Ingrid Fadelli is a writer for the website Phys.org.
Dark matter, or hypothetical matter in the universe that does not emit, absorb or reflect light, is very difficult to detect and is being observed by teams of astrophysicists around the world. Since it would be made of fermions, most of the exploration has been done theoretically.
The PandaX Collaboration, a large group of researchers in China involved in the PandaX-4T experiment, has recently carried out a study to extend the sensitive mass window for experiments aimed at directly detecting fermionicDM from above GeV to MeV or even keV ranges.
Two papers detailing the results of two searches for fermionic DM using data gathered as part of the Panda X-4T experiment have been published.
Prof. Shao-Feng Ge is one of the researchers who carried out the study
According to the Einstein relation, even keV can deposit a large amount of recoil energy in the recoil electron.
The idea of observing light fermionicDM by detecting the recoil energy resulting from the absorption of its mass has been explored by different groups of theoretical physicists. These studies offered valuable theoretical predictions, but they haven't been tested yet.
The basic features of this unique channel were established in the past. Real data was used to search for predicted signals.
Studies show that in nuclear absorption reactions, the mass ofDM is converted into energy that charges the nucleus and neutrinos. Nuclear recoil energy should be proportional to the square of theDM mass and result in a mono-energetic spectrum. In their first study, the PandaX-4T collaboration tried to detect the energy that comes from fermionicDM by nuclei.
The mono-energetic spectrum is different from the elastic scattering spectrum and has not been searched before in the Direct Detection experiment. We performed studies on the nuclear recoil energy reconstruction as part of the pandaX-4t search.
There was a good consistency in the data collected by the TPC and the model. The signal region they scanned corresponds to the recoil of nuclear energy up to 100 keV.
In the same way that nuclear absorption processes are sensitive to light, electronic absorption processes are also sensitive to light. The conversion of a hypothetical fermionicDM particle's static mass into the energy of electrons is implied by electronic absorption processes.
Liquid xenon detectors could be used to detect recoiling signals from fermionicDM. The second study was done by the PandaX-4T collaboration.
It's easier to be ejected from an electron than it is from a nucleic acid. Electronics can be sensitive to the sub-MeV mass range.
Most of the electronic recoiling energy is visible, unlike nuclear recoiling signals where a small amount of energy is quenched into heat and can't be detected.
The field theory approach has been used to study different hypothetical six-dimensional operators in the four-fermion process. The electronic absorption signals will be the same regardless of operators in the direct detection experiments, but the interpretations on the couplings are different.
There were no significant signals over the expected background when the search for sub-MeV fermionicDM was carried out. The team was able to set the strongest limits on the interactions with a mass of several tens keV/c 2
Two years ago, XENON1T reported a low-energy excess, which could be interpreted as an electronic absorption of 60 keV/c 2 fermionicDM. Our data is challenging this possibility.
The recent searches done by the PandaX-4T collaboration show the potential absorption of nuclear and electronic absorption processes. They could inspire other collaborations to perform similar searches.
"If any excess is observed, the energy of the excess would indicate the mass of the object," said Prof. Zhou. We obtained model-independent constraints on the sub-GeVDM-nucleon scattering cross section and probe down to the 10-50 cm 2 region for the first time. We study a UV- complete model with Z' mediation, which brings together the constraint of the collider, the constraint of the universe, and our limit from direct detection.
The Panda X-4T collaboration has set new limits for experiments that aim to detect fermionicDM. The team will soon be conducting additional searches for elusive, lightDM as their experiment continues.
The data we reported is equivalent to exposing a 600- kilogram liquid target for a year. We expect a cumulative exposure of 10 times greater whenPandaX-4T ends. We are excited to see how the story unfolds in the future, as we expect to get a more precise understanding of our detector to the nuclear recoil and electronic recoil signals.
The first search for the absorption of dark matter was done with the PandaX-4T experiment. There is a book titled "PhysRevLett.129.161803."
The Search for Light Fermionic Dark Matter Absorption on Electrons inPandaX-4T was published in the Physical Review Letters. There is a book titled "PhysRevLett.129.161804."
Jeff A. Dror and his team show how to directly detect signals from the absorption of dark matter. There is a book titled "PhysRevLett.124.181301."
Jeff A. Dror and his colleagues studied the absorption of sub-MeV fermionic dark matter by electron targets. There is a book titled "PhysRevD.103.035001."
Sub-MeV fermionic dark matter can be absorbed by electron targets. Rev. D 103 and Physical Review D are part of the same book. There is a DOI titled "10.103/PhysRevD.105.119903".
Jeff A. Dror and his colleagues studied the absorption of dark matter by nuclear targets. The book is titled "JHEP02(2020)134."
The fermionic absorption dark matter is discussed in the Journal of High Energy Physics. The book is titled "JHEP05(22)191."
Journal information: Physical Review Letters , Physical Review D
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