Light $$$$Z^\prime $$$$ and Dirac fermion dark matter in the $$B-L$$ model

Journal Article · Mon Oct 03 00:00:00 EDT 2022 · European Physical Journal. C, Particles and Fields (Online)

DOI:https://doi.org/10.1140/epjc/s10052-022-10801-3· OSTI ID:1890554

Nath, Newton; Okada, Nobuchika; Okada, Satomi; Raut, Digesh; Shafi, Qaisar

Abstract

We consider a $$$$U(1)_{B-L}$$$$ $U{\left(1\right)}_{B-L}$ model with a $$$$Z^\prime $$$$ $Z^{\prime }$ portal Dirac fermion dark matter (DM) $$$$\chi $$$$ $\chi$ of low mass which couples very weakly to the $$B - L$$ $B-L$ gauge boson $$$$Z^\prime $$$$ $Z^{\prime }$ . An arbitrary $$B-L$$ $B-L$ charge $$$$Q\ne \pm 1, \pm 3$$$$ $Q\ne \pm 1,\pm 3$ of the DM $$$$\chi $$$$ $\chi$ ensures its stability. Motivated by the sensitivity reach of forthcoming “Lifetime Frontier” experiments, we focus on the $$$$Z^\prime $$$$ $Z^{\prime }$ mass, $$$$m_{Z^\prime }$$$$ $m_{Z^{\prime }}$ , in the sub-GeV to few GeV range. To evaluate the DM relic abundance, we examine both the freeze-out  and freeze-in  DM scenarios. For the freeze-out  scenario, we show that the observed DM abundance is reproduced near the $$$$Z^\prime $$$$ $Z^{\prime }$ resonance, $$$$m_\chi \simeq m_{Z^\prime }/2$$$$ $m_{\chi }\simeq m_{Z^{\prime }}/2$ , where $$$$m_\chi $$$$ $m_{\chi }$ is the DM mass. For the freeze-in  scenario, we focus on $$$$m_\chi \ll m_{Z^\prime }$$$$ $m_{\chi }\ll m_{Z^{\prime }}$ . We show that for a fixed value of $$$$m_{Z^\prime }$$$$ $m_{Z^{\prime }}$ , $$$$g_{BL}$$$$ $g_{\mathrm{BL}}$ values roughly scale as 1/ Q to reproduce the observed DM abundance. For various Q values in the range between $$$$10^{-6}$$$$ ${10}^{-6}$ and $$10^2$$ ${10}^2$ , we show that the gauge coupling values $$$$g_{BL}$$$$ $g_{\mathrm{BL}}$ needed to reproduce the observed DM abundance lie in the search reach of future planned and/or proposed experiments such as FASER, Belle-II, LDMX, and SHiP. In the freeze-in  case, the Q values to realize observable $$$$g_{BL}$$$$ $g_{\mathrm{BL}}$ values are found to be much smaller than that in the freeze-out  case.

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0012447; SC0013880
• OSTI ID: 1890554
• Alternate ID(s): OSTI ID: 1997452; OSTI ID: 1998145
• Journal Information: European Physical Journal. C, Particles and Fields (Online), Journal Name: European Physical Journal. C, Particles and Fields (Online) Journal Issue: 10 Vol. 82; ISSN 1434-6052
• Publisher: Springer Science + Business Media
• Country of Publication: Germany
• Language: English