u c s b d n Hadron & Nuclear Physics Particle Physics Quarks Leptons Beam and SKS spectrometers at K1.8 beam line of Hadron Facilty K1.8 beam line provides mass-separated meson beams up to 2 GeV/c. High-resolution spectrometers for beam and scattered particles are instrumented at the K1.8 beam line in order to conduct spectroscopy experimets on hypernuclei and exotic hadrons. K1.8 Beam Spectrometer Beam particles Scattered particles SKS Spectrometer Hadron & Nuclear Physics Hadron and nuclear physics aim to understand ; how elementary quarks conbine each other and form hadrons? how hadron dynamical mass is obtained in this process? how protons and neutrons which are ones of hadrons, form nuclei. through the studies on hypernuclei, exotic hadrons, and meson-embedded nuclei. Ordinary nuclei comprise proton and neutron (nucleons) which contain only up and down quarks. Variety of nuclei are known to exist. In addition to the nucleon, hypernuclei contain hyperon(s), family members of nucleons containing strange quark(s). Studies on hypernuclei extend our knowledge on nuclear force, high- density nuclear matter which is expected to exist in the core of neutron star. Many kinds and numbers of hypernuclei can be produced by using high-intensity kaon beam at Hadron Facilty. Search for penta-quark baryon, Q+, using meson-beam The Q+ is an exotic baryon with a quark content of uuddsbar. Since the first report from LEP group, a lot of positive and negative results have been published. The existence of the Q+ is controversial. The Q+ was searched for via the p(p-,K+)X reaction at 1.92 and 2.0 GeV/c. Figure shows the results at 1.92GeV/c, showing no peak structure of Q+. The upper limit of 0.26mb/sr was obtained. Number of Neutrons strangeness (number of s-quark) Oridinary nuclei L, S hypernuclei LL, X hypernuclei S=0 S=-1 S=-2 Number of Protons L hypernuclei p L hyperon s n u d CsI CV Rare Kaon Decay Kaon Experiments SM: (2.477±0.001)·10-5 Lepton Universality Particle Physics n e m t u up c charm top d down s strange b bottom e-Neutrino m-Neutrino t-Neutrino electron muon tau Quarks Leptons I II III Generations of Matter Particle physics, which tries to shed light on the true nature of elementary particles such as quarks and leptons, is to reveal the history of the universe. It is known that the universe was composed of independent elementary particles in motion in the period immediately after the Big Bang (10-6 sec), which later formed nucleus and then matter. It was proved in recent studies that the characteristic structure of the current universe be determined by the behavior of elementary particles in this era; thus understanding the elementary particles leads directly understanding the universe evolution. A variety of particle physics experiments are conducted at J-PARC to this end. They use kaons, muons, and neutrinos produced by injecting proton beam from the J-PARC accelerator on nuclear targets. At J-PARC the “flavor” structure of elementary particles is studied intensively by using these secondary particle beams. Precision measurement of the n oscillation Muon neutrino disappearance Electron neutrino appearance (ne) nt ? n Experiment Phase-1 m-e conversion search Charged lepton flavor violation is not allowed in the Standard Model (SM) while physics models beyond the SM predict its existence. The COMET experiment aims at achieving the experiment sensitivity in a staging approach COMET Phase-1, 2017 S.E.S. 3x10-15 COMET full, 2021-2013 S.E.S. 3x10-17 m Experiment