Improving our ability to identify the top quark pair ($t\b
ar{t}$) primary vertex (PV) on an event-by-event basis is essentia
l for many analyses in the lepton-plus-jets channel performed by the
Collider Detector at Fermilab (CDF) Collaboration. We comp
are the algorithm currently used by CDF (A1) with another algorith
m (A2)using Monte Carlo simulation at high instantaneous luminos
ities. We confirm that A1 is more efficient than A2 at selecting
the $t\bar{t}$ PV at all PV multiplicities, both with efficien
cies larger than $99\%$. Event selection rejects events with a
distance larger than 5 cm along the proton beam between the the $t\
bar{t}$ PV and the charged lepton. We find flat distributions for
the signal over background significance of this cut for all cu
t values larger than 1 cm, for all PV multiplicities and for both
algorithms. We conclude that any cut value larger than 1 c
m is acceptable for both algorithms under the Tevatron's expect
ed instantaneous luminosity improvements.

Posted to /cdf/pub/thesis/cdf8683_highlumiPVtopselect.pdf
    http://www-cdf.fnal.gov/thesis/cdf8683_highlumiPVtopselect.pdf

Posted by abuzatu