Determination of Double Beta Decay Half-Life of ¹³⁶Xe with the PandaX-4T Natural Xenon Detector release_7yrtqpz6fzdmjj2t5mlea73zye

Abstract

Precise measurement of two-neutrino double beta decay (DBD) half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay. We report the measurement of DBD half-life of <jats:sup>136</jats:sup>Xe using the PandaX-4T dual-phase Time Projection Chamber (TPC) with 3.7-tonne natural xenon and the first 94.9-day physics data release. The background model in the fiducial volume is well constrained in situ by events in the outer active region. With a <jats:sup>136</jats:sup>Xe exposure of 15.5 kg-year, we establish the half-life as <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn>2.27</mml:mn><mml:mo>±</mml:mo><mml:mn>0.03</mml:mn><mml:mfenced open="(" close=")"><mml:mrow><mml:mi>s</mml:mi><mml:mi>t</mml:mi><mml:mi>a</mml:mi><mml:mi>t</mml:mi><mml:mo>.</mml:mo></mml:mrow></mml:mfenced><mml:mo>±</mml:mo><mml:mn>0.10</mml:mn><mml:mfenced open="(" close=")"><mml:mrow><mml:mi>s</mml:mi><mml:mi>y</mml:mi><mml:mi>s</mml:mi><mml:mi>t</mml:mi><mml:mo>.</mml:mo></mml:mrow></mml:mfenced><mml:mo>×</mml:mo><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mn>21</mml:mn></mml:mrow></mml:msup></mml:math> years. This is the first DBD half-life measurement with natural xenon and demonstrates the physics capability of a large-scale liquid xenon TPC in the field of rare event searches.
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