Exploring observable effects of scalar operators beyond SMEFT in the angular distribution of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mi>K</mml:mi><m

The <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>S</a:mi><a:mi>U</a:mi><a:mo stretchy="false">(</a:mo><a:mn>2</a:mn><a:msub><a:mo stretchy="false">)</a:mo><a:mi>L</a:mi></a:msub><a:mo>×</a:mo><a:mi>U</a:mi><a:mo stretchy="false">(</a:mo><a:mn>1</a:mn><a:msub><a:mo stretchy="false">)</a:mo><a:mi>Y</a:mi></a:msub></a:math> invariance of the Standard Model effective field theory (SMEFT) imposes relations among different low-energy effective field theory Wilson coefficients (WCs), any deviations from which would signal the presence of physics beyond SMEFT. In this work, we investigate two such relations (<g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi mathvariant="script">C</g:mi><g:mi>S</g:mi></g:msub><g:mo>=</g:mo><g:mo>−</g:mo><g:msub><g:mi mathvariant="script">C</g:mi><g:mi>P</g:mi></g:msub></g:math>, <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msubsup><k:mi mathvariant="script">C</k:mi><k:mi>S</k:mi><k:mo>′</k:mo></k:msubsup><k:mo>=</k:mo><k:msubsup><k:mi mathvariant="script">C</k:mi><k:mi>P</k:mi><k:mo>′</k:mo></k:msubsup></k:math>) among the scalar and the pseudoscalar new physics WCs that can contribute to <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>b</o:mi><o:mo stretchy="false">→</o:mo><o:mi>s</o:mi><o:mi>τ</o:mi><o:mi>τ</o:mi></o:math> processes. We show that, even when new physics violating these relations would not be measurable in the branching ratios of <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:msub><r:mi>B</r:mi><r:mi>s</r:mi></r:msub><r:mo stretchy="false">→</r:mo><r:msup><r:mi>τ</r:mi><r:mo>+</r:mo></r:msup><r:msup><r:mi>τ</r:mi><r:mo>−</r:mo></r:msup></r:math> and <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"><u:mi>B</u:mi><u:mo stretchy="false">→</u:mo><u:msup><u:mi>K</u:mi><u:mrow><u:mo stretchy="false">(</u:mo><u:mo>*</u:mo><u:mo stretchy="false">)</u:mo></u:mrow></u:msup><u:msup><u:mi>τ</u:mi><u:mo>+</u:mo></u:msup><u:msup><u:mi>τ</u:mi><u:mo>−</u:mo></u:msup></u:math> at HL-LHC and FCC-ee, it can still manifest itself in the angular distribution of <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:mi>B</z:mi><z:mo stretchy="false">→</z:mo><z:msup><z:mi>K</z:mi><z:mrow><z:mo>*</z:mo><z:mn>0</z:mn></z:mrow></z:msup><z:msup><z:mi>τ</z:mi><z:mo>+</z:mo></z:msup><z:msup><z:mi>τ</z:mi><z:mo>−</z:mo></z:msup></z:math>. We identify the combinations of angular observables in this decay channel that are sensitive to scenarios beyond SMEFT. We find that the two observables <cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" display="inline"><cb:msubsup><cb:mi>S</cb:mi><cb:mn>6</cb:mn><cb:mi>c</cb:mi></cb:msubsup></cb:math> and <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline"><eb:msub><eb:mi>A</eb:mi><eb:mn>7</eb:mn></eb:msub></eb:math>, and their combination, have the potential to identify physics beyond SMEFT. Published by the American Physical Society 2024