Validation Regions for non-prompt background estimation in same charged \(W^{\pm}W^{\pm}\) scattering
(Status report)
Sebastian Ordoñez
jsordonezs@unal.edu.co
27th of April 2021
Outline
- Introduction
-
The trilepton muon Validation Region
- New definition
- Composition
- Statistics and data modeling
- Conclusions
-
Next steps
- Muon VR
- Electron VR
In the data-driven background estimation we employ models reliying on three statistically independent regions: SR, CR and VR.
- Control Region: enriched in non-prompt background and extrapolated to SR using a fake factor (FF) → Max Dilepton CR
VR
SR
CR
FF apply
FF test
- Signal Region: phase space that is defined through selections on kinematic variables, enriched in potential signal of interest → ssWW
- Validation Region: regions in phase space between the CR and the SR where the extrapolation is verified→My work
- Validation Region for muons
- Validation Region for electrons
Introduction
We introduce the following four categories for our analysis. In truth level we define:
- Prompt leptons: originated from \(W^{\pm}\) or \(Z\) decay.
- Non-prompt leptons: coming from other sources e.g. hadron decays faking a signal lepton.
In reco level we have:
- Ana leptons: quite likely to be prompt. Tight kinematic and qualitative criteria, signal leptons in SR.
- Non-Ana leptons: kinematically close to Ana leptons but more likely to be non-promt, i.e. looser object quality selection.
Introduction
Trilepton muon VR
-
As final state we require one electron and two muons
- Electron Ana selected and at least one muon Ana selected.
- We expect the electron to be prompt and one muon to be prompt too.
- Non Prompt Muons in the SR are a motivation to define \(t\bar{t}\) validation regions for muons
Muon Validation Region Definition
In the new definition for the trilepton Validation Region we require the events to:
\boxed{N_{A}^{fake} = N_{N}^{fake}\cdot F}
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We need to guarantee that fake muons have a \(p_{T}>27\) GeV in order to be able to apply the fake factor
Closure Test →
Muon Validation Region Definition
\(l\)
\(l\)
\(l\)
\(\mp\)
\(\pm\)
\(\pm\)
A|N
A|N
A|N
\(l\)
\(l\)
\(l\)
\(\pm\)
\(\pm\)
\(\mp\)
A
A
A|N
1. Three leptons
2. At least two Ana leptons
\(p_{T}>15\) GeV
[2]
[1]
[0]
Muon Validation Region Definition
\(\mu\)
\(\mu\)
\(e\)
A
A|N
A
\(\pm\)
\(\pm\)
\(\mp\)
[2]
[1]
[0]
3. Two muons and one lectron
4. Ana electron
\(p_{T}>15\) GeV
\(e\)
\(\mu\)
\(\mu\)
A
A|N
A
\(\mp\)
\(\pm\)
\(\pm\)
Muon Validation Region Definition
\(\pm\)
\(\pm\)
\(\pm\)
A
A|N
A
\(\mu\)
\(e\)
\(\mu\)
5. Same charge muons
\(\mu\)
\(\pm\)
A
\(e\)
\(\pm\)
A
A|N
\(\mu\)
\(\pm\)
[0]
[2]
[1]
6. Leading muon \(p_{T}\)
\(p_{T}>15\) GeV
\boxed{p_{T}^{\mu_{lead.}}>27 GeV}
Muon Validation Region Definition
\(\pm\)
\(\pm\)
A
A
A|N
\(e\)
\(\mu\)
\(\mu\)
[0]
[2]
[1]
7. Subleading muon \(p_{T}\)
\(\pm\)
p_{T}^{\mu_{lead.}}>27 GeV
\boxed{p_{T}^{\mu_{sub.}}>27 GeV}
\(p_{T}>15\) GeV
Employing this definition we guarantee that one of the muons is quite likely to be non-prompt. We remove a lot of events coming from \(Z+jets\), \(W+jets\) and \(WZ\) processes, and at the end we are able to apply the fake factor \(F\).
Evaluation of the trilepton muon VR
By applying the previous selection we would like to have:
- Large number of total events and high purity in non-prompt muons.
- Good data modeling
- Agreement with the SR in the composition of non-prompt muons.
Subeading muon \(p_T\) cut
Leading muon \(p_{T}\) cut
Same charged muons Cut
Ana electron Cut
Lepton Flavor Cut
Three leptons Cut
Composition of the non-prompt muons
Ana leptons
Non-Ana leptons
Subeading muon \(p_T\) cut
Leading muon \(p_{T}\) cut
Same charged muons Cut
Ana electron Cut
Lepton Flavor Cut
Three leptons Cut
Let us take a closer look to a physical distribution again, but this time explicitly for Ana events.
MET for Non-Ana events
MET for Ana events
Statistics and data modeling
Subeading muon \(p_T\) cut
The contribution of non-prompt muons is about ~50%
Statistics and data modeling
Subeading muon \(p_T\) cut
The contribution of non-prompt for the LowMjj was about ~20%
MET for Non-Ana events
MET for Ana events
Leading muon \(p_T\) cut
MET for Non-Ana events
MET for Ana events
Same charge muon cut
MET for Ana and Non-Ana events
MET for only Ana events
Ana electron cut
MET for Ana and Non-Ana events
MET for only Ana events
Lepton Flavor cut
MET for Ana and Non-Ana events
MET for only Ana events
Three lepton cut
\(p_{T}\) fake muons
Condition: At least one fake lepton and \(pT>27\)
\boxed{N_{A}^{fake} = N_{N}^{fake}\cdot F}
Same charge muon cut
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Closure Test
1: Leading fake muon
2: Subleading fake muon
Subeading muon \(p_T\) cut
Leading muon \(p_T\) cut
Same charge muon cut
Ana electron cut
Lepton Flavor cut
Three lepton cut
Conclusion
- Non-prompt composition of this trilepton muon Validation Region is in agreement with the non-prompt composition in the Signal Region.
- Using a pre-selection such that \(p_{T}>15\) GeV for Ana and Non-Ana leptons we reached higher statistics and we are still able to apply the fake factor.
- The purity in non-prompt events was improved in comparison to the LowMjj validation region previoulsy employed in the study.
Next steps (Muon VR)
- Generate, apply and test (Closure Test) the fake factor for this trilepton muon Validation Region.
- Make corrections after applying the fake factor.
- Start writing.
First steps (Electron VR)
Non-prompt electrons in the Signal Region come mainly from Light Flavor Decay related to \(W+jets\) and also there is a significant contribution of B Hadron Decay associated to \(t\bar{t}\).
First steps (Electron VR)
Since we need to guarantee a composition closer to that of the Signal Region and we want to employ a trilepton electron Validation Region, we will require:
Thank you!
Questions?
[Dresden-VBS] Update II VR study
By Sebastian Ordoñez
