Search for pair production of heavy particles decaying to a top quark and a gluon in the lepton+jets final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV

Abstract

A search is presented for the pair production of new heavy resonances, each decaying into a top quark (t) or antiquark and a gluon (g). The analysis uses data recorded with the CMS detector from proton–proton collisions at a center-of-mass energy of 13$\,\text {Te}\hspace{-.08em}\text {V}$ at the LHC, corresponding to an integrated luminosity of 138$\,\text {fb}^{-1}$. Events with one muon or electron, multiple jets, and missing transverse momentum are selected. After using a deep neural network to enrich the data sample with signal-like events, distributions in the scalar sum of the transverse momenta of all reconstructed objects are analyzed in the search for a signal. No significant deviations from the standard model prediction are found. Upper limits at 95% confidence level are set on the product of cross section and branching fraction squared for the pair production of excited top quarks in the $\text {t}^{*} \rightarrow {\text {t}} {\text {g}} $ decay channel. The upper limits range from 120 to 0.8$\,\text {fb}$ for a $\text {t}^{*} $with spin-1/2 and from 15 to 1.0$\,\text {fb}$ for a $\text {t}^{*} $with spin-3/2. These correspond to mass exclusion limits up to 1050 and 1700$\,\text {Ge}\hspace{-.08em}\text {V}$ for spin-1/2 and spin-3/2 $\text {t}^{*} $particles, respectively. These are the most stringent limits to date on the existence of $\text {t}^{*} \rightarrow {\text {t}} {\text {g}} $ resonances.The European physical journal / C 85(3), 342 (2025). doi:10.1140/epjc/s10052-024-13729-yPublished by Springer, Heidelberg