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Jet/Met meeting 11/21/2002 Jet studies 2. Fake jets in p13.02.00 and p11.13.00 3. Effect of coarse hadronic layers and negative cells on jets 1. Jet chunk.

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Presentation on theme: "Jet/Met meeting 11/21/2002 Jet studies 2. Fake jets in p13.02.00 and p11.13.00 3. Effect of coarse hadronic layers and negative cells on jets 1. Jet chunk."— Presentation transcript:

1 Jet/Met meeting 11/21/2002 Jet studies 2. Fake jets in p and p Effect of coarse hadronic layers and negative cells on jets 1. Jet chunk certification in p Emmanuel Busato

2 JetChunk certification in p Comparison between JetChunk in p TMB and jet branches in p root-tuple (created from DSTs) (algo=JCCB)

3 n90 Root-tuple TMBTMB- root tuple

4 E Root-tuple TMBTMB- root tuple

5 Pt Root-tuple TMBTMB- root tuple

6 EMF Root-tuple TMBTMB-root tuple

7 Phi Root-tuple TMBTMB-root tuple

8 Eta Root-tuple TMBTMB-root tuple

9 JetChunk certification summary - For floats, difference TMB root- tuple  10**- 3 - An exception is variable EMF where difference is  5.10**- 3 - Problem with n90 ?

10 Fake jets in p and p Lot of fake jets in p => new quality cut : f90<- 0.5CHF What is the situation in p (where ZS : 2.5  ? - Criterion : f90 if high =>fake jet if low => good jet

11 in p data CHF Cone R=0.7 Cone R=0.5 N1 good jets N2 fake jets N2/N1  33  N2/N1  60  N1 N2

12 in p data N2/N1  16  Cone R=0.5 Cone R=0.7 N2/N1  30  N2 N1

13 The number of fake jets is reduced by a factor of  2 in p , where we have 2.5  of zero suppression (instead of 2.1 in p ) Fake jets in p and p summary

14 Current status of the algorithms : Jets are constructed with a list of positive energy towers. These towers are made of positive and negative energy cells. What happens if we remove corresponding layers (15, 16, 17) ? (input of the algorithm : calorimeter towers without CH layers) Not consistent with Met calculation, which is done with towers > 200MeV or cells > 100MeV Coarse Hadronic may be responsible for fake jets What happens if we keep only positive cells in jets ? Effect of coarse hadronic layers and negative cells on jets

15 Cone R=0.5 N2/N1  7.5  N2/N1  16  N1 N2 N1 N2 N1 N2/N1  7.5  Current algo Without CH layers and neg cells Without CH layers Cone R=0.7 N2 N1 N2 N1 N2 N1 N2/N1  14  N2/N1  30  N2/N1  14  Current algo Without CH layers and neg cells Without CH layers

16 Summary => reconstruction without CH layers reduces the number of fake jets by a factor of  2


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