Absorption of fermionic dark matter leads to a range of distinct and novel signatures at dark matter direct detection and neutrino experiments. We study the possible signals from fermionic absorption by nuclear targets, which we divide into two classes of four Fermi operators: neutral and charged current. In the neutral current signal, dark matter is absorbed by a target nucleus and a neutrino is emitted. This results in a characteristically different nuclear recoil energy spectrum from that of elastic scattering. The charged current channel leads to induced $β$ decays in isotopes which are stable in vacuum as well as shifts of the kinematic endpoint of $ β$ spectra in unstable isotopes. To confirm the possibility of observing these signals in light of other constraints, we introduce UV completions of example higher dimensional operators that lead to fermionic absorption signals and study their phenomenology. Most prominently, dark matter which exhibits fermionic absorption signals is necessarily unstable leading to stringent bounds from indirect detection searches. Nevertheless, we find a large viable parameter space in which dark matter is sufficiently long lived and detectable in current and future experiments.
We study a new class of signals where fermionic dark matter is absorbed by bound electron targets. Fermionic absorption signals in direct detection and neutrino experiments are sensitive to dark matter with sub-MeV mass, probing a region of parameter space in which dark matter is otherwise challenging to detect. We calculate the rate and energy deposition spectrum in xenon-based detectors, making projections for current and future experiments. We present two possible models that display fermionic absorption by electrons and study the detection prospects in light of other constraints.
We present a new class of direct detection signals; absorption of fermionic dark matter. We enumerate the operators through dimension six which lead to fermionic absorption, study their direct detection prospects, and summarize additional constraints on their suppression scale. Such dark matter is inherently unstable as there is no symmetry which prevents dark matter decays. Nevertheless, we show that fermionic dark matter absorption can be observed in direct detection and neutrino experiments while ensuring consistency with the observed dark matter abundance and required lifetime. For dark ma…
We perform a systematic study of the fermionic DM absorption interactions on electron target in the context of effective field theory. The fermionic DM absorption is not just sensitive to sub-MeV DM with efficient energy release, but also gives a unique signature with clear peak in the electron recoil spectrum whose shape is largely determined by the atomic effects. Fitting with the Xenon1T and PandaX-II data prefers DM mass at $m_χ= 59$keV and 105keV, respectively, while the cut-off scale is probed up to around 1TeV. The DM overproduction in the early Universe, the invisible decay effect on t…
The fermionic dark matter (DM) absorption by nucleus or electron targets provides a distinctive signal to search for sub-GeV DM. We consider a Dirac fermion DM charged under a dark gauge group and with the dark magnetic dipole operator. The DM field mixes with right-handed neutrino and interacts with the ordinary electromagnetic charge current via the kinetic mixing term of gauge fields. As a result, the incoming DM is absorbed and converted into neutrino in final state through the dipole-charge interaction. For the DM absorption by nucleus, the recoil energy spectrum exhibit a peak at $m_χ^2/…
The stronger than expected 21-cm absorption was observed by EDGES recently, and another anomaly of $^8$Be transitions would be signatures of new interactions. These two issues may be related to each other, e.g., pseudoscalar $A$ mediated fermionic millicharged dark matter (DM), and the 21-cm absorption could be induced by photon mediated scattering between MeV millicharged DM and hydrogen. This will be explored in this paper. For fermionic millicharged DM $\barχ χ$ with masses in a range of $2 m_A < 2 m_χ < 3 m_A$, the p-wave annihilation $\barχ χ\to A A$ would be dominant during DM freeze-out…
We confront admixture of dark matter inside neutron star using gravitational wave constraints coming from binary neutron star merger. We consider a relativistic mean field model including $σ-ω-ρ$ meson interaction with NL3 parameterization. We study fermionic dark matter interacting with nucleonic matter via Higgs portal mechanism. We show that admixture of dark matter inside the neutron star soften the equation state and lower the value of tidal deformability. Gravitational wave GW170817 observation puts an upper bound on tidal deformability of a binary neutron star with low spin prior at 90\…
The presence of thermal gluons reduces the stimulated gluon emission off a heavy quark propagating in the quark-gluon plasma (QGP) while absorption causes reduction of the radiative energy loss. On the other hand, the chromo-electromagnetic field fluctuations present in the QGP lead to collisional energy gain of the heavy quark. The net effect of the thermal gluon absorption and field fluctuations is a reduction of the total energy loss of the heavy quark, prominent at the lower momenta. We consider both kind of the energy gains along with the usual losses, and compute the nuclear modification…
First search for light fermionic dark matter absorption on electrons using germanium detector in CDEX-10 experiment
Tsinghua University（清华大学）；Institute of Physics, Academia Sinica（中央研究院物理研究所）；NUCTECH Company（同方威视技术股份有限公司）；YaLong River Hydropower Development Company（雅砻江流域水电开发有限公司）
We calculate the mean free path in a hot and dense nuclear environment for a fermionic dark matter particle candidate in the $\sim$GeV mass range interacting with nucleons via scalar and vector effective couplings. We focus on the effects of density and temperature in the nuclear medium in order to evaluate the importance of the final state blocking in the scattering process. We discuss qualitatively possible implications for opacities in stellar nuclear scenarios, where dark matter may be gravitationally accreted.
Stellar Superradiance and Low-Energy Absorption in Dense Nuclear Media
Weizmann Institute of Science（魏茨曼科学研究所）；Niels Bohr Institute（尼尔斯·玻尔研究所）；CENTRA, Departamento de Física, Instituto Superior Técnico (IST), Universidade de Lisboa (UL)（里斯本大学高级技术学院物理系中心引力研究中心）；Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交通大学李政道研究所）；Shanghai Jiao Tong University（上海交通大学）；University of Manchester（曼彻斯特大学）；The Hong Kong University of Science and Technology（香港科技大学）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器）
We propose a parametrization of the nuclear absorption mechanism relying on the proper time spent by $c\overline{c}$ bound states travelling in nuclear matter. Our approach could lead to the extraction of charmonium formation time. It is based on a large amount of proton-nucleus data, from nucleon-nucleon center-of-mass energies $\sqrt{s_{NN}}=27$ GeV to $\sqrt{s_{NN}}=5.02$ TeV, collected in the past 30~years, and for which the main effect on charmonium production must be its absorption by the nuclear matter it crosses.
Dark Matter constitutes most of the matter in the presently accepted cosmological model for our Universe. The extreme conditions of ordinary baryonic matter, namely high density and compactness, in Neutron Stars make these objects suitable to gravitationally accrete such a massive component provided interaction strength between both, luminous and dark sectors, at current experimental level of sensitivity. We consider several different DM phenomenological models from the myriad of those presently allowed. In this contribution we review astrophysical aspects of interest in the interplay of ordin…
The mass and decay width of the $ϕ$ meson in cold nuclear matter are computed in an effective Lagrangian approach, with the medium dependence of these properties obtained by evaluating kaon-antikaon loop contributions to the $ϕ$ self-energy. At normal nuclear matter density, we find a downward shift of the $ϕ$ mass by a few percent, while the decay width is enhanced by an order of magnitude. We also present $ϕ$--nucleus bound state energies and absorption widths for some selected nuclei, using complex optical potentials obtained in the local density approximation. Our results suggest that the …
