Электронный каталог

Статья

Hayrapetyan, A.
Measurements of Polarization and Spin Correlation and Observation of Entanglement in Top Quark Pairs Using Lepton+Jets Events from Proton-Proton Collisions at *%s=13 TeV / A.Hayrapetyan, S.Afanasiev, V.Alexakhin, D.Budkouski, I.Golutvin, I.Gorbunov, V.Karjavine, V.Korenkov, A.Lanev, A.Malakhov, V.Matveev, V.Palichik, V.Perelygin, M.Savina, V.Shalaev, S.Shmatov, S.Shulha, V.Smirnov, O.Teryaev, N.Voytishin, B.S.Yuldashev, A.Zarubin, I.Zhizhin, A.Khvedelidze, Z.Tsamalaidze, [CMS Collab.] // Physical Review D [Electronic resource]. – 2024. – Vol. 110, No. 11. – P. 112016. – URL: https://doi.org/10.1103/PhysRevD.110.112016. – Bibliogr.: 82.

Measurements of the polarization and spin correlation in top quark pairs (𝑡⁢𝑡*-) are presented using events with a single electron or muon and jets in the final state. The measurements are based on proton-proton collision data from the LHC at √𝑠 =13  TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138  fb*−*1. All coefficients of the polarization vectors and the spin correlation matrix are extracted simultaneously by performing a binned likelihood fit to the data. The measurement is performed inclusively and in bins of additional observables, such as the mass of the 𝑡⁢𝑡^- system and the top quark scattering angle in the 𝑡⁢𝑡^- rest frame. The measured polarization and spin correlation are in agreement with the standard model. From the measured spin correlation, conclusions on the 𝑡⁢𝑡^- spin entanglement are drawn by applying the Peres-Horodecki criterion. The standard model predicts entangled spins for 𝑡⁢𝑡^- states at the production threshold and at high masses of the 𝑡⁢𝑡^- system. Entanglement is observed for the first time in events at high 𝑡⁢𝑡^- mass, where a large fraction of the 𝑡⁢𝑡^- decays are spacelike separated, with an expected and observed significance of above 5 standard deviations.



ОИЯИ = ОИЯИ (JINR)2024
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