Experimental Limits on Solar Reflected Dark Matter with a New Approach on Accelerated-Dark-Matter–Electron Analysis in Semiconductors

Recently a dark matter–electron (DM–electron) paradigm has drawn much attention. Models beyond the standard halo model describing DM accelerated by high energy celestial bodies are under intense examination as well. In this Letter, a velocity components analysis (VCA) method dedicated to swift analysis of accelerated DM–electron interactions via semiconductor detectors is proposed and the first HPGe detector-based accelerated DM–electron analysis is realized. Utilizing the method, the first germanium based constraint on sub-GeV solar reflected DM–electron interaction is presented with the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>205.4</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>kg</a:mi><a:mo>·</a:mo><a:mi>day</a:mi></a:mrow></a:math> dataset from the CDEX-10 experiment. In the heavy mediator scenario, our result excels in the mass range of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mn>5</c:mn><c:mi>–</c:mi><c:mn>15</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:mi>keV</c:mi><c:mo>/</c:mo><c:msup><c:mrow><c:mi>c</c:mi></c:mrow><c:mrow><c:mn>2</c:mn></c:mrow></c:msup></c:mrow></c:math>, achieving a 3 orders of magnitude improvement comparing with previous semiconductor experiments. In the light mediator scenario, the strongest laboratory constraint for DM lighter than <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mn>0.1</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:mi>MeV</e:mi><e:mo>/</e:mo><e:msup><e:mi>c</e:mi><e:mn>2</e:mn></e:msup></e:math> is presented. The result proves the feasibility and demonstrates the vast potential of the VCA technique in future accelerated DM–electron analyses with semiconductor detectors.