Some more Work on ZH -> mumubb

Andy Haas

Columbia U. / Nevis Labs

ZH->llbb Meeting

November 3, 2007

QCD “Isolation”

QCD isolation is flat

Extrapolate into

“isolated region”

QCD “Isolation”

Choose a flat random

number for QCD isolation

Can now use in NN

directly

Well-modeled

MET in track-only Z events

Resolution is worse

in the forward region

MET in track-only Z events

Can see the same

effect in data

MET in track-only Z events

Can correct the MET

magnitude (and direction)

for this track

Resolution in these

events is then the same

as in other Z event types

Before correction

After correction

Standard Z's

MET in track-only Z events

Works just as well in data

There's some

contamination from

non-Z events (QCD, tt)

MET in track-only Z events

The angle of the MET

is now symmetric in phi!

Jet Width

Jet width is pretty

well-modeled

Seems different between

signal and background!

Jet Width

Same for second-leading

jet

Jet Width

Difference persists

after b-tagging

What physics causes this?

gluons vs. light-jets?

Jet Width

Same for second-leading

jet

Jet EM Fraction

Jet EM fraction is pretty

well-modeled

Seems different between

signal and background!

Jet EM Fraction

Difference persists

after b-tagging

What physics causes this?

b-jets with electron decays?

Note that Z+bb has similar

shape as signal, whereas

Z+light does not!

Andy Haas

2004-07-07T15:59:13