First measurements of the absolute branching fraction of Λc(2625)+→Λc+π</…

The absolute branching fraction of the decay <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mi mathvariant="normal">Λ</a:mi><a:mi>c</a:mi></a:msub><a:mo stretchy="false">(</a:mo><a:mn>2625</a:mn><a:msup><a:mo stretchy="false">)</a:mo><a:mo>+</a:mo></a:msup></a:mrow><a:mo stretchy="false">→</a:mo><a:msubsup><a:mi mathvariant="normal">Λ</a:mi><a:mi>c</a:mi><a:mo>+</a:mo></a:msubsup><a:msup><a:mi>π</a:mi><a:mo>+</a:mo></a:msup><a:msup><a:mi>π</a:mi><a:mo>−</a:mo></a:msup></a:math> is measured for the first time to be <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mo stretchy="false">(</h:mo><h:mn>50.2</h:mn><h:mo>±</h:mo><h:msub><h:mn>5.7</h:mn><h:mrow><h:mi>stat</h:mi></h:mrow></h:msub><h:mo>±</h:mo><h:msub><h:mn>3.5</h:mn><h:mrow><h:mi>syst</h:mi></h:mrow></h:msub><h:mo stretchy="false">)</h:mo><h:mo>%</h:mo></h:math> with <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:mn>368.48</l:mn><l:mtext> </l:mtext><l:mtext> </l:mtext><l:msup><l:mi>pb</l:mi><l:mrow><l:mo>−</l:mo><l:mn>1</l:mn></l:mrow></l:msup></l:math> of <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:msup><n:mi>e</n:mi><n:mo>+</n:mo></n:msup><n:msup><n:mi>e</n:mi><n:mo>−</n:mo></n:msup></n:math> collision data collected by the BESIII detector at the center-of-mass energies of <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline"><p:msqrt><p:mi>s</p:mi></p:msqrt><p:mo>=</p:mo><p:mn>4.918</p:mn></p:math> and 4.950 GeV. Although the central value of the result is lower than the theoretical prediction of 67%, obtained from isospin symmetry, they are consistent taking the uncertainties into account. This is the first absolute branching fraction measurement for <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:msub><r:mi mathvariant="normal">Λ</r:mi><r:mi>c</r:mi></r:msub><r:mo stretchy="false">(</r:mo><r:mn>2625</r:mn><r:msup><r:mo stretchy="false">)</r:mo><r:mo>+</r:mo></r:msup></r:math> since it was found. This measurement is necessary to obtain the coupling constants for the transitions between <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"><w:mi>s</w:mi></w:math>-wave and <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"><y:mi>p</y:mi></y:math>-wave charmed baryons in heavy hadron chiral perturbation theory. In addition, we search for the decay <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"><ab:mrow><ab:msub><ab:mi mathvariant="normal">Λ</ab:mi><ab:mi>c</ab:mi></ab:msub><ab:mo stretchy="false">(</ab:mo><ab:mn>2595</ab:mn><ab:msup><ab:mo stretchy="false">)</ab:mo><ab:mo>+</ab:mo></ab:msup></ab:mrow><ab:mo stretchy="false">→</ab:mo><ab:msubsup><ab:mi mathvariant="normal">Λ</ab:mi><ab:mi>c</ab:mi><ab:mo>+</ab:mo></ab:msubsup><ab:msup><ab:mi>π</ab:mi><ab:mo>+</ab:mo></ab:msup><ab:msup><ab:mi>π</ab:mi><ab:mo>−</ab:mo></ab:msup></ab:math>. No significant signal is observed, and the upper limit on its branching fraction is determined to be 85.0% at the 90% confidence level. Published by the American Physical Society 2024