tW generation

Asked by Mar on 2018-04-24

Hi everyone, my question is the next one. I'm trying to generate p p > t~ W+ [QCD], add process p p > t W- [QCD]. There are no processes, so I need to import model sm-ckm. But then I cannot launch it, because it stays for hours doing nothing. I'm using 4F. The same problem with p p > t w b, this time with no model imported besides sm. How do I run these processes at NLO?

Thank you!

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
marco zaro Edit question
Solved by:
marco zaro
Solved:
2018-05-02
Last query:
2018-05-02
Last reply:
2018-04-26
marco zaro (marco-zaro) said : #1

Hi Mar,
the problem with tw production is that, in the 5FS, the real emission can have contributions like g g> t W b with intermediate on-shell top, which need to be subtracted.
You can find details here
arXiv:1607.05862
Unfortunately, the automation of the subtraction used in that paper is not yet complete, so I don't think there is an easy way out (unless you kill the diagrams with intermediate tops by hand).
Note that if you do this in the 4FS, then the same problems will appear at the born level.
Let me know if you need more help on this.
Best,

Marco

Mar (septembris-forest) said : #2

Hi Marco, thank you for answering so quickly!

I've been reading that paper, it says that I should set to zero the top mass amplitudes (if I want to treat it with the DR1) in the files matrix_*.f, in the cases, as you said, where t is intermeadiate. Where exactly can I find that in the file? I haven't been able to find it so far, I'm sorry. This is one of the files

      SUBROUTINE SMATRIX_3(P,ANS)
C
C Generated by MadGraph5_aMC@NLO v. 2.6.0, 2017-08-16
C By the MadGraph5_aMC@NLO Development Team
C Visit launchpad.net/madgraph5 and amcatnlo.web.cern.ch
C
C Returns amplitude squared summed/avg over colors
C and helicities
C for the point in phase space P(0:3,NEXTERNAL)
C
C Process: u~ g > w- t b~ u~ WEIGHTED<=5 [ all = QCD ]
C Process: c~ g > w- t b~ c~ WEIGHTED<=5 [ all = QCD ]
C Process: d~ g > w- t b~ d~ WEIGHTED<=5 [ all = QCD ]
C Process: s~ g > w- t b~ s~ WEIGHTED<=5 [ all = QCD ]
C
      IMPLICIT NONE
C
C CONSTANTS
C
      INCLUDE 'nexternal.inc'
      INTEGER NCOMB
      PARAMETER ( NCOMB=96)
C
C ARGUMENTS
C
      REAL*8 P(0:3,NEXTERNAL),ANS
      DOUBLE PRECISION WGT_ME_BORN,WGT_ME_REAL
      COMMON /C_WGT_ME_TREE/ WGT_ME_BORN,WGT_ME_REAL
C
C LOCAL VARIABLES
C
      INTEGER IHEL,IDEN,I,T_IDENT(NCOMB)
      REAL*8 MATRIX_3
      REAL*8 T,T_SAVE(NCOMB)
      SAVE T_SAVE,T_IDENT
      INTEGER NHEL(NEXTERNAL,NCOMB)
      DATA (NHEL(I, 1),I=1,6) /-1,-1, 1,-1, 1, 1/
      DATA (NHEL(I, 2),I=1,6) /-1,-1, 1,-1, 1,-1/
      DATA (NHEL(I, 3),I=1,6) /-1,-1, 1,-1,-1, 1/
      DATA (NHEL(I, 4),I=1,6) /-1,-1, 1,-1,-1,-1/
      DATA (NHEL(I, 5),I=1,6) /-1,-1, 1, 1, 1, 1/
      DATA (NHEL(I, 6),I=1,6) /-1,-1, 1, 1, 1,-1/
      DATA (NHEL(I, 7),I=1,6) /-1,-1, 1, 1,-1, 1/
      DATA (NHEL(I, 8),I=1,6) /-1,-1, 1, 1,-1,-1/
      DATA (NHEL(I, 9),I=1,6) /-1,-1, 0,-1, 1, 1/
      DATA (NHEL(I, 10),I=1,6) /-1,-1, 0,-1, 1,-1/
      DATA (NHEL(I, 11),I=1,6) /-1,-1, 0,-1,-1, 1/
      DATA (NHEL(I, 12),I=1,6) /-1,-1, 0,-1,-1,-1/
      DATA (NHEL(I, 13),I=1,6) /-1,-1, 0, 1, 1, 1/
      DATA (NHEL(I, 14),I=1,6) /-1,-1, 0, 1, 1,-1/
      DATA (NHEL(I, 15),I=1,6) /-1,-1, 0, 1,-1, 1/
      DATA (NHEL(I, 16),I=1,6) /-1,-1, 0, 1,-1,-1/
      DATA (NHEL(I, 17),I=1,6) /-1,-1,-1,-1, 1, 1/
      DATA (NHEL(I, 18),I=1,6) /-1,-1,-1,-1, 1,-1/
      DATA (NHEL(I, 19),I=1,6) /-1,-1,-1,-1,-1, 1/
      DATA (NHEL(I, 20),I=1,6) /-1,-1,-1,-1,-1,-1/
      DATA (NHEL(I, 21),I=1,6) /-1,-1,-1, 1, 1, 1/
      DATA (NHEL(I, 22),I=1,6) /-1,-1,-1, 1, 1,-1/
      DATA (NHEL(I, 23),I=1,6) /-1,-1,-1, 1,-1, 1/
      DATA (NHEL(I, 24),I=1,6) /-1,-1,-1, 1,-1,-1/
      DATA (NHEL(I, 25),I=1,6) /-1, 1, 1,-1, 1, 1/
      DATA (NHEL(I, 26),I=1,6) /-1, 1, 1,-1, 1,-1/
      DATA (NHEL(I, 27),I=1,6) /-1, 1, 1,-1,-1, 1/
      DATA (NHEL(I, 28),I=1,6) /-1, 1, 1,-1,-1,-1/
      DATA (NHEL(I, 29),I=1,6) /-1, 1, 1, 1, 1, 1/
      DATA (NHEL(I, 30),I=1,6) /-1, 1, 1, 1, 1,-1/
      DATA (NHEL(I, 31),I=1,6) /-1, 1, 1, 1,-1, 1/
      DATA (NHEL(I, 32),I=1,6) /-1, 1, 1, 1,-1,-1/
      DATA (NHEL(I, 33),I=1,6) /-1, 1, 0,-1, 1, 1/
      DATA (NHEL(I, 34),I=1,6) /-1, 1, 0,-1, 1,-1/
      DATA (NHEL(I, 35),I=1,6) /-1, 1, 0,-1,-1, 1/
      DATA (NHEL(I, 36),I=1,6) /-1, 1, 0,-1,-1,-1/
      DATA (NHEL(I, 37),I=1,6) /-1, 1, 0, 1, 1, 1/
      DATA (NHEL(I, 38),I=1,6) /-1, 1, 0, 1, 1,-1/
      DATA (NHEL(I, 39),I=1,6) /-1, 1, 0, 1,-1, 1/
      DATA (NHEL(I, 40),I=1,6) /-1, 1, 0, 1,-1,-1/
      DATA (NHEL(I, 41),I=1,6) /-1, 1,-1,-1, 1, 1/
      DATA (NHEL(I, 42),I=1,6) /-1, 1,-1,-1, 1,-1/
      DATA (NHEL(I, 43),I=1,6) /-1, 1,-1,-1,-1, 1/
      DATA (NHEL(I, 44),I=1,6) /-1, 1,-1,-1,-1,-1/
      DATA (NHEL(I, 45),I=1,6) /-1, 1,-1, 1, 1, 1/
      DATA (NHEL(I, 46),I=1,6) /-1, 1,-1, 1, 1,-1/
      DATA (NHEL(I, 47),I=1,6) /-1, 1,-1, 1,-1, 1/
      DATA (NHEL(I, 48),I=1,6) /-1, 1,-1, 1,-1,-1/
      DATA (NHEL(I, 49),I=1,6) / 1,-1, 1,-1, 1, 1/
      DATA (NHEL(I, 50),I=1,6) / 1,-1, 1,-1, 1,-1/
      DATA (NHEL(I, 51),I=1,6) / 1,-1, 1,-1,-1, 1/
      DATA (NHEL(I, 52),I=1,6) / 1,-1, 1,-1,-1,-1/
      DATA (NHEL(I, 53),I=1,6) / 1,-1, 1, 1, 1, 1/
      DATA (NHEL(I, 54),I=1,6) / 1,-1, 1, 1, 1,-1/
      DATA (NHEL(I, 55),I=1,6) / 1,-1, 1, 1,-1, 1/
      DATA (NHEL(I, 56),I=1,6) / 1,-1, 1, 1,-1,-1/
      DATA (NHEL(I, 57),I=1,6) / 1,-1, 0,-1, 1, 1/
      DATA (NHEL(I, 58),I=1,6) / 1,-1, 0,-1, 1,-1/
      DATA (NHEL(I, 59),I=1,6) / 1,-1, 0,-1,-1, 1/
      DATA (NHEL(I, 60),I=1,6) / 1,-1, 0,-1,-1,-1/
      DATA (NHEL(I, 61),I=1,6) / 1,-1, 0, 1, 1, 1/
      DATA (NHEL(I, 62),I=1,6) / 1,-1, 0, 1, 1,-1/
      DATA (NHEL(I, 63),I=1,6) / 1,-1, 0, 1,-1, 1/
      DATA (NHEL(I, 64),I=1,6) / 1,-1, 0, 1,-1,-1/
      DATA (NHEL(I, 65),I=1,6) / 1,-1,-1,-1, 1, 1/
      DATA (NHEL(I, 66),I=1,6) / 1,-1,-1,-1, 1,-1/
      DATA (NHEL(I, 67),I=1,6) / 1,-1,-1,-1,-1, 1/
      DATA (NHEL(I, 68),I=1,6) / 1,-1,-1,-1,-1,-1/
      DATA (NHEL(I, 69),I=1,6) / 1,-1,-1, 1, 1, 1/
      DATA (NHEL(I, 70),I=1,6) / 1,-1,-1, 1, 1,-1/
      DATA (NHEL(I, 71),I=1,6) / 1,-1,-1, 1,-1, 1/
      DATA (NHEL(I, 72),I=1,6) / 1,-1,-1, 1,-1,-1/
      DATA (NHEL(I, 73),I=1,6) / 1, 1, 1,-1, 1, 1/
      DATA (NHEL(I, 74),I=1,6) / 1, 1, 1,-1, 1,-1/
      DATA (NHEL(I, 75),I=1,6) / 1, 1, 1,-1,-1, 1/
      DATA (NHEL(I, 76),I=1,6) / 1, 1, 1,-1,-1,-1/
      DATA (NHEL(I, 77),I=1,6) / 1, 1, 1, 1, 1, 1/
      DATA (NHEL(I, 78),I=1,6) / 1, 1, 1, 1, 1,-1/
      DATA (NHEL(I, 79),I=1,6) / 1, 1, 1, 1,-1, 1/
      DATA (NHEL(I, 80),I=1,6) / 1, 1, 1, 1,-1,-1/
      DATA (NHEL(I, 81),I=1,6) / 1, 1, 0,-1, 1, 1/
      DATA (NHEL(I, 82),I=1,6) / 1, 1, 0,-1, 1,-1/
      DATA (NHEL(I, 83),I=1,6) / 1, 1, 0,-1,-1, 1/
      DATA (NHEL(I, 84),I=1,6) / 1, 1, 0,-1,-1,-1/
      DATA (NHEL(I, 85),I=1,6) / 1, 1, 0, 1, 1, 1/
      DATA (NHEL(I, 86),I=1,6) / 1, 1, 0, 1, 1,-1/
      DATA (NHEL(I, 87),I=1,6) / 1, 1, 0, 1,-1, 1/
      DATA (NHEL(I, 88),I=1,6) / 1, 1, 0, 1,-1,-1/
      DATA (NHEL(I, 89),I=1,6) / 1, 1,-1,-1, 1, 1/
      DATA (NHEL(I, 90),I=1,6) / 1, 1,-1,-1, 1,-1/
      DATA (NHEL(I, 91),I=1,6) / 1, 1,-1,-1,-1, 1/
      DATA (NHEL(I, 92),I=1,6) / 1, 1,-1,-1,-1,-1/
      DATA (NHEL(I, 93),I=1,6) / 1, 1,-1, 1, 1, 1/
      DATA (NHEL(I, 94),I=1,6) / 1, 1,-1, 1, 1,-1/
      DATA (NHEL(I, 95),I=1,6) / 1, 1,-1, 1,-1, 1/
      DATA (NHEL(I, 96),I=1,6) / 1, 1,-1, 1,-1,-1/
      LOGICAL GOODHEL(NCOMB)
      DATA GOODHEL/NCOMB*.FALSE./
      INTEGER NTRY
      DATA NTRY/0/
      DATA IDEN/96/
C ----------
C BEGIN CODE
C ----------
      NTRY=NTRY+1
      ANS = 0D0
      DO IHEL=1,NCOMB
        IF (GOODHEL(IHEL) .OR. NTRY .LT. 2) THEN
          IF (NTRY.LT.2) THEN
C for the first ps-point, check for helicities that give
C identical matrix elements
            T=MATRIX_3(P ,NHEL(1,IHEL))
            T_SAVE(IHEL)=T
            T_IDENT(IHEL)=-1
            DO I=1,IHEL-1
              IF (T.EQ.0D0) EXIT
              IF (T_SAVE(I).EQ.0D0) CYCLE
              IF (ABS(T/T_SAVE(I)-1D0) .LT. 1D-12) THEN
C WRITE (*,*) 'FOUND IDENTICAL',T,IHEL,T_SAVE(I),I
                T_IDENT(IHEL) = I
              ENDIF
            ENDDO
          ELSE
            IF (T_IDENT(IHEL).GT.0) THEN
C if two helicity states are identical, dont recompute
              T=T_SAVE(T_IDENT(IHEL))
              T_SAVE(IHEL)=T
            ELSE
              T=MATRIX_3(P ,NHEL(1,IHEL))
              T_SAVE(IHEL)=T
            ENDIF
          ENDIF
C add to the sum of helicities
          ANS=ANS+T
          IF (T .NE. 0D0 .AND. .NOT. GOODHEL(IHEL)) THEN
            GOODHEL(IHEL)=.TRUE.
          ENDIF
        ENDIF
      ENDDO
      ANS=ANS/DBLE(IDEN)
      WGT_ME_REAL=ANS
      END

      REAL*8 FUNCTION MATRIX_3(P,NHEL)
C
C Generated by MadGraph5_aMC@NLO v. 2.6.0, 2017-08-16
C By the MadGraph5_aMC@NLO Development Team
C Visit launchpad.net/madgraph5 and amcatnlo.web.cern.ch
C
C Returns amplitude squared summed/avg over colors
C for the point with external lines W(0:6,NEXTERNAL)
C
C Process: u~ g > w- t b~ u~ WEIGHTED<=5 [ all = QCD ]
C Process: c~ g > w- t b~ c~ WEIGHTED<=5 [ all = QCD ]
C Process: d~ g > w- t b~ d~ WEIGHTED<=5 [ all = QCD ]
C Process: s~ g > w- t b~ s~ WEIGHTED<=5 [ all = QCD ]
C
      IMPLICIT NONE
C
C CONSTANTS
C
      INTEGER NGRAPHS
      PARAMETER (NGRAPHS=12)
      INTEGER NWAVEFUNCS, NCOLOR
      PARAMETER (NWAVEFUNCS=12, NCOLOR=4)
      REAL*8 ZERO
      PARAMETER (ZERO=0D0)
      COMPLEX*16 IMAG1
      PARAMETER (IMAG1=(0D0,1D0))
      INCLUDE 'nexternal.inc'
      INCLUDE 'coupl.inc'
C
C ARGUMENTS
C
      REAL*8 P(0:3,NEXTERNAL)
      INTEGER NHEL(NEXTERNAL)
C
C LOCAL VARIABLES
C
      INTEGER I,J
      INTEGER IC(NEXTERNAL)
      DATA IC /NEXTERNAL*1/
      REAL*8 DENOM(NCOLOR), CF(NCOLOR,NCOLOR)
      COMPLEX*16 ZTEMP, AMP(NGRAPHS), JAMP(NCOLOR), W(8,NWAVEFUNCS)
C
C COLOR DATA
C
      DATA DENOM(1)/1/
      DATA (CF(I, 1),I= 1, 4) / 12, 4, 0, 4/
C 1 T(1,5) T(2,4,6)
      DATA DENOM(2)/1/
      DATA (CF(I, 2),I= 1, 4) / 4, 12, 4, 0/
C 1 T(1,6) T(2,4,5)
      DATA DENOM(3)/1/
      DATA (CF(I, 3),I= 1, 4) / 0, 4, 12, 4/
C 1 T(2,1,5) T(4,6)
      DATA DENOM(4)/1/
      DATA (CF(I, 4),I= 1, 4) / 4, 0, 4, 12/
C 1 T(2,1,6) T(4,5)
C ----------
C BEGIN CODE
C ----------
      CALL OXXXXX(P(0,1),ZERO,NHEL(1),-1*IC(1),W(1,1))
      CALL VXXXXX(P(0,2),ZERO,NHEL(2),-1*IC(2),W(1,2))
      CALL VXXXXX(P(0,3),MDL_MW,NHEL(3),+1*IC(3),W(1,3))
      CALL OXXXXX(P(0,4),MDL_MT,NHEL(4),+1*IC(4),W(1,4))
      CALL IXXXXX(P(0,5),ZERO,NHEL(5),-1*IC(5),W(1,5))
      CALL IXXXXX(P(0,6),ZERO,NHEL(6),-1*IC(6),W(1,6))
      CALL FFV1_1(W(1,1),W(1,2),GC_5,ZERO,ZERO,W(1,7))
      CALL FFV2_1(W(1,4),W(1,3),GC_47,ZERO,ZERO,W(1,8))
      CALL FFV1P0_3(W(1,6),W(1,7),GC_5,ZERO,ZERO,W(1,9))
C Amplitude(s) for diagram number 1
      CALL FFV1_0(W(1,5),W(1,8),W(1,9),GC_5,AMP(1))
      CALL FFV2_2(W(1,5),W(1,3),GC_47,MDL_MT,MDL_WT,W(1,7))
C Amplitude(s) for diagram number 2
      CALL FFV1_0(W(1,7),W(1,4),W(1,9),GC_5,AMP(2))
      CALL FFV1P0_3(W(1,6),W(1,1),GC_5,ZERO,ZERO,W(1,9))
      CALL FFV1_1(W(1,4),W(1,2),GC_5,MDL_MT,MDL_WT,W(1,10))
      CALL FFV1_2(W(1,5),W(1,9),GC_5,ZERO,ZERO,W(1,11))
C Amplitude(s) for diagram number 3
      CALL FFV2_0(W(1,11),W(1,10),W(1,3),GC_47,AMP(3))
C Amplitude(s) for diagram number 4
      CALL FFV1_0(W(1,7),W(1,10),W(1,9),GC_5,AMP(4))
      CALL FFV1_2(W(1,5),W(1,2),GC_5,ZERO,ZERO,W(1,10))
      CALL FFV1_1(W(1,4),W(1,9),GC_5,MDL_MT,MDL_WT,W(1,12))
C Amplitude(s) for diagram number 5
      CALL FFV2_0(W(1,10),W(1,12),W(1,3),GC_47,AMP(5))
C Amplitude(s) for diagram number 6
      CALL FFV1_0(W(1,10),W(1,8),W(1,9),GC_5,AMP(6))
      CALL VVV1P0_1(W(1,9),W(1,2),GC_4,ZERO,ZERO,W(1,10))
C Amplitude(s) for diagram number 7
      CALL FFV1_0(W(1,5),W(1,8),W(1,10),GC_5,AMP(7))
C Amplitude(s) for diagram number 8
      CALL FFV1_0(W(1,11),W(1,8),W(1,2),GC_5,AMP(8))
C Amplitude(s) for diagram number 9
      CALL FFV1_0(W(1,7),W(1,4),W(1,10),GC_5,AMP(9))
C Amplitude(s) for diagram number 10
      CALL FFV1_0(W(1,7),W(1,12),W(1,2),GC_5,AMP(10))
      CALL FFV1_2(W(1,6),W(1,2),GC_5,ZERO,ZERO,W(1,12))
      CALL FFV1P0_3(W(1,12),W(1,1),GC_5,ZERO,ZERO,W(1,6))
C Amplitude(s) for diagram number 11
      CALL FFV1_0(W(1,5),W(1,8),W(1,6),GC_5,AMP(11))
C Amplitude(s) for diagram number 12
      CALL FFV1_0(W(1,7),W(1,4),W(1,6),GC_5,AMP(12))
      JAMP(1)=+1D0/2D0*(+AMP(3)+AMP(4)+IMAG1*AMP(7)+AMP(8)+IMAG1*AMP(9)
     $ +AMP(11)+AMP(12))
      JAMP(2)=+1D0/2D0*(-1D0/3D0*AMP(3)-1D0/3D0*AMP(4)-1D0/3D0*AMP(5)
     $ -1D0/3D0*AMP(6)-1D0/3D0*AMP(8)-1D0/3D0*AMP(10))
      JAMP(3)=+1D0/2D0*(+AMP(1)+AMP(2)+AMP(5)+AMP(6)-IMAG1*AMP(7)
     $ -IMAG1*AMP(9)+AMP(10))
      JAMP(4)=+1D0/2D0*(-1D0/3D0*AMP(1)-1D0/3D0*AMP(2)-1D0/3D0*AMP(11)
     $ -1D0/3D0*AMP(12))
      MATRIX_3 = 0.D0
      DO I = 1, NCOLOR
        ZTEMP = (0.D0,0.D0)
        DO J = 1, NCOLOR
          ZTEMP = ZTEMP + CF(J,I)*JAMP(J)
        ENDDO
        MATRIX_3 = MATRIX_3+ZTEMP*DCONJG(JAMP(I))/DENOM(I)
      ENDDO
      END

Thank you again!

Best marco zaro (marco-zaro) said : #3

Hi Mar,
ok, so take for example the subprocess g b~ > w+ t~

the troublesome real emission will be the b b~ initiated one and the gg one. These (do grep Process matrix*.f) are
matrix_5.f and matrix_6.f
If you look at the feynman diagrams (e.g. in the corresponding ps or jpeg files), you see that diagrams involving a resonant top are
diagram 2, for matrix_5
and diagrams 2,4,7 for matrix_6.f

In order to set them to zero, edit the .f file (take e.g. matrix_6.f), where you have the end of the helas calls
C Amplitude(s) for diagram number 8
      CALL FFV1_0(W(1,7),W(1,9),W(1,1),GC_5,AMP(8))
      JAMP(1)=-IMAG1*AMP(1)-IMAG1*AMP(2)+AMP(5)+AMP(6)+AMP(7)
      JAMP(2)=+IMAG1*AMP(1)+IMAG1*AMP(2)+AMP(3)+AMP(4)+AMP(8)

You must set to zero the AMP() that you do not want (in this case 2,4,7 ) right before the JAMP lines.
So in this case you would have
C Amplitude(s) for diagram number 8
      CALL FFV1_0(W(1,7),W(1,9),W(1,1),GC_5,AMP(8))
       AMP(2) = dcmplx(0d0,0d0)
       AMP(4) = dcmplx(0d0,0d0)
       AMP(7) = dcmplx(0d0,0d0)
      JAMP(1)=-IMAG1*AMP(1)-IMAG1*AMP(2)+AMP(5)+AMP(6)+AMP(7)
      JAMP(2)=+IMAG1*AMP(1)+IMAG1*AMP(2)+AMP(3)+AMP(4)+AMP(8)

The other partonic subprocesses follow in total analogy, note that the number of the matrix_x.f corresponding to the gg and bb~ initiated real emission may change, and also the number of the diagrams to be set to zero (there will always be 3 diagrams for gg and 1 for bb~).

This should work, please check that you manage to reproduce some number in arXiv:1607.05862

Let me know...
ciao,

Marco

Mar (septembris-forest) said : #4

Thank you! I see... just one last question, since I don't know what does dcmplx(0d0,0d0) mean, when I want to eliminate resonant tbar from the processes, is it the same line? Or does it change because it is t bar and not t?

Thanks again!

Mar

marco zaro (marco-zaro) said : #5

dcmplx(0d0,0d0) means the complex zero number in fortran.
For removing the t~, follow the procedure I have outlined, keeping in mind that the number of the matrix_X.f to be modified and of the diagrams (AMP(Y)) to be set to zero may change.
Cheers,

Marco

Mar (septembris-forest) said : #6

Hi Marco, that worked perfectly. Thank you very much!

Mar

Mar (septembris-forest) said : #7

Thanks marco zaro, that solved my question.