Speaker
Dr
Mark Williams
(Lancaster University / Fermilab)
Description
We report on a study of events containing at least two muons produced in
ppbar collisions at sqrt{s}=1.96 TeV, performed at the D0 experiment
using data corresponding to 0.9 fb-1 of integrated luminosity collected
during 2008. Motivated by a recent claim of an excess in muons produced at
large radius by the CDF collaboration, we study muons that appear to be
produced with a radius between 1.6 and 10 cm from the initial pbbar
collision point. The experimenta signature is a well reconstructed muon that
is missing hits in the innermost layer of the tracking detector. We record
28374 muons that appear to be produced without hits in the first layer of
the tracking detector. Based on the measured hit efficiency, we epect 27
662 pm 503 pm 1027 muons from the primary interaction to not have a
reconstructed hit in this layer. This gives an observed excess of
712 pm 462 pm 942 events in which one or both muons are produced in the
range 1.6 < r < 10 cm, which is expressed as a fraction
(0.40 pm 0.26 pm0.53)\% of the total dimuon sample. A small level of excess
is expected due to cosmic rays, decays-in-flight of pions and kaons, and
hadronic punchthrough, and first estimates of these contributions are made.
We therefore see no anomalously large excess of muons produced a few
centimeters away from the interaction point.
Primary authors
Aurelio Juste
(Fermilab)
Stefan Soldner-Rembold
(University of Manchester)
