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Free keywords:
High Energy Physics - Experiment, hep-ex
MPINP:
LHCb - Abteilung Hofmann
Abstract:
A search for the D0 to \pi+ \pi- \mu+ \mu- decay, where the muon pair does
not originate from a resonance, is performed using proton-proton collision data
corresponding to an integrated luminosity of 1.0 fb-1 recorded by the LHCb
experiment at a centre-of-mass energy of 7 TeV. No signal is observed and an
upper limit on the relative branching fraction with respect to the resonant
decay mode D0 to \pi+ \pi- \phi(to \mu+ \mu-), under the assumption of a
phase-space model, is found to be B(D0 to \pi+ \pi- mu+ mu-)/B(D0 to \pi+ \pi-
\phi(to \mu+ \mu-)) < 0.96 at the 90% confidence level. The upper limit on the
absolute branching fraction is evaluated to be B(D0 to \pi+ \pi- \mu+ \mu-) <
5.5 x 10-7 at 90% confidence level. This is the most stringent to date.