Abstract:
A search for charged-lepton-flavor violating <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>μ</a:mi><a:mi>τ</a:mi><a:mi>q</a:mi><a:mi>t</a:mi></a:math> (<c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mi>q</c:mi><c:mo>=</c:mo><c:mi>u</c:mi></c:mrow></c:math>, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mi>c</e:mi></e:mrow></e:math>) interactions is presented, considering both top-quark production and decay. The data analyzed correspond to <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mn>140</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:msup><g:mi>fb</g:mi><g:mrow><g:mo>−</g:mo><g:mn>1</g:mn></g:mrow></g:msup></g:math> of proton-proton collisions at a center-of-mass energy of <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msqrt><i:mi>s</i:mi></i:msqrt><i:mo>=</i:mo><i:mn>13</i:mn><i:mtext> </i:mtext><i:mtext> </i:mtext><i:mi>TeV</i:mi></i:math> recorded with the ATLAS detector at the Large Hadron Collider. The analysis targets events containing two muons with the same electric charge, a hadronically decaying <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>τ</k:mi></k:math>-lepton and at least one jet, with exactly one <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>b</m:mi></m:math>-tagged jet, produced by a <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>μ</o:mi><o:mi>τ</o:mi><o:mi>q</o:mi><o:mi>t</o:mi></o:math> interaction. Agreement with the Standard Model expectation within 1.6 standard deviations is observed, and limits are set at the 95% confidence level (CL) on the charged-lepton-flavor violation branching ratio of <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi mathvariant="script">B</q:mi><q:mo stretchy="false">(</q:mo><q:mi>t</q:mi><q:mo stretchy="false">→</q:mo><q:mi>μ</q:mi><q:mi>τ</q:mi><q:mi>q</q:mi><q:mo stretchy="false">)</q:mo><q:mo><</q:mo><q:mn>8.7</q:mn><q:mo>×</q:mo><q:msup><q:mn>10</q:mn><q:mrow><q:mo>−</q:mo><q:mn>7</q:mn></q:mrow></q:msup></q:math>. An effective field theory interpretation is performed yielding 95% CL limits on Wilson coefficients, dependent on the flavor of the associated light quark and the Lorentz structure of the coupling. These range from <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"><w:mo stretchy="false">|</w:mo><w:msubsup><w:mi>c</w:mi><w:mi mathvariant="sans-serif">lequ</w:mi><w:mrow><w:mn>3</w:mn><w:mo stretchy="false">(</w:mo><w:mn>2313</w:mn><w:mo stretchy="false">)</w:mo></w:mrow></w:msubsup><w:mo stretchy="false">|</w:mo><w:mo>/</w:mo><w:msup><w:mi mathvariant="normal">Λ</w:mi><w:mn>2</w:mn></w:msup><w:mo><</w:mo><w:mn>0.10</w:mn><w:mtext> </w:mtext><w:mtext> </w:mtext><w:msup><w:mi>TeV</w:mi><w:mrow><w:mo>−</w:mo><w:mn>2</w:mn></w:mrow></w:msup></w:math> for <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline"><eb:mi>μ</eb:mi><eb:mi>τ</eb:mi><eb:mi>u</eb:mi><eb:mi>t</eb:mi></eb:math> to <gb:math xmlns:gb="http://www.w3.org/1998/Math/MathML" display="inline"><gb:mo stretchy="false">|</gb:mo><gb:msubsup><gb:mi>c</gb:mi><gb:mi mathvariant="sans-serif">lequ</gb:mi><gb:mrow><gb:mn>1</gb:mn><gb:mo stretchy="false">(</gb:mo><gb:mn>2323</gb:mn><gb:mo stretchy="false">)</gb:mo></gb:mrow></gb:msubsup><gb:mo stretchy="false">|</gb:mo><gb:mo>/</gb:mo><gb:msup><gb:mi mathvariant="normal">Λ</gb:mi><gb:mn>2</gb:mn></gb:msup><gb:mo><</gb:mo><gb:mn>1.8</gb:mn><gb:mtext> </gb:mtext><gb:mtext> </gb:mtext><gb:msup><gb:mi>TeV</gb:mi><gb:mrow><gb:mo>−</gb:mo><gb:mn>2</gb:mn></gb:mrow></gb:msup></gb:math> for <ob:math xmlns:ob="http://www.w3.org/1998/Math/MathML" display="inline"><ob:mi>μ</ob:mi><ob:mi>τ</ob:mi><ob:mi>c</ob:mi><ob:mi>t</ob:mi></ob:math>. An additional interpretation is performed for scalar leptoquark production inducing charged-lepton-flavor violation, with fixed intergenerational couplings. Upper limits on leptoquark coupling strengths are set at the 95% CL, ranging from <qb:math xmlns:qb="http://www.w3.org/1998/Math/MathML" display="inline"><qb:msup><qb:mi>λ</qb:mi><qb:mi>LQ</qb:mi></qb:msup><qb:mo>=</qb:mo><qb:mn>1.3</qb:mn></qb:math> to <sb:math xmlns:sb="http://www.w3.org/1998/Math/MathML" display="inline"><sb:msup><sb:mi>λ</sb:mi><sb:mi>LQ</sb:mi></sb:msup><sb:mo>=</sb:mo><sb:mn>3.7</sb:mn></sb:math> for leptoquark masses between 0.5 and 2.0 TeV. © 2024 CERN, for the ATLAS Collaboration 2024 CERN
Tópico:
Particle physics theoretical and experimental studies
