Constraints on light dark matter from primordial black hole evaporation at dark matter direct detection experiments

Primordial black holes (PBHs) are able to produce light dark matter (DM) particles via Hawking radiation, and yield a flux of boosted DM that can be probed at underground DM direct detection experiments. We analyze both galactic and extragalactic contributions to the differential flux of light DM from PBH evaporation, and then compute the expected event rate from PBH boosted DM scattering off electrons or nuclei after taking into account the attenuation effect. Using recent data from DM direct detection experiments XENONnT, PandaX-4T, and LZ, we set constraints on both DM-electron and DM-nucleus scattering cross sections, as well as the fraction of DM composed of PBHs <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msub> <a:mi>f</a:mi> <a:mrow> <a:mi>PBH</a:mi> </a:mrow> </a:msub> </a:math> for <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mn>9</c:mn> <c:mo>×</c:mo> <c:msup> <c:mn>10</c:mn> <c:mn>14</c:mn> </c:msup> <c:mo>−</c:mo> <c:mn>1</c:mn> <c:mo>×</c:mo> <c:msup> <c:mn>10</c:mn> <c:mn>16</c:mn> </c:msup> <c:mtext> </c:mtext> <c:mtext> </c:mtext> <c:mi mathvariant="normal">g</c:mi> </c:math> PBHs that are not fully evaporated today. We also investigate the spectral evolution induced by Hawking evaporation throughout the evaporation and postevaporation regimes. The constraints on the PBH mass are then extended into the <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mn>1</f:mn> <f:mo>×</f:mo> <f:msup> <f:mn>10</f:mn> <f:mn>13</f:mn> </f:msup> <f:mo>−</f:mo> <f:mn>6</f:mn> <f:mo>×</f:mo> <f:msup> <f:mn>10</f:mn> <f:mn>14</f:mn> </f:msup> <f:mtext> </f:mtext> <f:mtext> </f:mtext> <f:mi mathvariant="normal">g</f:mi> </f:math> window for fully evaporated PBHs.