1. 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,
S.E.S. 3x10-17
m Experiment