Search for top-philic heavy resonances in pp collisions at $$\sqrt{s}=13$$ s = 13 $$\text {TeV}$$ TeV with the ATLAS detector

Abstract

Abstract A search for the associated production of a heavy resonance with a top-quark or a top-antitop-quark pair, and decaying into a

$$t{\bar{t}}$$

t

t

¯

pair is presented. The search uses the data recorded by the ATLAS detector in pp collisions at

$$\sqrt{s}= 13$$

s

= 13

$$\text {TeV}$$

TeV

at the Large Hadron Collider during the years 2015–2018, corresponding to an integrated luminosity of 139

$$\text {fb}^{-1}$$

fb

- 1

. Events containing exactly one electron or muon are selected. The two hadronically decaying top quarks from the resonance decay are reconstructed using jets clustered with a large radius parameter of

$$R=1$$

R = 1

. The invariant mass spectrum of the two top quark candidates is used to search for a resonance signal in the range of 1.0

$$\text {TeV}$$

TeV

to 3.2

$$\text {TeV}$$

TeV

. The presence of a signal is examined using an approach with minimal model dependence followed by a model-dependent interpretation. No significant excess is observed over the background expectation. Upper limits on the production cross section times branching ratio at 95% confidence level are provided for a heavy

$$Z^\prime $$

Z ′

boson based on a simplified model, for

$$Z^\prime $$

Z ′

mass between 1.0

$$\text {TeV}$$

TeV

and 3.0

$$\text {TeV}$$

TeV

. The observed (expected) limits range from 21 (14) fb to 119 (86) fb depending on the choice of model parameters.