Search for bottom-type vectorlike quark pair production in dileptonic and fully hadronic final states in proton-proton collisions at s=13 TeV

A search is described for the production of a pair of bottom-type vectorlike quarks (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>B</a:mi></a:math> VLQs) with mass greater than 1000 GeV. Each <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>B</c:mi></c:math> VLQ decays into a <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>b</e:mi></e:math> quark and a Higgs boson, a <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>b</g:mi></g:math> quark and a <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>Z</i:mi></i:math> boson, or a <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>t</k:mi></k:math> quark and a <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>W</m:mi></m:math> boson. This analysis considers both fully hadronic final states and those containing a charged lepton pair from a <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>Z</o:mi></o:math> boson decay. The products of the <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>H</q:mi><q:mo stretchy="false">→</q:mo><q:mi>b</q:mi><q:mi>b</q:mi></q:math> boson decay and of the hadronic <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mi>Z</t:mi></t:math> or <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:mi>W</v:mi></v:math> boson decays can be resolved as two distinct jets or merged into a single jet, so the final states are classified by the number of reconstructed jets. The analysis uses data corresponding to an integrated luminosity of <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"><x:mn>138</x:mn><x:mtext> </x:mtext><x:mtext> </x:mtext><x:msup><x:mi>fb</x:mi><x:mrow><x:mo>−</x:mo><x:mn>1</x:mn></x:mrow></x:msup></x:math> collected in proton-proton collisions at <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:msqrt><z:mi>s</z:mi></z:msqrt><z:mo>=</z:mo><z:mn>13</z:mn><z:mtext> </z:mtext><z:mtext> </z:mtext><z:mi>TeV</z:mi></z:math> with the CMS detector at the LHC from 2016 to 2018. No excess over the expected background is observed. Lower limits are set on the <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"><bb:mi>B</bb:mi></bb:math> VLQ mass at the 95% confidence level. These depend on the <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:mi>B</db:mi></db:math> VLQ branching fractions and are 1570 and 1540 GeV for 100% <fb:math xmlns:fb="http://www.w3.org/1998/Math/MathML" display="inline"><fb:mi>B</fb:mi><fb:mo stretchy="false">→</fb:mo><fb:mi>b</fb:mi><fb:mi>H</fb:mi></fb:math> and 100% <ib:math xmlns:ib="http://www.w3.org/1998/Math/MathML" display="inline"><ib:mi>B</ib:mi><ib:mo stretchy="false">→</ib:mo><ib:mi>b</ib:mi><ib:mi>Z</ib:mi></ib:math>, respectively. In most cases, the mass limits obtained exceed previous limits by at least 100 GeV.