na-atlas mtg
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NA-ATLAS mtg
Experience from the Tevatron – Chlebana FNAL
Experience from the Tevatron – Chlebana FNAL
Experience from the Tevatron – Chlebana FNAL
Experience from the Tevatron – Chlebana FNAL
• Z ee, + jets gives a large statistics sample for the calibration of jets all the way to the forward region– Signal extraction does not
depend directly on jet energy scale. Enough to have 5% (10%) energy scale uncertainty for central (forward) jets
• Study central jet veto with same sample
Rate of leading jet in Zee, + jets after
central jet vetoJet Tagging and
Jet Veto
See W.Quayle’s talk
Mellado – Performance requirements
Huston
Huston
Huston
Seuster Jet/Et-miss
Technique
• Quite a few Taggers are available:– Impact Parameter based taggers (IP2D, IP3D)– Secondary vertex reconstruction based
• Provide discrimination based on a comparison between two hypotheses:– likelihood for a jet to originate from a b-quark (b) OR a light-quark/gluon (u)
• For each discriminating variable x in a tagger, build calibration functions for the two hypotheses – Pb(x) and Pu(x)
• The final discriminating variable (jet level) :
W = x ln(Pb (x) /Pu (x)) Large W ~ high probability that the jet originates from a b quark
Narain – b-tagging
Performance ( )• H events
– Model u-jets using ttjj– release 10.0.1
– High eff crucial: εb4
SV1+IP3DIP3DIP2DLifetime2DlhSig
Ru (εb=50%) Ru (εb=60%)
IP2D 192 ± 2 61 ± 1
SV1+IP3D 610 ± 12 229 ± 3
as a function of pT and ||
@ 60% efficiency
J.-B. de Vivie, V.KostyukhinA. Rozanov, L Vacavant
Planned Improvements
• goal to reach εb=70 % with Ru=100
• A few planned improvements:(Some are already in 11.X.0 or will be in release 12)– combine space and soft leptons in jets– K0 and Λ0 impact parameters, no direct tracks IP – New tracking– track quality classification– multiple secondary vertices– shared/ambiguous hits, kill interactions – +…
Software Changes• Transition from JetTag (‘previous’) and ParticleJet (‘new’)
– A single collection for jets (calo+btagging information)– In the 11.X.0 branch
• Implies that ‘previous’ AOD not readable w/ ‘new’ release. • For ‘previous’ btagging:
– All releases 11.0.X are OK– Recommended: 11.0.4(,1,2)
• For ‘new’ btagging:– 11.4.0 not recommended– 11.5.0:
• Will be useable for b-tagging, including soft lepton taggers
– 12.0.0: scheduled for 1st half of May…– possible to run ‘new’ btagging in 11.0.4(1,2)
L Vacavant
Beam xing angle
Half-angle 143rad – vertical(CMS same angle, horizontal)
~ 1 GeV
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