Flavor-violating Higgs and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi></mml:math> boson decays at a future circular lepton collider
Jernej F. Kamenik, Arman Korajac, Manuel Szewc, Michele Tammaro, Jure Zupan
Abstract
Recent advances in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>b</a:mi></a:math>, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>c</c:mi></c:math>, and <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>s</e:mi></e:math> quark tagging coupled with novel statistical analysis techniques will allow future high energy and high statistics electron-positron colliders, such as the FCC-ee, to place phenomenologically relevant bounds on flavor violating Higgs and <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>Z</g:mi></g:math> decays to quarks. We assess the FCC-ee reach for <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:mi>Z</i:mi><i:mo>/</i:mo><i:mi>h</i:mi><i:mo stretchy="false">→</i:mo><i:mi>b</i:mi><i:mi>s</i:mi><i:mo>,</i:mo><i:mi>c</i:mi><i:mi>u</i:mi></i:mrow></i:math> decays as a function of jet tagging performance. We also update the standard model (SM) predictions for the corresponding branching ratios, as well as the indirect constraints on the flavor violating Higgs and <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:mi>Z</l:mi></l:math> couplings to quarks. Using the type III two Higgs doublet model as an example of beyond the standard model physics, we show that the searches for <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:mi>h</n:mi><n:mo stretchy="false">→</n:mo><n:mi>b</n:mi><n:mi>s</n:mi><n:mo>,</n:mo><n:mi>c</n:mi><n:mi>u</n:mi></n:math> decays at FCC-ee can probe new parameter space not excluded by indirect searches. We also reinterpret the FCC-ee reach for <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>Z</q:mi><q:mo stretchy="false">→</q:mo><q:mi>b</q:mi><q:mi>s</q:mi><q:mo>,</q:mo><q:mi>c</q:mi><q:mi>u</q:mi></q:math> in terms of the constraints on models with vectorlike quarks. Published by the American Physical Society 2024