Review of Kaon Physics at CERN and in Europe

The Kaon physics program at CERN and in Europe will be presented. I will first give a short review of recent results form the NA48/2 and NA62 experiments, with special emphasis to the measurement of RK , the ratio of Kaon leptonic decays rates, K → eν and K → μν, using the full minimum bias data sample collected in 2007-2008. The main subject of the talk will be the study of the highly suppressed decay K → πνν. While its rate can be predicted with minimal theoretical uncertainty in the Standard Model (BR ∼ 8 × 10−11), the smallness of BR and the challenging experimental signature make it very difficult to measure. The branching ratio for this decay is thus a sensitive probe of the flavour sector of the SM. The aim of NA62 is the measurement of the K → πνν BR with ∼ 10% precision in two years of data taking. This will require the observation of 10K decays in the experiment's fiducial volume, as well as the use of high-performance systems for precision tracking, particle identification, and photon vetoing. These aspects of the experiment will also allow NA62 to carry out a rich program of searches for lepton flavour and/or number violating K decays. Data taking will start in October 2014. The physics prospects and the status of the construction and commissioning of the NA62 experiment will be presented. In the last part of the talk I will report on Kaon physics results and prospects from other experiments at CERN (e.g. LHCb) and in Europe (e.g. KLOE and KLOE-2) and briefly mention the status in US

Observation of a spin 4 neutral meson with 2 GeV mass decaying in π0π0\pi^{0} \pi^{0}

The invariant mass spectrum of neutral meson states from π−p interactions at 40 GeV/c incident momentum has been investigated in a high statistics experiment performed at the 70 GeV IHEP accelerator. To detect the high energy photons coming from the produced neutral states, a hodoscope spectrometer with a computer on-line was used. A clear structure on the mass spectrum of dipions produced in the reaction π−p→π°π°n is observed at 2 GeV. The decay angular distributions show in this mass region the variation with mass typical of a state with a spin J = 4. The mass of the observed meson is found to be M = (2020±30)MeV and the estimate of the full width is (180±60) MeV

Observation of a second charmed particle produced by a high energy neutrino and decaying after a few times 10-13s

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

First direct observation of the decay of neutral charmed particles produced by neutrinos in emulsion

Three examples of the production in emulsion by neutrinos and subsequent decay of neutral short-lived particles are reported. The flight times are ≈ 10-13s, similar in order of magnitude to those previously determined for charged charmed particles in the same experiment. © 1979.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

On the lifetime of charged charmed particles first direct observation of a charmed baryon decay

Two new examples of production by neutrinos and subsequent decay of charged charmed hadrons are reported. Together with two similar events reported previously they show that the lifetime of charged charmed particles is in the neighbourhood of 5 × 10-13 s, as expected from current theoretical models. One of the new events is identified as a baryon λc+ of mass 2.295 ± 0.015 GeV/c2 which undergoes the decay process λc+ → pπ+K- with a proper decay time (7.3 ± 0.1) × 10-13 s. © 1979.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe