jetset vs herwig … once more
DESCRIPTION
Jetset vs Herwig … Once more. c quark effect Jetset vs Herwig on same selected events. c quark effect. Questions : Is there a difference in efficiency between Jetset and Herwig for the different types of quark flavour in final state ? - PowerPoint PPT PresentationTRANSCRIPT
14-Jun-2000 Eric Lançon 1
Jetset vs Herwig… Once more
c quark effectJetset vs Herwig on same selected
events
14-Jun-2000 Eric Lançon 2
c quark effect
• Questions :
– Is there a difference in efficiency between Jetset and Herwig for the different types of quark flavour in final state ?
– Are the fitted masses sensitive to quark flavour content of final state?
14-Jun-2000 Eric Lançon 3
Selection efficiency - same 4f evtsJetset 34511 evts
Herwig35011 evts
Number of selected evts for mass analysis
1.5 % more selected evts for Herwig
Number of c quarks in event
Relative difference of efficiency Herwig / Jetset vs number of c quarks in event
No real effect
14-Jun-2000 Eric Lançon 4
DMW vs nb c quarks in eventAll EventsBackground
in reference but not in fitted samples (1093 evt/sample)
No quark flavour
selection
14-Jun-2000 Eric Lançon 5
DMW vs nb c quarks in eventCommon eventsBackground
in reference but not in fitted samples
No quark flavour
selection
14-Jun-2000 Eric Lançon 6
No c quark in event
Mmin
Nchmin
22)(
HerwigJetset
HerwigJetsetHerwigJetset
2 (Jetset-Herwig)
14-Jun-2000 Eric Lançon 7
No c quark in event
Slimmer Herwig jetsMmin Nchmin
14-Jun-2000 Eric Lançon 8
One c quark in event
Mmin
14-Jun-2000 Eric Lançon 9
Two c quarks in event
BtagMmin
14-Jun-2000 Eric Lançon 10
Variation with Nb of c quarks in evt<Mmin> vs nb of c quark in events
B evt tag and Nch1 vs nb of c quark in events
2 of distributions Jetset vs Herwig
The are the only variables with a linear variation
Typical shape
14-Jun-2000 Eric Lançon 11
Conclusions from c quark study
• 4q mass selection is 1.5% more efficient on Herwig events, – No real dependence with quark flavour
• The are differences between Jetset and Herwig for the c and non-c final states :– those differences tend to compensate
(except Btag, Nch1)
• The mass shift between Jetset and Herwig is independent of the number of c quarks in final state
14-Jun-2000 Eric Lançon 12
Jetset - Herwig comparison
• Same events in same Ntuple– after mass selection (including pairing)– 600K events each before selection– use events which correspond to same jet-
jet combination for jetset and herwig
• Look at :– global event properties– event/event properties
14-Jun-2000 Eric Lançon 13
Total Event energy
300 Mev more energy in Herwig
•Pb of Eflow calibration?•Need Herwig Z0 events
This explain the higher efficiency of the selection for Herwig ?
14-Jun-2000 Eric Lançon 14
Charged energy
300 Mev less charged energy in Jetset
14-Jun-2000 Eric Lançon 15
Electromagnetic energy
same electromagnetic energy for Jetset and Herwig
14-Jun-2000 Eric Lançon 16
Charge multiplicity
0.16 more charged particles in Jetset
14-Jun-2000 Eric Lançon 17
Multiplicity per jet
Nb of charged tracks/jet Nb of Eflow objects/jet
More objects/jet in Jetset
14-Jun-2000 Eric Lançon 18
E jet jetset/Herwig vs
14-Jun-2000 Eric Lançon 19
Em fraction in jet vs
No dependence
14-Jun-2000 Eric Lançon 20
Multiplicity in jets vs
No dependence
Nb of charged tracks/jet Nb of Eflow objects/jet
14-Jun-2000 Eric Lançon 21
Fitted mass : Herwig - JetsetMHerwig - Mjetset = 90 8 MeV
Before rescaling
14-Jun-2000 Eric Lançon 22
Fitted mass vs Fch and Fem
No real dependence / difference Jetset-Herwig
14-Jun-2000 Eric Lançon 23
Fitted mass vs charged multiplicity
Some dependence and difference Jetset-Herwig?
14-Jun-2000 Eric Lançon 24
and (Jetset-Herwig)
(Jetset-Herwig) (Jetset-Herwig)
Worst ? … see later
14-Jun-2000 Eric Lançon 25
(raw-generated) vs gen.
Z
generated
Herwig
Jetset(rec.-gen.) vs gen.
• Jetset jets are more inside• Herwig jets less biased at low
14-Jun-2000 Eric Lançon 26
resolutionBetter resolution for Herwig
(rec.-gen.)
<> = -0.019 0.009RMS = 6.22
<> = -0.006 0.008RMS = 5.51
14-Jun-2000 Eric Lançon 27
after fit
(fit-gen.) vs gen.(fit-rec.) vs gen.
Fit does not correct for the difference in reconstruction at low angle between Jetset and Herwig
14-Jun-2000 Eric Lançon 28
Delta fitted mass vs Nb jets in Barrel
An effect when NO jet in barrel ?
MJetset - MHerwig vs number jets in barrel
14-Jun-2000 Eric Lançon 29
Delta fitted mass vs gen. Min.
MJetset - MHerwig vs Min( jet-gen.)
14-Jun-2000 Eric Lançon 30
Sum of Pt2
Jets JetParticles
TP 2
Wider Jetset jets
14-Jun-2000 Eric Lançon 31
Delta fitted mass vs Sum of Pt2MJetset - MHerwig vs Sum Pt2
Strong dependence
14-Jun-2000 Eric Lançon 32
Jet-jet angle
Jet1
Jet2
Herwig Ws are more ‘opened’
= -0.32 0.04 deg.
Strongly related to W mass
14-Jun-2000 Eric Lançon 33
Delta jet-jet angle vs (jetset-Herwig) vs number jets in barrel
(jetset-Herwig) vs W gen
No real variation
14-Jun-2000 Eric Lançon 34
Conclusions
• More reconstructed energy (300 MeV) with Herwig
• More charged energy in Herwig (300 MeV)– Calibration of Eflow? Herwig Z0 events
needed– Explain difference in efficiency
• Larger particle multiplicity in Jetset• Jetset jets are wider
– More losses are low/high
• Jetset resolution worst than Herwig• Jet-Jet angle larger for Herwig than JetsetWhich of the two MC data prefer?
14-Jun-2000 Eric Lançon 35
The 18 Variables
• Global properties of the event– # charged tracks in an event Nch
– charged/total energy Fch
– em E fraction in event Fem
• Parton-shower related– Minimum jet mass Mmin
– Maximum jet mass Mmax
– Sum of Pt2 wrt jets SumPT2
– Sum of Angles Ch. Part. wrt Jet 1,2
SumAng12
Jets JetParticles
TP 2
2,1arg
,JetsParticlesedCh
JetParticleCos
14-Jun-2000 Eric Lançon 36
The 18 Variables (Contd.)
• Hadronisation related– minimum # object in a jet Nobjmin
– minimum # of charged track in a jet Nchmin
– Max. e.m. energy fraction in 1 deg. cone
Max-em-frac
– Max. charged track energy fraction Max-ch-trk
– # charged particles in leading E jet Nch1
– # charged particles in lowest E jet Nch4
– # objects particles in leading E jet Nobj1
– # objects particles in lowest E jet Nobj4
– Sum Jets Btag SUMPROB
– QIPBTAG event prob. PROBE
Jets
jetobPrlog
10