Better Hadronic Top Quark Polarimetry

Abstract

Observables sensitive to top quark polarization are important for characterizing or even discovering new physics. The most powerful spin analyzer in top decay is the down-type fermion from the W, which in the case of leptonic decay allows for very clean measurements. However, in many applications it is useful to measure the polarization of hadronically decaying top quarks. Usually it is assumed that at most 50% of the spin analyzing power can be recovered in this case. This paper introduces a simple and truly optimal hadronic spin analyzer, with a power of 64% at leading-order. The improvement is demonstrated to be robust at next-to-leading order, and in a handful of simulated measurements including the spins and spin correlations of boosted top quarks from multi-TeV top-antitop resonances, the spins of semi-boosted tops from chiral stop decays, and the potentially CP-violating spin correlations induced in continuum top pairs by color dipole operators. For the boosted studies, we explore jet substructure techniques that exhibit improved mapping between subjets and quarks.

32 pages plus appendix and refs, 10 figures; v2, published in PRD: new section on NLO corrections, extra discussion of pileup effects, added references, other minor edits

References in corpus (19)

• PYTHIA 6.4 Physics and Manual
• Jet substructure as a new Higgs search channel at the LHC
• Top-tagging: A Method for Identifying Boosted Hadronic Tops
• Jet substructure as a new Higgs search channel at the LHC
• Boosted objects: a probe of beyond the Standard Model physics
• The Bulk RS KK-gluon at the LHC
• Boosted objects and jet substructure at the LHC
• Top pair invariant mass distribution: a window on new physics
• Efficient Identification of Boosted Semileptonic Top Quarks at the LHC
• Spin Correlation Effects in Top Quark Pair Production at the LHC
• Measurements of t t-bar spin correlations and top-quark polarization using dilepton final states in pp collisions at sqrt(s) = 7 TeV
• Polarized Tops from Stop Decays at the LHC
• Polarized tops from new physics: signals and observables
• Measurement of the top quark mass with the template method in the top antitop -> lepton + jets channel using ATLAS data
• Measurements of spin correlation in top-antitop quark events from proton-proton collisions at $\sqrt{s}=7$ TeV using the ATLAS detector
• Top quark spin correlations in the Randall-Sundrum model at the CERN Large Hadron Collider
• Top Polarization and Stop Mixing from Boosted Jet Substructure
• Data driving the top quark forward--backward asymmetry with a lepton-based handle
• Implications of effective axial-vector coupling of gluon for $t\bar{t}$ spin polarizations at the LHC

Cited by in corpus (13)

• When the Machine Chimes the Bell: Entanglement and Bell Inequalities with Boosted $t\bar{t}$
• Quantum tops at circular lepton colliders
• Boosted Top quark polarization
• Hadronic Top Quark Polarimetry with ParticleNet
• Jet substructures of boosted polarized hadronic tops
• Analytical Insights on Hadronic Top Quark Polarimetry
• Discovering and profiling Z' bosons using asymmetry observables in top quark pair production with the lepton-plus-jets final state at the LHC
• Top-Tagging at the Energy Frontier
• Top-quark spin correlations as a tool to distinguish pseudoscalar $A\to ZH$ and scalar $H\to ZA$ signatures in $Zt\bar{t}$ final states at the LHC
• Constraining new resonant physics with top spin polarisation information
• Analyzing polarized boosted top from stop decay at high luminosity and high energy LHC
• Single-spin measurements and heavy new physics in the $e^{+}{e}^{-}\to t\bar{t}$ process at an FCC-ee
• Why the angular distribution of the top decay lepton is unchanged by anomalous $tbW$ coupling