Ultraheavy diquark decaying into vectorlike quarks at the LHC

We explore the discovery potential of ultraheavy <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mo stretchy="false">(</a:mo><a:mn>7</a:mn><a:mi>–</a:mi><a:mn>8.5</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>TeV</a:mi><a:mo stretchy="false">)</a:mo></a:mrow></a:math> diquark scalars <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mo stretchy="false">(</e:mo><e:msub><e:mi>S</e:mi><e:mrow><e:mi>u</e:mi><e:mi>u</e:mi></e:mrow></e:msub><e:mo stretchy="false">)</e:mo></e:math> produced in the collision of two up quarks at the LHC. Assuming that the diquark scalar decays into two vectorlike quarks of mass around 2 TeV, each of them decaying into a <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msup><i:mi>W</i:mi><i:mo>+</i:mo></i:msup></i:math> boson and a <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>b</k:mi></k:math> quark, we focus on the fully hadronic final state. We present a signal-from-background separation study based on a discriminator built with machine learning techniques. For this six-jet final state and a luminosity of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mn>3000</m:mn><m:mtext> </m:mtext><m:mtext> </m:mtext><m:msup><m:mi>fb</m:mi><m:mrow><m:mo>−</m:mo><m:mn>1</m:mn></m:mrow></m:msup></m:math>, we estimate that a diquark scalar of mass near 8 TeV may be discovered or ruled out even when its coupling to up quarks is as low as 0.2.