Speaker
Description
We construct a model in which the standard model
is extended by a hidden sector with two gauge $U(1)$ bosons.
A Dirac fermion $\psi$ charged under both $U(1)$ fields
is introduced in the hidden sector which
can be a subcomponent of the dark matter in the Universe.
Stueckelberg mass terms between the two
new gauge $U(1)$ fields
and the hypercharge gauge boson mediate
the interactions between the standard model
sector and the hidden sector.
A remarkable collider signature of this model
is the enhanced long-lived dark photon events at the LHC
than the conventional dark photon models;
the long-lived dark photons in the model can be
discriminated from the background
by measuring the time delay signal in the
precision timing detectors which are proposed
to be installed in the
LHC upgrades and have an
${\cal O} (10)$ pico-second detection efficiency.
Searches with current LHCb data are also investigated.
Various experimental constraints on the model
including collider constraints and cosmological constraints
are also discussed.
