# Search for a heavy resonance decaying to a top quark and a vector-like top quark at sqrt(s) = 13 TeV

## TL;DR

This paper reports a search for heavy Z' resonances decaying into a top quark and a vector-like T quark using all-jet final states at 13 TeV, setting new limits on such particles with advanced jet substructure techniques.

## Contribution

First search for a neutral spin-1 heavy resonance decaying to a top quark and a vector-like T quark in all-hadronic final states at the LHC.

## Key findings

- Excluded several Z' models at 95% confidence level.
- Set upper limits on cross sections from 0.13 to 10 pb.
- Demonstrated effectiveness of jet substructure techniques.

## Abstract

A search is presented for massive spin-1 Z' resonances decaying to a top quark and a heavy vector-like top quark partner T. The search is based on a 2.6 inverse femtobarns sample of proton-proton collisions at 13 TeV collected with the CMS detector at the LHC. The analysis is optimized for final states in which the T quark decays to a W boson and a bottom quark. The focus is on all-jet final states in which both the W boson and the top quark decay into quarks that evolve into jets. The decay products of the top quark and of the W boson are assumed to be highly Lorentz-boosted and cannot be reconstructed as separate jets, but are instead reconstructed as merged, wide jets. Techniques for the identification of jet substructure and jet flavour are used to distinguish signal from background events. Several models for Z' bosons decaying to T quarks are excluded at 95% confidence level, with upper limits on the cross section ranging from 0.13 to 10 pb, depending on the chosen hypotheses. This is the first search for a neutral spin-1 heavy resonance decaying to a top quark and a vector-like T quark in the all-hadronic final state.