Measurement of the Jet Energy Scale in the CMS experiment ... - IIHE

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124 CHAPTER 5: Estimating of the Jet Energy Scale Calibration Factor1.41.31.21.1∆E b10.90.80.70.60.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4∆E lFigure 5.35: The distribution of the χ 2 (∆E l , ∆E b ) which is obtained by the sum of theχ 2 distributions for all selected collision data events.2∆ χ7006005002∆ χ2502004001503002001001005000.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4∆ E l00.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4∆ E bFigure 5.36: The projected distribution of the χ 2 (∆E l , ∆E b ) into the (left) ∆E l and(right) ∆E b axis which are fitted with a second-degree polynomial. The results areobtained for 36.1pb −1 of real proton collision data.
CHAPTER 5: Estimating of the Jet Energy Scale Calibration Factor 125simulationdata∆ε est∆ε estl(%) -8.5±2.4(stat.)±0.9(sys.) -8.6±2.7(stat.)b(%) -3.2±3.5(stat.)±1.0(sys.) -5.0±3.9(stat.)Table 5.17: The final estimated residual jet energy corrections obtained in the 36.1pb −1data set. The results found on the simulation and the collision data events, are listedseparately. The statistical uncertainties are corrected for the non-unity width of thepull distributions.reduced by using a larger sample of data events, as will be discussed in more detail inthe next chapter. Obviously the residual corrections are found to be equal in data andsimulation. They are in reasonable agreement within the quoted uncertainties.Summary of the AnalysisThe method to estimate residual jet energy corrections has been applied on 36.1pb −1of integrated real proton collisions collected by the CMS experiment in 2010. The residualcorrections are estimated based on the e+jets t¯t candidates. Event selection cutshave been applied to enhance the signal over background ratio followed by imposing themass constraints of the W boson and the top quark with the use of a kinematic fit technique.The kinematic fit procedure provides a χ 2 value used to fill a two-dimensionaldistribution in the directions of ∆E l and ∆E b , on which the final estimation is based.As it is seen from Table 5.17, the estimated residual jet energy corrections which areobtained using the collision data events are compatible with the results derived basedon the simulation. Then it can be claimed that the method works reasonably on the36.1pb −1 of accumulated 2010 collision data taken by the CMS experiment at the LHC.
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Vrije Universiteit BrusselFaculteit
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IntroductionThe Standard Model of p
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Chapter 1The Standard Model of Part
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CHAPTER 1: The Standard Model of Pa
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Chapter 2The CMS experiment at the
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CHAPTER 2: The CMS experiment at th
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Chapter 3Object ReconstructionThe e
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Chapter 4Reconstructing and Selecti
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CHAPTER 4: Reconstructing and Selec
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Chapter 5Estimating of the Jet Ener
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CHAPTER 5: Estimating of the Jet En
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CHAPTER 5: Estimating of the Jet En
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Page 141 and 142: SummaryJets appear in the final sta
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Measurement of the Jet Energy Scale in the CMS experiment ... - IIHE

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