Tests of discrete symmetries and quantum coherence with neutral kaons at the KLOE-2 experiment

The KLOE-2 detector records decays of quantum-entangled pairs of neutral kaons produced in decays of phi mesons provided by the DAFNE accelerator at the Laboratori Nazionali di Frascati, Italy. This system allows for a broad range of studies of fundamental discrete symmetries including tests which are only feasible with entangled neutral mesons. This work reports on the Lorentz non-invariance and CPT violation searches with the KSKL->pi+pi-pi+pi- process in the framework of the Standard Model Extension. Moreover, status and results of quantum coherence tests with the same process are discussed. Finally, the status of ongoing direct tests of T and CPT in neutral kaon transitions is presented. For each of thereported studies, perspectives are discussed for the KLOE-2 experiment, which is presently taking data.Comment: 8 pages, 3 figures Presented at the 2nd Jagiellonian Symposium for Fundamental and Applied Subatomic Physics, June 4-11 2017, Krak\'ow, Poland. Accepted for publication in Acta Physica Polonica

Study of the KSKL→πℓν3π0K_SK_L\to\pi\ell\nu 3 \pi^0 process for time reversal symmetry test at KLOE-2

This work presents prospects for conducting a novel direct test of time-reversal symmetry at the KLOE-2 experiment. Quantum entanglement of neutral K meson pairs uniquely available at KLOE-2 allows to probe directly the time-reversal symmetry (T) independently of CP violation. This is achieved by a comparison of probabilities for a transition between flavour and CP-definite states and its inverse obtained through exchange of initial and final states. As such a test requires the reconstruction of the $K_L\to 3\pi^0$ decay accompanied by $K_S\to\pi^{\pm}\ell^{\mp}\nu$ with good timing information, a new reconstruction method for this process is also presented which is capable of reconstructing the $K_L\to 3\pi^0$ decay with decay time resolution of O(1$\tau_S$).Comment: Submitted to Acta Physica Polonica B (5 pages, 3 figures

Search for dark forces with KLOE

During the last years several Dark Sector Models have been proposed in order to address striking astrophysical observations which failed standard interpretations. In the minimal case a new vector particle, the so called dark photon, or A′ or U boson, is introduced, with small coupling with Standard Model particles. Also, the existence of a dark Higgs boson h′ is postulated, in analogy with the Standard Model, to give mass to the U boson through the Spontaneous Symmetry Breaking mechanism. The KLOE experiment working at DAΦNE, an e+e− collider operating in Frascati (near Rome), searched for the existence of the U boson investigating three different processes and six different final states: (1) in Dalitz decays of the ϕ meson ϕ → ηU, with U → e+e− and η → π+π−π0 and π0π0π0, (2) in e+e− → Uh′ events, with U decaying into lepton and pion pairs, (3) in the dark Higgsstrahlung process, e+e− → Uh′, U → μ+μ−, h′ invisible. Limits on the model parameters have been set at 90 % CL for U boson masses below 1 GeV. Further improvements are expected in terms of sensitivity and discovery potential with the new KLOE-2 detector

Testing CPT symmetry in ortho-positronium decays with J-PET detector

Search for possible violation of combined charge, parity, and time-reversal symmetries is yet another approach for a test of New Physics, therefore a bound state of electron and positron (positronium) as the lightest matter-antimatter system and at the same time an eigenstate of the C and P operators is an unique probe in such endeavour. The test is performed by measurement of angular correlations in the annihilations of the lightest leptonic bound system. With the Jagiellonian Positron Emission Tomograph (J-PET) we have collected an unprecedented range of kinematical configurations of exclusively-recorded annihilations of the positronium triplet state (ortho-positronium) into three photons. Employing a novel technique for estimation of positronium spin axis on the basis of a single event, we determined the complete distribution of an angular correlation between spin and annihilation plane of ortho-positronium. We present recently published result of determined expectation value of this correlation at the precision level of 10$^{−4}$ , with an over three-fold improvement on the previous measurement. We discuss also the prospects for reaching the precision level of 10$^{−5}$ with the CPT symmetry test at the J-PET detector

Sensitivity of discrete symmetry tests in the positronium system with the J-PET detector

Study of certain angular correlations in the three-photon annihilations of the triplet state of positronium, the electron–positron bound state, may be used as a probe of potential CP and CPT-violating effects in the leptonic sector. We present the perspectives of CP and CPT tests using this process recorded with a novel detection system for photons in the positron annihilation energy range, the Jagiellonian Positron Emission Tomography (J-PET). We demonstrate the capability of this system to register three-photon annihilations with an unprecedented range of kinematical configurations and to measure the CPT-odd correlation between positronium spin and annihilation plane orientation with a precision improved by at least an order of magnitude with respect to present results. We also discuss the means to control and reduce detector asymmetries in order to allow J-PET to set the first measurement of the correlation between positronium spin and momentum of the most energetic annihilation photon which has never been studied to dat