Alain Romeyer - March 2005 1

Light h0 decay in SUSY cascade

Jet Reconstruction & B tagging

Introduction

First use of DST

Jet reconstruction and calibration issues

B tagging

Conclusion

Filip Moortgat (CERN)Alain Romeyer (Mons - Belgium)

Alain Romeyer - March 2005 2

Introduction

Benchmark point LM5Tan = 10AO = 0µ > 0M1/2 = 360 GeVM0 = 230 GeV

MSUGRA 5 parameters : m0, m1/2, A, tan , sign(µ)

S. Abdullin – L. Pape Update II of the new MSUGRA test points proposal

0 02 1

0 0

g

q

χ χ

H h

m ~ 860GeV

m ~ 800 GeV

m ~ 273 GeV m ~ 142 GeV

m ~ 570 GeV m ~ 116 GeV

Alain Romeyer - March 2005 3

Signatures

p

p

01χ

0h

q

gor

q

02χ

q

b

b

LSPMET

B tagging

85 %

72 %

~35 %

Alain Romeyer - March 2005 4

Signatures…

Main background expected to come from SUSY itself!!! (sbottom…)

100 000 evt production of all SUSY channels (20% of them contain our signal)

SM background expected small (Z+jets, top…) rejected by high jet multiplicity and important MET was not our priority (analysis has just started CRAB & LCG)

Reconstruction strategy focus on jet reconstruction, b tagging and MET

Access info from DST using ORCA_8_7_2 test of official Jet Calibration (GammaJet) Try different Track Counting significance threshold

Alain Romeyer - March 2005 5

DST Jet calibrationOnly b jets coming from h0 decay (mh = 116 GeV)

Alain Romeyer - March 2005 6

Jet E resolutionOnly b jets coming from h0 decay (mh = 116 GeV)

Alain Romeyer - March 2005 7

Minv (Signal + SUSY bkg)

Alain Romeyer - March 2005 8

Comparison with private calib.

Only b jets coming from h0 decay (mh = 116 GeV)

Alain Romeyer - March 2005 9

Jet E resolutionOnly b jets coming from h0 decay (mh = 116 GeV)

Alain Romeyer - March 2005 10

IC with 0.7 cone size

No calibration for 0.7 cone 0.5 cone calibration used !!!

Only b jets coming from h0 decay (mh = 116 GeV)

Alain Romeyer - March 2005 11

BtaggingTrack Counting Algo. (only b tagged jets)

Tag jet if 2 tracks are found above a given Significance threshold

Alain Romeyer - March 2005 12

B tagging eff/mistag

54.151.4

4.9

16.6

47.845.1

3.5

12.3

42.840.2

2.9

9.7

0.0

10.0

20.0

30.0

40.0

50.0

60.0

b b from h uds c

Eff

icie

ncy

/ I

nef

fici

ency (

%)

S > 3

S > 4

S > 5

IC cone = 0.5

Alain Romeyer - March 2005 13

Impact on Minv (Signal)Only b jets coming from h0 decay (mh = 116 GeV)

Alain Romeyer - March 2005 14

Minv (Signal + SUSY bkg)

Alain Romeyer - March 2005 15

Conclusion Jet calibration on DST for 0.5 cone and IC algo

is working

Jet reconstruction performance with other cone size cannot be done with DST info (no calibration)

Hardest cut for B tagging Track Counting does not improve the S/B ratio

Solution : try to reconstruct the jet charge

SM bkg analysis started (on LCG using CRAB) in particular for tt inclusive

Alain Romeyer - March 2005 16

Conclusion…