.eq.21) ya(no)=splitg2(xa(no))
551 if(nzur.eq.3) ya(no)=splitqqbar(xa(no))
557 XAUX=XAUX+(XA(I)-XA(I-1))*0.5D0*
560 IF (XAUX .GE. RAL) GOTO 2011
562 IF (I .EQ. Numb) THEN
569 2011 SIMDIS=(XA(I)-XA(I-1))*(RAL-XAUXOLD)/(XAUX-XAUXOLD)+
574 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
576 C PYSHOW ROUTINE FOR Q-PYTHIA version 1.0.
580 C AUTHORS: N. Armesto, L. Cunqueiro and C. A. Salgado
581 C Departamento de Fisica de Particulas and IGFAE
582 C Universidade de Santiago de Compostela
583 C 15706 Santiago de Compostela, Spain
585 C EMAILS: nestor@fpaxp1.usc.es, leticia@fpaxp1.usc.es,
586 C Carlos.Salgado@cern.ch
588 C CONTENT: auxiliary files for modified PYSHOW, fixed to PYTHIA-6.4.18.
590 C WHEN USING Q-PYTHIA, PLEASE QUOTE:
592 C 1) N. Armesto, G. Corcella, L. Cunqueiro and C. A. Salgado,
594 C 2) T. Sjostrand, S. Mrenna and P. Skands,
595 C ``PYTHIA 6.4 physics and manual,''
596 C JHEP 0605 (2006) 026 [arXiv:hep-ph/0603175].
598 C INSTRUCTIONS: initial parton position is initialized by a call
599 C to user-defined routine qpygin(x0,y0,z0,t0),
600 C where these are the initial coordinates in the
601 C center-of-mass frame of the hard collision
602 C (if applicable for the type of process you study).
603 C The values of qhatL and omegac have to be computed
604 C by the user, using his preferred medium model, in
605 C routine qpygeo, which takes as input the position
606 C x,y,z,t of the parton to branch, the trajectory
607 C defined by the three-vector betax,betay,betaz,
608 C (all values in the center-of-mass frame of the
609 C hard collision), and returns the value of qhatL
610 C (in GeV**2) and omegac (in GeV).
611 C Both routines are to be found at the end of this file.
613 C DISCLAIMER: this program comes without any guarantees. Beware of
614 C errors and use common sense when interpreting results.
615 C Any modifications are done under exclusive
616 C maker's resposibility.
618 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
619 C*********************************************************************
622 C...Generates timelike parton showers from given partons.
624 SUBROUTINE PYSHOWQ(IP1,IP2,QMAX)
626 C...Double precision and integer declarations.
627 IMPLICIT DOUBLE PRECISION(A-H, O-Z)
628 IMPLICIT INTEGER(I-N)
629 INTEGER PYK,PYCHGE,PYCOMP
630 C...Parameter statement to help give large particle numbers.
631 PARAMETER (KSUSY1=1000000,KSUSY2=2000000,KTECHN=3000000,
632 &KEXCIT=4000000,KDIMEN=5000000)
633 PARAMETER (MAXNUR=500)
635 PARAMETER (NNPOS=4000)
636 DIMENSION PPOS(NNPOS,4)
639 COMMON/PYPART/NPART,NPARTD,IPART(MAXNUR),PTPART(MAXNUR)
640 COMMON/PYJETS/N,NPAD,K(4000,5),P(4000,5),V(4000,5)
641 COMMON/PYDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
642 COMMON/PYDAT2/KCHG(500,4),PMAS(500,4),PARF(2000),VCKM(4,4)
643 COMMON/PYPARS/MSTP(200),PARP(200),MSTI(200),PARI(200)
644 COMMON/PYINT1/MINT(400),VINT(400)
645 SAVE /PYPART/,/PYJETS/,/PYDAT1/,/PYDAT2/,/PYPARS/,/PYINT1/
647 common/qpc1/eee,qhatl,omegac
650 COMMON/QPLT/QPLTA1,QPLTA2,QPLTBX,QPLTBY,QPLTBZ
659 DIMENSION PMTH(5,140),PS(5),PMA(100),PMSD(100),IEP(100),IPA(100),
660 &KFLA(100),KFLD(100),KFL(100),ITRY(100),ISI(100),ISL(100),DP(100),
661 &DPT(5,4),KSH(0:140),KCII(2),NIIS(2),IIIS(2,2),THEIIS(2,2),
662 &PHIIIS(2,2),ISII(2),ISSET(2),ISCOL(0:140),ISCHG(0:140),
665 IF (IFLAG .EQ. 0) THEN
667 WRITE(MSTU(11),*) '*******************************************'
669 WRITE(MSTU(11),*) ' Q-PYTHIA version 1.0'
671 WRITE(MSTU(11),*) 'DATE: 26.09.2008'
673 WRITE(MSTU(11),*) 'AUTHORS: N. Armesto, L. Cunqueiro and'
674 WRITE(MSTU(11),*) ' C. A. Salgado'
675 WRITE(MSTU(11),*) ' Departamento de Fisica de Particulas'
676 WRITE(MSTU(11),*) ' and IGFAE'
677 WRITE(MSTU(11),*) ' Universidade de Santiago de Compostela'
678 WRITE(MSTU(11),*) ' 15706 Santiago de Compostela, Spain'
680 WRITE(MSTU(11),*) 'EMAILS: nestor@fpaxp1.usc.es,'
681 WRITE(MSTU(11),*) ' leticia@fpaxp1.usc.es,'
682 WRITE(MSTU(11),*) ' Carlos.Salgado@cern.ch'
684 WRITE(MSTU(11),*) 'NOTE: fixed to PYTHIA-6.4.18'
686 WRITE(MSTU(11),*) 'WHEN USING Q-PYTHIA, PLEASE QUOTE:'
687 WRITE(MSTU(11),*) '1) N. Armesto, G. Corcella, L. Cunqueiro'
688 WRITE(MSTU(11),*) ' and C. A. Salgado, in preparation.'
689 WRITE(MSTU(11),*) '2) T. Sjostrand, S. Mrenna and P. Skands,'
690 WRITE(MSTU(11),*) ' PYTHIA 6.4 physics and manual,'
691 WRITE(MSTU(11),*) ' JHEP 0605 (2006) 026'
692 WRITE(MSTU(11),*) ' [arXiv:hep-ph/0603175].'
694 WRITE(MSTU(11),*) 'INSTRUCTIONS: look at the web page and'
695 WRITE(MSTU(11),*) ' header of modfied routine PYSHOW at the'
696 WRITE(MSTU(11),*) ' end of Q-PYTHIA file.'
698 WRITE(MSTU(11),*) 'DISCLAIMER: this program comes without any'
699 WRITE(MSTU(11),*) ' guarantees. Beware of errors and use'
700 WRITE(MSTU(11),*) ' common sense when interpreting results.'
701 WRITE(MSTU(11),*) ' Any modifications are done under exclusive'
702 WRITE(MSTU(11),*) ' makers resposibility.'
704 WRITE(MSTU(11),*) '*******************************************'
710 C...Check that QMAX not too low.
711 IF(MSTJ(41).LE.0) THEN
713 ELSEIF(MSTJ(41).EQ.1.OR.MSTJ(41).EQ.11) THEN
714 IF(QMAX.LE.PARJ(82).AND.IP2.GE.-80) RETURN
716 IF(QMAX.LE.MIN(PARJ(82),PARJ(83),PARJ(90)).AND.IP2.GE.-80)
720 C...Store positions of shower initiating partons.
722 IF(IP1.GT.0.AND.IP1.LE.MIN(N,MSTU(4)-MSTU(32)).AND.IP2.EQ.0) THEN
725 ELSEIF(MIN(IP1,IP2).GT.0.AND.MAX(IP1,IP2).LE.MIN(N,MSTU(4)-
730 ELSEIF(IP1.GT.0.AND.IP1.LE.MIN(N,MSTU(4)-MSTU(32)).AND.IP2.LT.0
731 & .AND.IP2.GE.-80) THEN
736 ELSEIF(IP1.GT.0.AND.IP1.LE.MIN(N,MSTU(4)-MSTU(32)).AND.
744 & '(PYSHOW:) failed to reconstruct showering system')
745 IF(MSTU(21).GE.1) RETURN
748 C...Send off to PYPTFS for pT-ordered evolution if requested,
749 C...if at least 2 partons, and without predefined shower branchings.
750 IF((MSTJ(41).EQ.11.OR.MSTJ(41).EQ.12).AND.NPA.GE.2.AND.
755 PTPART(II)=0.5D0*QMAX
757 CALL PYPTFS(2,0.5D0*QMAX,0D0,PTGEN)
761 C...Initialization of cutoff masses etc.
769 PMTH(1,21)=PYMASS(21)
770 PMTH(2,21)=SQRT(PMTH(1,21)**2+0.25D0*PARJ(82)**2)
771 PMTH(3,21)=2D0*PMTH(2,21)
772 PMTH(4,21)=PMTH(3,21)
773 PMTH(5,21)=PMTH(3,21)
774 PMTH(1,22)=PYMASS(22)
775 PMTH(2,22)=SQRT(PMTH(1,22)**2+0.25D0*PARJ(83)**2)
776 PMTH(3,22)=2D0*PMTH(2,22)
777 PMTH(4,22)=PMTH(3,22)
778 PMTH(5,22)=PMTH(3,22)
780 IF(MSTJ(41).GE.2) PMQTH1=MIN(PARJ(82),PARJ(83))
781 PMQT1E=MIN(PMQTH1,PARJ(90))
783 IF(MSTJ(41).GE.2) PMQTH2=MIN(PMTH(2,21),PMTH(2,22))
784 PMQT2E=MIN(PMQTH2,0.5D0*PARJ(90))
787 IF(MSTJ(41).GE.2) ISCHG(IFL)=1
789 PMTH(1,IFL)=PYMASS(IFL)
790 PMTH(2,IFL)=SQRT(PMTH(1,IFL)**2+0.25D0*PMQTH1**2)
791 PMTH(3,IFL)=PMTH(2,IFL)+PMQTH2
792 PMTH(4,IFL)=SQRT(PMTH(1,IFL)**2+0.25D0*PARJ(82)**2)+PMTH(2,21)
793 PMTH(5,IFL)=SQRT(PMTH(1,IFL)**2+0.25D0*PARJ(83)**2)+PMTH(2,22)
796 IF(MSTJ(41).EQ.2.OR.MSTJ(41).GE.4) ISCHG(IFL)=1
797 IF(MSTJ(41).EQ.2.OR.MSTJ(41).GE.4) KSH(IFL)=1
798 PMTH(1,IFL)=PYMASS(IFL)
799 PMTH(2,IFL)=SQRT(PMTH(1,IFL)**2+0.25D0*PARJ(90)**2)
800 PMTH(3,IFL)=PMTH(2,IFL)+0.5D0*PARJ(90)
801 PMTH(4,IFL)=PMTH(3,IFL)
802 PMTH(5,IFL)=PMTH(3,IFL)
804 PT2MIN=MAX(0.5D0*PARJ(82),1.1D0*PARJ(81))**2
806 ALFM=LOG(PT2MIN/ALAMS)
808 C...Check on phase space available for emission.
816 KFLA(I)=IABS(K(IPA(I),2))
818 C...Special cutoff masses for initial partons (may be a heavy quark,
819 C...squark, ..., and need not be on the mass shell).
821 IF(NPA.LE.1) IREF(I)=IR
822 IF(NPA.GE.2) IREF(I+1)=IR
826 IF(KFLA(I).LE.8) THEN
828 IF(MSTJ(41).GE.2) ISCHG(IR)=1
829 ELSEIF(KFLA(I).EQ.11.OR.KFLA(I).EQ.13.OR.KFLA(I).EQ.15.OR.
830 & KFLA(I).EQ.17) THEN
831 IF(MSTJ(41).EQ.2.OR.MSTJ(41).GE.4) ISCHG(IR)=1
832 ELSEIF(KFLA(I).EQ.21) THEN
834 ELSEIF((KFLA(I).GE.KSUSY1+1.AND.KFLA(I).LE.KSUSY1+8).OR.
835 & (KFLA(I).GE.KSUSY2+1.AND.KFLA(I).LE.KSUSY2+8)) THEN
837 ELSEIF(KFLA(I).EQ.KSUSY1+21) THEN
840 C...same for QQ~[3S18]
841 ELSEIF(MSTP(148).GE.1.AND.(KFLA(I).EQ.9900443.OR.
842 & KFLA(I).EQ.9900553)) THEN
846 IF(ISCOL(IR).EQ.1.OR.ISCHG(IR).EQ.1) KSH(IR)=1
848 IF(ISCOL(IR).EQ.1.AND.ISCHG(IR).EQ.1) THEN
849 PMTH(2,IR)=SQRT(PMTH(1,IR)**2+0.25D0*PMQTH1**2)
850 PMTH(3,IR)=PMTH(2,IR)+PMQTH2
851 PMTH(4,IR)=SQRT(PMTH(1,IR)**2+0.25D0*PARJ(82)**2)+PMTH(2,21)
852 PMTH(5,IR)=SQRT(PMTH(1,IR)**2+0.25D0*PARJ(83)**2)+PMTH(2,22)
853 ELSEIF(ISCOL(IR).EQ.1) THEN
854 PMTH(2,IR)=SQRT(PMTH(1,IR)**2+0.25D0*PARJ(82)**2)
855 PMTH(3,IR)=PMTH(2,IR)+0.5D0*PARJ(82)
856 PMTH(4,IR)=PMTH(3,IR)
857 PMTH(5,IR)=PMTH(3,IR)
858 ELSEIF(ISCHG(IR).EQ.1) THEN
859 PMTH(2,IR)=SQRT(PMTH(1,IR)**2+0.25D0*PARJ(90)**2)
860 PMTH(3,IR)=PMTH(2,IR)+0.5D0*PARJ(90)
861 PMTH(4,IR)=PMTH(3,IR)
862 PMTH(5,IR)=PMTH(3,IR)
864 IF(KSH(IR).EQ.1) PMA(I)=PMTH(3,IR)
866 IF(KSH(IR).EQ.0.OR.PMA(I).GT.10D0*QMAX) IREJ=IREJ+1
868 PS(J)=PS(J)+P(IPA(I),J)
871 IF(IREJ.EQ.NPA.AND.IP2.GE.-7) RETURN
872 PS(5)=SQRT(MAX(0D0,PS(4)**2-PS(1)**2-PS(2)**2-PS(3)**2))
873 IF(NPA.EQ.1) PS(5)=PS(4)
874 IF(PS(5).LE.PM+PMQT1E) RETURN
876 C...Identify source: q(1), ~q(2), V(3), S(4), chi(5), ~g(6), unknown(0).
879 ELSEIF(K(IP1,3).EQ.K(IP2,3).AND.K(IP1,3).GT.0) THEN
880 KFSRCE=IABS(K(K(IP1,3),2))
882 IPAR1=MAX(1,K(IP1,3))
883 IPAR2=MAX(1,K(IP2,3))
884 IF(K(IPAR1,3).EQ.K(IPAR2,3).AND.K(IPAR1,3).GT.0)
885 & KFSRCE=IABS(K(K(IPAR1,3),2))
888 IF(KFSRCE.GE.1.AND.KFSRCE.LE.8) ITYPES=1
889 IF(KFSRCE.GE.KSUSY1+1.AND.KFSRCE.LE.KSUSY1+8) ITYPES=2
890 IF(KFSRCE.GE.KSUSY2+1.AND.KFSRCE.LE.KSUSY2+8) ITYPES=2
891 IF(KFSRCE.GE.21.AND.KFSRCE.LE.24) ITYPES=3
892 IF(KFSRCE.GE.32.AND.KFSRCE.LE.34) ITYPES=3
893 IF(KFSRCE.EQ.25.OR.(KFSRCE.GE.35.AND.KFSRCE.LE.37)) ITYPES=4
894 IF(KFSRCE.GE.KSUSY1+22.AND.KFSRCE.LE.KSUSY1+37) ITYPES=5
895 IF(KFSRCE.EQ.KSUSY1+21) ITYPES=6
897 C...Identify two primary showerers.
899 IF(KFLA(1).GE.1.AND.KFLA(1).LE.8) ITYPE1=1
900 IF(KFLA(1).GE.KSUSY1+1.AND.KFLA(1).LE.KSUSY1+8) ITYPE1=2
901 IF(KFLA(1).GE.KSUSY2+1.AND.KFLA(1).LE.KSUSY2+8) ITYPE1=2
902 IF(KFLA(1).GE.21.AND.KFLA(1).LE.24) ITYPE1=3
903 IF(KFLA(1).GE.32.AND.KFLA(1).LE.34) ITYPE1=3
904 IF(KFLA(1).EQ.25.OR.(KFLA(1).GE.35.AND.KFLA(1).LE.37)) ITYPE1=4
905 IF(KFLA(1).GE.KSUSY1+22.AND.KFLA(1).LE.KSUSY1+37) ITYPE1=5
906 IF(KFLA(1).EQ.KSUSY1+21) ITYPE1=6
908 IF(KFLA(2).GE.1.AND.KFLA(2).LE.8) ITYPE2=1
909 IF(KFLA(2).GE.KSUSY1+1.AND.KFLA(2).LE.KSUSY1+8) ITYPE2=2
910 IF(KFLA(2).GE.KSUSY2+1.AND.KFLA(2).LE.KSUSY2+8) ITYPE2=2
911 IF(KFLA(2).GE.21.AND.KFLA(2).LE.24) ITYPE2=3
912 IF(KFLA(2).GE.32.AND.KFLA(2).LE.34) ITYPE2=3
913 IF(KFLA(2).EQ.25.OR.(KFLA(2).GE.35.AND.KFLA(2).LE.37)) ITYPE2=4
914 IF(KFLA(2).GE.KSUSY1+22.AND.KFLA(2).LE.KSUSY1+37) ITYPE2=5
915 IF(KFLA(2).EQ.KSUSY1+21) ITYPE2=6
917 C...Order of showerers. Presence of gluino.
918 ITYPMN=MIN(ITYPE1,ITYPE2)
919 ITYPMX=MAX(ITYPE1,ITYPE2)
921 IF(ITYPE1.GT.ITYPE2) IORD=2
923 IF(ITYPE1.EQ.6.OR.ITYPE2.EQ.6) IGLUI=1
925 C...Check if 3-jet matrix elements to be used.
928 IF(NPA.EQ.2.AND.MSTJ(47).GE.1.AND.MPSPD.EQ.0) THEN
929 IF(MSTJ(38).NE.0) THEN
933 ELSEIF(MSTJ(47).GE.6) THEN
939 C...Vector/axial vector -> q + qbar; q -> q + V.
940 IF(ITYPMN.EQ.1.AND.ITYPMX.EQ.1.AND.(ITYPES.EQ.0.OR.
943 IF(KFSRCE.EQ.21.OR.KFSRCE.EQ.22) THEN
945 ELSEIF(KFSRCE.EQ.23.OR.(KFSRCE.EQ.0.AND.
946 & K(IPA(1),2)+K(IPA(2),2).EQ.0)) THEN
947 C...gamma*/Z0: assume e+e- initial state if unknown.
949 IF(KFSRCE.EQ.23) THEN
952 KANNFL=IABS(K(IANNFL,2))
953 IF(KANNFL.GE.1.AND.KANNFL.LE.18) EI=KCHG(KANNFL,1)/3D0
956 AI=SIGN(1D0,EI+0.1D0)
957 VI=AI-4D0*EI*PARU(102)
958 EF=KCHG(KFLA(1),1)/3D0
959 AF=SIGN(1D0,EF+0.1D0)
960 VF=AF-4D0*EF*PARU(102)
961 XWC=1D0/(16D0*PARU(102)*(1D0-PARU(102)))
964 SQWZ=PS(5)*PMAS(23,2)
965 SBWZ=1D0/((SH-SQMZ)**2+SQWZ**2)
966 VECT=EI**2*EF**2+2D0*EI*VI*EF*VF*XWC*SH*(SH-SQMZ)*SBWZ+
967 & (VI**2+AI**2)*VF**2*XWC**2*SH**2*SBWZ
968 AXIV=(VI**2+AI**2)*AF**2*XWC**2*SH**2*SBWZ
970 ALPHA=VECT/(VECT+AXIV)
971 ELSEIF(KFSRCE.EQ.24.OR.KFSRCE.EQ.0) THEN
974 C...For chi -> chi q qbar, use V/A -> q qbar as first approximation.
975 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.1.AND.ITYPES.EQ.5) THEN
977 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.3.AND.(ITYPES.EQ.0.OR.
981 C...Scalar/pseudoscalar -> q + qbar; q -> q + S.
982 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.1.AND.ITYPES.EQ.4) THEN
984 IF(KFSRCE.EQ.25.OR.KFSRCE.EQ.35.OR.KFSRCE.EQ.37) THEN
986 ELSEIF(KFSRCE.EQ.36) THEN
989 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.4.AND.(ITYPES.EQ.0.OR.
993 C...V -> ~q + ~qbar; ~q -> ~q + V; S -> ~q + ~qbar; ~q -> ~q + S.
994 ELSEIF(ITYPMN.EQ.2.AND.ITYPMX.EQ.2.AND.(ITYPES.EQ.0.OR.
997 ELSEIF(ITYPMN.EQ.2.AND.ITYPMX.EQ.3.AND.(ITYPES.EQ.0.OR.
1000 ELSEIF(ITYPMN.EQ.2.AND.ITYPMX.EQ.2.AND.ITYPES.EQ.4) THEN
1002 ELSEIF(ITYPMN.EQ.2.AND.ITYPMX.EQ.4.AND.(ITYPES.EQ.0.OR.
1003 & ITYPES.EQ.2)) THEN
1006 C...chi -> q + ~qbar; ~q -> q + chi; q -> ~q + chi.
1007 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.2.AND.(ITYPES.EQ.0.OR.
1008 & ITYPES.EQ.5)) THEN
1010 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.5.AND.(ITYPES.EQ.0.OR.
1011 & ITYPES.EQ.2)) THEN
1013 ELSEIF(ITYPMN.EQ.2.AND.ITYPMX.EQ.5.AND.(ITYPES.EQ.0.OR.
1014 & ITYPES.EQ.1)) THEN
1017 C...~g -> q + ~qbar; ~q -> q + ~g; q -> ~q + ~g.
1018 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.2.AND.ITYPES.EQ.6) THEN
1020 ELSEIF(ITYPMN.EQ.1.AND.ITYPMX.EQ.6.AND.(ITYPES.EQ.0.OR.
1021 & ITYPES.EQ.2)) THEN
1023 ELSEIF(ITYPMN.EQ.2.AND.ITYPMX.EQ.6.AND.(ITYPES.EQ.0.OR.
1024 & ITYPES.EQ.1)) THEN
1027 C...g -> ~g + ~g (eikonal approximation).
1028 ELSEIF(ITYPMN.EQ.6.AND.ITYPMX.EQ.6.AND.ITYPES.EQ.0) THEN
1031 M3JC=5*ICLASS+ICOMBI
1035 C...Find if interference with initial state partons.
1037 IF(MSTJ(50).GE.1.AND.MSTJ(50).LE.3.AND.NPA.EQ.2.AND.KFSRCE.EQ.0
1038 &.AND.MPSPD.EQ.0) MIIS=MSTJ(50)
1039 IF(MSTJ(50).GE.4.AND.MSTJ(50).LE.6.AND.NPA.EQ.2.AND.MPSPD.EQ.0)
1045 IF(KCA.NE.0) KCII(I)=KCHG(KCA,2)*ISIGN(1,K(IPA(I),2))
1047 IF(KCII(I).NE.0) THEN
1049 ICSI=MOD(K(IPA(I),3+J)/MSTU(5),MSTU(5))
1050 IF(ICSI.GT.0.AND.ICSI.NE.IPA(1).AND.ICSI.NE.IPA(2).AND.
1051 & (KCII(I).EQ.(-1)**(J+1).OR.KCII(I).EQ.2)) THEN
1053 IIIS(I,NIIS(I))=ICSI
1058 IF(NIIS(1)+NIIS(2).EQ.0) MIIS=0
1061 C...Boost interfering initial partons to rest frame
1062 C...and reconstruct their polar and azimuthal angles.
1073 K(N+I,J)=K(IPA(I),J)
1074 P(N+I,J)=P(IPA(I),J)
1078 DO 230 I=3,2+NIIS(1)
1080 K(N+I,J)=K(IIIS(1,I-2),J)
1081 P(N+I,J)=P(IIIS(1,I-2),J)
1085 DO 250 I=3+NIIS(1),2+NIIS(1)+NIIS(2)
1087 K(N+I,J)=K(IIIS(2,I-2-NIIS(1)),J)
1088 P(N+I,J)=P(IIIS(2,I-2-NIIS(1)),J)
1092 CALL PYROBO(N+1,N+2+NIIS(1)+NIIS(2),0D0,0D0,-PS(1)/PS(4),
1093 & -PS(2)/PS(4),-PS(3)/PS(4))
1094 PHI=PYANGL(P(N+1,1),P(N+1,2))
1095 CALL PYROBO(N+1,N+2+NIIS(1)+NIIS(2),0D0,-PHI,0D0,0D0,0D0)
1096 THE=PYANGL(P(N+1,3),P(N+1,1))
1097 CALL PYROBO(N+1,N+2+NIIS(1)+NIIS(2),-THE,0D0,0D0,0D0,0D0)
1105 DO 260 I=3,2+NIIS(1)
1106 THEIIS(1,I-2)=PYANGL(P(N+I,3),SQRT(P(N+I,1)**2+P(N+I,2)**2))
1107 PHIIIS(1,I-2)=PYANGL(P(N+I,1),P(N+I,2))
1109 DO 270 I=3+NIIS(1),2+NIIS(1)+NIIS(2)
1110 THEIIS(2,I-2-NIIS(1))=PARU(1)-PYANGL(P(N+I,3),
1111 & SQRT(P(N+I,1)**2+P(N+I,2)**2))
1112 PHIIIS(2,I-2-NIIS(1))=PYANGL(P(N+I,1),P(N+I,2))
1116 C...Boost 3 or more partons to their rest frame.
1118 c IF(NPA.GE.3) CALL PYROBO(IPA(1),IPA(NPA),0D0,0D0,-PS(1)/PS(4),
1119 c &-PS(2)/PS(4),-PS(3)/PS(4))
1121 CALL PYROBO(IPA(1),IPA(NPA),0D0,0D0,-PS(1)/PS(4),
1122 &-PS(2)/PS(4),-PS(3)/PS(4))
1132 C...Define imagined single initiator of shower for parton system.
1134 IF(N.GT.MSTU(4)-MSTU(32)-10) THEN
1135 CALL PYERRM(11,'(PYSHOW:) no more memory left in PYJETS')
1136 IF(MSTU(21).GE.1) RETURN
1159 call qpygin(pposx0,pposy0,pposz0,ppost0) ! in fm
1160 do 10101 iijj=1, nnpos, 1
1172 C...Loop over partons that may branch.
1175 IF(NPA.EQ.1) IM=NS-1
1178 IF(IM.GT.N) GOTO 600
1181 IF(KSH(IR).EQ.0) GOTO 290
1182 IF(P(IM,5).LT.PMTH(2,IR)) GOTO 290
1187 IF(N+NEP.GT.MSTU(4)-MSTU(32)-10) THEN
1188 CALL PYERRM(11,'(PYSHOW:) no more memory left in PYJETS')
1189 IF(MSTU(21).GE.1) RETURN
1192 C...Position of aunt (sister to branching parton).
1193 C...Origin and flavour of daughters.
1196 IF(K(IM-1,3).EQ.IGM) IAU=IM-1
1197 IF(N.GE.IM+1.AND.K(IM+1,3).EQ.IGM) IAU=IM+1
1209 K(N+I,2)=K(IPA(I),2)
1211 ELSEIF(KFLM.NE.21) THEN
1214 IREF(N+1-NS)=IREF(IM-NS)
1215 IREF(N+2-NS)=IABS(K(N+2,2))
1216 ELSEIF(K(IM,5).EQ.21) THEN
1224 IREF(N+1-NS)=IABS(K(N+1,2))
1225 IREF(N+2-NS)=IABS(K(N+2,2))
1228 C...Reset flags on daughters and tries made.
1233 KFLD(IP)=IABS(K(N+IP,2))
1234 IF(KCHG(PYCOMP(KFLD(IP)),2).EQ.0) K(N+IP,1)=1
1238 IF(KSH(IREF(N+IP-NS)).EQ.1) ISI(IP)=1
1242 C...Maximum virtuality of daughters.
1245 IF(NPA.GE.3) P(N+I,4)=P(IPA(I),4)
1246 P(N+I,5)=MIN(QMAX,PS(5))
1248 IF(IP2.LE.-8) P(N+I,5)=MAX(P(N+I,5),2D0*PMTH(3,IR))
1249 IF(ISI(I).EQ.0) P(N+I,5)=P(IPA(I),5)
1252 IF(MSTJ(43).LE.2) PEM=V(IM,2)
1253 IF(MSTJ(43).GE.3) PEM=P(IM,4)
1254 P(N+1,5)=MIN(P(IM,5),V(IM,1)*PEM)
1255 P(N+2,5)=MIN(P(IM,5),(1D0-V(IM,1))*PEM)
1256 IF(K(N+2,2).EQ.22) P(N+2,5)=PMTH(1,22)
1260 IF(ISI(I).EQ.1) THEN
1262 IF(P(N+I,5).LE.PMTH(3,IR)) P(N+I,5)=PMTH(1,IR)
1264 V(N+I,5)=P(N+I,5)**2
1267 C...Choose one of the daughters for evolution.
1271 IF(INUM.EQ.0.AND.ISL(I).EQ.1) INUM=I
1274 IF(INUM.EQ.0.AND.ITRY(I).EQ.0.AND.ISI(I).EQ.1) THEN
1276 IF(P(N+I,5).GE.PMTH(2,IR)) INUM=I
1282 IF(ISI(I).EQ.1.AND.PMSD(I).GE.PMQT2E) THEN
1283 RPM=P(N+I,5)/PMSD(I)
1285 IF(RPM.GT.RMAX.AND.P(N+I,5).GE.PMTH(2,IR)) THEN
1293 C...Cancel choice of predetermined daughter already treated.
1296 IF(MPSPD.EQ.1.AND.IGM.EQ.0.AND.ITRY(INUMT).GE.1) THEN
1297 IF(K(IP1-1+INUM,4).GT.0) INUM=3-INUM
1298 ELSEIF(MPSPD.EQ.1.AND.IM.EQ.NS+2.AND.ITRY(INUMT).GE.1) THEN
1299 IF(KFLD(INUMT).NE.21.AND.K(IP1+2,4).GT.0) INUM=3-INUM
1300 IF(KFLD(INUMT).EQ.21.AND.K(IP1+3,4).GT.0) INUM=3-INUM
1303 C...Store information on choice of evolving daughter.
1310 if (nep .gt. 1 .and. inum .eq. 2) then
1314 if(zz1.gt.0.d0) then
1320 if (xkt .gt. 0.d0) then
1321 xlcoh=(2.d0*eee/(zz1*zz2*ttt))*0.1973d0
1325 if (idf .eq. 0) then ! for the initial parton if it has no father
1326 xbx=p(iep(1),1)/p(iep(1),4)
1327 xby=p(iep(1),2)/p(iep(1),4)
1328 xbz=p(iep(1),3)/p(iep(1),4)
1329 call qpygeo(pposx0,pposy0,pposz0,ppost0,
1330 > xbx,xby,xbz,qhatl,omegac)
1332 xbx=p(idf,1)/p(idf,4)
1333 xby=p(idf,2)/p(idf,4)
1334 xbz=p(idf,3)/p(idf,4)
1335 ppos(iep(1),1)=ppos(idf,1)+xbx*xlcoh
1336 ppos(iep(1),2)=ppos(idf,2)+xby*xlcoh
1337 ppos(iep(1),3)=ppos(idf,3)+xbz*xlcoh
1338 ppos(iep(1),4)=ppos(idf,4)+xlcoh
1339 call qpygeo(ppos(iep(1),1),ppos(iep(1),2),ppos(iep(1),3),
1340 > ppos(iep(1),4),xbx,xby,xbz,qhatl,omegac)
1346 IF(IEP(I).GT.N+NEP) IEP(I)=N+1
1349 KFL(I)=IABS(K(IEP(I),2))
1351 ITRY(INUM)=ITRY(INUM)+1
1352 IF(ITRY(INUM).GT.200) THEN
1353 CALL PYERRM(14,'(PYSHOW:) caught in infinite loop')
1354 IF(MSTU(21).GE.1) RETURN
1358 IF(KSH(IR).EQ.0) GOTO 450
1359 IF(P(IEP(1),5).LT.PMTH(2,IR)) GOTO 450
1361 C...Check if evolution already predetermined for daughter.
1363 IF(MPSPD.EQ.1.AND.IGM.EQ.0) THEN
1364 IF(K(IP1-1+INUM,4).GT.0) IPSPD=IP1-1+INUM
1365 ELSEIF(MPSPD.EQ.1.AND.IM.EQ.NS+2) THEN
1366 IF(KFL(1).NE.21.AND.K(IP1+2,4).GT.0) IPSPD=IP1+2
1367 IF(KFL(1).EQ.21.AND.K(IP1+3,4).GT.0) IPSPD=IP1+3
1369 IF(INUM.EQ.1.OR.INUM.EQ.2) THEN
1371 IF(IPSPD.NE.0) ISSET(INUM)=1
1374 C...Select side for interference with initial state partons.
1375 IF(MIIS.GE.1.AND.IEP(1).LE.NS+3) THEN
1378 IF(IABS(KCII(III)).EQ.1.AND.NIIS(III).EQ.1) THEN
1380 ELSEIF(KCII(III).EQ.2.AND.NIIS(III).EQ.1) THEN
1381 IF(PYR(0).GT.0.5D0) ISII(III)=1
1382 ELSEIF(KCII(III).EQ.2.AND.NIIS(III).EQ.2) THEN
1384 IF(PYR(0).GT.0.5D0) ISII(III)=2
1388 C...Calculate allowed z range.
1391 ELSEIF(IGM.EQ.0.OR.MSTJ(43).LE.2) THEN
1394 IF(INUM.EQ.1) PMED=V(IM,1)*PEM
1395 IF(INUM.EQ.2) PMED=(1D0-V(IM,1))*PEM
1397 IF(MOD(MSTJ(43),2).EQ.1) THEN
1400 IF(ISCOL(IR).EQ.0) ZCE=0.5D0*PARJ(90)/PMED
1402 ZC=0.5D0*(1D0-SQRT(MAX(0D0,1D0-(2D0*PMTH(2,21)/PMED)**2)))
1403 IF(ZC.LT.1D-6) ZC=(PMTH(2,21)/PMED)**2
1405 IF(ISCOL(IR).EQ.0) PMTMPE=0.5D0*PARJ(90)
1406 ZCE=0.5D0*(1D0-SQRT(MAX(0D0,1D0-(2D0*PMTMPE/PMED)**2)))
1407 IF(ZCE.LT.1D-6) ZCE=(PMTMPE/PMED)**2
1410 ZCE=MIN(ZCE,0.49991D0)
1411 IF(((MSTJ(41).EQ.1.AND.ZC.GT.0.49D0).OR.(MSTJ(41).GE.2.AND.
1412 &MIN(ZC,ZCE).GT.0.4999D0)).AND.IPSPD.EQ.0) THEN
1413 P(IEP(1),5)=PMTH(1,IR)
1414 V(IEP(1),5)=P(IEP(1),5)**2
1418 C...Integral of Altarelli-Parisi z kernel for QCD.
1419 C...(Includes squark and gluino; with factor N_C/C_F extra for latter).
1420 IF(MSTJ(49).EQ.0.AND.KFL(1).EQ.21) THEN
1422 C FBR= 6D0*LOG((1D0-ZC)/ZC)+MSTJ(45)*0.5D0
1423 FBR=dgauss1(splitg1,zc,1.d0-zc,1.d-3)
1426 C...Evolution of QQ~[3S18] state if MSTP(148)=1.
1427 ELSEIF(MSTJ(49).EQ.0.AND.MSTP(149).GE.0.AND.
1428 & (KFL(1).EQ.9900443.OR.KFL(1).EQ.9900553)) THEN
1429 FBR=6D0*LOG((1D0-ZC)/ZC)
1431 ELSEIF(MSTJ(49).EQ.0) THEN
1433 C FBR=(8D0/3D0)*LOG((1D0-ZC)/ZC)
1434 FBR=dgauss1(splitq1,zc,1.d0-zc,1.d-3)
1437 IF(IGLUI.EQ.1.AND.IR.GE.31) FBR=FBR*(9D0/4D0)
1439 C...Integral of Altarelli-Parisi z kernel for scalar gluon.
1440 ELSEIF(MSTJ(49).EQ.1.AND.KFL(1).EQ.21) THEN
1441 FBR=(PARJ(87)+MSTJ(45)*PARJ(88))*(1D0-2D0*ZC)
1442 ELSEIF(MSTJ(49).EQ.1) THEN
1443 FBR=(1D0-2D0*ZC)/3D0
1444 IF(IGM.EQ.0.AND.M3JC.GE.1) FBR=4D0*FBR
1446 C...Integral of Altarelli-Parisi z kernel for Abelian vector gluon.
1447 ELSEIF(KFL(1).EQ.21) THEN
1448 FBR=6D0*MSTJ(45)*(0.5D0-ZC)
1450 FBR=2D0*LOG((1D0-ZC)/ZC)
1453 C...Reset QCD probability for colourless.
1454 IF(ISCOL(IR).EQ.0) FBR=0D0
1456 C...Integral of Altarelli-Parisi kernel for photon emission.
1458 IF(MSTJ(41).GE.2.AND.ISCHG(IR).EQ.1) THEN
1459 IF(KFL(1).LE.18) THEN
1460 FBRE=(KCHG(KFL(1),1)/3D0)**2*2D0*LOG((1D0-ZCE)/ZCE)
1462 IF(MSTJ(41).EQ.10) FBRE=PARJ(84)*FBRE
1465 C...Inner veto algorithm starts. Find maximum mass for evolution.
1472 IF(KSH(IRI).EQ.1) PM=PMTH(2,IRI)
1475 PMS=MIN(PMS,(P(IM,5)-PM2)**2)
1478 C...Select mass for daughter in QCD evolution.
1480 DO 430 IFF=4,MSTJ(45)
1481 IF(PMS.GT.4D0*PMTH(2,IFF)**2) B0=(33D0-2D0*IFF)/6D0
1483 C...Shift m^2 for evolution in Q^2 = m^2 - m(onshell)^2.
1484 PMSC=MAX(0.5D0*PARJ(82),PMS-PMTH(1,IR)**2)
1485 C...Already predetermined choice.
1487 PMSQCD=P(IPSPD,5)**2
1488 ELSEIF(FBR.LT.1D-3) THEN
1490 ELSEIF(MSTJ(44).LE.0) THEN
1491 PMSQCD=PMSC*EXP(MAX(-50D0,LOG(PYR(0))*PARU(2)/(PARU(111)*FBR)))
1492 ELSEIF(MSTJ(44).EQ.1) THEN
1493 PMSQCD=4D0*ALAMS*(0.25D0*PMSC/ALAMS)**(PYR(0)**(B0/FBR))
1495 PMSQCD=PMSC*EXP(MAX(-50D0,ALFM*B0*LOG(PYR(0))/FBR))
1497 C...Shift back m^2 from evolution in Q^2 = m^2 - m(onshell)^2.
1498 IF(IPSPD.EQ.0) PMSQCD=PMSQCD+PMTH(1,IR)**2
1499 IF(ZC.GT.0.49D0.OR.PMSQCD.LE.PMTH(4,IR)**2) PMSQCD=PMTH(2,IR)**2
1503 C...Select mass for daughter in QED evolution.
1504 IF(MSTJ(41).GE.2.AND.ISCHG(IR).EQ.1.AND.IPSPD.EQ.0) THEN
1505 C...Shift m^2 for evolution in Q^2 = m^2 - m(onshell)^2.
1506 PMSE=MAX(0.5D0*PARJ(83),PMS-PMTH(1,IR)**2)
1507 IF(FBRE.LT.1D-3) THEN
1510 PMSQED=PMSE*EXP(MAX(-50D0,LOG(PYR(0))*PARU(2)/
1511 & (PARU(101)*FBRE)))
1513 C...Shift back m^2 from evolution in Q^2 = m^2 - m(onshell)^2.
1514 PMSQED=PMSQED+PMTH(1,IR)**2
1515 IF(ZCE.GT.0.4999D0.OR.PMSQED.LE.PMTH(5,IR)**2) PMSQED=
1517 IF(PMSQED.GT.PMSQCD) THEN
1523 C...Check whether daughter mass below cutoff.
1524 P(IEP(1),5)=SQRT(V(IEP(1),5))
1525 IF(P(IEP(1),5).LE.PMTH(3,IR)) THEN
1526 P(IEP(1),5)=PMTH(1,IR)
1527 V(IEP(1),5)=P(IEP(1),5)**2
1534 C...Already predetermined choice of z, and flavour in g -> qqbar.
1538 PMSGD1=P(IPSGD1,5)**2
1539 PMSGD2=P(IPSGD2,5)**2
1540 ALAMPS=SQRT(MAX(1D-10,(PMSQCD-PMSGD1-PMSGD2)**2-
1541 & 4D0*PMSGD1*PMSGD2))
1542 Z=0.5D0*(PMSQCD*(2D0*P(IPSGD1,4)/P(IPSPD,4)-1D0)+ALAMPS-
1543 & PMSGD1+PMSGD2)/ALAMPS
1544 Z=MAX(0.00001D0,MIN(0.99999D0,Z))
1545 IF(KFL(1).NE.21) THEN
1548 K(IEP(1),5)=IABS(K(IPSGD1,2))
1551 C...Select z value of branching: q -> qgamma.
1552 ELSEIF(MCE.EQ.2) THEN
1553 Z=1D0-(1D0-ZCE)*(ZCE/(1D0-ZCE))**PYR(0)
1554 IF(1D0+Z**2.LT.2D0*PYR(0)) GOTO 410
1558 C...Select z value of branching: QQ~[3S18] -> QQ~[3S18]g.
1559 ELSEIF(MSTJ(49).EQ.0.AND.
1560 & (KFL(1).EQ.9900443.OR.KFL(1).EQ.9900553)) THEN
1561 Z=(1D0-ZC)*(ZC/(1D0-ZC))**PYR(0)
1562 C...Select always the harder 'gluon' if the switch MSTP(149)<=0.
1563 IF(MSTP(149).LE.0.OR.PYR(0).GT.0.5D0) Z=1D0-Z
1564 IF((1D0-Z*(1D0-Z))**2.LT.PYR(0)) GOTO 410
1568 C...Select z value of branching: q -> qg, g -> gg, g -> qqbar.
1569 ELSEIF(MSTJ(49).NE.1.AND.KFL(1).NE.21) THEN
1571 C Z=1D0-(1D0-ZC)*(ZC/(1D0-ZC))**PYR(0)
1572 C...Only do z weighting when no ME correction afterwards.
1573 C IF(M3JC.EQ.0.AND.1D0+Z**2.LT.2D0*PYR(0)) GOTO 410
1575 anfbr=dgauss1(splitq2,zc,1.d0-zc,1.d-3)
1576 z=simdis(500,zc,1,anfbr)
1579 ELSEIF(MSTJ(49).EQ.0.AND.MSTJ(45)*0.5D0.LT.PYR(0)*FBR) THEN
1581 c Z=(1D0-ZC)*(ZC/(1D0-ZC))**PYR(0)
1582 anfbr=dgauss1(splitg2,zc,1.d0-zc,1.d-3)
1584 z=simdis(500,zc,21,anfbr)
1586 IF(PYR(0).GT.0.5D0) Z=1D0-Z
1587 c IF((1D0-Z*(1D0-Z))**2.LT.PYR(0)) GOTO 410
1590 ELSEIF(MSTJ(49).NE.1) THEN
1593 c IF(Z**2+(1D0-Z)**2.LT.PYR(0)) GOTO 410
1594 anfbr=dgauss1(splitqqbar,zc,1.d0-zc,1.d-3)
1595 z=simdis(500,zc,3,anfbr)
1598 KFLB=1+INT(MSTJ(45)*PYR(0))
1599 PMQ=4D0*PMTH(2,KFLB)**2/V(IEP(1),5)
1600 IF(PMQ.GE.1D0) GOTO 410
1601 IF(MSTJ(44).LE.2.OR.MSTJ(44).EQ.4) THEN
1602 IF(Z.LT.ZC.OR.Z.GT.1D0-ZC) GOTO 410
1603 PMQ0=4D0*PMTH(2,21)**2/V(IEP(1),5)
1604 IF(MOD(MSTJ(43),2).EQ.0.AND.(1D0+0.5D0*PMQ)*SQRT(1D0-PMQ)
1605 & .LT.PYR(0)*(1D0+0.5D0*PMQ0)*SQRT(1D0-PMQ0)) GOTO 410
1607 IF((1D0+0.5D0*PMQ)*SQRT(1D0-PMQ).LT.PYR(0)) GOTO 410
1611 C...Ditto for scalar gluon model.
1612 ELSEIF(KFL(1).NE.21) THEN
1613 Z=1D0-SQRT(ZC**2+PYR(0)*(1D0-2D0*ZC))
1615 ELSEIF(PYR(0)*(PARJ(87)+MSTJ(45)*PARJ(88)).LE.PARJ(87)) THEN
1616 Z=ZC+(1D0-2D0*ZC)*PYR(0)
1619 Z=ZC+(1D0-2D0*ZC)*PYR(0)
1620 KFLB=1+INT(MSTJ(45)*PYR(0))
1621 PMQ=4D0*PMTH(2,KFLB)**2/V(IEP(1),5)
1622 IF(PMQ.GE.1D0) GOTO 410
1626 C...Correct to alpha_s(pT^2) (optionally m^2/4 for g -> q qbar).
1627 IF(MCE.EQ.1.AND.MSTJ(44).GE.2.AND.IPSPD.EQ.0) THEN
1628 IF(KFL(1).EQ.21.AND.K(IEP(1),5).LT.10.AND.
1629 & (MSTJ(44).EQ.3.OR.MSTJ(44).EQ.5)) THEN
1630 IF(ALFM/LOG(V(IEP(1),5)*0.25D0/ALAMS).LT.PYR(0)) GOTO 410
1632 PT2APP=Z*(1D0-Z)*V(IEP(1),5)
1633 IF(MSTJ(44).GE.4) PT2APP=PT2APP*
1634 & (1D0-PMTH(1,IR)**2/V(IEP(1),5))**2
1635 IF(PT2APP.LT.PT2MIN) GOTO 410
1636 IF(ALFM/LOG(PT2APP/ALAMS).LT.PYR(0)) GOTO 410
1640 C...Check if z consistent with chosen m.
1641 IF(KFL(1).EQ.21) THEN
1642 IRGD1=IABS(K(IEP(1),5))
1646 IRGD2=IABS(K(IEP(1),5))
1650 ELSEIF(NEP.GE.3) THEN
1652 ELSEIF(IGM.EQ.0.OR.MSTJ(43).LE.2) THEN
1653 PED=0.5D0*(V(IM,5)+V(IEP(1),5)-PM2**2)/P(IM,5)
1655 IF(IEP(1).EQ.N+1) PED=V(IM,1)*PEM
1656 IF(IEP(1).EQ.N+2) PED=(1D0-V(IM,1))*PEM
1658 IF(MOD(MSTJ(43),2).EQ.1) THEN
1659 PMQTH3=0.5D0*PARJ(82)
1660 IF(IRGD2.EQ.22) PMQTH3=0.5D0*PARJ(83)
1661 IF(IRGD2.EQ.22.AND.ISCOL(IR).EQ.0) PMQTH3=0.5D0*PARJ(90)
1662 PMQ1=(PMTH(1,IRGD1)**2+PMQTH3**2)/V(IEP(1),5)
1663 PMQ2=(PMTH(1,IRGD2)**2+PMQTH3**2)/V(IEP(1),5)
1664 ZD=SQRT(MAX(0D0,(1D0-V(IEP(1),5)/PED**2)*((1D0-PMQ1-PMQ2)**2-
1668 ZD=SQRT(MAX(0D0,1D0-V(IEP(1),5)/PED**2))
1671 IF(KFL(1).EQ.21.AND.K(IEP(1),5).LT.10.AND.
1672 &(MSTJ(44).EQ.3.OR.MSTJ(44).EQ.5)) THEN
1673 ELSEIF(IPSPD.NE.0) THEN
1677 IF(Z.LT.ZL.OR.Z.GT.ZU) GOTO 410
1679 IF(KFL(1).EQ.21) V(IEP(1),3)=LOG(ZU*(1D0-ZL)/MAX(1D-20,ZL*
1681 IF(KFL(1).NE.21) V(IEP(1),3)=LOG((1D0-ZL)/MAX(1D-10,1D0-ZU))
1683 C...Width suppression for q -> q + g.
1684 IF(MSTJ(40).NE.0.AND.KFL(1).NE.21.AND.IPSPD.EQ.0) THEN
1686 EGLU=0.5D0*PS(5)*(1D0-Z)*(1D0+V(IEP(1),5)/V(NS+1,5))
1690 CHI=PARJ(89)**2/(PARJ(89)**2+EGLU**2)
1691 IF(MSTJ(40).EQ.1) THEN
1692 IF(CHI.LT.PYR(0)) GOTO 410
1693 ELSEIF(MSTJ(40).EQ.2) THEN
1694 IF(1D0-CHI.LT.PYR(0)) GOTO 410
1698 C...Three-jet matrix element correction.
1703 C...QED matrix elements: only for massless case so far.
1704 IF(MCE.EQ.2.AND.IGM.EQ.0) THEN
1705 X1=Z*(1D0+V(IEP(1),5)/V(NS+1,5))
1706 X2=1D0-V(IEP(1),5)/V(NS+1,5)
1707 X3=(1D0-X1)+(1D0-X2)
1709 KI2=K(IPA(3-INUM),2)
1710 QF1=KCHG(PYCOMP(KI1),1)*ISIGN(1,KI1)/3D0
1711 QF2=KCHG(PYCOMP(KI2),1)*ISIGN(1,KI2)/3D0
1712 WSHOW=QF1**2*(1D0-X1)/X3*(1D0+(X1/(2D0-X2))**2)+
1713 & QF2**2*(1D0-X2)/X3*(1D0+(X2/(2D0-X1))**2)
1714 WME=(QF1*(1D0-X1)/X3-QF2*(1D0-X2)/X3)**2*(X1**2+X2**2)
1715 ELSEIF(MCE.EQ.2) THEN
1717 C...QCD matrix elements, including mass effects.
1718 ELSEIF(MSTJ(49).NE.1.AND.K(IEP(1),2).NE.21) THEN
1722 IF(IR.GE.31.AND.IGM.EQ.0) THEN
1723 C...QCD ME: original parton, first branching.
1726 ELSEIF(IR.GE.31) THEN
1727 C...QCD ME: original parton, subsequent branchings.
1729 PEDME=PEM*(V(IM,1)+(1D0-V(IM,1))*PS1ME/V(IM,5))
1730 ECMME=PEDME+SQRT(MAX(0D0,PEDME**2-PS1ME+PM2ME**2))
1731 ELSEIF(K(IM,2).EQ.21) THEN
1732 C...QCD ME: secondary partons, first branching.
1735 IF(IEP(1).GT.IEP(2)) ZMME=1D0-ZMME
1736 PMLME=SQRT(MAX(0D0,(V(IM,5)-PS1ME-PM2ME**2)**2-
1737 & 4D0*PS1ME*PM2ME**2))
1738 PEDME=PEM*(0.5D0*(V(IM,5)-PMLME+PS1ME-PM2ME**2)+PMLME*ZMME)/
1740 ECMME=PEDME+SQRT(MAX(0D0,PEDME**2-PS1ME+PM2ME**2))
1743 C...QCD ME: secondary partons, subsequent branchings.
1745 PEDME=PEM*(V(IM,1)+(1D0-V(IM,1))*PS1ME/V(IM,5))
1746 ECMME=PEDME+SQRT(MAX(0D0,PEDME**2-PS1ME+PM2ME**2))
1749 C...Construct ME variables.
1752 X1=(1D0+PS1ME/ECMME**2-R2ME**2)*(Z+(1D0-Z)*PM1ME**2/PS1ME)
1753 X2=1D0+R2ME**2-PS1ME/ECMME**2
1754 C...Call ME, with right order important for two inequivalent showerers.
1755 IF(IR.EQ.IORD+30) THEN
1756 WME=PYMAEL(M3JCC,X1,X2,R1ME,R2ME,ALPHA)
1758 WME=PYMAEL(M3JCC,X2,X1,R2ME,R1ME,ALPHA)
1760 C...Split up total ME when two radiating partons.
1762 IF((M3JCC.GE.16.AND.M3JCC.LE.19).OR.
1763 & (M3JCC.GE.26.AND.M3JCC.LE.29).OR.
1764 & (M3JCC.GE.36.AND.M3JCC.LE.39).OR.
1765 & (M3JCC.GE.46.AND.M3JCC.LE.49).OR.
1766 & (M3JCC.GE.56.AND.M3JCC.LE.64)) ISPRAD=0
1767 IF(ISPRAD.EQ.1) WME=WME*MAX(1D-10,1D0+R1ME**2-R2ME**2-X1)/
1768 & MAX(1D-10,2D0-X1-X2)
1769 C...Evaluate shower rate to be compared with.
1770 WSHOW=2D0/(MAX(1D-10,2D0-X1-X2)*
1771 & MAX(1D-10,1D0+R2ME**2-R1ME**2-X2))
1772 IF(IGLUI.EQ.1.AND.IR.GE.31) WSHOW=(9D0/4D0)*WSHOW
1773 ELSEIF(MSTJ(49).NE.1) THEN
1775 C...Toy model scalar theory matrix elements; no mass effects.
1777 X1=Z*(1D0+V(IEP(1),5)/V(NS+1,5))
1778 X2=1D0-V(IEP(1),5)/V(NS+1,5)
1779 X3=(1D0-X1)+(1D0-X2)
1780 WSHOW=4D0*X3*((1D0-X1)/(2D0-X2)**2+(1D0-X2)/(2D0-X1)**2)
1782 IF(MSTJ(102).GE.2) WME=X3**2-2D0*(1D0+X3)*(1D0-X1)*(1D0-X2)*
1786 IF(WME.LT.PYR(0)*WSHOW) GOTO 410
1789 C...Impose angular ordering by rejection of nonordered emission.
1790 IF(MCE.EQ.1.AND.IGM.GT.0.AND.MSTJ(42).GE.2.AND.IPSPD.EQ.0) THEN
1791 PEMAO=V(IM,1)*P(IM,4)
1792 IF(IEP(1).EQ.N+2) PEMAO=(1D0-V(IM,1))*P(IM,4)
1793 IF(IR.GE.31.AND.MSTJ(42).GE.5) THEN
1795 ELSEIF(KFL(1).EQ.21.AND.K(IEP(1),5).LE.10.AND.(MSTJ(42).EQ.4
1796 & .OR.MSTJ(42).EQ.7)) THEN
1798 ELSEIF(KFL(1).EQ.21.AND.K(IEP(1),5).LE.10.AND.(MSTJ(42).EQ.3
1799 & .OR.MSTJ(42).EQ.6)) THEN
1801 PMDAO=PMTH(2,K(IEP(1),5))
1802 THE2ID=Z*(1D0-Z)*PEMAO**2/(V(IEP(1),5)-4D0*PMDAO**2)
1805 THE2ID=Z*(1D0-Z)*PEMAO**2/V(IEP(1),5)
1806 IF(MSTJ(42).GE.3.AND.MSTJ(42).NE.5) THE2ID=THE2ID*
1807 & (1D0+PMTH(1,IR)**2*(1D0-Z)/(V(IEP(1),5)*Z))**2
1811 440 IF(K(IAOM,5).EQ.22) THEN
1813 IF(K(IAOM,3).LE.NS) MAOM=0
1814 IF(MAOM.EQ.1) GOTO 440
1816 IF(MAOM.EQ.1.AND.MAOD.EQ.1) THEN
1817 THE2IM=V(IAOM,1)*(1D0-V(IAOM,1))*P(IAOM,4)**2/V(IAOM,5)
1818 IF(THE2ID.LT.THE2IM) GOTO 410
1822 C...Impose user-defined maximum angle at first branching.
1823 IF(MSTJ(48).EQ.1.AND.IPSPD.EQ.0) THEN
1824 IF(NEP.EQ.1.AND.IM.EQ.NS) THEN
1825 THE2ID=Z*(1D0-Z)*PS(4)**2/V(IEP(1),5)
1826 IF(PARJ(85)**2*THE2ID.LT.1D0) GOTO 410
1827 ELSEIF(NEP.EQ.2.AND.IEP(1).EQ.NS+2) THEN
1828 THE2ID=Z*(1D0-Z)*(0.5D0*P(IM,4))**2/V(IEP(1),5)
1829 IF(PARJ(85)**2*THE2ID.LT.1D0) GOTO 410
1830 ELSEIF(NEP.EQ.2.AND.IEP(1).EQ.NS+3) THEN
1831 THE2ID=Z*(1D0-Z)*(0.5D0*P(IM,4))**2/V(IEP(1),5)
1832 IF(PARJ(86)**2*THE2ID.LT.1D0) GOTO 410
1836 C...Impose angular constraint in first branching from interference
1837 C...with initial state partons.
1838 IF(MIIS.GE.2.AND.IEP(1).LE.NS+3) THEN
1839 THE2D=MAX((1D0-Z)/Z,Z/(1D0-Z))*V(IEP(1),5)/(0.5D0*P(IM,4))**2
1840 IF(IEP(1).EQ.NS+2.AND.ISII(1).GE.1) THEN
1841 IF(THE2D.GT.THEIIS(1,ISII(1))**2) GOTO 410
1842 ELSEIF(IEP(1).EQ.NS+3.AND.ISII(2).GE.1) THEN
1843 IF(THE2D.GT.THEIIS(2,ISII(2))**2) GOTO 410
1847 C...End of inner veto algorithm. Check if only one leg evolved so far.
1851 IF(NEP.EQ.1) GOTO 490
1852 IF(NEP.EQ.2.AND.P(IEP(1),5)+P(IEP(2),5).GE.P(IM,5)) GOTO 350
1855 IF(ITRY(I).EQ.0.AND.KSH(IR).EQ.1) THEN
1856 IF(P(N+I,5).GE.PMTH(2,IR)) GOTO 350
1860 C...Check if chosen multiplet m1,m2,z1,z2 is physical.
1864 PMSUM=PMSUM+P(N+I,5)
1866 IF(PMSUM.GE.PS(5)) GOTO 350
1867 ELSEIF(IGM.EQ.0.OR.MSTJ(43).LE.2.OR.MOD(MSTJ(43),2).EQ.0) THEN
1870 IF(KSH(IRDA).EQ.0) GOTO 480
1871 IF(P(I1,5).LT.PMTH(2,IRDA)) GOTO 480
1880 IF(IGM.EQ.0.OR.MSTJ(43).LE.2) THEN
1881 PED=0.5D0*(V(IM,5)+V(I1,5)-V(I2,5))/P(IM,5)
1883 IF(I1.EQ.N+1) ZM=V(IM,1)
1884 IF(I1.EQ.N+2) ZM=1D0-V(IM,1)
1885 PML=SQRT((V(IM,5)-V(N+1,5)-V(N+2,5))**2-
1886 & 4D0*V(N+1,5)*V(N+2,5))
1887 PED=PEM*(0.5D0*(V(IM,5)-PML+V(I1,5)-V(I2,5))+PML*ZM)/
1890 IF(MOD(MSTJ(43),2).EQ.1) THEN
1891 PMQTH3=0.5D0*PARJ(82)
1892 IF(IRGD2.EQ.22) PMQTH3=0.5D0*PARJ(83)
1893 IF(IRGD2.EQ.22.AND.ISCOL(IRDA).EQ.0) PMQTH3=0.5D0*PARJ(90)
1894 PMQ1=(PMTH(1,IRGD1)**2+PMQTH3**2)/V(I1,5)
1895 PMQ2=(PMTH(1,IRGD2)**2+PMQTH3**2)/V(I1,5)
1896 ZD=SQRT(MAX(0D0,(1D0-V(I1,5)/PED**2)*((1D0-PMQ1-PMQ2)**2-
1900 ZD=SQRT(MAX(0D0,1D0-V(I1,5)/PED**2))
1903 IF(IRDA.EQ.21.AND.IRGD1.LT.10.AND.
1904 & (MSTJ(44).EQ.3.OR.MSTJ(44).EQ.5)) THEN
1908 IF(I1.EQ.N+1.AND.(V(I1,1).LT.ZL.OR.V(I1,1).GT.ZU).AND.
1909 & ISSET(1).EQ.0) THEN
1911 ELSEIF(I1.EQ.N+2.AND.(V(I1,1).LT.ZL.OR.V(I1,1).GT.ZU).AND.
1912 & ISSET(2).EQ.0) THEN
1916 IF(IRDA.EQ.21) V(I1,4)=LOG(ZU*(1D0-ZL)/MAX(1D-20,
1918 IF(IRDA.NE.21) V(I1,4)=LOG((1D0-ZL)/MAX(1D-10,1D0-ZU))
1920 IF(ISL(1).EQ.1.AND.ISL(2).EQ.1.AND.ISLM.NE.0) THEN
1923 ELSEIF(ISL(1).EQ.1.AND.ISL(2).EQ.1) THEN
1924 ZDR1=MAX(0D0,V(N+1,3)/MAX(1D-6,V(N+1,4))-1D0)
1925 ZDR2=MAX(0D0,V(N+2,3)/MAX(1D-6,V(N+2,4))-1D0)
1926 IF(ZDR2.GT.PYR(0)*(ZDR1+ZDR2)) ISL(1)=0
1927 IF(ISL(1).EQ.1) ISL(2)=0
1928 IF(ISL(1).EQ.0) ISLM=1
1929 IF(ISL(2).EQ.0) ISLM=2
1931 IF(ISL(1).EQ.1.OR.ISL(2).EQ.1) GOTO 350
1936 IF(MOD(MSTJ(43),2).EQ.1.AND.(P(N+1,5).GE.
1937 & PMTH(2,IRD1).OR.P(N+2,5).GE.PMTH(2,IRD2))) THEN
1938 PMQ1=V(N+1,5)/V(IM,5)
1939 PMQ2=V(N+2,5)/V(IM,5)
1940 ZD=SQRT(MAX(0D0,(1D0-V(IM,5)/PEM**2)*((1D0-PMQ1-PMQ2)**2-
1945 IF(V(IM,1).LT.ZL.OR.V(IM,1).GT.ZU) GOTO 350
1949 C...Accepted branch. Construct four-momentum for initial partons.
1955 P(N+1,3)=SQRT(MAX(0D0,(P(IPA(1),4)+P(N+1,5))*(P(IPA(1),4)-
1957 P(N+1,4)=P(IPA(1),4)
1959 ELSEIF(IGM.EQ.0.AND.NEP.EQ.2) THEN
1960 PED1=0.5D0*(V(IM,5)+V(N+1,5)-V(N+2,5))/P(IM,5)
1963 P(N+1,3)=SQRT(MAX(0D0,(PED1+P(N+1,5))*(PED1-P(N+1,5))))
1968 P(N+2,4)=P(IM,5)-PED1
1971 ELSEIF(NEP.GE.3) THEN
1972 C...Rescale all momenta for energy conservation.
1978 P(N+I,J)=P(IPA(I),J)
1981 PQS=PQS+P(N+I,5)**2/P(N+I,4)
1984 FAC=(PS(5)-PQS)/(PES-PQS)
1989 P(N+I,J)=FAC*P(N+I,J)
1991 P(N+I,4)=SQRT(P(N+I,5)**2+P(N+I,1)**2+P(N+I,2)**2+P(N+I,3)**2)
1994 PQS=PQS+P(N+I,5)**2/P(N+I,4)
1996 IF(LOOP.LT.10.AND.ABS(PES-PS(5)).GT.1D-12*PS(5)) GOTO 520
1998 C...Construct transverse momentum for ordinary branching in shower.
2003 PZM=SQRT(MAX(0D0,(PEM+P(IM,5))*(PEM-P(IM,5))))
2004 PMLS=(V(IM,5)-V(N+1,5)-V(N+2,5))**2-4D0*V(N+1,5)*V(N+2,5)
2007 ELSEIF(K(IM,2).EQ.21.AND.IABS(K(N+1,2)).LE.10.AND.
2008 & (MSTJ(44).EQ.3.OR.MSTJ(44).EQ.5)) THEN
2009 PTS=PMLS*ZM*(1D0-ZM)/V(IM,5)
2010 ELSEIF(MOD(MSTJ(43),2).EQ.1) THEN
2011 PTS=(PEM**2*(ZM*(1D0-ZM)*V(IM,5)-(1D0-ZM)*V(N+1,5)-
2012 & ZM*V(N+2,5))-0.25D0*PMLS)/PZM**2
2014 PTS=PMLS*(ZM*(1D0-ZM)*PEM**2/V(IM,5)-0.25D0)/PZM**2
2016 IF(PTS.LT.0D0.AND.LOOPPT.LT.10) THEN
2019 ELSEIF(PTS.LT.0D0) THEN
2022 PT=SQRT(MAX(0D0,PTS))
2024 C...Global statistics.
2025 MINT(353)=MINT(353)+1
2026 VINT(353)=VINT(353)+PT
2027 IF (MINT(353).EQ.1) VINT(358)=PT
2029 C...Find coefficient of azimuthal asymmetry due to gluon polarization.
2031 IF(MSTJ(49).NE.1.AND.MOD(MSTJ(46),2).EQ.1.AND.K(IM,2).EQ.21
2032 & .AND.IAU.NE.0) THEN
2033 IF(K(IGM,3).NE.0) MAZIP=1
2035 IF(IAU.EQ.IM+1) ZAU=1D0-V(IGM,1)
2036 IF(MAZIP.EQ.0) ZAU=0D0
2037 IF(K(IGM,2).NE.21) THEN
2038 HAZIP=2D0*ZAU/(1D0+ZAU**2)
2040 HAZIP=(ZAU/(1D0-ZAU*(1D0-ZAU)))**2
2042 IF(K(N+1,2).NE.21) THEN
2043 HAZIP=HAZIP*(-2D0*ZM*(1D0-ZM))/(1D0-2D0*ZM*(1D0-ZM))
2045 HAZIP=HAZIP*(ZM*(1D0-ZM)/(1D0-ZM*(1D0-ZM)))**2
2049 C...Find coefficient of azimuthal asymmetry due to soft gluon
2052 IF(MSTJ(49).NE.2.AND.MSTJ(46).GE.2.AND.(K(N+1,2).EQ.21.OR.
2053 & K(N+2,2).EQ.21).AND.IAU.NE.0) THEN
2054 IF(K(IGM,3).NE.0) MAZIC=N+1
2055 IF(K(IGM,3).NE.0.AND.K(N+1,2).NE.21) MAZIC=N+2
2056 IF(K(IGM,3).NE.0.AND.K(N+1,2).EQ.21.AND.K(N+2,2).EQ.21.AND.
2057 & ZM.GT.0.5D0) MAZIC=N+2
2058 IF(K(IAU,2).EQ.22) MAZIC=0
2060 IF(MAZIC.EQ.N+2) ZS=1D0-ZM
2062 IF(IAU.EQ.IM-1) ZGM=1D0-V(IGM,1)
2063 IF(MAZIC.EQ.0) ZGM=1D0
2064 IF(MAZIC.NE.0) HAZIC=(P(IM,5)/P(IGM,5))*
2065 & SQRT((1D0-ZS)*(1D0-ZGM)/(ZS*ZGM))
2066 HAZIC=MIN(0.95D0,HAZIC)
2070 C...Construct energies for ordinary branching in shower.
2071 560 IF(NEP.EQ.2.AND.IGM.GT.0) THEN
2072 IF(K(IM,2).EQ.21.AND.IABS(K(N+1,2)).LE.10.AND.
2073 & (MSTJ(44).EQ.3.OR.MSTJ(44).EQ.5)) THEN
2074 P(N+1,4)=0.5D0*(PEM*(V(IM,5)+V(N+1,5)-V(N+2,5))+
2075 & PZM*SQRT(MAX(0D0,PMLS))*(2D0*ZM-1D0))/V(IM,5)
2076 ELSEIF(MOD(MSTJ(43),2).EQ.1) THEN
2077 P(N+1,4)=PEM*V(IM,1)
2079 P(N+1,4)=PEM*(0.5D0*(V(IM,5)-SQRT(PMLS)+V(N+1,5)-V(N+2,5))+
2080 & SQRT(PMLS)*ZM)/V(IM,5)
2083 C...Already predetermined choice of phi angle or not
2086 IF(MPSPD.EQ.1.AND.IGM.EQ.NS+1) THEN
2088 IF(K(IPSPD,4).GT.0) THEN
2091 PHI=PYANGL(P(IPSGD1,1),P(IPSGD1,2))
2093 PHI=PYANGL(-P(IPSGD1,1),P(IPSGD1,2))
2096 ELSEIF(MPSPD.EQ.1.AND.IGM.EQ.NS+2) THEN
2098 IF(K(IPSPD,4).GT.0) THEN
2100 PHIPSM=PYANGL(P(IPSPD,1),P(IPSPD,2))
2101 THEPSM=PYANGL(P(IPSPD,3),SQRT(P(IPSPD,1)**2+P(IPSPD,2)**2))
2102 CALL PYROBO(IPSGD1,IPSGD1,0D0,-PHIPSM,0D0,0D0,0D0)
2103 CALL PYROBO(IPSGD1,IPSGD1,-THEPSM,0D0,0D0,0D0,0D0)
2104 PHI=PYANGL(P(IPSGD1,1),P(IPSGD1,2))
2105 CALL PYROBO(IPSGD1,IPSGD1,THEPSM,PHIPSM,0D0,0D0,0D0)
2109 C...Construct momenta for ordinary branching in shower.
2110 P(N+1,1)=PT*COS(PHI)
2111 P(N+1,2)=PT*SIN(PHI)
2112 IF(K(IM,2).EQ.21.AND.IABS(K(N+1,2)).LE.10.AND.
2113 & (MSTJ(44).EQ.3.OR.MSTJ(44).EQ.5)) THEN
2114 P(N+1,3)=0.5D0*(PZM*(V(IM,5)+V(N+1,5)-V(N+2,5))+
2115 & PEM*SQRT(MAX(0D0,PMLS))*(2D0*ZM-1D0))/V(IM,5)
2116 ELSEIF(PZM.GT.0D0) THEN
2117 P(N+1,3)=0.5D0*(V(N+2,5)-V(N+1,5)-V(IM,5)+
2118 & 2D0*PEM*P(N+1,4))/PZM
2124 P(N+2,3)=PZM-P(N+1,3)
2125 P(N+2,4)=PEM-P(N+1,4)
2126 IF(MSTJ(43).LE.2) THEN
2127 V(N+1,2)=(PEM*P(N+1,4)-PZM*P(N+1,3))/P(IM,5)
2128 V(N+2,2)=(PEM*P(N+2,4)-PZM*P(N+2,3))/P(IM,5)
2132 C...Rotate and boost daughters.
2134 IF(MSTJ(43).LE.2) THEN
2135 BEX=P(IGM,1)/P(IGM,4)
2136 BEY=P(IGM,2)/P(IGM,4)
2137 BEZ=P(IGM,3)/P(IGM,4)
2138 GA=P(IGM,4)/P(IGM,5)
2139 GABEP=GA*(GA*(BEX*P(IM,1)+BEY*P(IM,2)+BEZ*P(IM,3))/(1D0+GA)-
2148 PTIMB=SQRT((P(IM,1)+GABEP*BEX)**2+(P(IM,2)+GABEP*BEY)**2)
2149 THE=PYANGL(P(IM,3)+GABEP*BEZ,PTIMB)
2150 IF(PTIMB.GT.1D-4) THEN
2151 PHI=PYANGL(P(IM,1)+GABEP*BEX,P(IM,2)+GABEP*BEY)
2156 DP(1)=COS(THE)*COS(PHI)*P(I,1)-SIN(PHI)*P(I,2)+
2157 & SIN(THE)*COS(PHI)*P(I,3)
2158 DP(2)=COS(THE)*SIN(PHI)*P(I,1)+COS(PHI)*P(I,2)+
2159 & SIN(THE)*SIN(PHI)*P(I,3)
2160 DP(3)=-SIN(THE)*P(I,1)+COS(THE)*P(I,3)
2162 DBP=BEX*DP(1)+BEY*DP(2)+BEZ*DP(3)
2163 DGABP=GA*(GA*DBP/(1D0+GA)+DP(4))
2164 P(I,1)=DP(1)+DGABP*BEX
2165 P(I,2)=DP(2)+DGABP*BEY
2166 P(I,3)=DP(3)+DGABP*BEZ
2167 P(I,4)=GA*(DP(4)+DBP)
2171 C...Weight with azimuthal distribution, if required.
2172 IF(MAZIP.NE.0.OR.MAZIC.NE.0) THEN
2178 DPMA=DPT(1,1)*DPT(2,1)+DPT(1,2)*DPT(2,2)+DPT(1,3)*DPT(2,3)
2179 DPMD=DPT(1,1)*DPT(3,1)+DPT(1,2)*DPT(3,2)+DPT(1,3)*DPT(3,3)
2180 DPMM=DPT(1,1)**2+DPT(1,2)**2+DPT(1,3)**2
2182 DPT(4,J)=DPT(2,J)-DPMA*DPT(1,J)/MAX(1D-10,DPMM)
2183 DPT(5,J)=DPT(3,J)-DPMD*DPT(1,J)/MAX(1D-10,DPMM)
2185 DPT(4,4)=SQRT(DPT(4,1)**2+DPT(4,2)**2+DPT(4,3)**2)
2186 DPT(5,4)=SQRT(DPT(5,1)**2+DPT(5,2)**2+DPT(5,3)**2)
2187 IF(MIN(DPT(4,4),DPT(5,4)).GT.0.1D0*PARJ(82)) THEN
2188 CAD=(DPT(4,1)*DPT(5,1)+DPT(4,2)*DPT(5,2)+
2189 & DPT(4,3)*DPT(5,3))/(DPT(4,4)*DPT(5,4))
2191 IF(1D0+HAZIP*(2D0*CAD**2-1D0).LT.PYR(0)*(1D0+ABS(HAZIP)))
2195 IF(MAZIC.EQ.N+2) CAD=-CAD
2196 IF((1D0-HAZIC)*(1D0-HAZIC*CAD)/(1D0+HAZIC**2-2D0*HAZIC*CAD)
2197 & .LT.PYR(0)) GOTO 560
2202 C...Azimuthal anisotropy due to interference with initial state partons.
2203 IF(MOD(MIIS,2).EQ.1.AND.IGM.EQ.NS+1.AND.(K(N+1,2).EQ.21.OR.
2204 &K(N+2,2).EQ.21)) THEN
2206 IF(ISII(III).GE.1) THEN
2208 IF(K(N+1,2).NE.21) IAZIID=N+2
2209 IF(K(N+1,2).EQ.21.AND.K(N+2,2).EQ.21.AND.
2210 & P(N+1,4).GT.P(N+2,4)) IAZIID=N+2
2211 THEIID=PYANGL(P(IAZIID,3),SQRT(P(IAZIID,1)**2+P(IAZIID,2)**2))
2212 IF(III.EQ.2) THEIID=PARU(1)-THEIID
2213 PHIIID=PYANGL(P(IAZIID,1),P(IAZIID,2))
2214 HAZII=MIN(0.95D0,THEIID/THEIIS(III,ISII(III)))
2215 CAD=COS(PHIIID-PHIIIS(III,ISII(III)))
2216 PHIREL=ABS(PHIIID-PHIIIS(III,ISII(III)))
2217 IF(PHIREL.GT.PARU(1)) PHIREL=PARU(2)-PHIREL
2218 IF((1D0-HAZII)*(1D0-HAZII*CAD)/(1D0+HAZII**2-2D0*HAZII*CAD)
2219 & .LT.PYR(0)) GOTO 560
2223 C...Continue loop over partons that may branch, until none left.
2224 IF(IGM.GE.0) K(IM,1)=14
2227 IF(N.GT.MSTU(4)-MSTU(32)-10) THEN
2228 CALL PYERRM(11,'(PYSHOW:) no more memory left in PYJETS')
2229 IF(MSTU(21).GE.1) N=NS
2230 IF(MSTU(21).GE.1) RETURN
2234 C...Set information on imagined shower initiator.
2235 600 IF(NPA.GE.2) THEN
2239 IF(IP2.GT.0.AND.IP2.LT.IP1) K(NS+1,3)=IP2
2247 C...Reconstruct string drawing information.
2249 KQ=KCHG(PYCOMP(K(I,2)),2)
2250 IF(K(I,1).LE.10.AND.K(I,2).EQ.22) THEN
2252 ELSEIF(K(I,1).LE.10.AND.IABS(K(I,2)).GE.11.AND.
2253 & IABS(K(I,2)).LE.18) THEN
2255 ELSEIF(K(I,1).LE.10) THEN
2256 K(I,4)=MSTU(5)*(K(I,4)/MSTU(5))
2257 K(I,5)=MSTU(5)*(K(I,5)/MSTU(5))
2258 ELSEIF(K(MOD(K(I,4),MSTU(5))+1,2).NE.22) THEN
2259 ID1=MOD(K(I,4),MSTU(5))
2260 IF(KQ.EQ.1.AND.K(I,2).GT.0) ID1=MOD(K(I,4),MSTU(5))+1
2261 IF(KQ.EQ.2.AND.(K(ID1,2).EQ.21.OR.K(ID1+1,2).EQ.21).AND.
2262 & PYR(0).GT.0.5D0) ID1=MOD(K(I,4),MSTU(5))+1
2263 ID2=2*MOD(K(I,4),MSTU(5))+1-ID1
2264 K(I,4)=MSTU(5)*(K(I,4)/MSTU(5))+ID1
2265 K(I,5)=MSTU(5)*(K(I,5)/MSTU(5))+ID2
2266 K(ID1,4)=K(ID1,4)+MSTU(5)*I
2267 K(ID1,5)=K(ID1,5)+MSTU(5)*ID2
2268 K(ID2,4)=K(ID2,4)+MSTU(5)*ID1
2269 K(ID2,5)=K(ID2,5)+MSTU(5)*I
2271 ID1=MOD(K(I,4),MSTU(5))
2273 K(I,4)=MSTU(5)*(K(I,4)/MSTU(5))+ID1
2274 K(I,5)=MSTU(5)*(K(I,5)/MSTU(5))+ID1
2275 IF(KQ.EQ.1.OR.K(ID1,1).GE.11) THEN
2276 K(ID1,4)=K(ID1,4)+MSTU(5)*I
2277 K(ID1,5)=K(ID1,5)+MSTU(5)*I
2287 C...Transformation from CM frame.
2289 THE=PYANGL(P(IPA(1),3),SQRT(P(IPA(1),1)**2+P(IPA(1),2)**2))
2290 PHI=PYANGL(P(IPA(1),1),P(IPA(1),2))
2292 CALL PYROBO(NS+1,N,THE,PHI,0D0,0D0,0D0)
2293 ELSEIF(NPA.EQ.2) THEN
2298 GABEP=GA*(GA*(BEX*P(IPA(1),1)+BEY*P(IPA(1),2)+BEZ*P(IPA(1),3))
2299 & /(1D0+GA)-P(IPA(1),4))
2300 THE=PYANGL(P(IPA(1),3)+GABEP*BEZ,SQRT((P(IPA(1),1)
2301 & +GABEP*BEX)**2+(P(IPA(1),2)+GABEP*BEY)**2))
2302 PHI=PYANGL(P(IPA(1),1)+GABEP*BEX,P(IPA(1),2)+GABEP*BEY)
2304 CALL PYROBO(NS+1,N,THE,PHI,BEX,BEY,BEZ)
2306 CALL PYROBO(IPA(1),IPA(NPA),0D0,0D0,PS(1)/PS(4),PS(2)/PS(4),
2309 CALL PYROBO(NS+1,N,0D0,0D0,PS(1)/PS(4),PS(2)/PS(4),PS(3)/PS(4))
2312 C...Decay vertex of shower.
2319 C...Delete trivial shower, else connect initiators.
2320 IF(N.LE.NS+NPA+IIM) THEN
2325 K(IPA(IP),4)=K(IPA(IP),4)+NS+IIM+IP
2326 K(IPA(IP),5)=K(IPA(IP),5)+NS+IIM+IP
2327 K(NS+IIM+IP,3)=IPA(IP)
2328 IF(IIM.EQ.1.AND.MSTU(16).NE.2) K(NS+IIM+IP,3)=NS+1
2329 IF(K(NS+IIM+IP,1).NE.1) THEN
2330 K(NS+IIM+IP,4)=MSTU(5)*IPA(IP)+K(NS+IIM+IP,4)
2331 K(NS+IIM+IP,5)=MSTU(5)*IPA(IP)+K(NS+IIM+IP,5)
2339 SUBROUTINE QPYGIN(X0,Y0,Z0,T0)
2340 C USER-DEFINED ROUTINE: IT SETS THE INITIAL POSITION AND TIME OF THE
2341 C PARENT BRANCHING PARTON (X, Y, Z, T, IN FM) IN THE CENTER-OF-MASS
2342 C FRAME OF THE HARD COLLISION (IF APPLICABLE FOR THE TYPE OF EVENTS
2343 C YOU ARE SIMULATING). INFORMATION ABOUT THE BOOST AND ROTATION IS
2344 C CONTAINED IN THE IN COMMON QPLT BELOW.
2345 IMPLICIT DOUBLE PRECISION (A-H,O-Z)
2346 C NOW THE COMMON CONTAINING THE VALUES OF THE TWO ANGLES AND THREE BOSST
2347 C PARAMETERS USED, IN PYSHOW, TO CHANGE THROUGH PYROBO FROM THE
2348 C CENTER-OF-MASS OF THE COLLISION TO THE CENTER-OF-MASS OF THE HARD
2349 C SCATTERING. THEY ARE THE ENTRIES THREE TO SEVEN IN ROUTINE PYROBO.
2350 COMMON/QPLT/AA1,AA2,BBX,BBY,BBZ
2352 c Here the transverse coordinates of the hard scattering are set by
2354 call GetRandomXY(xrang,yrang)
2363 SUBROUTINE QPYGEO(x,y,z,t,bx,by,bz,qhl,oc)
2364 C USER-DEFINED ROUTINE:
2365 C The values of qhatL and omegac have to be computed
2366 C by the user, using his preferred medium model, in
2367 C this routine, which takes as input the position
2368 C x,y,z,t (in fm) of the parton to branch, the trajectory
2369 C defined by the three-vector bx,by,bz (in units of c),
2370 C (all values in the center-of-mass frame of the
2371 C hard collision), and returns the value of qhatL
2372 C (in GeV**2) and omegac (in GeV).
2373 IMPLICIT DOUBLE PRECISION (A-H,O-Z)
2374 C NOW THE COMMON CONTAINING THE VALUES OF THE TWO ANGLES AND THREE BOSST
2375 C PARAMETERS USED, IN PYSHOW, TO CHANGE THROUGH PYROBO FROM THE
2376 C CENTER-OF-MASS OF THE COLLISION TO THE CENTER-OF-MASS OF THE HARD
2377 C SCATTERING. THEY ARE THE ENTRIES THREE TO SEVEN IN ROUTINE PYROBO.
2378 COMMON/QPLT/AA1,AA2,BBX,BBY,BBZ
2379 COMMON/PYDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
2383 c Here we give five options for the geometry of the medium:
2386 c (0) we call routine CalculateI0I1 in AliFastGlauber. Given the position
2387 c of the parton in the reaction plane (x,y), the direction in the
2388 c reaction plane phi=atan(py/px) and the impact parameter of the
2389 c collision bimp, it gives back the transverse path length to the
2390 c "end" of the medium and the integrated qhat along that path length.
2391 c See the seter for this option in Configqpythia.C(one can set the
2392 c value of xkscale by doing SetQhat(xkscale), with xkscale in fm).
2393 c The set value is passed here through the pythia free parameter parj(198).
2400 if((bx.eq.0.d0).and.(by.eq.0.d0)) then
2404 phi=dacos(-1.d0)-aa2
2407 bx1=dcos(aa2)*bx+dsin(-1.d0*aa2)*by
2408 by1=dsin(aa2)*bx+dcos(aa2)*by
2417 call CalculateI0I1(xlcero,xlone,bimpa,xa,ya,phia,ellcuta)
2418 if(xlcero.eq.0.d0) then
2422 xlp=2.d0*xlone/xlcero
2423 qhl=0.1973d0*0.1973d0*xlcero*xkscale !GeV**2
2426 c To use any of these folowing 1,2,3 or 4 options the user should specify
2427 c a constant value for the transport coefficient and an initial in medium length.
2428 c This can be done in the user Config file by setting: SetQhat(qhat), with qhat in
2429 c GeV2/fm and SetLength(xl), with xl in fm. Those values are passed here through
2430 c pythia free parameters parj(198) and parj(199).
2432 c (1) to fix the length to the initial value, uncomment the next three lines
2433 c and comment the other definitions of xlp and qhl above and below.
2435 c if (xlp .lt. 0.d0) xlp=0.d0
2436 c qhl=xlp*qhat ! GeV**2
2438 c (2) simplest ansatz: for an initial parton along the z-axis (approximate)
2439 c starting in the center of a medium (-xl,+xl) along the z-axis
2440 c if (bz .gt. 0.d0) then
2445 c if (xlp .gt. (2.d0*xl)) xlp=2.d0*xl
2446 c if (xlp .lt. 0.d0) xlp=0.d0
2447 c qhl=xlp*qhat ! GeV**2
2449 c (3) for a parton at midrapidity inside a cylinder (approximate)
2450 c xlp=xl-dsqrt(x*x+y*y)
2451 c if (xlp .lt. 0.d0) xlp=0.d0
2452 c qhl=xlp*qhat ! GeV**2
2454 c (4) for a brick defined by planes (x,y,0) and (x,y,xl), comment
2455 c the previous lines and uncomment lines between the comment 'brick'.
2457 c if (z .ge. 0.d0 .and. z .le. xl)
2459 c if (bz .gt. 0.d0) then
2461 c xlp=dsqrt((bx*ttpp)**2.d0+(by*ttpp)**2.d0+
2465 c xlp=dsqrt((bx*ttpp)**2.d0+(by*ttpp)**2.d0+
2468 c elseif (z .lt. 0.d0) then
2469 c if (bz .lt. 0.d0) then
2478 c xlp=dsqrt((xxpp1-xxpp2)**2.d0+(yypp1-yypp2)**2.d0+
2481 c elseif (z .gt. xl) then
2482 c if (bz .gt. 0.d0) then
2486 c ttpp2=(-xl+z)/dabs(bz)
2491 c xlp=dsqrt((xxpp1-xxpp2)**2.d0+(yypp1-yypp2)**2.d0+
2495 c if (xlp .lt. 0.d0) xlp=0.d0
2496 c qhl=xlp*qhat ! GeV**2
2499 oc=0.5d0*qhl*xlp/0.1973d0 ! GeV