Measurement of Reactor Antineutrino Oscillation at SNO+

<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>SNO</a:mi><a:mo>+</a:mo></a:mrow></a:math> Collaboration reports its second spectral analysis of reactor antineutrino oscillation using 286 ton-yr of new data. The measured energies of reactor antineutrino candidates were fitted to obtain the second-most precise determination of the neutrino mass-squared difference <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mrow><c:mi mathvariant="normal">Δ</c:mi><c:msubsup><c:mrow><c:mi>m</c:mi></c:mrow><c:mrow><c:mn>21</c:mn></c:mrow><c:mrow><c:mn>2</c:mn></c:mrow></c:msubsup><c:mo>=</c:mo></c:mrow><c:mo stretchy="false">(</c:mo><c:msubsup><c:mrow><c:mn>7.96</c:mn></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>0.42</c:mn></c:mrow><c:mrow><c:mo>+</c:mo><c:mn>0.48</c:mn></c:mrow></c:msubsup><c:mo stretchy="false">)</c:mo><c:mo>×</c:mo><c:mrow><c:msup><c:mrow><c:mn>10</c:mn></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>5</c:mn></c:mrow></c:msup><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mrow><c:mi>eV</c:mi></c:mrow><c:mrow><c:mn>2</c:mn></c:mrow></c:msup></c:mrow></c:mrow></c:math>. Constraining <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mi mathvariant="normal">Δ</h:mi><h:msubsup><h:mi>m</h:mi><h:mn>21</h:mn><h:mn>2</h:mn></h:msubsup></h:math> and <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msup><k:mi>sin</k:mi><k:mn>2</k:mn></k:msup><k:msub><k:mi>θ</k:mi><k:mn>12</k:mn></k:msub></k:math> with measurements from long-baseline reactor antineutrino and solar neutrino experiments yields <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mrow><m:mi mathvariant="normal">Δ</m:mi><m:msubsup><m:mrow><m:mi>m</m:mi></m:mrow><m:mrow><m:mn>21</m:mn></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow></m:msubsup><m:mo>=</m:mo><m:mo stretchy="false">(</m:mo><m:msubsup><m:mrow><m:mn>7.58</m:mn></m:mrow><m:mrow><m:mo>−</m:mo><m:mn>0.17</m:mn></m:mrow><m:mrow><m:mo>+</m:mo><m:mn>0.18</m:mn></m:mrow></m:msubsup><m:mo stretchy="false">)</m:mo><m:mo>×</m:mo><m:mrow><m:msup><m:mrow><m:mn>10</m:mn></m:mrow><m:mrow><m:mo>−</m:mo><m:mn>5</m:mn></m:mrow></m:msup><m:mtext> </m:mtext><m:mtext> </m:mtext><m:msup><m:mrow><m:mi>eV</m:mi></m:mrow><m:mrow><m:mn>2</m:mn></m:mrow></m:msup></m:mrow></m:mrow></m:math> and <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mrow><r:msup><r:mrow><r:mi>sin</r:mi></r:mrow><r:mrow><r:mn>2</r:mn></r:mrow></r:msup><r:msub><r:mrow><r:mi>θ</r:mi></r:mrow><r:mrow><r:mn>12</r:mn></r:mrow></r:msub><r:mo>=</r:mo><r:mn>0.308</r:mn><r:mo>±</r:mo><r:mn>0.013</r:mn></r:mrow></r:math>. This fit also yields a first measurement of the flux of geoneutrinos in the Western Hemisphere, with <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:msubsup><t:mn>73</t:mn><t:mrow><t:mo>−</t:mo><t:mn>43</t:mn></t:mrow><t:mrow><t:mo>+</t:mo><t:mn>47</t:mn></t:mrow></t:msubsup></t:math> TNU at <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:mrow><v:mi>SNO</v:mi><v:mo>+</v:mo></v:mrow></v:math>.