Recent results on entangled neutral kaons at KLOE-2

<!--HTML--><p>The entanglement of $K^0\bar{K^0}$ pairs produced in $\phi$-meson decays, in combination<br /> with the unique properties of the neutral kaon system – such as flavour oscillations, charge-parity (CP)<br /> and time-reversal (T ) violation – opens up new horizons in testing the basic principles<br /> of quantum mechanics and its fundamental discrete symmetries T , CP, CPT.</p> <p>The KLOE and KLOE-2 experiments at the Frascati Laboratories of INFN<br /> collected at the DA$\Phi$NE collider an integrated luminosity of about 8 fb$^{-1}$,<br /> corresponding to $\simeq 8 \times 10^{9}$ $K_SK_L$ entangled pairs produced.<br /> This is the world largest available data sample of this kind<br /> and represents a unique tool to improve the precision on these studies.</p> <p>The seminar will illustrate the most recent KLOE-2 results, including:</p> <p>(i) an improved search for decoherence and CPT violation effects that exploits EPR correlations<br /> in the process $\phi\rightarrow K_S K_L \rightarrow\pi^+\pi^-\pi^+\pi^-$, and constraints<br /> the parameters of various phenomenological models with a precision that reaches - for some of them -<br /> the interesting level at which – in the most optimistic scenarios – quantum gravity effects might show up.</p> <p>(ii) the first direct test of the T and CPT symmetries in neutral kaon transitions between flavor and CP eigenstates,<br /> by studying the processes $\phi\rightarrow K_S K_L \rightarrow \pi^+\pi^- \, \pi e \nu$ and<br /> $\phi\rightarrow K_S K_L \rightarrow \pi e \nu \,&nbsp; 3\pi^0$~;</p> <p>(iii) a new measurement of the $K_S \rightarrow \pi e \nu $ branching fraction, that in combination<br /> with the previous KLOE result improves the total precision by almost a factor of two, and allows<br /> a new derivation of $f_+(0)|V_{us}|$.</p> <p>&nbsp;</p>