Violation of a Bell inequality in particle physics experimentally verified?

Relevant aspects for testing Bell inequalities with entangled meson-antimeson systems are analyzed. In particular, we argue that the result of A. Go, J. Mod. Optics 51, 991 (2004), which nicely illustrate the quantum entanglement of B-meson pairs, cannot be considered as a Bell-test refuting local realism.Comment: 9 page

Entanglement witnesses and geometry of entanglement of two--qutrit states

We construct entanglement witnesses with regard to the geometric structure of the Hilbert--Schmidt space and investigate the geometry of entanglement. In particular, for a two--parameter family of two--qutrit states that are part of the magic simplex we calculate the Hilbert--Schmidt measure of entanglement. We present a method to detect bound entanglement which is illustrated for a three--parameter family of states. In this way we discover new regions of bound entangled states. Furthermore we outline how to use our method to distinguish entangled from separable states.Comment: 23 pages, 8 figure

Bell inequality and CP violation in the neutral kaon system

For the entangled neutral kaon system we formulate a Bell inequality sensitive to CP violation in mixing. Via this Bell inequality we obtain a bound on the leptonic CP asymmetry which is violated by experimental data. Furthermore, we connect the Bell inequality with a decoherence approach and find a lower bound on the decoherence parameter which practically corresponds to Furry's hypothesis.Comment: 10 pages, latex, no figure

Gluon Condensates and m_b(m_b) from QCD-Exponential Moments at Higher Orders

We test the convergence of the QCD exponential moments by including PT corrections to order \alpha_s^3 and the NP contributions up to D=8 condensates. Then, using the ratio of exponential sum rules where the QCD PT series is more convergent, we study the correlation between the gluon condensates and . From charmonium systems and using the charm quark mass as input, we deduce: =(8.2+-1.0)GeV^2 corresponding to =(7.5+- 2.0) 10^{-2} GeV^4. Using these results for the bottomium systems, we obtain: m_b(m_b)= 4212(32) MeV, which is slightly higher but consistent within the errrors with the ones from Q^2-moments and their ratios: m_b(m_b)= 4172(12) MeV. We are tempted to consider as a final result from the sum rules approaches, the average m_b(m_b)= 4177(11) MeV of the two previous determinations.Comment: 5 pages, 4 figures, 2 references added on the proofs (Phys. Lett. B in press

Nonlocality and entanglement in a strange system

We show that the relation between nonlocality and entanglement is subtler than one naively expects. In order to do this we consider the neutral kaon system--which is oscillating in time (particle--antiparticle mixing) and decaying--and describe it as an open quantum system. We consider a Bell--CHSH inequality and show a novel violation for non--maximally entangled states. Considering the change of purity and entanglement in time we find that, despite the fact that only two degrees of freedom at a certain time can be measured, the neutral kaon system does not behave like a bipartite qubit system.Comment: 7 pages, 2 figures, extended versio

Spin geometry of entangled qubits under bilocal decoherence modes

The Lindblad generators of the master equation define which kind of decoherence happens in an open quantum system. We are working with a two qubit system and choose the generators to be projection operators on the eigenstates of the system and unitary bilocal rotations of them. The resulting decoherence modes are studied in detail. Besides the general solutions we investigate the special case of maximally entangled states - the Bell singlet states. The results are depicted in the so-called spin geometry picture which allows to illustrate the evolution of the (nonlocal) correlations stored in a certain state. The question for which conditions the path traced out in the geometric picture depends only on the relative angle between the bilocal rotations is addressed.Comment: 12 pages, 3 figure

An open quantum system approach to EPR correlations in K0-K0 system

We find the time evolution of the system of two non-interacting unstable particles, distinguishable as well as identical ones, in arbitrary reference frame having only the Kraus operators governing the evolution of its components in the rest frame. We than calculate in the rigorous way Einstein-Podolsky-Rosen quantum correlation functions for K0-K0 system in the singlet state taking into account CP-violation and decoherence and show that the results are exactly the same despite the fact we treat kaons as distinguishable or identical particles which means that the statistics of the particles plays no role, at least in considered cases.Comment: 14 pp. no fig