First search for light fermionic dark matter absorption on electrons using germanium detector in CDEX-10 experiment

We present the first results of the search for sub-MeV fermionic dark matter absorbed by electron targets of germanium using 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> data collected by the CDEX-10 experiment, with the analysis threshold of 160 eVee. No significant dark matter (DM) signals over the background are observed. Results are presented as limits on the cross section of DM–electron interaction. We present new constraints of cross section in the DM range of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:mn>0.1</c:mn> <c:mi>–</c:mi> <c:mn>10</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> for vector and axial-vector interaction. The upper limit on the cross section is set to be <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mn>6.8</e:mn> <e:mo>×</e:mo> <e:msup> <e:mn>10</e:mn> <e:mrow> <e:mo>−</e:mo> <e:mn>46</e:mn> </e:mrow> </e:msup> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:msup> <e:mrow> <e:mi>cm</e:mi> </e:mrow> <e:mn>2</e:mn> </e:msup> </e:math> for vector interaction, and <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mn>2.3</g:mn> <g:mo>×</g:mo> <g:msup> <g:mn>10</g:mn> <g:mrow> <g:mo>−</g:mo> <g:mn>46</g:mn> </g:mrow> </g:msup> <g:mtext> </g:mtext> <g:mtext> </g:mtext> <g:msup> <g:mrow> <g:mi>cm</g:mi> </g:mrow> <g:mn>2</g:mn> </g:msup> </g:math> for axial-vector interaction at DM mass of <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mn>5</i:mn> <i:mtext> </i:mtext> <i:mtext> </i:mtext> <i:mi>keV</i:mi> <i:mo>/</i:mo> <i:msup> <i:mi>c</i:mi> <i:mn>2</i:mn> </i:msup> </i:math> .