A search for electroweak production of a single vectorlike <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>T</a:mi></a:math> quark in association with a bottom (<c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>b</c:mi></c:math>) quark in the all-hadronic decay channel is presented. This search uses proton-proton collision data at <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msqrt><e:mi>s</e:mi></e:msqrt><e:mo>=</e:mo><e:mn>13</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:mi>TeV</e:mi></e:math> collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mn>138</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>. The <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>T</i:mi></i:math> quark is assumed to have charge <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mn>2</k:mn><k:mo>/</k:mo><k:mn>3</k:mn></k:math> and decay to a top (<m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>t</m:mi></m:math>) quark and a Higgs (<o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>H</o:mi></o:math>) or <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>Z</q:mi></q:math> boson. Hadronic decays of the <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:mi>t</s:mi></s:math> quark and the <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"><u:mi>H</u:mi></u:math> or <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"><w:mi>Z</w:mi></w:math> boson are reconstructed from the kinematic properties of jets, including those containing <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"><y:mi>b</y:mi></y:math> hadrons. No deviation from the standard model prediction is observed in the reconstructed <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"><ab:mi>t</ab:mi><ab:mi>H</ab:mi></ab:math> and <cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" display="inline"><cb:mi>t</cb:mi><cb:mi>Z</cb:mi></cb:math> invariant mass distributions. The 95% confidence level upper limits on the product of the production cross section and branching fraction of a <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline"><eb:mi>T</eb:mi></eb:math> quark produced in association with a <gb:math xmlns:gb="http://www.w3.org/1998/Math/MathML" display="inline"><gb:mi>b</gb:mi></gb:math> quark and decaying via <ib:math xmlns:ib="http://www.w3.org/1998/Math/MathML" display="inline"><ib:mi>t</ib:mi><ib:mi>H</ib:mi></ib:math> or <kb:math xmlns:kb="http://www.w3.org/1998/Math/MathML" display="inline"><kb:mi>t</kb:mi><kb:mi>Z</kb:mi></kb:math> range from 1260 to 68 fb for <mb:math xmlns:mb="http://www.w3.org/1998/Math/MathML" display="inline"><mb:mi>T</mb:mi></mb:math> quark masses of 600–1200 GeV. © 2024 CERN, for the CMS Collaboration 2024 CERN