Observation of Bell inequality violation in B mesons

According to Quantum Mechanics (QM), two systems can remain correlatedregardless of their spatial separation. This non-local property of QM hasgenerated many discussions in the context of Einstein, Podolsky and Rosen(EPR) paradox. EPR challenges the completeness of QM and hinted for theneed of local realist theories in the forms of hidden variables tocomplement QM. These discussions remained theoretical until the advent ofBell Inequality which puts the locality principle into a testable form.Many experiments have been performed since, mostly with photons and inpolarization correlation. Nevertheless, it is of considerableimportance to show that such non-local correlation exists not only formassless photons and for spin polarization quantum number. In particlephysics, both phi --> K0 K0bar and Upsilin(4S) --> B0 B0bar exhibit thesame EPR non-local correlation. In this talk, I will discuss thesimilarities and differences of these decays with the spin 1/2 and photonsystem. I will then discuss the possibility of testing Bell Inequalitywith Kaons and B-mesons. Finally, the result of violation of BellInequality using semileptonic B0 decays at BELLE experiment in KEK willbe presented. This is the first time such measurement is performed at ahigh-energy particle physics experiment with particle anti-particlequantum number.