Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Subnuclear System Research Division
Meson Science Laboratory
1. Abstract

Particles like muons, pions, and kaons have ﬁnite lifetimes, so they do not exist in natural nuclei or matters. By implanting theseparticles into nuclei/matters, exotic phenomena in various objects can be studied from new point of view.
For example, kaon is the second lightest meson, which has strange quark as a constituent quark. It is expected that if one embeds
mesons into nuclei, the sizes of the nuclei become smaller, and one can form a high-density object beyond the normal nuclear density.
Study of this object could lead to better understanding of the origin of the mass of the matter and may reveal the quark degree of
freedom beyond the quark-conﬁnement. The other example is the weak interaction in nuclear matter. It can only be studied by the
weak decay of hypernuclei, which have Lambda particle in the nuclei.
Muon provides even wider scope of studies, covering condensed matter physics as well as nuclear and atomic physics, and weare trying to extend the application ﬁeld further into chemical and biological studies. For instance, stopping positively charged muonin a material, we obtain information on the magnetic properties or the local ﬁeld at the muon trapped site (µSR). Injecting negatively
charged muon to hydrogen gas, muonic hydrogen atom (µp) is formed. We use muonic atoms for proton magnetic radius measurement,muon catalyzed fusion and elemental analysis with muonic X-rays. We are also interested in precision measurement of muon property
itself, such as muon anomalous magnetic moment (g 2).
In our research, we introduce diﬀerent kind of impurities into nuclei/matters, and study new states of matter, new phenomena, or
the object properties.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Study of meson property and interaction in nuclei
Origin of matter mass/quark degree of freedom in nuclei
Condensed matter and material studies with muon
Nuclear and particle physics studies via muonic hydrogen
Development of ultra cold muon beam, and its application from material science to particle physics

3. Summary of Research Activity(1) Hadron physics at J-PARC, RIKEN-RIBF, GSI and SPring-8
Kaon and pion will shed a new insight to the nuclear physics. The recent discovery of deeply bound pionic atom enables us toinvestigate the properties of mesons in nuclear matter. At RIKEN-RIBF, we are preparing precise experimental study of the pionicatom. Very lately, we succeeded to discover kaonic nuclear bound state, “K-pp,” at J-PARC. The yield dependence on momentumtransfer shows that observed system is unexpectedly small. We extended our study on Λ(1405) that could be K-p bound state. By theseexperiments, we are studying the KN − interaction, and clarify the nature of kaon in nuclei. At Spring-8 and at GSI, we are planning tostudy omega and η1 nuclei. By these experiments, we aim to be a world-leading scientiﬁc research group using these light meta-stableparticles.
(1-1) Deeply bound kaonic nuclei
J-PARC E15 experiment had been performed to explore the simplest kaonic nuclear bound state, “K − pp.” Because of the strong
attraction between KN − , the K − in nuclei may attract surrounding nucleons, resulting in forming a deeply bound and extremely dense
object. Measurement of the kaon properties at such a high-density medium will provide precious information on the origin of hadron
masses, if the standard scenario of the hadron-mass-generation mechanism, in which the hadron masses are depends on matter densityand energy, is correct. Namely, one may study the chiral symmetry breaking of the universe and its partial restoration in nuclear
medium.
The E15 experiment was completed to observe the “K − pp” bound state by the in-ﬂight 3 He(K − , n) reaction, which allows us
the formation via the invariant-mass spectroscopy by detecting decay particles from “K − pp.” For the experiment, we constructed a
dedicated spectrometer system at the secondary beam-line, K1.8BR, in the hadron hall of J-PARC.
With the Λpn ﬁnal states obtained in the ﬁrst stage experiment, we observed a kinematic anomaly in the Λp invariant mass
near the mass threshold of M(K − -pp) (total mass of kaon and two protons) at the lower momentum transfer q region. We conducteda successive experiment to examine the nature of the observed kinematical anomaly in the Λpn ﬁnal state, and we conﬁrmed theexistence of the bound state below the mass threshold of M(K − pp) at as deep as the binding energy of 40 MeV. The momentum
transfer q naturally prefers lower momentum for the bound state formation, but the observed event concentration extended having theform-factor parameter ∼400 MeV/c. Based on the PWIA calculation, the data indicated that the “K − pp” system could be as small as∼0.6 fm. It is astonishingly compact in contrast to the mean nucleon distance ∼1.8 fm.
This observed signal shows that a meson (qq− ) forms a quantum state where baryons (qqq) exist as nuclear medium, i.e., ahighly excited novel form of nucleus with a kaon, in which the mesonic degree-of-freedom still holds. This is totally new form of
nuclear system, which never been observed before.
(1-2) Precision X-ray measurement of kaonic atom
To study the KN − interaction at zero energy from the atomic state level shift and width of kaon, we have performed an X-ray
spectroscopy of atomic 3d → 2p transition of negatively charged K-mesons captured by helium atoms. However, our ﬁrst experimentis insuﬃcient in energy resolution to see the K − -nucleus potential. Aiming to provide a breakthrough from atomic level observation,- 346 -

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RIKEN Accel. Prog. Rep. 56 (2023)

we introduce a novel X-ray detector, namely superconducting transition-edge-sensor (TES) microcalorimeter oﬀering unprecedented
high energy resolution, being more than one order of magnitude better than that achieved in the past experiments using conventional
semiconductor detectors. The experiment J-PARC E62 aims to determine 2p-level strong interaction shifts of kaonic 3 He and 4 He
atoms by measuring the atomic 3d → 2p transition X-rays using TES detector with 240 pixels having about 23 mm2 eﬀective area
and the average energy resolution of 7 eV (FWHM) at 6 keV. We carried out the experiment at J-PARC in June 2018 and successfully
observed distinct X-ray peaks from both atoms. The energies were determined to be 6224.5 +/ 0.4 (stat) +/ 0.2 (syst) eV and 6463.7+/ 0.3 (stat) +/ 0.1 (syst) eV, and widths to be 2.5 +/ 1.0 (stat) +/ 0.4 (syst) eV and 1.0 +/ 0.6 (stat) +/ 0.3 (syst) eV, for kaonic 3 He and4
He, respectively. These values are nearly 10 times more precise than in previous measurements. The results exclude the large stronginteraction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential
models.
Another important X-ray measurement of kaonic atom would be 2p → 1 stransition of kaonic deuteron (K − -d). We have measured
same transition of kaonic hydrogen (K − -p), but the width and shift from electro-magnetic (EM) value reﬂect only isospin average ofthe K bar N interaction. We can resolve isospin dependence of the strong interaction by the measurements both for K − -p and K − -d. The
experiment J-PARC E57 aims at pioneering measurement of the X-rays from K − -d atoms. Prior to full (stage-2) approval of the E57
proposal, we performed a pilot run with hydrogen target in March 2019.
(1-3) Deeply bound pionic atoms and η1 mesonic nuclei
We have been working on precision spectroscopy of pionic atoms systematically, which leads to understanding of the non-trivial
structure of the vacuum and the origin of hadron masses. The precision data set stringent constraints on the chiral condensate at
nuclear medium. We are presently preparing for the precision systematic measurements at RIBF. A pilot experiment performed in2010 showed a unprecedented results of pionic atom formation spectra with ﬁnite reaction angles. The measurement of pionic 121 Sn
performed in 2014 provided high-precision data and set constraints on the pion-nucleus strong interaction, which led to deductionof the chiral condensate at the normal nuclear density. In 2021, systematic high precision spectroscopy of pionic Sn atoms were
performed and the analysis is ongoing.
We are also working on spectroscopy of η1 mesonic nuclei in GSI/FAIR. Theoretically, peculiarly large mass of η1 is attributed
to UA (1) symmetry and chiral symmetry breaking. As a result, large binding energy is expected for η1 meson bound states in nuclei(η1 -mesonic nuclei). From the measurement, we can access information about gluon dynamics in the vacuum via the binding energy
and decay width of η1 -nuclear bound state. In 2022, we performed a new experiment using a large solid angle detector of WASA at
GSI to search for the η1 -nucleus bound state with an enhanced signal-to-noise ratio.
(1-4) 3Λ H3, 4 H lifetime puzzle and our approach
Three recent heavy ion experiments (HypHI, STAR, and ALICE) announced surprisingly short lifetime for 3Λ H hyper-nucleus’s
Mesonic Weak Decay (MWD), which seems to be inconsistent with the fact that the 3Λ H is a very loosely bound system. It is very
interesting to study this with a diﬀerent experimental approach. We proposed a direct measurement of Λ H MWD lifetime withresolution at J-PARC hadron facility by using K-meson beam at 1 GeV/c. As for the feasibility test, we also measure 4Λ H lifetime.
A Cylindrical Detector System (CDS) used in J-PARC E15/E31 experiment is employed to capture the delayed π− as a weak decay
40
product from 3,
Λ H a calorimeter is installed in the very forward region to tag fast π meson emission at ∼0 degree, which ensures that4
the Λ hyperon production with small recoil momentum. By this selection, we can improve the ratio between 3,
Λ H and quasi-free Λ and4
Σ background. A test beam for feasibility study with He target has been conditionally approved by J-PARC PAC. We will conduct
the experiment and to present the data in short.
(1-5) Study of properties of vector mesons in nuclei
Preparation of the experiment E16 at J-PARC Hadron Experimental Facility is underway with several Grant-in-Aids. This experiment aims to perform a systematic study of the spectral modiﬁcation of low-mass vector mesons in nuclei through the dielectron
decay channel, in order to explore the physics of chiral symmetry breaking and restoration in dense nuclear matter.
In JFY 2020, a new primary beam line for E16 was completed in J-PARC. Commissioning runs of the beam line and of ourspectrometer were performed. The detectors almost satisﬁed the design performance. Unexpected beam micro structures which
deteriorates the DAQ performance were found, and countermeasures were proposed. They will be applied in the test beam time,
which is planned in 2023. Based on the result, approval of physics beam time will be discussed in PAC held in Winter 2023–24.
This activity was moved to Meson Science Laboratory after the closing of Radiation Laboratory.
(2) Muon science at RIKEN-RAL branch
The research area ranges over particle physics, condensed matter studies, chemistry and life science. Our core activities are
based on the RIKEN-RAL Muon Facility located at the Rutherford-Appleton Laboratory (UK), which provides intense pulsed-muonbeams. We have variety of important research activities such as particle/nuclear physics studies with muon’s spin and condensed
matter physics by muon spin rotation/relaxation/resonance (µSR).
(2-1) Condensed matter/materials studies with µSR
We share experimental equipment with those of RAL in order to make organization of RIKEN beam time schedules easier andto enhance the eﬃciency to carry out RIKEN’s experiments. We use shared cryostats and manpower supports available from RAL
as well we other experimental areas. Both two µSR spectrometers, ARGUS (Port-2) and CHRNUS (Port-4), are working well withmaintenance supports provide from RAL. Among our scientiﬁc activities on µSR studies from year 2017 to 2022, following studies
are most important subjects of material sciences at the RIKEN-RAL muon facility:(1) Multi magnetic transitions in the Ru-based pyrochlore systems, R2 Ru2 O7 ;(2) Magnetic properties of the nano-cluster gold in the border of macro- and micro- scale;- 347 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)(3) Novel magnetic and superconducting properties of nano-size La-based high-TC superconducting curates;(4) Novel superconducting properties in quasi two-dimensional organic molecular systems.
(5) Determination of muon positions estimated from density functional theory (DFT) and dipole-ﬁeld calculations;(6) Chemical muonic states in DNA molecules.
(2-2) Nuclear and particle physics studies via ultra-cold muon beam and muonic atoms
If we can improve muon beam emittance, timing and energy dispersion (so-called “ultra-cold muon”), then the capability of µSR
studies will be drastically improved. The ultra-cold muon beam can stop in a thin foil, multi-layered materials and artiﬁcial lattices, so
one can apply the µSR techniques to surface and interface science. The development of ultra-cold muon beam is also very importantas the source of pencil-like small emittance muon beam for muon g − 2 measurement. Ultra-cold muon beam has been produced bylaser ionization of muoniums in vacuum (bound system of µ+ and electron). We developed a very promising materials for muonium
production, laser ablated silica aerogel. We also developed a high power Lyman-α laser in collaboration with laser group at RIKEN.
In this laser development, we succeeded to synthesize novel laser crystals Nd:YGAG and Nd:YSAG, which has an ideal wavelength
property for laser ampliﬁcation to generate Lyman-α by four-wave mixing in Kr gas cell. We are now building the actual muon source
to be used for muon g-2. The ﬁrst part of the muon ionization chamber was manufactured and is being tested using the muon beam at
J-PARC.
(3) QED study of the lepton g-2
We are conducting research on Quantum Electrodynamics (QED) theory related to the determination of the theoretical and experimental values of the lepton anomalous magnetic moment (g-2). The contribution of QED to g-2 can be obtained through perturbative
calculations using Feynman diagrams. We are carrying out both analytical validation and numerical computation improvements todetermine the value of the 10th-order perturbation term. Additionally, we are also investigating the quantum corrections by QED to
the experimental determination formula of the electron g-2.

Members
Director
Masahiko IWASAKI
Senior Research Scientists
Kenta ITAHASHI
Yue MA
Haruhiko OUTA

Fuminori SAKUMA
Isao WATANABE
Satoshi YOKKAICHI

Senior Scientist
Makiko NIO
Contract Researchers
Katsuhiko ISHIDA

Tomonori TAKAHASHI

Special Postdoctoral Researcher
Koki KANNO
Postdoctoral Researchers
Koki KANNO

Rie MURAYAMA

Junior Research Associate
Tomoki MURAKAMIInternational Program Associates
Supparat CHAROENPHON (Kasetsart Univ.)
Muhammad H.B. CHE LAH (Univ. Sains Malaysia)

Li DENG (The Univ. of Sci. and Tech. of China)
Anita E. PUTRI (Univ. of Indonesia)

Research Consultant
Masayasu KAMIMURA
Senior Visiting Scientists
Hiroyuki NOUMI (Osaka Univ.)

Kazuhiro TANAKA (KEK)

Visiting Scientists
Tadashi ADACHI (Sophia Univ.)
Kazuya AOKI (KEK)
Tatsumi AOYAMA (KEK)
Retno ASIH (Inst. Teknologi Sepuluh Nopember)
Fahmi ASTUTI (Inst. Teknologi Sepuluh Nopember)

Wen-Chen CHANG (Inst. of Phys., Academia Sinica)
Catalina Oana CURCEANU (INFN)
Zyun EZAWA (Tohoku Univ.)
Hiroyuki FUJIOKA (Tokyo Tech)
Masaki FUJITA (Tohoku Univ.)- 348 -

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Shuhei FUKUOKA (Hokkaido Univ.)
Takayuki GOTO (Sophia Univ.)
Masashi HAYAKAWA (Nagoya Univ.)
Wataru HIGEMOTO (JAEA)
Ko-ichi HIRAKI (Fukushima Medical Univ.)
Satoru HIRENZAKI (Nara Women’s Univ.)
Koichi ICHIMURA (Hokkaido Univ.)
Yasuyuki ISHII (Shibaura Inst. of Tech.)
Ryosuke KADONO (KEK)
Takayuki KAWAMATA (Tokyo Denki Univ.)
Seiko KAWAMURA (JAEA)
Hikomitsu KIKUCHI (Univ. of Fukui)
Takuya KOBAYASHI (Saitama Univ.)
Yoji KOIKE (Tohoku Univ.)
Kenji MATSUDA (Univ. of Toyama)
Hiroyasu MATSUURA (Univ. of Tokyo)
Mototsugu MIHARA (Osaka Univ.)
Takaaki MINAMIDATE (Tokyo Univ. Sci)
Yasuhiro MIYAKE (KEK)
Yuhei MORINO (KEK)
Wataru NAKAI (KEK)
Takehito NAKANO (Ibaraki Univ.)
Takahiro NAMIKI (Univ. of Toyama)
Megumi NARUKI (Kyoto Univ.)
Katsuhiko NISHIMURA (Univ. of Toyama)
Agustinus NUGROHO (Inst. Teknologi Bandung)

Kazuki OHISHI (Comprehensive Res. Org. for Sci. and Soc.)
Yu OISHI (KEK)
Kyoichiro OZAWA (KEK)
Dita PUSPITA SARI (Shibaura Inst. of Tech.)
Muhammad R. RAMADHAN (Univ. Pertahanan Republik Indonesia)
Irwan RAMLI (Univ. Cokroaminoto Palopo)
RISDIANA (Padjadjaran Univ.)
Lusi SAFRIANI (Padjadjaran Univ.)
Naohito SAITO (KEK)
Shinichi SHAMOTO (Comprehensive Res. Org. for Sci. and
Soc.)
Ichiro SHIRAKI (Univ. of Yamanashi)
Shukri SULAIMAN (Univ. Sains Malaysia)
Takao SUZUKI (Shibaura Inst. of Tech.)Takanori TANIGUCHI (Tohoku Univ.)
Andrea VACCHI (Udine Univ. (Italy))
Eberhard WIDMANN (Stefan Meyer Inst.)
Yasuhiro YAMAGUCHI (Nagoya Univ.)
Ichihiro YAMAUCHI (Saga Univ.)
Yukio YASUI (Meiji Univ.)
Masaru YOSOI (Osaka Univ.)
Wan Nurfadhilah B. ZAHARIM (UNIVERSITI SAINSMALAYSIA)
Xu-Guang ZHENG (Saga Univ.)
Johann ZMESKAL (Austrian Academy of Sci.)

Visiting Technician
Che-Sheng LIN (Academia Sinica)
Research Fellow
Harison B. ROZAK (Shibaura Inst. of Tech.)Student Trainees
Tomoya ASANO (Saitama Univ.)
Masaya ICHIKAWA (Kyoto Univ.)
Shota MATSUMOTO (Kyoto Univ.)
Shunnosuke NAGAFUSA (Kyoto Univ.)
Satomi NAKASUGA (Kyoto Univ.)

Shuta OCHIAI (Kyoto Univ.)
Po-Hung WANG (Nat’l Central Univ.)
Utami WIDYAISWARI (Univ. Indonesia)
Kanako YAMAGUCHI (Kyoto Univ.)
Ryota YAMAZAKI (Saitama Univ.)

Research Part-time Worker
Utami WIDYAISWARI
Assistants
Kumiko TAKAHASHI

Mitsue YAMAMOTO

List of Publications & Presentations
Publications[Original Papers]
A. Jamaludin et al., “Density functional theory investigation of muon hyperﬁne interaction in guanine-cytosine double-strand DNA,” J.
Phys. Soc. Jpn. 91, 024301 (2022).
M. Redo Ramadhan et al., “Estimation of the on-site coulomb potential and covalent state in La2 CuO4 by muon spin rotation and density
functional theory calculations,” Phys. Rev. Res. 4, 033044 (2022).
A. Ito et al., “Antiferromagnetic ordering of organic mott insulator λ-(BEDSe-TTF)2 GaCl4 ,” Phys. Rev. B 106, 045114 (2022).
W. N. Zaharim et al., “Density functional theory study of muon hyperﬁne interactions in 12 mer single-strand adenine, cytosine, andthymine oligomers,” J. Phys. Soc. Jpn. 91, 094301 (2022).
T. Takayama et al., “Competing spin-orbital singlet states in the 4d4 honeycomb ruthenate Ag3 LiRu2 O6 ,” Phys. Rev. Res. 4, 043079(2022).
M. Cataldo et al., “A novel non-destructive technique for cultural heritage: Depth proﬁling and elemental analysis underneath the surface
with negative muons,” J. Phys. Soc. Jpn. 91, 024301 (2022).

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C. Zhang et al., “Modeling the diﬀusion of muonium in silica aerogel and its application to a novel design of multi-layer target for thermalmuon generation,” Nucl. Instrum. Methods Phys. Res. A 1042, 167443 (2022).
G. A. Green et al., “Negative muons reveal the economic chaos of rome’s AD 68/9 civil wars,” Archaeol. Anthropol. Sci. 14, 165 (2022).
J-PARC E31 Collaboration, “Pole position of Λ (1405) measured in d(K − , n)π Σ reactions,” Phys. Lett. B 837, 137637 (2023).
T. Nishi et al., piAF Collaboration, “Chiral symmetry restoration at high matter density observed in pionic atoms,” Nat. Phys. 19, 788(2023).
N. Ikeno et al., “Pion-nucleon sigma term σπN and deeply bound pionic atoms,” Prog. Theor. Exp. Phys. 2023, 033D03 (2023).

[Books]A. D. Hillier et al., “Depth-dependent bulk elemental analysis using negative muons,” in Handbook of Cultural Heritage Analysis, S.
D’Amico and V. Venuti (eds.), Springer 2022, pp. 23–44.
K. Itahashi, “Pionic Atoms in Experiment,” in Handbook of Nuclear Physics, I. Tanihata, H. Toki, and T. Kajino, (eds.), Springer,
Singapore, https://doi.org/10.1007/978-981-15-8818-1_36-1 .

[Proceedings]
Y. Ma et al., “Status of J-PARC E73 experiment: ﬁrst direct Hypertriton lifetime measurement with 3 He(K − ,pi0)H3 L reaction,” Suplemento de la Revista Mexicana de Fisica 30308120, 1 (2022).
F. Sakuma et al., “J-PARC hadron experimental facility extension project,” EPJ Web Conf. 271, 11001 (2022).
F. Sakuma et al., “Summary of the K − pp bound-state observation in E15 and future prospects,” EPJ Web Conf. 262, 01008 (2022).
S. Nakasuga et al., “Commissioning of the electron identiﬁcation system for Dilepton measurement in pA collisions at J-PARC,” Nucl.
Instrum. Methods Phys. Res. A 1041, 167335 (2022).
K. Ozawa et al., “Towards the measurement of the mass modiﬁcations of vector mesons in a ﬁnite density matter,” Acta Phys. Pol. A 142,399 (2022).
M. Ichikawa et al., “Commissioning runs of J-PARC E16 experiment,” Acta Phys. Pol. B Proc. Suppl. 16, 1-A143 (2023).
K. Ozawa et al., “J-PARC heavy ion project,” EPJ Web Conf. 271, 11004 (2022).
Ce Zhang, T. Hiraki, K. Ishida, S. Kamal, S. Kamioka, T. Mibe, A. Olin, N. Saito, K. Suzuki, S. Uetake, and Y. Mao, “Modeling thediﬀusion of muonium in silica aerogel and its application to a novel design of multi-layer target for thermal muon generation,” Nucl.
Instrum. Methods Phys. Res. A 1042, 167443G (2022).

Presentations[International Conferences/Workshops]
T. Yamaga (invited), “Kaonic nuclei at J-PARC,” Third International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (3rd J-PARC HEF-ex WS), J-PARC, March 14–16, 2023.
T. Hashimoto (invited), “Experimental study of the four-body kaonic nuclear state, KbarNNN,” EXOTICO: EXOTIc Atoms Meet Nuclear
Collisions for a New Frontier Precision Era in Low Energy Strangeness Nuclear Physics ECT*, Trento, Italy, October 17, 2022.
T. Yamaga (invited), “Result of KbaRNN search at J-PARC and future projects,” EXOTICO: EXOTIc Atoms Meet Nuclear Collisions fora New Frontier Precision Era in Low Energy Strangeness Nuclear Physics ECT*, October 17, 2022.
T. Yamaga (invited), “Experimental investigation of KbarNN state using K − + 3 He reaction at J-PARC,” EMMI workshop, “Meson andhyperon interactions with nuclei,” Kitzbuhel, Austria, September 14–16, 2022.
M. Iwasaki (invited), “Kbar nuclear bound state—Toward revolutionary Nuclear Study via revealing Internal Structure of Kaonic Nuclei,”
The 28th International Nuclear Physics Conference (INPC 2022), Cape Town, South Africa, September 11–16, 2022.
T. Yamaga (invited), “Experimental study of KbarNN and future Kbar-nuclei experiments at J-PARC,” The 9th International Conferenceon Quarks and Nuclear Physics (QNP2022), Online, September 5–9, 2022.
T. Hashimoto (invited), “Experimental study of kaonic nuclei and kaonic atoms at J-PARC,” the 15th Asia Paciﬁc Physics Conference(APPC15), South Korea, August 21–26, 2022.
F. Sakuma (invited), “J-PARC hadron hall extension project,” 14th International Conference on Hypernuclear and Strange Particle Physics- HYP2022, Prague, Czech Republic, June 27–July 1, 2022.
T. Yamaga (invited), “Experimental study of KbarNN and future experiments for kaonic nuclei,” 14th International Conference on Hypernuclear and Strange Particle Physics - HYP2022, Prague, Czech Republic, June 27–July 1, 2022,
Y. Ma (invited), “Current status of hypertriton lifetime measurement with J-PARC E73 experiment,” 14th International Conference onHypernuclear and Strange Particle Physics - HYP2022, Prague, Czech Republic, June 27–July 1, 2022.
T. Hashimoto (oral), “Search for the KbarNNN bound state in the Λ dn ﬁnal states of the in-ﬂight K- reaction on 4 He,” 14th International
Conference on Hypernuclear and Strange Particle Physics - HYP2022, Prague, Czech Republic, June 27–July 1, 2022.
K. Kanno (oral), “Commissioning of a hadron blind detector for dielectron measurement in pA reactions at J-PARC,” MPGD2022,
Weizmann Institute, Rehovot, Israel/Hybrid, December 11–16, 2022.
S. Yokkaichi (invited), “Measurements of spectral change of vector mesons in nuclear matter at ﬁnite density,” Third International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility, J-PARC, Tokai, Japan & Online, March 14–16, 2023.
K. Ishida on behalf of the J-PARC muon g-2/EDM Collaboration (E34), “Muon g-2/EDM experiment at J-PARC,” Fifth Plenary Workshopof the Muon g-2 Theory Initiative, Edinburgh, September 5–9, 2022.
K. Itahashi (invited), “What ca npionic atoms tell about the QCD vacuum,” XVth Quark conﬁnement and the hadron spectrum, Stavanger,- 350 -

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August 1–6, 2022.
K. Itahashi (invited), “Pionic atoms and chiral symmetry,” 4th Jagiellonian Symposium, Krakow, July, 2022.

[Domestic Conferences/Workshops]

山我拓巳 (招待講演), “Study of mesonic decay of KNN and perspectives of kaonic nuclei experiments at J-PARC,” J-PARC ハドロン研究会, 東海村 (KEK), 2023 年 3 月 27–29 日.
橋本直 (招待講演), 「J-PARC における K 中間子原子核研究の状況と展望」, ELPH 研究会 C033「ハドロン分光に迫る反応と構造の物理」, 仙台市 (東北大学電子光理学研究センター), 2022 年 12 月 6–7 日.
高橋智則 (口頭発表), 「J-PARC E16 実験の DAQ の現状と課題」, RCNP 研究会「原子核実験の次世代データ収集システム基盤開発にむけて」, 茨木市 (RCNP) & オンライン, 2022 年 5 月 16–17 日.
T. N. Takahashi (招待講演), “Development of continuous readout electronics for precise measurement of dielectron spectra at J-PARC,”
第 8 回クラスター階層領域研究会, 大阪大学 & オンライン, 2023 年 2 月 9–11 日.
石田勝彦, 「ラザフォードアップルトン研究所ミュオン施設の紹介」, 第 7 回文理融合シンポジウム 量子ビームで歴史を探る—加速器が紡ぐ文理融合の地平—, つくば市 (KEK), 2022 年 11 月 3 日.
石田勝彦, 「ミュオン触媒核融合の利用」, 中間子科学の将来討論会, 和光市 (理研), 2022 年 11 月 9–11 日.
石田勝彦, 「理研 RAL 施設と原子・原子核研究」, 第 13 回 muon 科学と加速器研究研究会, 和光市 (理研), 2023 年 1 月 10–11 日.

[Seminar]

四日市悟, 「J-PARC E16 実験の現状と展望」, 第 14 回 J-PARC-HI の物理を語る夕べ (セミナーシリーズ), オンライン, 2022 年 8 月
19 日.

Press Releases「K 中間子と陽子が織りなす風変わりなバリオンを測定」, 大阪大学核物理研究センター, 高エネルギー加速器研究機構, J-PARC センター, 理化学研究所, 日本原子力開発機構, 東北大学電子光理学研究センター, INFN-LNF, SMI 共同プレスリリース, 2023 年 1
月 26 日.
「π で探る真空の秘密」, 理化学研究所, 奈良女子大, 鳥取大学, 阪大核物理研究センター, 共同プレスリリース, 2023 年 3 月 27 日.

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