In this thesis, we study the quantum entanglement of neutral B-mesons from the decay of the Υ(5S). The experiment which provided real data for this decay is the Belle experiment which ran from 1999 to 2010 and gathered about 121fb−1 of data for the Υ(5S). The decay of the Υ(5S) particle is expected to produce entangled pairs of neutral B-mesons, therefore any deviations of the theoretical predictions for such entangled pairs to the measured data can be attributed to an effect called Quantum Decoherence (QD). QD is a more general term for the loss of the quantum properties of a system. In this thesis QD will refer specifically to the loss of entanglement (=ˆ disentanglement). To start with, we will briefly go over the basics of the flavor physics of the neutral meson system and study effects of mixing and the time dependence of the flavor states for B0 mesons. Then we will use this framework to calculate the theoretical probability density of measuring possible states for these entangled systems and compare them to the disentangled system. We will further analyse how QD can manifest by considering the entanglement of formation, which refers to a system that consists of multiple entangled states. It will be shown how disentanglement can arise in such systems and then apply this theory directly to the B0-meson systems we expect from the Υ(5S) decay. In the end, there is a brief introduction to the experimental uncertainties of the Belle detector, which is captured by the resolution function, and its impact on the theoretical prediction.In this thesis, we study the quantum entanglement of neutral B-mesons from the decay of the Υ(5S). The experiment which provided real data for this decay is the Belle experiment which ran from 1999 to 2010 and gathered about 121fb−1 of data for the Υ(5S). The decay of the Υ(5S) particle is expected to produce entangled pairs of neutral B-mesons, therefore any deviations of the theoretical predictions for such entangled pairs to the measured data can be attributed to an effect called Quantum Decoherence (QD). QD is a more general term for the loss of the quantum properties of a system. In this thesis QD will refer specifically to the loss of entanglement (=ˆ disentanglement). To start with, we will briefly go over the basics of the flavor physics of the neutral meson system and study effects of mixing and the time dependence of the flavor states for B0 mesons. Then we will use this framework to calculate the theoretical probability density of measuring possible states for these entangled systems and compare them to the disentangled system. We will further analyse how QD can manifest by considering the entanglement of formation, which refers to a system that consists of multiple entangled states. It will be shown how disentanglement can arise in such systems and then apply this theory directly to the B0-meson systems we expect from the Υ(5S) decay. In the end, there is a brief introduction to the experimental uncertainties of the Belle detector, which is captured by the resolution function, and its impact on the theoretical prediction.

Apr 30, 20250 citations

Neutral kaon system reinvestigated

Qing Wang, A. I. Sanda

There has been a revival of interest in testing quantum-mechanical postulates, and also $\mathrm{CPT}$ symmetry in the neutral $K$ meson system. These effects are bound to be very small. If some deviation from our expectation is found, it can be either from new physics, or from use of an invalid formalism. The neutral $K$ -$\mathrm{K\ifmmode\bar\else\textasciimacron\fi{}}$ system is described by $2\ifmmode\times\else\texttimes\fi{}2$ time-independent non-Hermitian effective Hamiltonian. The effective Hamiltonian is derived within the framework of perturbation theory up to the second order in the weak Hamiltonian. In addition, the Wigner-Weisskopf approximation is used. It is known that the correction to this approximation deviates from the exponential decay law. If the correction is large, it will have grave consequences. In this paper, we reexamine these questions. We conclude that all proposed searches for new physics in the $K$ meson decays can proceed without worrying about these corrections to the formalism.There has been a revival of interest in testing quantum-mechanical postulates, and also $\mathrm{CPT}$ symmetry in the neutral $K$ meson system. These effects are bound to be very small. If some deviation from our expectation is found, it can be either from new physics, or from use of an invalid formalism. The neutral $K$-$\mathrm{K\ifmmode\bar\else\textasciimacron\fi{}}$ system is described by $2\ifmmode\times\else\texttimes\fi{}2$ time-independent non-Hermitian effective Hamiltonian. The effective Hamiltonian is derived within the framework of perturbation theory up to the second order in the weak Hamiltonian. In addition, the Wigner-Weisskopf approximation is used. It is known that the correction to this approximation deviates from the exponential decay law. If the correction is large, it will have grave consequences. In this paper, we reexamine these questions. We conclude that all proposed searches for new physics in the $K$ meson decays can proceed without worrying about these corrections to the formalism.

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fieldsMar 1, 199711 citations

There has been a revival of interest in testing quantum-mechanical postulates, and also

\mathrm{CPT}

symmetry in the neutral

K

meson system. These effects are bound to be very small. If some deviation from our expectation is found, it can be either from new physics, or from use of an invalid formalism. The neutral

K

-$\mathrm{K\ifmmode\bar\else\textasciimacron\fi{}}$ system is described by $2\ifmmode\times\else\texttimes\fi{}2$ time-independent non-Hermitian effective Hamiltonian. The effective Hamiltonian is derived within the framework of perturbation theory up to the second order in the weak Hamiltonian. In addition, the Wigner-Weisskopf approximation is used. It is known that the correction to this approximation deviates from the exponential decay law. If the correction is large, it will have grave consequences. In this paper, we reexamine these questions. We conclude that all proposed searches for new physics in the

K

meson decays can proceed without worrying about these corrections to the formalism.