Compact Muon Solenoid
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| CMS-PAS-TOP-23-001 | ||
| Probing entanglement in top quark production with the CMS detector | ||
| CMS Collaboration | ||
| 27 March 2024 | ||
| Abstract: Entanglement is an intrinsic property of quantum mechanics and its measurement probes the current understanding of the underlying quantum nature of elementary particles at a fundamental level. A measurement of the extent of entanglement in top quark-antiquark ($ \mathrm{t\bar{t}} $) events produced in proton-proton collisions at a center-of-mass energy of 13 TeV is performed on the data recorded by the CMS experiment at the CERN LHC in 2016, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The events are selected based on the presence of two oppositely charged high transverse momentum leptons. An entanglement-sensitive observable $ D $ is derived from the top quark spin-dependent parts of the $ \mathrm{t\bar{t}} $ production density matrix. Values of $ D $ smaller than $ -$1/3 are evidence of entanglement and, within a particular phase space, $ D $ is measured to be $-$0.478 $ ^{+0.025}_{-0.027} $. With an expected (observed) significance of 5.1 (5.7) standard deviations, this provides observation for quantum mechanical entanglement within $ \mathrm{t\bar{t}} $ pairs in this phase space. This measurement provides a new quantum probe of the inner workings of the standard model at the highest energy ever tested. | ||
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Links:
CDS record (PDF) ;
Physics Briefing ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, Submitted to ROPP. The superseded preliminary plots can be found here. |
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Compact Muon Solenoid LHC, CERN |
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