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New Findings in Light Dark Matter via PandaX Experiment

June 09, 2021      Author:

Led by Shanghai Jiao Tong University, researcher at Jinping Laboratory of China used PandaX phase II data (PandaX-II) to search for light dark matter for the first time through the collision of dark matter with electrons. The latest research results were published in Physical Review Letters on May 28th, 2021, under the title “Search for Light Dark Matter–Electron Scattering in the PandaX-II Experiment”. This paper is the sixth article using PandaX-II that has been published in Physical Review Letters.


According to the data of 46.9 tonnes/day exposure in the PandaX-II dark matter detection experiment, a total of 1821 candidates were identified in this study, and the world’s most stringent limit within the dark matter mass ranging from 15 to 30 MeV/c2 was obtained.

Dark matter accounts for 27% of the composition of the universe, much higher than the proportion for ordinary matter, which is 5%. The essence of dark matter is one of the most basic problems in the frontier of physics. In order to further search and study dark matter, China’s new generation of four-ton liquid xenon detector PandaX-4T is being put into trial operation in Jinping Laboratory. Compared with PandaX-II, PandaX-4T has lower detection threshold, lower radioactive background and larger exposure, and it is expected that the detection sensitivity for various dark matter candidates will be significantly improved.

The first- and second-authors of this paper are Cheng Chen, Ph.D. student of Sun Yat-sen University, and Xie Pengwei, postdoctoral student of SJTU. The corresponding author is Meng Yue, SJTU assistant professor. This research was supported by Shanghai Science and Technology Commission, Shanghai Jiao Tong University, Ministry of Science and Technology, Natural Science Foundation of China, Shandong University, Sichuan Science and Technology Department, Hong Kong Hongwen Charity Foundation, etc.



Author: Meng Yue

Source: School of Physics and Astronomy, SJTU

Translated by Zhou Rong

Proofread by Xiao Yangning, Fu Yuhe




We report constraints on light dark matter through its interactions with shell electrons in the PandaX-II liquid xenon detector with a total 46.9  tonnes/day exposure. To effectively search for these very low energy electron recoils, ionization-only signals are selected from the data. 1821 candidates are identified . The 90% C.L. exclusion limit on the scattering cross section between the dark matter and electron is calculated with systematic uncertainties properly taken into account. Under the assumption of point interaction, we provide the world’s most stringent limit within the dark matter mass range from 15 to 30 MeV/c2, with the corresponding cross section from 2.5×10−37 to 3.1×10−38 cm2.