Probing CPV mixing in the Higgs sector in vector boson fusion at a 1 TeV ILC

With the current precision of measurements by the ATLAS and CMS experiments, it cannot be excluded that a standard model (SM)-like Higgs boson is a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>C</a:mi><a:mi>P</a:mi></a:math> violating mixture of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>C</c:mi><c:mi>P</c:mi></c:math>-even and <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>C</e:mi><e:mi>P</e:mi></e:math>-odd states. We explore this possibility here, assuming Higgs boson production in ZZ-fusion, at 1 TeV ILC, with unpolarized beams. The full simulation of SM background and fast simulation of the signal is performed, simulating <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:mn>8</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:msup><g:mrow><g:mi>ab</g:mi></g:mrow><g:mrow><g:mo>−</g:mo><g:mn>1</g:mn></g:mrow></g:msup></g:mrow></g:math> of data collected with the ILD detector. We demonstrate that the <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>C</i:mi><i:mi>P</i:mi></i:math> mixing angle <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msub><k:mi mathvariant="normal">Ψ</k:mi><k:mrow><k:mi>C</k:mi><k:mi>P</k:mi></k:mrow></k:msub></k:math> between scalar and pseudoscalar states can be measured with the statistical uncertainty of 3.8 mrad at 68% CL, corresponding to <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:mn>1.44</n:mn><n:mo>×</n:mo><n:msup><n:mn>10</n:mn><n:mrow><n:mo>−</n:mo><n:mn>5</n:mn></n:mrow></n:msup></n:math> for the <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline"><p:mi>C</p:mi><p:mi>P</p:mi></p:math> parameter <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:msub><r:mi>f</r:mi><r:mrow><r:mi>C</r:mi><r:mi>P</r:mi></r:mrow></r:msub></r:math>, for the pure scalar state. This is the first result on sensitivity of an <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:msup><t:mi>e</t:mi><t:mo>+</t:mo></t:msup><t:msup><t:mi>e</t:mi><t:mo>−</t:mo></t:msup></t:math> collider to measure <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:msub><v:mi>f</v:mi><v:mrow><v:mi>C</v:mi><v:mi>P</v:mi></v:mrow></v:msub></v:math> in the Higgs production vertex in vector boson fusion. Published by the American Physical Society 2024