JOURNAL OF HIGH ENERGY PHYSICS, v.2016, no.6, pp.110 -
We consider extending the Standard Model by including an additional Abelian gauge group broken at low energies under which the right-handed top quark is the only eﬀectively charged Standard Model fermion. The associated gauge boson (Z) is then naturally top-philic and couples only to the rest of the SM particle content at loop-level or via kinetic mixing with the hypercharge gauge boson which is assumed to be small. Working at the eﬀective theory level, we demonstrate that such a minimal extension allows for an improved ﬁtting of the∼2σexcess observed intt¯hsearches at the LHC in a region of parameter space that satisﬁes existing collider constraints. We also present the reach of the LHC at 13 TeV in constraining the relevant region of parameter space. Additionally we show that within the same framework a suitably chosen fermion charged only under the exotic Abelian group can, in the region of parameter space preferred by thet¯thmeasurements, simultaneously explain the dark matter relic density and theγ-ray excess at the galactic center observed by the Fermi-LAT experiment. (c) The Authors.