The "Top Priority" at the LHC

TL;DR

The paper surveys the role of the top quark as a central probe of electroweak symmetry breaking and TeV-scale new physics at the LHC. It systematically reviews SM expectations for top production and decay, including $t\bar t$, single-top, and $t\bar tH$ processes, while outlining how high-statistics top samples enable sensitive tests of couplings and rare decays. It then outlines multiple new-physics pathways in the top sector, such as charged- and neutral-current decays, resonant production via heavy states, top partners, and exotic top-rich signatures, with quantitative sensitivity estimates and reconstruction strategies. The study emphasizes that the top quark provides a rich, high-impact avenue for discovering or constraining naturalness-motivated theories and other TeV-scale dynamics, making top-quark studies a high-priority component of the LHC program.

Abstract

The LHC will be a top-quark factory. With 80 million pairs of top quarks and an additional 34 million single tops produced annually at the designed high luminosity, the properties of this particle will be studied to a great accuracy. The fact that the top quark is the heaviest elementary particle in the Standard Model with a mass right at the electroweak scale makes it tempting to contemplate its role in electroweak symmetry breaking, as well as its potential as a window to unknown new physics at the TeV scale. We summarize the expectations for top-quark physics at the LHC, and outline new physics scenarios in which the top quark is crucially involved.

Figures (9)

• Figure 1: Top-quark pair production in hadronic collisions via QCD interaction. This figure is taken from Ref. Willenbrock:2002ta.
• Figure 2: (a) Invariant mass distribution of $t\bar{t}$ at the LHC and (b) integrated cross section versus a minimal cutoff on $m(t\bar{t})$. Decay branching fractions of one top decaying hadronically and the other leptonically ($e,\mu$) have been included.
• Figure 3: Single top-quark production in hadronic collisions via the charged-current weak interaction. This figure is taken from Ref. Willenbrock:2002ta.
• Figure 4: Normalization factor versus the resonance mass for the scalar (dashed) with a width-mass ratio of $20\%$, vector (dot-dashed) with 5%, and graviton (solid) 2%, respectively. The region above each curve represents values of $\omega$ that give 5$\sigma$ or greater statistical significance with 10 fb$^{-1}$ integrated luminosity.
• Figure 5: