Hide and seek with the third family hypercharge model’s Z^′ at the large hadron collider

Abstract

<jats:title>Abstract</jats:title><jats:p>The Third Family Hypercharge Model predicts a <jats:inline-formula><jats:alternatives><jats:tex-math>$$Z^\prime $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>Z</mml:mi> <mml:mo>′</mml:mo> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula> gauge boson with flavour dependent couplings which has been used to explain anomalies in meson decay processes which involve the <jats:inline-formula><jats:alternatives><jats:tex-math>$$b\rightarrow s\mu ^+\mu ^-$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>b</mml:mi> <mml:mo>→</mml:mo> <mml:mi>s</mml:mi> <mml:msup> <mml:mi>μ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>μ</mml:mi> <mml:mo>-</mml:mo> </mml:msup> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> transition. The model predicts that a TeV-scale <jats:inline-formula><jats:alternatives><jats:tex-math>$$Z^\prime $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>Z</mml:mi> <mml:mo>′</mml:mo> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula> should decay to particle-antiparticle pairs of muons, taus, top quarks and bottom quarks with appreciable branching ratios. We reinterpret various ATLAS and CMS search limits for <jats:inline-formula><jats:alternatives><jats:tex-math>$$Z^\prime $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>Z</mml:mi> <mml:mo>′</mml:mo> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula> production followed by such decays at the LHC over a parameter space of the model that results from a successful combined fit to the <jats:inline-formula><jats:alternatives><jats:tex-math>$$b\rightarrow s l^+ l^-$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>b</mml:mi> <mml:mo>→</mml:mo> <mml:mi>s</mml:mi> <mml:msup> <mml:mi>l</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>l</mml:mi> <mml:mo>-</mml:mo> </mml:msup> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> data and precision electroweak observables. Current exclusions in parameter space and expected sensitivities of the various different channels in the high-luminosity run are compared. We find that the high-luminosity run of the LHC will significantly increase the sensitivity to the model beyond the existing empirical limits, which we find to be surprisingly weak.</jats:p>