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Register a new userBounds on Dipole Moments of hidden Dark Matter through kinetic mixing
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The existence of dark sectors, consisting of weakly-coupled particles that do not interact with the known Standard Model forces, is theoretically and phenomenologically motivated. The hidden particles are candidates for Dark Matter and can interact with photon through electric dipole moment (EDM) and magnetic dipole moment (MDM). We investigate the possibility a hidden sectors Dark Matter which is charged under a hidden $U(1)_X$ gauge symmetry can interact with photon at loop level. We evaluate the scattering cross section of hidden Dirac fermion with nuclei and set bounds for dipole moment. Using the results of the XENON1T experiment for direct detection of Dark Matter, we get bounds of electromagnetic dipole moment $(mu_chi)$ for mass $m_chi=100$ GeV : $ 1.93448 times 10^{-8}mu_B leq mu_chi leq 1.9496 times 10^{-8}mu_B$ and electric dipole moment $(d_chi): 3.3204 times 10^{-23}embox{.}cm leq d_chi leq 3.3464 times 10^{-23}embox{.}cm$. Using the condition of the existence of dipole moment we constraint the kinetic mixing parameter $ 3times 10^{-3} leq epsilon leq 10^{-2}$ and the mass of the hidden $U(1)_X$ gauge boson to be in the range of 5 GeV $leq m_X leq$ 9 GeV. Our results complement previous works and are within detection capability of LHC.
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We show for the first time that the loop-driven kinetic mixing between visible and dark Abelian gauge bosons can facilitate dark matter production in the early Universe by creating a dynamic portal, which depends on the energy of the process. The required smallness of the strength of the portal interaction, suited for freeze-in, is justified by a suppression arising from the mass of a heavy vector-like fermion. The strong temperature sensitivity associated with the interaction is responsible for most of the dark matter production during the early stages of reheating.
Electric dipole moments are extremely sensitive probes for additional sources of CP violation in new physics models. The multi-scale problem of relating the high-precision measurements with neutrons, atoms and molecules to fundamental parameters can be approached model-independently to a large extent; however, care must be taken to include the uncertainties from especially nuclear and QCD calculations properly. The resulting bounds on fundamental parameters are illustrated in the context of Two-Higgs-Doublet models.
Extra dimensions have proven to be a very useful tool in constructing new physics models. In earlier work, we began investigating toy models for the 5-D analog of the kinetic mixing/vector portal scenario where the interactions of dark matter, taken to be, e.g., a complex scalar, with the brane-localized fields of the Standard Model (SM) are mediated by a massive $U(1)_D$ dark photon living in the bulk. These models were shown to have many novel features differentiating them from their 4-D analogs and which, in several cases, avoided some well-known 4-D model building constraints. However, these gains were obtained at the cost of the introduction of a fair amount of model complexity, e.g., dark matter Kaluza-Klein excitations. In the present paper, we consider an alternative setup wherein the dark matter and the dark Higgs, responsible for $U(1)_D$ breaking, are both localized to the dark brane at the opposite end of the 5-D interval from where the SM fields are located with only the dark photon now being a 5-D field. The phenomenology of such a setup is explored for both flat and warped extra dimensions and compared to the previous more complex models.
We examine the sensitivity of electric dipole moments (EDMs) to new $CP$-violating physics in a hidden (or dark) sector, neutral under the Standard Model (SM) gauge groups, and coupled via renormalizable portals. In the absence of weak sector interactions, we show that the electron EDM can be induced purely through the gauge kinetic mixing portal, but requires five loops, and four powers of the kinetic mixing parameter $epsilon$. Allowing weak interactions, and incorporating the Higgs and neutrino portals, we show that the leading contributions to $d_e$ arise at two-loop order, with the main source of $CP$-violating being in the interaction of dark Higgs and heavy singlet neutrinos. In such models, EDMs can provide new sensitivity to portal couplings that is complementary to direct probes at the intensity frontier or high energy colliders.
If cosmic inflation was driven by an electrically neutral scalar field stable on cosmological time scales, the field necessarily constitutes all or part of dark matter (DM). We study this possibility in a scenario where the inflaton field $s$ resides in a hidden sector, which is coupled to the Standard Model sector through the Higgs portal $lambda_{hs} s^2mathcal{H}^daggermathcal{H}$ and non-minimally to gravity via $xi_s s^2 R$. We study scenarios where the field $s$ first drives inflation, then reheats the Universe, and later constitutes all DM. We consider two benchmark scenarios where the DM abundance is generated either by production during reheating or via non-thermal freeze-in. In both cases, we take into account all production channels relevant for DM in the mass range from keV to PeV scale. On the inflationary side, we compare the dynamics and the relevant observables in two different but well-motivated theories of gravity (metric and Palatini), discuss multifield effects in case both fields ($s$ and $h$) were dynamical during inflation, and take into account the non-perturbative nature of particle production during reheating. We find that, depending on the initial conditions for inflation, couplings and the DM mass, the scenario works well especially for large DM masses, $10^2$ GeV$lesssim m_{s}lesssim 10^6$ GeV, although there are also small observationally allowed windows at the keV and MeV scales. We discuss how the model can be tested through astrophysical observations.
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