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Constraining a general U(1)$^prime$ inverse seesaw model from vacuum stability, dark matter and collider

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 نشر من قبل Arindam Das
 تاريخ النشر 2019
  مجال البحث
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We consider a class of gauged $U(1)$ extensions of the Standard Model (SM), where the light neutrino masses are generated by an inverse seesaw mechanism. In addition to the three right handed neutrinos, we add three singlet fermions and demand an extra $Z_2$ symmetry under which, the third generations of both of the neutral fermions are odd, which in turn gives us a stable dark matter candidate. We express the $U(1)$ charges of all the fermions in terms of the U(1) charges of the standard model Higgs and the new complex scalar. We study the bounds on the parameters of the model from vacuum stability, perturbative unitarity, dark matter relic density and direct detection constraints. We also obtain the collider constraints on the $Z$ mass and the $U(1)$ gauge coupling. Finally we compare all the bounds on the $Z$ mass versus the $U(1)$ gauge coupling plane.

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We study a class of general U$(1)^prime$ models to explain the observed dark matter relic abundance and light neutrino masses. The model contains three right handed neutrinos and three gauge singlet Majorana fermions to generate the light neutrino ma ss via the inverse seesaw mechanism. We assign one pair of degenerate sterile neutrinos to be the dark matter candidate whose relic density is generated by the freeze-in mechanism. We consider different regimes of the masses of the dark matter particle and the ${Z^prime}$ gauge boson. The production of the dark matter can occur at different reheating temperatures in various scenarios depending on the masses of the ${Z^prime}$ boson and the dark matter candidate. We also note that if the mass of the sterile neutrino dark matter is $gtrsim 1 rm{MeV}$ and if the $Z^prime$ is heavier than the dark matter, the decay of the dark matter candidate into positrons can explain the long standing puzzle of the galactic $511rm{keV}$ line in the Milky Way center observed by the INTEGRAL satellite. We constrain the model parameters from the dark matter analysis, vacuum stability and the collider searches of heavy ${Z^prime}$ at the LHC. For the case with light $Z^prime$, we also compare how far the parameter space allowed from dark matter relic density can be probed by the future lifetime frontier experiments SHiP and FASERs in the special case of $U(1)_{B-L}$ model.
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