No Arabic abstract
ORKA is a proposed experiment to measure the K+ -> pi+ nu nubar branching ratio with 5% precision using the Fermilab Main Injector high intensity proton source. The detector design is based on the BNL E787/E949 experiments, which detected seven candidate events. Two orders of magnitude improvement in sensitivity relative to the BNL experiments comes from enhancements to the beam line and the detector acceptance. Precise measurement of the K+ -> pi+ nu nubar branching ratio with the same level of uncertainty as the well-understood Standard Model prediction allows for sensitivity to new physics at and beyond the LHC mass scale.
ORKA is a proposed experiment to measure the K+ -> pi+nunubar branching ratio with 5% precision using the Fermilab Main Injector high-intensity proton source. The detector design is based on the BNL E787/E949 experiments, which detected seven K+ -> pi+nunubar candidate events. ORKA is expected to acheive two orders of magnitude improvement in sensitivity relative to the BNL experiments as a result of enhancements to the beam line and the detector acceptance. Precise measurement of the K+ -> pi+nunubar branching ratio with the same level of uncertainty as the well-understood Standard Model prediction allows for sensitivity to new physics at and beyond the LHC mass scale. Detector R&D, simulation-based optimization of the experiment design, and preparation of the experiment location are underway.
We describe the development and testing of a novel beam stop for use in a rare kaon decay experiment at the Brookhaven AGS. The beam stop is located inside a dipole spectrometer magnet in close proximity to straw drift chambers and intercepts a high-intensity neutral hadron beam. The design process, involving both Monte Carlo simulations and beam tests of alternative beam-stop shielding arrangements, had the goal of minimizing the leakage of particles from the beam stop and the resulting hit rates in detectors, while preserving maximum acceptance for events of interest. The beam tests consisted of measurements of rates in drift chambers, scintilation counter hodoscopes, a gas threshold Cherenkov counter, and a lead glass array. Measurements were also made with a set of specialized detectors which were sensitive to low-energy neutrons, photons, and charged particles. Comparisons are made between these measurements and a detailed Monte Carlo simulation.
We report on the measurement of the one-dimensional charged kaon correlation functions using 600~GeV/{it c} $Sigma^-$, $pi^-$ and 540~GeV/{it c} $p$ beams from the SELEX~(E781) experiment at the Fermilab Tevatron. $K^{pm}K^{pm}$ correlation functions are studied for three transverse pair momentum, $k_T$, ranges and parameterized by a Gaussian form. The emission source radii, $R$, and the correlation strength, $lambda$, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types.
We calculate the signal rate of hypothetical heavy neutral leptons (HNL or sterile neutrinos) from kaon decays expected in the framework of the SHiP experiment. The kaons are produced in the hadronic shower initiated in the beam-dump mode by 400 GeV protons from CERN SPS. For a sufficiently light HNL (when the decays are kinematically allowed) we find kaon decays to be a noticeably richer source of HNL as compared to $D$-meson decays adopted in previous studies of the HNL phenomenology at SHiP. In particular, SHiP is capable of fully exploring the central part of the kinematically allowed region of the HNL mass and mixing with electron and muon neutrinos down to the lower cosmological bound. The latter is associated with HNL decays in the early Universe to energetic products rescattering off and thus destroying light nuclei produced at the primordial nucleosynthesis. A consistency of the HNL model with smaller mixing would require either a hierarchy -- much larger mixing of all the HNL with tau neutrino -- or non-standard cosmology and new ingredients in the HNL sector, closing the room for the minimal non-seesaw type I model with sterile neutrinos lighter than kaons.
In this paper we discuss the recent finalized analyses by the KLOE experiment at DA$Phi$NE: the CPT and Lorentz invariance test with entangled $K^0 bar{K}^0$ pairs, and the precision measurement of the branching fraction of the decay ${ K^+} rightarrow pi^+pi^-pi^+(gamma)$. We also present the status of an ongoing analysis aiming to precisely measure the $K^{pm} $ mass.