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

Boos, E.; Bunichev, V.; Dubinin, M.; Dudko, L.; Ershov, A.A.; Klyukhin, V.; Obraztsov, S.; Perfilov, M.; Petrushanko, S.V.; Savrin, V.; Volkov, P.; Vorotnikov, G.A.; CMS, C.

Авторы: Boos E., Bunichev V., Dubinin M., Dudko L., Ershov A.A., Klyukhin V., Obraztsov S., Perfilov M., Petrushanko S.V., Savrin V., Volkov P., Vorotnikov G.A., CMS Collaboration
Журнал: Physical Review D
Том: 110
Номер: 11
Год издания: 2024
Издательство: American Physical Society
Местоположение издательства: United States
Первая страница: 112016
DOI: 10.1103/PhysRevD.110.112016
Аннотация: Measurements of the polarization and spin correlation in top quark pairs (tt¯) 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 tt¯ system and the top quark scattering angle in the tt¯ rest frame. The measured polarization and spin correlation are in agreement with the standard model. From the measured spin correlation, conclusions on the tt¯ spin entanglement aredrawn by applying the Peres-Horodecki criterion. The standard model predicts entangled spins for tt¯ states at the production threshold and at high masses of the tt¯ system. Entanglement is observed for the first time in events at high tt¯ mass, where a large fraction of the tt¯ decays are spacelike separated, with an expected and observed significance of above 5 standard deviations.
Добавил в систему: Клюхин Вячеслав Иванович

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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 TeVстатья Исследовательская статья

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