A search is performed for long-lived particles that decay into final
states that include a pair of electrons or a pair of muons. The
experimental signature is a distinctive topology consisting of a pair of
charged leptons originating from a displaced secondary vertex. Events
corresponding to an integrated luminosity of 19.6 (20.5) fb(-1) in the
electron (muon) channel were collected with the CMS detector at the CERN
LHC in proton-proton collisions at root s TeV. No significant excess is
observed above standard model expectations. Upper limits on the product
of the cross section and branching fraction of such a signal are
presented as a function of the long-lived particle’s mean proper decay
length. The limits are presented in an approximately model-independent
way, allowing them to be applied to a wide class of models yielding the
above topology. Over much of the investigated parameter space, the
limits obtained are the most stringent to date. In the specific case of
a model in which a Higgs boson in the mass range 125-1000 GeV/c(2)
decays into a pair of long-lived neutral bosons in the mass range 20-350
GeV= c(2), each of which can then decay to dileptons, the upper limits
obtained are typically in the range 0.2-10 fb for mean proper decay
lengths of the long-lived particles in the range 0.01-100 cm. In the
case of the lowest Higgs mass considered (125 GeV/c(2)), the limits are
in the range 2-50 fb. These limits are sensitive to Higgs boson
branching fractions as low as 10(-1)