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- Committer: Chia-Hsien Shen
- Date: 2012-06-30 05:53:02 UTC
- mto: (36.21.97 decay_calculator_205) (238.3.11 1.6.0)
- mto: This revision was merged to the branch mainline in revision 249.
- Revision ID: anakin8120@gmail.com-20120630055302-5azmh3tx4vv2hlp1
move ./decay to ./mg5decay; resolve unit tests (n.b. __init__ does not check keys of input dictionaries, followed last revision)
- files added:
- DECAY
- mg5decay
- files removed:
- MG4_DECAY
- files modified:
- tests/input_files/full_sm_UFO/model.pkl
added
removed
DECAY/decay_mom.f
1
c***********************************************************************
2
c Routines for generating momentum of decay products
3
c***********************************************************************
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SUBROUTINE PHASESPACE(PD,PSWGT)
6
C************************************************************************
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C WRAPPER FOR CALLING THE PHASE SPACE ROUTINES
8
C************************************************************************
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IMPLICIT NONE
10
include 'decay.inc'
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C
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C ARGUMENTS
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C
14
REAL*8 PD(0:3,MaxDecPart)
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REAL*8 PSWGT
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C
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C LOCAL
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C
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LOGICAL DONE
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INTEGER IMAX
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C
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C----------
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C START
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C----------
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C
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PSWGT=0d0
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IMAX=0
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IF(ND.EQ.2) THEN
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CALL TWOMOM(PD(0,1),PD(0,2),PD(0,3),PSWGT)
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ELSEIF(ND.EQ.3) THEN
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CALL THREEMOM(PD(0,1),PD(0,2),PD(0,3),PD(0,4),PSWGT)
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ELSEIF(ND.EQ.4) THEN
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CALL FOURMOM(PD(0,1),PD(0,2),PD(0,3),PD(0,4),PD(0,5),PSWGT)
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ELSE
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WRITE(*,*) 'NO PS AVAILABLE '
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STOP
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ENDIF
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RETURN
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END
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SUBROUTINE TWOMOM(P1,P2,P3,PSWGT)
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C************************************************************************
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C GENERIC TWO BODY PHACE SPACE FOR THE DECAYS P1->P2+P3
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C
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C GIVEN P1 MOMENTUM SETS UP THE MOMENTA P2,P3
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C ALSO SETS UP THE APPROPRIATE PHASESPACE WEIGTH PSWGT
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C
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C X(1) = COSTHETA OF FIRST DECAY
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C X(2) = PHI OF FIRST DECAY
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C
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C************************************************************************
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IMPLICIT NONE
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include 'decay.inc'
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C
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C ARGUMENTS
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C
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REAL*8 P1(0:3),P2(0:3),P3(0:3)
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REAL*8 PSWGT
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C
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C LOCAL
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C
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REAL*8 COSTH,PHI,JACPOLE
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REAL*8 RS
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REAL*8 XA2,XB2,S,JAC
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REAL*8 a
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integer i
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C
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C EXTERNAL
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C
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REAL*8 LAMBDA,DOT
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C
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C----------
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C BEGIN
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C----------
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C
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C CMS ENERGY = (P1)^2
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C
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S=DOT(P1,P1)
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RS=SQRT(S)
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C
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C PICK VALUE OF THETA AND PHI
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C
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COSTH=-1.D0+2.D0*X(1)
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PHI = 2D0*PI*X(2)
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C
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C DETERMINE JACOBIAN FOR THETA AND PHI
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C
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JAC = 4D0*PI
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C
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C CALCULATE COMPONENTS OF MOMENTUM FOUR-VECTORS
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C OF THE FINAL STATE MASSLESS PARTONS IN THEIR CM FRAME
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C
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CALL MOM2CX(RS,M2,M3,COSTH,PHI,P2,P3) !DECAY P1
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CALL BOOSTX(P2,P1,P2) !BOOST DECAY TO LAB
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CALL BOOSTX(P3,P1,P3) !BOOST DECAY TO LAB
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C
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JAC = JAC /(2D0*PI)**2 !FOR THE (2 PI)^3N-4 OUT FRONT
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C
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C CALCULATE PHASE SPACE FACTOR DSIG/DCOS(THETA)
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C
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PSWGT = 1.D0/(2.D0*RS) !FLUX FACTOR
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XA2 = M2*M2/S
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XB2 = M3*M3/S
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PSWGT = PSWGT*.5D0*PI*SQRT(LAMBDA(ONE,XA2,XB2))/(4.D0*PI)
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PSWGT=PSWGT*JAC
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c write(*,*) 'from decay_mom',x(1),x(2),pswgt
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RETURN
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END
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SUBROUTINE THREEMOM(P1,P2,P3,P4,PSWGT)
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C************************************************************************
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C This routine generates the momenta for the decay products of
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C
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C 1 -> 2 W -> 2 3 4
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C
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C when the W can be on-shell or not.
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C It ALSO SETS UP THE APPROPRIATE PHASESPACE WEIGTH PSWGT
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C
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C X(1) = COSTHETA OF FIRST DECAY TOP -> W*+B
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C X(2) = PHI OF FIRST DECAY TOP -> W*+B
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C X(3) = M_W*
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C X(4) = COSTHETA OF DECAY W* -> E+VE
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C X(5) = PHI OF DECAY W* -> E+VE
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C
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C************************************************************************
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IMPLICIT NONE
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include 'decay.inc'
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C
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C ARGUMENTS
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C
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REAL*8 P1(0:3),P2(0:3),P3(0:3),P4(0:3),PW(0:3)
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REAL*8 PSWGT
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C
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C LOCAL
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C
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REAL*8 COSTH,PHI,JACPOLE
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REAL*8 RS
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REAL*8 COSTH1,PHI1,S1,RS1
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REAL*8 COSTH2,PHI2,S2,RS2
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REAL*8 XA2,XB2,S,JAC
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REAL*8 a
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INTEGER I
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C
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C EXTERNAL
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C
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REAL*8 LAMBDA,DOT
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C
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C LOGICAL
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C
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LOGICAL FIRSTTIME
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DATA FIRSTTIME /.TRUE./
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C
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C----------
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C BEGIN
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C----------
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C
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C CMS ENERGY
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C
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S=DOT(P1,P1)
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RS=SQRT(S)
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IF(RS.GT.(M2+MV)) THEN ! W CAN BE ON SHELL
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CALL TRANSPOLE(MV**2/S,MV*GV/S,X(3),S2,JACPOLE)
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S2 = S2*S
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RS2 = SQRT(S2)
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JAC=JACPOLE*S
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ELSE ! W is off-shell
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S2=(S-M2*M2)*X(3)+M2*M2 ! generated uniformily
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RS2 = SQRT(S2)
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JAC=(S-M2*M2)
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ENDIF
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C
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C check total energy conservation
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C
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IF(RS2.GE.(RS-M2).or.RS2.LT.(M3+M4)) THEN
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PSWGT=0D0
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RETURN
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ENDIF
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C
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C PICK VALUE OF THETA AND PHI FOR FIRST DECAY TOP -> W*+B
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C
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COSTH=-1.D0+2.D0*X(1)
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PHI = 2D0*PI*X(2)
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C
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C DETERMINE JACOBIAN FOR THETA AND PHI
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C
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JAC = JAC * 4D0*PI
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C
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C CHOOSE COS(THETA) AND PHI FOR DECAY W*-> E+VE
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C
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COSTH1 = -1 + 2.*X(4)
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PHI1 = 2D0*PI*X(5)
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C
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C JACOBIAN FACTOR FOR DECAY OF W*-> E+VE
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C
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JAC=JAC*4D0*PI
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C
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C CALCULATE COMPONENTS OF MOMENTUM FOUR-VECTORS
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C OF THE FINAL STATE MASSLESS PARTONS IN THEIR CM FRAME
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C
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CALL MOM2CX(RS,RS2,M2,COSTH ,PHI ,PW,P2) !DECAY 1
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CALL MOM2CX(RS2,M3,M4,COSTH1,PHI1,P3,P4) !DECAY W*
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CALL BOOSTX(P2,P1,P2) !BOOST DECAY TO LAB
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CALL BOOSTX(PW,P1,PW) !BOOST DECAY TO LAB
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CALL BOOSTX(P3,PW,P3) !BOOST DECAY TO LAB
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CALL BOOSTX(P4,PW,P4) !BOOST DECAY TO LAB
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JAC = JAC /(2D0*PI)**5 !FOR THE (2 PI)^3N-4 OUT FRONT
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C
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C CALCULATE PHASE SPACE FACTOR DSIG/DCOS(THETA)
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C
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PSWGT = 1.D0/(2.D0*RS) !FLUX FACTOR
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XA2 = S2/S
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XB2 = M2*M2/S
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PSWGT = PSWGT*.5D0*PI*SQRT(LAMBDA(ONE,XA2,XB2))/(4.D0*PI) !T->W*+B
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XA2 = M3*M3/S
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XB2 = M4*M4/S
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PSWGT = PSWGT*.5D0*PI*SQRT(LAMBDA(ONE,XA2,XB2))/(4.D0*PI) !W*->E+VE
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PSWGT=PSWGT*JAC
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RETURN
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END
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SUBROUTINE FOURMOM(P1,P2,P3,P4,P5,PSWGT)
238
C************************************************************************
239
C This routine generates the momenta for the decay products of
240
C
241
C 1 -> v v'* -> 2 3 4 5
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C
243
C where the v'* can be on-shell or not.
244
c
245
C GIVEN X(8) AND THE P1 MOMENTUM SETS UP THE MOMENTA
246
C ALSO SETS UP THE APPROPRIATE PHASESPACE WEIGTH PSWGT
247
C
248
C X(1) = COSTHETA OF FIRST DECAY SH -> M_(2+3)+M_(4,5)
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C X(2) = PHI OF FIRST DECAY SH -> M_(2+3)+M_(4,5)
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C X(3) = M_(2,3)
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C X(4) = M_(4,5)
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C X(5) = COSTHETA OF DECAY M_(2,3) -> M2+M3
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C X(6) = PHI OF FIRST DECAY M_(2,3) -> M2+M3
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C X(7) = COSTHETA OF DECAY M_(4,5) -> M4+M5
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C X(8) = PHI OF FIRST DECAY M_(4,5) -> M4+M5
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C
257
C************************************************************************
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IMPLICIT NONE
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include "decay.inc"
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C
261
C ARGUMENTS
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C
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REAL*8 P1(0:3),P2(0:3),P3(0:3),P4(0:3),P5(0:3)
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REAL*8 PSWGT
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C
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C LOCAL
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C
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REAL*8 JAC,JACPOLE
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REAL*8 RSH,SH,COSINIT,PHIINIT,COSTH,PHI
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REAL*8 COSTH1,PHI1,S1,PTEMP1(0:3),X3MIN,X3MAX,RS1
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REAL*8 COSTH2,PHI2,S2,PTEMP2(0:3),X4MIN,X4MAX,RS2
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REAL*8 XA2,XB2,SMIN
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REAL*8 TEMP
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INTEGER I
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C
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C EXTERNAL
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C
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REAL*8 LAMBDA,DOT
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real xran1
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integer iseed
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data iseed/1/ !no effect if already called
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C
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C LOGICAL
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C
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LOGICAL FIRSTTIME
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DATA FIRSTTIME /.TRUE./
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C
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C----------
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C BEGIN
290
C----------
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c
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JAC=1D0
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C
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C CMS ENERGY = (HIGGS MASS)^2
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C
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SH=DOT(P1,P1)
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RSH=SQRT(SH)
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C
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C PICK VALUE OF THETA AND PHI FOR FIRST DECAY SH->M3+S1
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C
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COSTH=-1.D0+2.D0*X(1)
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PHI = 2D0*PI*X(2)
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C
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C DETERMINE JACOBIAN FOR THETA AND PHI
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C
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JAC = JAC * 4D0*PI
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C
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C MASSES OF THE DECAY 1->V V
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C
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IF(RSH.GT.MV) THEN ! AT LEAST A W CAN BE ON SHELL
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CALL TRANSPOLE(MV**2/SH,MV*GV/SH,X(3),S1,JACPOLE)
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S1 = S1*SH
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RS1 = SQRT(S1)
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JAC=JACPOLE*SH*JAC
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ELSE ! NO W'S CAN BE ON SHELL
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S1=SH*X(3) ! generated uniformily
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RS1 = SQRT(S1)
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JAC=SH*JAC
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ENDIF
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IF(RS1.GE.RSH) THEN ! ENERGY CONSERVATION
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PSWGT=0D0
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RETURN
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ENDIF
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C
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C DETERMINE INVARIENT MASS OF SYSTEM M4+M5
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C
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IF(RSH-RS1.GT.MV) THEN ! THE SECOND W CAN BE ON-SHELL
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CALL TRANSPOLE(MV**2/SH,MV*GV/SH,X(4),S2,JACPOLE)
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S2 = S2*SH
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RS2 = SQRT(S2)
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JAC=JACPOLE*SH*JAC
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else ! the second w cannot be on-shell
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c X4MIN = (M4+M5)**2/SH
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X4MIN = 0d0 ! less efficient but symmetric in m2,m3 <-> m4,m5
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X4MAX = (1D0-RS1/RSH)**2
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S2 = ((X4MAX-X4MIN)*X(4)+X4MIN)*SH
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RS2 = SQRT(S2)
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JAC = JAC*SH*(X4MAX-X4MIN)
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ENDIF
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IF(RS2+RS1.GT.RSH) THEN ! ENERGY CONSERVATION
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PSWGT=0D0
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RETURN
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ENDIF
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c
347
c switch order to ensure no bias
348
c
349
IF(xran1(iseed).lt.0.5e0)then
350
temp=rs1
351
rs1=rs2
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rs2=temp
353
temp=s1
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s1=s2
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s2=temp
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ENDIF
357
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IF(RS1 .LT. (M2+M3)) THEN ! MINIMUM inv mass
359
PSWGT=0D0
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RETURN
361
ENDIF
362
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IF(RS2 .LT. (M4+M5)) THEN ! MINIMUM inv mass
364
PSWGT=0D0
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RETURN
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ENDIF
367
368
369
C
370
C CHOOSE COS(THETA) AND PHI FOR DECAY S1->M3+M4
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C
372
COSTH1 = -1 + 2.*X(5)
373
PHI1 = 2D0*PI*X(6)
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C
375
C CHOOSE COS(THETA) AND PHI FOR DECAY S2->M4+M5
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C
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COSTH2 = -1 + 2.*X(7)
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PHI2 = 2D0*PI*X(8)
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C
380
C JACOBIAN FACTOR FOR DECAY OF S1->M3+M4
381
C
382
JAC=JAC*4D0*PI
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C
384
C JACOBIAN FACTOR FOR DECAY OF S2->M4+M5
385
C
386
JAC=JAC*4D0*PI
387
C
388
C CALCULATE COMPONENTS OF MOMENTUM FOUR-VECTORS
389
C OF THE FINAL STATE
390
C
391
CALL MOM2CX(RSH,RS1,RS2,COSTH,PHI,PTEMP1,PTEMP2)
392
CALL MOM2CX(RS1,M2,M3,COSTH1,PHI1,P2,P3) !DECAY PTEMP1
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CALL MOM2CX(RS2,M4,M5,COSTH2,PHI2,P4,P5) !DECAY PTEMP2
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CALL BOOSTX(PTEMP1,P1,PTEMP1) !BOOST DECAY TO CM
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CALL BOOSTX(PTEMP2,P1,PTEMP2) !BOOST DECAY TO CM
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CALL BOOSTX(P2,PTEMP1,P2) !BOOST DECAY TO CM
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CALL BOOSTX(P3,PTEMP1,P3) !BOOST DECAY TO CM
398
CALL BOOSTX(P4,PTEMP2,P4) !BOOST DECAY TO CM
399
CALL BOOSTX(P5,PTEMP2,P5) !BOOST DECAY TO CM
400
C
401
C
402
JAC = JAC /(2D0*PI)**8 !FOR THE (2 PI)^3N-4 OUT FRONT
403
C
404
C
405
C CALCULATE PHASE SPACE FACTOR DSIG/DCOS(THETA)
406
C
407
408
PSWGT = 1.D0/(2.D0*RSH) !FLUX FACTOR
409
XA2 = S1/SH
410
XB2 = S2/SH
411
PSWGT = PSWGT*.5D0*PI*SQRT(LAMBDA(ONE,XA2,XB2))/(4.D0*PI) !S->S1+S2
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XA2 = M2*M2/S1
413
XB2 = M3*M3/S1
414
PSWGT = PSWGT*.5D0*PI*SQRT(LAMBDA(ONE,XA2,XB2))/(4.D0*PI) !S1->M2+M3
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XA2 = M4*M4/S2
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XB2 = M5*M5/S2
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PSWGT = PSWGT*.5D0*PI*SQRT(LAMBDA(ONE,XA2,XB2))/(4.D0*PI) !S2->M4+M5
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419
PSWGT=PSWGT*JAC
420
421
422
423
RETURN
424
END
425
426
427
REAL*8 FUNCTION LAMBDA(S,MA2,MB2)
428
IMPLICIT NONE
429
C****************************************************************************
430
C THIS IS THE LAMBDA FUNCTION FROM VERNONS BOOK COLLIDER PHYSICS P 662
431
C MA2 AND MB2 ARE THE MASS SQUARED OF THE FINAL STATE PARTICLES
432
C 2-D PHASE SPACE = .5*PI*SQRT(1.,MA2/S^2,MB2/S^2)*(D(OMEGA)/4PI)
433
C****************************************************************************
434
REAL*8 MA2,MB2,S
435
LAMBDA=S**2+MA2**2+MB2**2-2.*S*MA2-2.*MA2*MB2-2.*S*MB2
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RETURN
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END
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439
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SUBROUTINE TRANSPOLE(POLE,WIDTH,X,Y,JAC)
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C**********************************************************************
442
C THIS ROUTINE TRANSFERS EVENLY SPACED X VALUES BETWEEN 0 AND 1
443
C TO Y VALUES WITH A POLE AT Y=POLE WITH WIDTH WIDTH AND RETURNS
444
C THE APPROPRIATE JACOBIAN FOR THIS
445
C**********************************************************************
446
IMPLICIT NONE
447
C
448
C ARGUMENTS
449
C
450
REAL*8 POLE,WIDTH,Y,JAC
451
REAL*4 X
452
C
453
C LOCAL
454
C
455
REAL*8 Z,ZMIN,ZMAX
456
c-----
457
c Begin Code
458
c-----
459
460
ZMIN = ATAN((-POLE)/WIDTH)/WIDTH
461
ZMAX = ATAN((1.-POLE)/WIDTH)/WIDTH
462
Z = ZMIN+(ZMAX-ZMIN)*X
463
Y = POLE+WIDTH*TAN(WIDTH*Z)
464
JAC= (WIDTH/COS(WIDTH*Z))**2*(ZMAX-ZMIN)
465
RETURN
466
END
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