Probing GeV-scale MSSM neutralino dark matter in collider and direct detection experiments

Given the recent constraints from the dark matter (DM) direct detections, we examine a light GeV-scale (2-30 GeV) neutralino DM in the alignment limit of the Minimal Supersymmetric Standard Model (MSSM). In this limit without decoupling, the heavy CP-even scalar $H$ plays the role of the Standard Model (SM) Higgs boson while the other scalar $h$ can be rather light so that the DM can annihilate through the $h$ resonance or into a pair of $h$ to achieve the observed relic density. With the current collider and cosmological constraints, we find that such a light neutralino DM above 6 GeV can be excluded by the XENON-1T (2017) limits while the survivied parameter space below 6 GeV can be fully covered by the future germanium-based light dark matter detections (such as CDEX), by the Higgs coupling precison measurements or by the production process $e^+e^- \to hA$ at an electron-positron collider (Higgs factory).Comment: 15 pages, 5 figures. Discussions and references added, version accepted by PL

A hidden self-interacting dark matter sector with first order cosmological phase transition and gravitational wave

A dark scalar mediator can easily realize the self-interacting dark matter scenario and satisfy the constraint of the relic density of the dark matter. When the hidden sector is highly decoupled from the visible sector, the gravitational waves produced by the first order phase transition resulted from this dark scalar mediator will be an important signature to probe the dark sector physics. The simplest dark sector with one scalar and one Dirac fermion is studied in this work. A generic quartic finite-temperature potential is used to induce the strong first order phase transition. A joint analysis of the self-interacting dark matter, the relic density of the dark matter and the first order phase transition shows that the mass range of the dark scalar is about $(4\times 10^{-4} \sim 3)~\rm GeV$. For the dark matter, when the temperature ratio $\xi$ between the hidden sector and the visible sector is larger than 0.1, its mass range is about $(10~ \rm MeV\sim 10~ \rm GeV)$. The produced gravitational waves have a peak frequency of $(10^{-6}\sim 10^{-3}) ~\rm Hz$ for a temperature ratio $0.1<\xi<1$, which may be detectable in future measurements.Comment: 17 pages, 3 figure

Direct detection of finite-size dark matter via electron recoil

In direct dark matter (DM) detection via scattering off the electrons, the momentum transfer plays a crucial role. Previous work showed that for self-interacting DM, if the DM particle has a size (the so-called puffy DM), the radius effect could dominate the momentum transfer and become another source of velocity dependence for self-scattering cross section. In this work we investigate the direct detection of puffy DM particles with different radii through electron recoil. We find that comparing with the available experimental exclusion limits dominated by the mediator effect for XENON10, XENON100 and XENON1T, the constraints on the puffy DM-electron scattering cross-section become much weaker for large radius DM particles. For small-radius DM particles, the constraints remain similar to the point-like DM case.Comment: 11 pages, 2 figure

Revisiting Puffy Dark Matter with Novel Insights: Partial Wave Analysis

We present a comprehensive study on the self-interaction cross-section of puffy dark matter (DM) particles, which have a significant intrinsic size compared to their Compton wavelength. For such puffy DM self-interaction cross-section in the resonant and classical regimes, our study demonstrates the significance of the Yukawa potential and the necessity of partial wave analysis: (i) Due to the finite-size effect of puffy DM particles, the new Yukawa potential of puffy DM is found to enlarge the Born-effective regime for the self-interaction cross-section, compared with the point-like DM; (ii) Our partial wave analysis shows that depending on the value of the ratio between $R_{\chi}$ (radius of a puffy DM particle) and $1/m_{\phi}$ (force range), the three regimes (Born-effective, resonant and classical) for puffy DM self-interaction cross-section can be very different from the point-like DM; (iii) We find that to solve the small-scale anomalies via self-interacting puffy DM, the Born-effective and the resonant regimes exist for dwarf galaxies, while for the cluster and Milky Way galaxy the non-Born regime is necessary.Comment: 17 pages, 8 figures, accepted by JHE