Search

We consider a U (1) B - L model with a Z ′ portal Dirac fermion dark matter (DM) χ of low mass which couples very weakly to the B - L gauge boson Z ′ . An arbitrary B - L charge Q ≠ ± 1 , ± 3 of the DM χ ensures its stability. Motivated by the sensitivity reach of forthcoming "Lifetime Frontier" experiments, we focus on the Z ′ mass, m Z ′ , in the sub-GeV to few GeV range. To evaluate the DM relic abundance, we examine both the freeze-out and freeze-in DM scenarios. For the freeze-out scenario, we show that the observed DM abundance is reproduced near the Z ′ resonance, m χ ≃ m Z ′ / 2 , where m χ is the DM mass. For the freeze-in scenario, we focus on m χ ≪ m Z ′ . We show that for a fixed value of m Z ′ , g BL values roughly scale as 1/Q to reproduce the observed DM abundance. For various Q values in the range between 10 - 6 and 10 2 , we show that the gauge coupling values g BL needed to reproduce the observed DM abundance lie in the search reach of future planned and/or proposed experiments such as FASER, Belle-II, LDMX, and SHiP. In the freeze-in case, the Q values to realize observable g BL values are found to be much smaller than that in the freeze-out case. [ABSTRACT FROM AUTHOR]

We consider a class of SUSY models in which the MSSM gauge group is supplemented with a gauged U(1)B−L symmetry and a global U(1)R symmetry. This extension introduces only electrically neutral states, and the new SUSY partners effectively double the number of states in the neutralino sector that now includes a blino (from B − L) and singlino from a gauge singlet superfield. If the DM density is saturated by a LSP neutralino, the model yields quite a rich phenomenology depending on the DM composition. The LSP relic density constraint provides a lower bound on the stop and gluino masses of about 3 TeV and 4 TeV respectively, which is testable in the near future collider experiments such as HL-LHC. The chargino mass lies between 0.24 TeV and about 2.0 TeV, which can be tested based on the allowed decay channels. We also find m τ ˜ 1 ≳ 500 GeV, and m e ˜ , m μ ˜ , m v ˜ S , P ≳ 1 TeV. We identify chargino-neutralino coannihilation processes in the mass region 0.24 TeV ≲ m χ ˜ 1 0 ≈ m χ ˜ 1 ± ≲ 1.5 TeV, and also coannihilation processes involving stau, selectron, smuon and sneutrinos for masses around 1 TeV. In addition, A2 resonance solutions are found around 1 TeV, and H2 and H3 resonance solutions are also shown around 0.5 TeV and 1 TeV. Some of the A2 resonance solutions with tan β ≳ 20 may be tested by the A/H → τ+τ− LHC searches.. While the relic density constraint excludes the bino-like DM, it is still possible to realize higgsino, singlino and blino-like DM for various mass scales. We show that all these solutions will be tested in future direct detection experiments such as LUX-Zeplin and Xenon-nT. [ABSTRACT FROM AUTHOR]