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