generate a EW process

Asked by Mingxuan Zhang

Dear experts,

How can I generate process like VBF but in which real Higgs is not produced and not in s-channel? The Feynman diagram of it is that a virtual Higgs contacts the two Z bosons emitted by two quarks and the final state is 2 quark-jet and 2 Z bosons. Just like a ladder. I've tried q q > h > j j z z where q = u c d s u~ c~ d~ s~, but it didn't work.
Thanks a lot for your help!

best,
Mingxuan

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Olivier Mattelaer (olivier-mattelaer) said :
#1

I do not understand which diagram you do want but this FAQ might help you
FAQ #3322: “How to select of subset of diagram for LO computation?”.

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Mingxuan Zhang (mingxuanzh) said (last edit ):
#2

Dear Olivier,

Thanks for your reply and sorry for my ambiguousness. I draw a schematic diagram for this process, in which initial state is 2 quarks, Higgs is in t-channel and 2jets and 2 Z bosons are final state. That's I said that a virtual Higgs contacts the two Z bosons emitted by two quarks and the final state is 2 quark-jet and 2 Z bosons. How can I get this process through MadGraph? Thanks and looking forward to your reply.

q
\
\
  \
   -----------------------------jet
   ~~~~~~~~~~Z
           |
           |
          H
           |
           |
    ~~~~~~~~~~~Z
   / --------------------------jet
  /
 /
q

Best,
Mingxuan

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said :
#3

So here the following syntax might be what your are looking for:
generate q q > j j z z QCD=0 $$ z / q a w+ w-

I did run the sanity check for diagram removal and gauge/lorentz invariance seems ok:

DEBUG: Note That all width have been set to zero for those checks

Lorentz invariance results:
Process Min element Max element Relative diff. Result
u u > u u z z 1.6067743932e-14 1.6067743932e-14 3.7312910294e-15 Passed
u c > u c z z 2.9306564367e-15 2.9306564367e-15 3.3646937224e-15 Passed
u d > u d z z 4.3746970538e-15 4.3746970538e-15 7.0326184705e-15 Passed
u s > u s z z 1.1806103160e-15 1.1806103160e-15 2.5056772371e-15 Passed
c c > c c z z 7.7941619576e-14 7.7941619576e-14 2.7529600666e-15 Passed
c d > c d z z 1.3968389624e-13 1.3968389624e-13 1.9879101751e-15 Passed
c s > c s z z 9.1396988464e-14 9.1396988464e-14 5.6620328801e-15 Passed
d d > d d z z 1.3231100088e-14 1.3231100088e-14 1.0970395930e-14 Passed
d s > d s z z 1.6463675218e-12 1.6463675218e-12 2.5759231583e-15 Passed
s s > s s z z 4.3649745325e-14 4.3649745325e-14 5.0603056632e-15 Passed
Summary: 10/10 passed, 0/10 failed
Gauge results (switching between Unitary/Feynman/axial gauge):
Process Unitary Feynman Relative diff. Result
u u > u u z z 1.3236977408e-12 1.3236977408e-12 7.9333189494e-15 Passed
u c > u c z z 4.5895196123e-14 4.5895196123e-14 2.6126232748e-15 Passed
u d > u d z z 4.2742403654e-12 4.2742403654e-12 7.5596456716e-15 Passed
u s > u s z z 1.3327114800e-14 1.3327114800e-14 3.5515304719e-16 Passed
c c > c c z z 1.4521924761e-13 1.4521924761e-13 2.2597978021e-15 Passed
c d > c d z z 1.5729794299e-14 1.5729794299e-14 5.2156774959e-15 Passed
c s > c s z z 2.0922569176e-13 2.0922569176e-13 4.4641329844e-15 Passed
d d > d d z z 2.6329929719e-14 2.6329929719e-14 1.5579520154e-15 Passed
d s > d s z z 4.6506441902e-15 4.6506441902e-15 6.7849603019e-16 Passed
s s > s s z z 7.9489052247e-12 7.9489052247e-12 1.6259719679e-15 Passed
Summary: 10/10 passed, 0/10 failed
Process permutation results:
Process Min element Max element Relative diff. Result
u u > u u z z 1.4925155999e-14 1.4925155999e-14 4.2283559664e-16 Passed
u c > u c z z 3.6382112741e-15 3.6382112741e-15 2.1682657927e-16 Passed
u d > u d z z 4.2493656028e-14 4.2493656028e-14 5.9405453253e-16 Passed
d d > d d z z 3.7186842239e-14 3.7186842239e-14 5.0912259782e-16 Passed
d s > d s z z 3.5014898300e-15 3.5014898300e-15 2.2529293059e-16 Passed
Summary: 5/5 passed, 0/5 failed

But the above also include some S-channel Higgs.
The following syntax does remove those:
q q > j j z z QCD=0 $$ z h / q a w+ w-

But here they are issue with the gauge invariance (strangely lorentz seems ok)
DEBUG: Note That all width have been set to zero for those checks

Lorentz invariance results:
Process Min element Max element Relative diff. Result
u u > u u z z 1.7693137748e-14 1.7693137748e-14 1.7834279402e-14 Passed
u c > u c z z 1.7969727793e-15 1.7969727793e-15 5.7069266078e-15 Passed
u d > u d z z 4.6282729370e-15 4.6282729370e-15 2.7271024538e-15 Passed
u s > u s z z 4.6006384131e-17 4.6006384131e-17 1.3395914368e-15 Passed
c c > c c z z 4.4318857498e-14 4.4318857498e-14 1.5663706959e-15 Passed
c d > c d z z 7.9750155704e-17 7.9750155704e-17 1.7001279419e-15 Passed
c s > c s z z 4.6544364126e-15 4.6544364126e-15 1.1864006395e-15 Passed
d d > d d z z 3.0066892591e-13 3.0066892591e-13 4.8695615473e-15 Passed
d s > d s z z 2.0089053323e-15 2.0089053323e-15 6.8719344904e-15 Passed
s s > s s z z 1.1591796482e-13 1.1591796482e-13 2.6132497069e-15 Passed
Summary: 10/10 passed, 0/10 failed
Gauge results (switching between Unitary/Feynman/axial gauge):
Process Unitary Feynman Relative diff. Result
u u > u u z z 5.9615778106e-12 5.9615778106e-12 2.7099992405e-16 Passed
u c > u c z z 2.4555799441e-15 1.0947663876e-15 5.5417196243e-01 Failed
   JAMP 0 1.9644639553e-14 8.7581311007e-15 5.5417196243e-01 Failed
u d > u d z z 2.7976469382e-16 2.7976469382e-16 1.9385643875e-15 Passed
u s > u s z z 2.5385585631e-14 2.5385585631e-14 6.2150301883e-16 Passed
c c > c c z z 1.6895484678e-15 1.6895484678e-15 6.4199622879e-15 Passed
c d > c d z z 9.1560395412e-14 9.1560395412e-14 1.9299266017e-15 Passed
c s > c s z z 2.2170836445e-13 2.2170836445e-13 4.3266516494e-15 Passed
d d > d d z z 2.4651325896e-14 3.6404693716e-14 3.2285308899e-01 Failed
   JAMP 0 2.5518993732e-13 1.8020861781e-13 2.9382553366e-01 Failed
   JAMP 1 2.9321793479e-13 5.5741845699e-13 4.7397160767e-01 Failed
d s > d s z z 1.8686865358e-14 6.9659406762e-15 6.2722797308e-01 Failed
   JAMP 0 1.4949492286e-13 5.5727525409e-14 6.2722797308e-01 Failed
s s > s s z z 2.9018154276e-14 2.9018154276e-14 3.2622098472e-15 Passed
Summary: 7/10 passed, 3/10 failed
Failed processes: u c > u c z z, d d > d d z z, d s > d s z z
Process permutation results:
Process Min element Max element Relative diff. Result
u u > u u z z 1.3123718294e-13 1.3123718294e-13 3.8470117083e-16 Passed
u c > u c z z 1.4198274764e-16 1.4198274764e-16 3.4725209503e-16 Passed
u d > u d z z 5.3923059510e-15 5.3923059510e-15 2.9258759143e-16 Passed
d d > d d z z 4.5353389867e-15 4.5353389867e-15 5.5659674042e-15 Passed
d s > d s z z 2.2333829150e-13 2.2333829150e-13 3.3908492087e-16 Passed
Summary: 5/5 passed, 0/5 failed

Revision history for this message
Mingxuan Zhang (mingxuanzh) said :
#4

Dear Olivier,

That's a big help for me! Thanks for your immediate response and enthusiastic help.

Best,
Mingxuan