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DiscoveringHeavyParticles

Introduction

This note demonstrates a recently proposed method for determining the mass of boosted particles from their decay products by exploiting the substructure of the resulting single collimated jet using the kT algorithm. We illustrate this method with a simple RPV SUSY model using the ATLAS detector at the LHC. We consider the hadronic decay of boosted neutralinos into single jets composed of three collimated subjets. We consider up to 1fb-1 of integrated luminosity with 10TeV simulated data. The ATL-PHYS-PUB-2009-076 note can be found here


Figure1.eps
Pseudo cone-radius as a function of neutralino pT
Figure2.eps
pT vs. mass for jets in events with at least four jets with |eta| < 2.5 for 1 fb−1
Figure3.eps
Jet mass for jets with pT > 275GeV in events with at least four jets with |eta| < 2.5
Figure4.eps
y2 vs. y1 for jets with pT >275GeV in events with at least four jets with |h|<2.5 (distributions normalised to unity)
Figure5.eps
Jet mass for jets with pT > 275GeV and y2 > −0.17y1 +0.08 in events passing all event selection cuts
Figure6.eps
Jet pT for jets with pT > 275GeV and y2 > −0.17y1+0.08 in signal events passing all event selection cuts
Figure7.eps
Jet mass for jets with pT > 275 GeV and y2 > −0.17y1 +0.08 in events passing all event selection cuts
  Cut 1 Cuts 1 & 2 Cuts 1,2 & 3 Cuts 1,2,3 & 4
SUSY 14577 5849 792 347
t t 2.310^5 2,000 200 1
dijets 3.210^9 1.110^6 1.810^4 1100
W+jets 1500 20 20 0
Z+jets 1.910^4 210 2 1
Table 2: Offline Cut Flow (all counts are Events per 1 fb−1)
Trigger Name Total Prescale Effic. before event selection (%) Effic. after event selection (%)
J350 1 50.0 82.7
3J180 1 56.0 98.3
4J95 20 77.6 99.6
3J60 1000 95.0 99.6
J265 15 75.5 99.6
4J125 1 55.8 99.6
JE280 2 91.0 100
JE340 1 83.2 100
Table 3: Trigger efficiencies for various jet triggers on RPV SUSY events.
Topic attachments
I Attachment History Action Size Date Who Comment
Unknown file formateps Figure1.eps r1 manage 187.1 K 2009-09-01 - 15:04 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 1 ]
GIFgif Figure1.gif r1 manage 50.8 K 2009-09-01 - 15:22 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 1 ]
Unknown file formateps Figure2.eps r1 manage 110.5 K 2009-09-01 - 15:04 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 2 ]
GIFgif Figure2.gif r1 manage 39.0 K 2009-09-01 - 15:23 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 2 ]
Unknown file formateps Figure3.eps r1 manage 27.6 K 2009-09-01 - 15:05 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 3 ]
GIFgif Figure3.gif r1 manage 10.8 K 2009-09-01 - 15:23 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 3 ]
Unknown file formateps Figure4.eps r1 manage 154.0 K 2009-09-01 - 15:06 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 4 ]
GIFgif Figure4.gif r1 manage 28.8 K 2009-09-01 - 15:23 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 4 ]
Unknown file formateps Figure5.eps r1 manage 25.5 K 2009-09-01 - 15:06 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 5 ]
GIFgif Figure5.gif r1 manage 12.7 K 2009-09-01 - 15:24 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 5 ]
Unknown file formateps Figure6.eps r1 manage 12.2 K 2009-09-01 - 15:07 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 6 ]
GIFgif Figure6.gif r1 manage 13.9 K 2009-09-01 - 15:24 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 6 ]
Unknown file formateps Figure7.eps r1 manage 19.7 K 2009-09-01 - 15:07 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 7 ]
GIFgif Figure7.gif r1 manage 21.0 K 2009-09-01 - 15:25 ChristopherCowden ATL-PHYS-PUB-2009-076 [ Figure 7 ]
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Topic revision: r7 - 2010-12-06 - ElmarRitsch
 
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