MonoTop

Monotop Simplified models

Two models were considered so far, a resonant and a non-resonant production, and ATLAS only considered right-handed top quarks and lepton+jets final state. The models are based on:

The Madgraph models can be found here

Parameters definition

ATLAS

The public ATLAS $\ell\mathrm{+jets}$ paper, with additional material, can be found here: TOPQ-2013-11.
Signal samples produced with Madgraph5 v1.5.11 interfaced with Pythia 8.175, using the MSTW2008LO PDF set (lhapdf ID: 21000).
The mass of the top quark was set at 172.5 GeV.
Dynamic renormalisation and factorisation scales were used.
We changed the MET particle mass, and in the case of the resonant model the resonance mass was fixed at 500 GeV:
  • 110148-110153: resonant model, missing ET particle mass: 0,20,40,60,80,100 GeV - resonance mass: 500 GeV
  • 110160-110169, 110181-110186: non-resonant model, missing ET particle mass: 0,25,50,75,100,125,150,200,250,300,400,500,600,700,800,900,1000 GeV
The default effective coupling value is $a_{\rm res}=a_{\rm non-res}=0.2$, with the notation used in the ATLAS l+jets paper.
Using the notations of the Monotops at the LHC arXiv:1106.6199 paper above (Eq. 1), this corresponds to:
  • resonant model: $(a^q_{SR})_{12}=-(a^q_{SR})_{21}=(b^q_{SR})_{12}=-(b^q_{SR})_{21}=(a^{1/2}_{SR})_{3}=(b^{1/2}_{SR})_{3}=0.1$, all other elements of the coupling matrices being equal to 0;
  • non-resonant model: $(a^1_{FC})_{13}=(a^1_{FC})_{31}=(b^1_{FC})_{13}=(b^1_{FC})_{31}=0.1$, all other elements of the coupling matrices being equal to 0.
For the resonant model, we also produced some samples changing the coupling to $a_{\rm res}=0.5$ and $a_{\rm res}=1.0$, for the 100 GeV mass point.
Below are given the cross-sections times branching ratios, plus the width of the resonance, for the resonant model.
Mass of invisible particle [GeV] Total width of resonance [GeV] Xsec.BR(l+jets) [pb] Xsec.BR(full-had) [pb]
0 ($a_{\rm res}=0.2$) 3.492 1.107 2.214
20 ($a_{\rm res}=0.2$) 3.491 1.102 2.205
40 ($a_{\rm res}=0.2$) 3.487 1.089 2.180
60 ($a_{\rm res}=0.2$) 3.481 1.068 2.137
80 ($a_{\rm res}=0.2$) 3.472 1.039 2.078
100 ($a_{\rm res}=0.2$) 3.461 1.001 2.003
100 ($a_{\rm res}=0.5$) 21.63 6.091 12.13
100 ($a_{\rm res}=1.0$) 86.52 21.77 43.72

Below are given the cross-sections times branching ratios, for the non-resonant model with $a_{\rm non-res}=0.2$.
Mass of invisible particle [GeV] Xsec.BR(l+jets) [pb] Xsec.BR(full-had) [pb]
0 96.03 192.4
25 359.0 717.9
50 113.4 226.9
75 59.86 119.5
100 37.45 74.82
125 25.35 50.68
150 18.00 35.96
200 9.662 19.28
250 5.506 11.02
300 3.328 6.656
400 1.372 2.738
500 0.6345 1.270
600 0.3192 0.6354
700 0.1698 0.3383
800 0.09417 0.1883
900 0.05472 0.1091
1000 0.03259 0.06479

The plan for the future MC sample request is to keep the non-resonant parameters, invisible particle mass from 0 to 1.5 TeV. However for the resonant model, we were planning to vary the resonance mass fixing the invisible particle mass at 100 GeV. The range is not fixed yet, but from 500 GeV to 1.5 TeV is a possible idea.

Open Questions

  • Verify with CMS that we are using the same model definition

ATLAS Specific info/JO

The dataset that were used are: [110148-110153], [110160-110169], and [110180-110186].
They can be found at here.
The main joboption file is at here.

CMS Specific info/JO

-- PriscillaPani - 2015-01-12

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Topic revision: r8 - 2015-03-19 - TimotheeTheveneauxPelzer
 
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