Search for the Rare Decay D0→μ+μ− in Proton-Proton Collisions at <…

A search for the rare decay <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>D</a:mi></a:mrow><a:mrow><a:mn>0</a:mn></a:mrow></a:msup><a:mo stretchy="false">→</a:mo><a:msup><a:mrow><a:mi>μ</a:mi></a:mrow><a:mrow><a:mo>+</a:mo></a:mrow></a:msup><a:msup><a:mrow><a:mi>μ</a:mi></a:mrow><a:mrow><a:mo>−</a:mo></a:mrow></a:msup></a:mrow></a:math> is reported using proton-proton collision events at <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:msqrt><d:mi>s</d:mi></d:msqrt><d:mo>=</d:mo><d:mn>13.6</d:mn><d:mtext> </d:mtext><d:mtext> </d:mtext><d:mi>TeV</d:mi></d:math> collected by the CMS detector in 2022–2023, corresponding to an integrated luminosity of <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mn>64.5</f:mn><f:mtext> </f:mtext><f:mtext> </f:mtext><f:msup><f:mi>fb</f:mi><f:mrow><f:mo>−</f:mo><f:mn>1</f:mn></f:mrow></f:msup></f:math>. This is the first analysis to use a newly developed inclusive dimuon trigger, expanding the scope of the CMS flavor physics program. The search uses <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:msup><h:mi>D</h:mi><h:mn>0</h:mn></h:msup></h:math> mesons obtained from <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:mrow><j:msup><j:mrow><j:mi>D</j:mi></j:mrow><j:mrow><j:mo>*</j:mo><j:mo>+</j:mo></j:mrow></j:msup><j:mo stretchy="false">→</j:mo><j:msup><j:mrow><j:mi>D</j:mi></j:mrow><j:mrow><j:mn>0</j:mn></j:mrow></j:msup><j:msup><j:mrow><j:mi>π</j:mi></j:mrow><j:mrow><j:mo>+</j:mo></j:mrow></j:msup></j:mrow></j:math> decays. No significant excess is observed. A limit on the branching fraction of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mrow><m:mi mathvariant="script">B</m:mi><m:mo stretchy="false">(</m:mo><m:msup><m:mrow><m:mi>D</m:mi></m:mrow><m:mrow><m:mn>0</m:mn></m:mrow></m:msup><m:mo stretchy="false">→</m:mo><m:msup><m:mrow><m:mi>μ</m:mi></m:mrow><m:mrow><m:mo>+</m:mo></m:mrow></m:msup><m:msup><m:mrow><m:mi>μ</m:mi></m:mrow><m:mrow><m:mo>−</m:mo></m:mrow></m:msup><m:mo stretchy="false">)</m:mo><m:mo><</m:mo><m:mn>2.4</m:mn><m:mo>×</m:mo><m:msup><m:mrow><m:mn>10</m:mn></m:mrow><m:mrow><m:mo>−</m:mo><m:mn>9</m:mn></m:mrow></m:msup></m:mrow></m:math> at 95% confidence level is set. This is the most stringent upper limit set on any flavor changing neutral current decay in the charm sector.