Difference: JetEtmissJetPerformancePileup (1 vs. 2)

Revision 22012-07-20 - JohnBackusMayes

Line: 1 to 1
 
META TOPICPARENT name="JetEtMissPublicResults"
AtlasPublicTopicHeader.png
Line: 19 to 19
 
Changed:
<
<
[Mean jet pt vs number of vertices]
>
>
[Mean jet pT vs number of vertices]
 
Changed:
<
<
Average reconstructed jet pt at the EM scale versus the number of reconstructed primary vertices (NPV), for matched truth-jet pt between 20 and 25 GeV. Requiring that all matched tracks originate from the hard scatter (JVF = 1) reduces the pile-up induced pt offset by roughly 40%, indicating that tracks effectively
>
>
Average reconstructed jet pT at the EM scale versus the number of reconstructed primary vertices (NPV), for matched truth-jet pT between 20 and 25 GeV. Requiring that all matched tracks originate from the hard scatter (JVF = 1) reduces the pile-up induced pT offset by roughly 40%, indicating that tracks effectively
 describe only 40% of the impact of pile-up on reconstructed jets.

eps file

Line: 38 to 38
 
Changed:
<
<
[Response vs the true jet pt]
>
>
[Response vs the true jet pT]
 
Changed:
<
<
Calorimeter response to central jets at the LCW scale, as a function of the MC truth jet pt. The pt offset induced by a mean of 40 pile-up interactions ( = 40) causes a shift in the reconstructed jet pt of approximately 25 GeV. Application of an average offset correction, parametrized by the number of reconstructed primary vertices (NPV), recovers the response observed in the absence of pile-up ( = 0).
>
>
Calorimeter response to central jets at the LCW scale, as a function of the MC truth jet pT. The pT offset induced by a mean of 40 pile-up interactions (⟨μ⟩ = 40) causes a shift in the reconstructed jet pT of approximately 25 GeV. Application of an average offset correction, parametrized by the number of reconstructed primary vertices (NPV), recovers the response observed in the absence of pile-up (⟨μ⟩ = 0).
  eps file gif file
Line: 57 to 57
  [Subtraction of in-time pile-up using the “jet areas” method, central]
Changed:
<
<
Average MC truth-based jet pt offset at the LCW scale versus the number of reconstructed primary vertices (NPV). Out-of-time pile-up is constrained by using only events with 5 < mu < 6. In the central region (0.0 < |eta| < 0.3) the jet areas correction removes the impact of in-time pile-up on the jet pt, though a small overcorrection is apparent.
>
>
Average MC truth-based jet pT offset at the LCW scale versus the number of reconstructed primary vertices (NPV). Out-of-time pile-up is constrained by using only events with 5 < ⟨μ⟩ < 6. In the central region (0.0 < |η| < 0.3) the jet areas correction removes the impact of in-time pile-up on the jet pT, though a small overcorrection is apparent.
  eps file gif file
Line: 75 to 75
  [Subtraction of in-time pile-up using the “jet areas” method, forward]
Changed:
<
<
Average MC truth-based jet pt offset at the LCW scale versus the number of reconstructed primary vertices (NPV). Out-of-time pile-up is constrained by using only events with 5 < mu < 6. In the forward region (3.6 < |eta| < 4.5), the jet areas correction removes the impact of in-time pile-up on the jet pt, though a small overcorrection is apparent.
>
>
Average MC truth-based jet pT offset at the LCW scale versus the number of reconstructed primary vertices (NPV). Out-of-time pile-up is constrained by using only events with 5 < ⟨μ⟩ < 6. In the forward region (3.6 < |η| < 4.5), the jet areas correction removes the impact of in-time pile-up on the jet pT, though a small overcorrection is apparent.
  eps file gif file
Line: 93 to 93
  [Subtraction of out-of-time pile-up using the “jet areas” method, central]
Changed:
<
<
Average MC truth-based jet pt offset at the LCW scale versus the average number of interactions per bunch crossing (mu), which is sensitive to out-of-time pile-up. In-time pile-up is constrained by using only events with NPV = 6. In the central region (0.0 < |eta| < 0.3), the jet areas correction over-corrects slightly for the impact of out-of-time pile-up.
>
>
Average MC truth-based jet pT offset at the LCW scale versus the average number of interactions per bunch crossing (⟨μ⟩), which is sensitive to out-of-time pile-up. In-time pile-up is constrained by using only events with NPV = 6. In the central region (0.0 < |η| < 0.3), the jet areas correction over-corrects slightly for the impact of out-of-time pile-up.
  eps file gif file
Line: 111 to 111
  [Subtraction of out-of-time pile-up using the “jet areas” method, forward region]
Changed:
<
<
Average MC truth-based jet pt offset at the LCW scale versus the average number of interactions per bunch crossing (mu), which is sensitive to out-of-time pile-up. In-time pile-up is constrained by using only events with NPV = 6. In the forward region (3.6 < |eta| < 4.5), sensitivity to out-of-time pile-up is substantially different then in the central region.
>
>
Average MC truth-based jet pT offset at the LCW scale versus the average number of interactions per bunch crossing (⟨μ⟩), which is sensitive to out-of-time pile-up. In-time pile-up is constrained by using only events with NPV = 6. In the forward region (3.6 < |η| < 4.5), sensitivity to out-of-time pile-up is substantially different then in the central region.
 Since we calculate rho in the central region, the jet areas correction does not account for the impact of out-of-time pile-up on forward jets

eps file

Line: 130 to 130
  [Jet multiplicity vs number of vertices]
Changed:
<
<
Average multiplicity of pile-up jets with LCW-scale pt > 20 GeV versus the number of reconstructed primary vertices (NPV) before and after correcting for the pt offset induced by pile-up, in simulated dijet events with a mean of 20 overlaid pile-up interactions. The average offset correction, parametrized by NPV, shifts up to 90% of pile-up jets below the pt threshold. By estimating the pile-up offset event by event using low-pt calorimeter deposits, the jet areas correction rejects a substantial fraction of the remaining 10%.
>
>
Average multiplicity of pile-up jets with LCW-scale pT > 20 GeV versus the number of reconstructed primary vertices (NPV) before and after correcting for the pT offset induced by pile-up, in simulated dijet events with a mean of 20 overlaid pile-up interactions. The average offset correction, parametrized by NPV, shifts up to 90% of pile-up jets below the pT threshold. By estimating the pile-up offset event by event using low-pT calorimeter deposits, the jet areas correction rejects a substantial fraction of the remaining 10%.
 

eps file

Line: 150 to 150
  [Jet multiplicity of pile-up jets vs number of vertices]
Changed:
<
<
Average multiplicity of pile-up jets with LCW-scale pt > 20 GeV versus the number of reconstructed primary vertices (NPV) after correcting for the pt offset induced by pile-up, in simulated dijet events with a mean of 20 overlaid pile-up interactions (mu).
>
>
Average multiplicity of pile-up jets with LCW-scale pT > 20 GeV versus the number of reconstructed primary vertices (NPV) after correcting for the pT offset induced by pile-up, in simulated dijet events with a mean of 20 overlaid pile-up interactions (⟨μ⟩).
  There is a significant residual number of pile-up jets, even after the jet areas correction. To reject the remaining jets, we can use tracking information.
Changed:
<
<
Pile-up jets are virtually eliminated by requiring at least a quarter of the matched track pt to come from the hard scatter vertex (JVF > 0.25).
>
>
Pile-up jets are virtually eliminated by requiring at least a quarter of the matched track pT to come from the hard scatter vertex (JVF > 0.25).
 

eps file

Line: 170 to 170
  [Jet resolution for various pile-up subtraction methods]
Changed:
<
<
The width of the MC truth-based jet pt offset at the LCW scale, in a sample with zero pile-up ( = 0), compared to a mean of 40 pile-up interactions, before and after correcting for the pt offset induced by pile-up. Pile-up increases the width by nearly a factor of 3,
>
>
The width of the MC truth-based jet pT offset at the LCW scale, in a sample with zero pile-up (⟨μ⟩ = 0), compared to a mean of 40 pile-up interactions, before and after correcting for the pT offset induced by pile-up. Pile-up increases the width by nearly a factor of 3,
 and the average offset correction does not help to recover this degradation in resolution. However, the jet areas correction recovers 30-40% of the degradation. The remaining 60-70% is due to localized fluctuations in pile-up, which may be reduced by using information from tracks matched to jets.

Revision 12012-07-19 - TancrediCarli

Line: 1 to 1
Added:
>
>
META TOPICPARENT name="JetEtMissPublicResults"
AtlasPublicTopicHeader.png

JetEtmissJetPerformancePileup

<!-- this line is optional -->

<!-- Add an introduction here, describing the purpose of this topic. -->

Jet performance under pile-up

<!-- Add the main topic here. i.e. create some new headings as follows: -->

<!---------------------------------------------------------------------------------------->

[Mean jet pt vs number of vertices]

Average reconstructed jet pt at the EM scale versus the number of reconstructed primary vertices (NPV), for matched truth-jet pt between 20 and 25 GeV. Requiring that all matched tracks originate from the hard scatter (JVF = 1) reduces the pile-up induced pt offset by roughly 40%, indicating that tracks effectively describe only 40% of the impact of pile-up on reconstructed jets.

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Response vs the true jet pt]

Calorimeter response to central jets at the LCW scale, as a function of the MC truth jet pt. The pt offset induced by a mean of 40 pile-up interactions ( = 40) causes a shift in the reconstructed jet pt of approximately 25 GeV. Application of an average offset correction, parametrized by the number of reconstructed primary vertices (NPV), recovers the response observed in the absence of pile-up ( = 0).

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Subtraction of in-time pile-up using the “jet areas” method, central]

Average MC truth-based jet pt offset at the LCW scale versus the number of reconstructed primary vertices (NPV). Out-of-time pile-up is constrained by using only events with 5 < mu < 6. In the central region (0.0 < |eta| < 0.3) the jet areas correction removes the impact of in-time pile-up on the jet pt, though a small overcorrection is apparent.

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Subtraction of in-time pile-up using the “jet areas” method, forward]

Average MC truth-based jet pt offset at the LCW scale versus the number of reconstructed primary vertices (NPV). Out-of-time pile-up is constrained by using only events with 5 < mu < 6. In the forward region (3.6 < |eta| < 4.5), the jet areas correction removes the impact of in-time pile-up on the jet pt, though a small overcorrection is apparent.

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Subtraction of out-of-time pile-up using the “jet areas” method, central]

Average MC truth-based jet pt offset at the LCW scale versus the average number of interactions per bunch crossing (mu), which is sensitive to out-of-time pile-up. In-time pile-up is constrained by using only events with NPV = 6. In the central region (0.0 < |eta| < 0.3), the jet areas correction over-corrects slightly for the impact of out-of-time pile-up.

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Subtraction of out-of-time pile-up using the “jet areas” method, forward region]

Average MC truth-based jet pt offset at the LCW scale versus the average number of interactions per bunch crossing (mu), which is sensitive to out-of-time pile-up. In-time pile-up is constrained by using only events with NPV = 6. In the forward region (3.6 < |eta| < 4.5), sensitivity to out-of-time pile-up is substantially different then in the central region. Since we calculate rho in the central region, the jet areas correction does not account for the impact of out-of-time pile-up on forward jets

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Jet multiplicity vs number of vertices]

Average multiplicity of pile-up jets with LCW-scale pt > 20 GeV versus the number of reconstructed primary vertices (NPV) before and after correcting for the pt offset induced by pile-up, in simulated dijet events with a mean of 20 overlaid pile-up interactions. The average offset correction, parametrized by NPV, shifts up to 90% of pile-up jets below the pt threshold. By estimating the pile-up offset event by event using low-pt calorimeter deposits, the jet areas correction rejects a substantial fraction of the remaining 10%.

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Jet multiplicity of pile-up jets vs number of vertices]

Average multiplicity of pile-up jets with LCW-scale pt > 20 GeV versus the number of reconstructed primary vertices (NPV) after correcting for the pt offset induced by pile-up, in simulated dijet events with a mean of 20 overlaid pile-up interactions (mu). There is a significant residual number of pile-up jets, even after the jet areas correction. To reject the remaining jets, we can use tracking information. Pile-up jets are virtually eliminated by requiring at least a quarter of the matched track pt to come from the hard scatter vertex (JVF > 0.25).

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Jet resolution for various pile-up subtraction methods]

The width of the MC truth-based jet pt offset at the LCW scale, in a sample with zero pile-up ( = 0), compared to a mean of 40 pile-up interactions, before and after correcting for the pt offset induced by pile-up. Pile-up increases the width by nearly a factor of 3, and the average offset correction does not help to recover this degradation in resolution. However, the jet areas correction recovers 30-40% of the degradation. The remaining 60-70% is due to localized fluctuations in pile-up, which may be reduced by using information from tracks matched to jets.

eps file gif file

<!---------------------------------------------------------------------------------------->

<!---------------------------------------------------------------------------------------->

[Track-based pile-up activity vs calorimeter based]

Track-based local versus global estimates of pile-up activity in a jet, in simulated events with a mean of 40 pile-up interactions. For a given amount of global pile-up activity, there are significant fluctuations in the activity that is directly affecting a specific jet.

eps file gif file

<!---------------------------------------------------------------------------------------->

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Major updates:
-- TancrediCarli - 19-Jul-2012

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