Hayrapetyan, A.Tumasyan, A.Adam, W.Andrejkovic, J. W.Benato, L.Bergauer, T.Druzhkin, D.2025-02-102025-02-1020242470-00102470-0029https://doi.org/10.1103/PhysRevD.110.112016Ivanov, Andrew/0000-0002-9270-5643; Yang, Tianyu Justin/0000-0003-4317-4660; Sandro, Fonseca De Souza/0000-0001-7830-0837; Levchuk, Leonid/0000-0001-5889-7410; Park, Mary/0000-0003-4282-1969; Cussans, David/0000-0001-8192-0826; Giammanco, Andrea/0000-0001-9640-8294; Malara, Andrea/0000-0001-8645-9282; Dreimanis, Karlis/0000-0003-0972-5641; Mundim, Luiz/0000-0001-9964-7805; Shchelina, Ksenia/0000-0003-3742-0693; Fernandez Bedoya, Cristina/0000-0001-8057-9152; Purohit, Arnab/0000-0003-0881-612X; Goldstein, Joel/0000-0003-1591-6014; Kolberg, Ted/0000-0002-0211-6109; Mcginnis, Michael/0000-0002-9833-6316; Cassese, Antonio/0000-0003-3010-4516; Gandrakota, Abhijith/0000-0003-4860-3233; Pradhan, Raghunath/0000-0001-7000-6510; Madrid, Christopher/0000-0003-3301-2246; Tinoco Mendes, Andre David/0000-0001-5854-7699; Matorras, Francisco/0000-0003-4295-5668; Lavoryk, Olha/0000-0001-5071-9783; Paulini, Manfred/0000-0002-6714-5787; Mousa, Jehad/0000-0002-2978-2718; Belyaev, Alexander/0000-0002-1733-4408; Mora Herrera, Maria Clemencia/0000-0003-3915-3170; Murillo Quijada, Javier Alberto/0000-0003-4933-2092; Feld, Lutz/0000-0001-9813-8646; Dozen, Candan/0000-0002-4301-634X; Arneodo, Michele/0000-0002-7790-7132; Ajmal, Sehar/0000-0002-2726-2858; Verdier, Patrice/0000-0003-3090-2948; Ngadiuba, Jennifer/0000-0002-0055-2935; De Moor, Alexandre/0000-0001-5964-1935; Polikarpov, Sergey/0000-0001-6839-928X; Acharya, Shriniketan/0009-0001-2997-7523; Sehrawat, Ashish/0000-0002-6816-7814; Longo, Luigi/0000-0002-2357-7043; Hall, Geoffrey/0000-0002-6299-8385; Duarte, Javier Mauricio/0000-0002-5076-7096; Schwandt, Joern/0000-0002-0052-597X; Grosso, Gaia/0000-0002-8303-3291; Sharma, Ram Krishna/0000-0003-1181-1426; Dolek, Furkan/0000-0001-7092-5517; Smith, Wesley/0000-0003-3195-0909; Ligabue, Franco/0000-0002-1549-7107; Barone, Gaetano Athanassios/0000-0001-5163-5936; Tiwari, Praveen Chandra/0000-0002-3667-3843; D'Anzi, Brunella/0000-0002-9361-3142; D'Enterria, David/0000-0002-5754-4303; Felcini, Marta/0000-0002-2051-9331; Lipton, Ronald/0000-0002-6665-7289; Raidal, Martti/0000-0001-7040-9491; Phor, Saumya/0000-0001-7842-9518; Elliot, Alison/0000-0003-0921-0314; Gadallah, Mahmoud Moussa Abdelkhalek/0000-0002-8305-6661; Hussain, Priya Sajid/0000-0002-4825-5278; Chatterjee, Sayan/0000-0003-0185-9872; Giommi, Luca/0000-0003-3539-4313; Novak, Andrzej/0000-0002-0389-5896; Grunewald, Martin/0000-0002-5754-0388; Stein, Annika/0000-0003-0713-811X; Khvedelidze, Arsen/0000-0002-5953-0140; Klyukhin, Vyacheslav/0000-0002-8577-6531; Escalante Del Valle, Alberto/0000-0002-9702-6359; Colaleo, Anna/0000-0002-0711-6319; Venditti, Rosamaria/0000-0001-6925-8649; Shopova, Mariana/0000-0001-6664-2493; Elmer, Peter/0000-0001-6830-3356; Guzzi, Luca/0000-0002-3086-8260; Cepeda, Maria/0000-0002-6076-4083; Lapertosa, Alessandro/0000-0001-6246-6787; Navarrete Ramos, Efren/0000-0002-5180-4020; Mccauley, Thomas/0000-0001-6589-8286; Orzari, Breno/0000-0003-4232-4743; Bakhshiansohi, Hamed/0000-0001-5741-3357; Macchiolo, Anna/0000-0003-0199-6957; Kyberd, Paul/0000-0002-7353-7090; Alves, Gilvan/0000-0002-8369-1446; Pedraza Morales, Maria Isabel/0000-0002-2669-4659; Heath, Helen/0000-0001-6576-9740; Martinez Rivero, Celso/0000-0002-3224-956X; Llorente Merino, Javier/0000-0003-0027-7969; De La Cruz Burelo, Eduard/0000-0002-7469-6974; Waltenberger, Wolfgang/0000-0002-6215-7228; Gutsche, Oliver/0000-0002-8015-9622; Dragicevic, Marko/0000-0003-1967-6783; Wardle, Nicholas/0000-0003-1344-3356; Al Kadhim, Ali/0000-0003-3490-8407; Benato, Lisa/0000-0001-5135-7489; Brooke, James/0000-0003-2529-0684; Moureaux, Louis/0000-0002-2310-9266; Geurts, Frank/0000-0003-2856-9090; Bortignon, Pierluigi/0000-0002-5360-1454; Tapper, Alexander/0000-0003-4543-864X; Erice Cid, Carlos Francisco/0000-0002-6469-3200; Tytgat, Michael/0000-0002-3990-2074; Fiorendi, Sara/0000-0003-3273-9419; Della Ricca, Giuseppe/0000-0003-2831-6982; Heikkila, Jaana/0000-0002-0538-1469; Gerosa, Raffaele/0000-0001-8359-3734; Kreczko, Luke/0000-0003-2341-8330; Chatterjee, Suman/0000-0003-2660-0349; Garcia, Francisco/0000-0002-4023-7964; Theofilatos, Konstantinos/0000-0001-8448-883X; Bruschini, Davide/0000-0001-7248-2967; Lassila-Perini, Kati/0000-0002-5502-1795Measurements of the polarization and spin correlation in top quark pairs (t (t) over bar) 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 root 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) over bar system and the top quark scattering angle in the t (t) over bar 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) over bar spin entanglement are drawn by applying the Peres-Horodecki criterion. The standard model predicts entangled spins for t (t) over bart states at the production threshold and at high masses of the t (t) over bart system. Entanglement is observed for the first time in events at high t (t) over bar mass, where a large fraction of the t (t) over bar decays are spacelike separated, with an expected and observed significance of above 5 standard deviations.eninfo:eu-repo/semantics/openAccessArticle10.1103/PhysRevD.110.1120162-s2.0-85214239868