Электронный каталог

Статья

Aad, G.
Observation of a Cross-Section Enhancement near the tt^- Production Threshold in *%s=13 TeV pp Collisions with the ATLAS Detector / G.Aad, F.Ahmadov, I.N.Aleksandrov, V.A.Bednyakov, I.R.Boyko, G.Chelkov, A.Cheplakov, M.V.Chizhov, D.V.Dedovich, M.Demichev, A.R.Didenko, M.I.Gostkin, S.N.Karpov, Z.M.Karpova, U.Kruchonak, V.Kukhtin, Y.Kulchitsky, E.Ladygin, V.Lyubushkin, T.Lyubushkina, S.Malyukov, M.Mineev, E.Plotnikova, I.N.Potrap, N.A.Rusakovich, M.Shiyakova, A.Soloshenko, A.Tropina, P.V.Tsiareshka, T.Turtuvshin, A.Vasyukov, I.Yeletskikh, A.Zhemchugov, N.I.Zimine, [ATLAS Collab.]. – Text : electronic // Reports on Progress in Physics. – 2026. – Vol. 89, No. 5. – P. 057801. – URL: https://doi.org/10.1088/1361-6633/ae60a0. – Bibliogr.: 142.

A measurement of $tbar{t}$ production is presented in the invariant-mass region near the pair production threshold, $m_{tbar{t}} sim 345$ GeV, in final states with two charged leptons and multiple jets. The measurement is based on $140,mathrm{fb}^{-1}$ of proton–proton collision data collected at $sqrt{s} = 13$ TeV with the ATLAS detector at the Large Hadron Collider. The data are compared to two models of $tbar{t}$ production: a baseline model including only perturbative quantum chromodynamics (pQCD) predictions for the hard process at approximate next-to-next-to leading order accuracy in the strong coupling, and an extended model that, in addition, incorporates non-relativistic QCD simulations that also include the formation of colour-singlet quasi-bound-states near the $tbar{t}$ threshold. The agreement between the data and the models is quantified via a profile-likelihood fit to the reconstructed $m_{tbar{t}}$ distributions, in bins of two angular observables sensitive to spin-correlations in the $tbar{t}$ system. An excess of events is observed over the baseline pQCD prediction, with an observed significance over 8 standard deviations. This excess is consistent with the formation of colour-singlet and spin-singlet S-wave quasi-bound $tbar{t}$ states, as predicted by non-relativistic QCD, and corresponds to an observed cross-section of 9.3&sup(+1.4)&sub(-1.3)pb.



ОИЯИ = ОИЯИ (JINR)2026
Спец.(статьи,препринты) = С 346.2в - Взаимодействие протонов с протонами
Спец.(статьи,препринты) = С 346.6д1 - Чармоний, боттомоний, топ-кварк. Очарованные частицы и др. резонансы из тяжелых кварков