pythiaeRHIC/pythia/pystbh.f

0001
0002 C*********************************************************************
0003
0004 C...PYSTBH (and auxiliaries)
0005 C.. Evaluates the matrix elements for t + b + H production.
0006
0007       SUBROUTINE PYSTBH(WTTBH)
0008
0009 C...DOUBLE PRECISION AND INTEGER DECLARATIONS
0010       IMPLICIT DOUBLE PRECISION(A-H, O-Z)
0011       IMPLICIT INTEGER(I-N)
0012       INTEGER PYK,PYCHGE,PYCOMP
0013
0014 C...COMMONBLOCKS
0015       COMMON/PYDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
0016       COMMON/PYDAT2/KCHG(500,4),PMAS(500,4),PARF(2000),VCKM(4,4)
0017       COMMON/PYPARS/MSTP(200),PARP(200),MSTI(200),PARI(200)
0018       COMMON/PYINT1/MINT(400),VINT(400)
0019       COMMON/PYINT2/ISET(500),KFPR(500,2),COEF(500,20),ICOL(40,4,2)
0020       COMMON/PYINT3/XSFX(2,-40:40),ISIG(1000,3),SIGH(1000)
0021       COMMON/PYINT4/MWID(500),WIDS(500,5)
0022       COMMON/PYSUBS/MSEL,MSELPD,MSUB(500),KFIN(2,-40:40),CKIN(200)
0023       COMMON/PYMSSM/IMSS(0:99),RMSS(0:99)
0024       COMMON/PYSGCM/ISUB,ISUBSV,MMIN1,MMAX1,MMIN2,MMAX2,MMINA,MMAXA,
0025      &KFAC(2,-40:40),COMFAC,FACK,FACA,SH,TH,UH,SH2,TH2,UH2,SQM3,SQM4,
0026      &SHR,SQPTH,TAUP,BE34,CTH,X(2),SQMZ,SQMW,GMMZ,GMMW,
0027      &AEM,AS,XW,XW1,XWC,XWV,POLL,POLR,POLLL,POLRR
0028       COMMON/PYCTBH/ ALPHA,ALPHAS,SW2,MW2,TANB,VTB,V,A
0029       DOUBLE PRECISION MW2
0030       SAVE /PYDAT1/,/PYDAT2/,/PYPARS/,/PYINT1/,/PYINT2/,/PYINT3/,
0031      &/PYINT4/,/PYSUBS/,/PYMSSM/,/PYSGCM/,/PYCTBH/
0032
0033 C...LOCAL ARRAYS AND COMPLEX VARIABLES
0034       DIMENSION QQ(4,2),PP(4,3)
0035       DATA QQ/8*0D0/
0036
0037       WTTBH=0D0
0038
0039 C...KINEMATIC PARAMETERS.
0040       SHPR=SQRT(VINT(26))*VINT(1)
0041       PH=SQRT(VINT(21))*VINT(1)
0042       SPH=PH**2
0043
0044 C...SET UP OUTGOING KINEMATICS: 1=T, 2=TBAR, 3=H.
0045       DO 100 I=1,2
0046         PT=SQRT(MAX(0D0,VINT(197+5*I)))
0047         PP(1,I)=PT*COS(VINT(198+5*I))
0048         PP(2,I)=PT*SIN(VINT(198+5*I))
0049   100 CONTINUE
0050       PP(1,3)=-PP(1,1)-PP(1,2)
0051       PP(2,3)=-PP(2,1)-PP(2,2)
0052       PMS1=VINT(201)**2+PP(1,1)**2+PP(2,1)**2
0053       PMS2=VINT(206)**2+PP(1,2)**2+PP(2,2)**2
0054       PMS3=SPH+PP(1,3)**2+PP(2,3)**2
0055       PMT3=SQRT(PMS3)
0056       PP(3,3)=PMT3*SINH(VINT(211))
0057       PP(4,3)=PMT3*COSH(VINT(211))
0058       PMS12=(SHPR-PP(4,3))**2-PP(3,3)**2
0059       PP(3,1)=(-PP(3,3)*(PMS12+PMS1-PMS2)+
0060      &VINT(213)*(SHPR-PP(4,3))*VINT(220))/(2D0*PMS12)
0061       PP(3,2)=-PP(3,1)-PP(3,3)
0062       PP(4,1)=SQRT(PMS1+PP(3,1)**2)
0063       PP(4,2)=SQRT(PMS2+PP(3,2)**2)
0064
0065 C...CM SYSTEM, INGOING QUARKS/GLUONS
0066       QQ(3,1) = SHPR/2.D0
0067       QQ(4,1) = QQ(3,1)
0068       QQ(3,2) = -QQ(3,1)
0069       QQ(4,2) = QQ(4,1)
0070
0071 C...PARAMETERS FOR AMPLITUDE METHOD
0072       ALPHA = AEM
0073       ALPHAS = AS
0074       SW2 = PARU(102)
0075       MW2 = PMAS(24,1)**2
0076       TANB = PARU(141)
0077       VTB = VCKM(3,3)
0078       RMB=PYMRUN(5,VINT(52))
0079
0080       ISUB=MINT(1)
0081
0082       IF (ISUB.EQ.401) THEN
0083         CALL PYTBHG(QQ(1,1),QQ(1,2),PP(1,1),PP(1,2),PP(1,3),
0084      &  VINT(201),VINT(206),RMB,VINT(43),WTTBH)
0085       ELSE IF (ISUB.EQ.402) THEN
0086         CALL PYTBHQ(QQ(1,1),QQ(1,2),PP(1,1),PP(1,2),PP(1,3),
0087      &  VINT(201),VINT(206),RMB,VINT(43),WTTBH)
0088       END IF
0089
0090       RETURN
0091       END