FPUA 2024

14 Mar 2024, 08:00 → 15 Mar 2024, 18:00 Asia/Tokyo

OUX (Kyoiku Kyoso Commons) (Okayama University)

The 15th International Workshop on Fundamental Physics Using Atoms (FPUA2024)

Workshop objectives:   
The workshop aims to explore new frontiers of fundamental physics   
research using various methods of quantum state control and precise   
measurement of atoms and molecules. The latest results and prospects   
of fundamental physics research will be discussed, which is pioneering   
both experimentally and theoretically by integrating the advanced   
experimental techniques in various research fields including nuclear   
physics, particle physics, atomic physics, quantum optics, and   
more. The objective of this workshop is to strengthen these efforts   
and expand research networks.

Scientific program and abstract submission:   
The program will consist of invited and contributed talks including poster presentations.    
Participants who wish to be considered for contributed talks must submit their    
contribution at the time of registration.

Registration Deadline:   
February 29, 2024 (any time zone)

Invited Speakers (Confirmed):

Makoto Fujiwara (TRIUMF)    
    "Fundamental Physics Using (Anti)hydrogen Atoms: ALPHA at CERN and HAICU at TRIUMF"

Hiroaki Yamamoto (CALTECH)   
   "Study of Gravitational Wave by LIGO : past, present and future"

Xing Wu (MSU)    
  "Advancing EDM searches with ultracold radioactive molecules at FRIB"

Chi Zhang (CALTECH)   
  "New methods for quantum control of polar molecules for symmetry-violation searches"

Akio Kawasaki (AIST)    
   "Nuclear and particle physics with cold ytterbium and Rydberg atoms"

Jiro Murata (Rikkyo University)    
   "Towards quantum gravity: Test of Gravitational Inverse Square Law and Lorentz Invariance"

Shinji Okada (Chubu University)   
  "Fundamental physics using exotic atoms at J-PARC"

Kazunori Nakayama (Tohoku University)   
  “Light Dark Matter Search with Nitrogen-Vacancy Centers in Diamonds"

Hideo Iizuka (KEK / Toyota Central R&D Labs)   
  "Control of equilibrium and non-equilibrium Casimir forces"

Yutaka Shikano (University of Tsukuba)    
  "Three-particle Aharonov-Bohm Effect" 
 

Organizer:   
Y. Ichikawa (Kyushu), M.Tanaka (Osaka), K. Sugiyama (Kyoto), Y. Takasu (Kyoto)   
H. Shimizu (Nagoya), M Kitaguchi (Nagoya), K. Shimomura (KEK),    
T. Mibe (KEK), Y. Sakemi (Tokyo), A.Ishida (Tokyo)   
T. Masuda(Okayama),A. Yoshimi (Okayama),N. Sasao (Okayama University), K. Yoshimura (Okayama)

Sponsors:   
Research Institute for Interdisciplinary Science 
MEXT Grant-in-Aid for Scientific Research (C): 18K03621 
Fund for Promotion of Joint International Research (Fostering Joint International Research (B)):　20KK0068

Thursday, 14 March

08:00 → 09:00 Registration

09:00 → 09:10 Opening

FPUA2024_Opening.pdf

09:10 → 10:35 Oral: Session 1

Convener: Takahiko Masuda (Okayama University)

09:10 Advancing EDM searches with ultracold radioactive molecules at FRIB

"Searches for non-zero electric dipole moment (EDM) in fundamental particles shed light on discrete symmetries of nature and constrain new physics beyond the Standard Model. The most sensitive electron EDM and many ongoing nuclear EDM searches are performed with molecules, benefiting from the substantial intra-molecular electric field. At the Facility for Rare Isotope Beams (FRIB), we are building a new generation of EDM searches using ultracold radioactive molecules. This project will leverage the unique opportunity to access pear-shaped nuclei (e.g. Ra-225) at FRIB, and the state-of-the-art technology in precision measurement using polar molecules. The former amplifies the Nuclear Schiff Moment and hence the sensitivity to hadronic CP-violation, thanks to the nuclear octupole deformation. The latter, built upon recent advances in atomic and optical physics, aims to bring the Ra-containing molecules into the ultracold regime, where both high phase-space density and seconds-long spin precession time have been demonstrated. With the nuclear enhancement and the quantum upgrades combined, this new project envisions to enhance the EDM sensitivity by orders of magnitude from the current best effort."

Speaker: Xing Wu (Facility for Rare Isotope Beams, Michigan State University)

FPUA2024_frib_Mar14.pdf

09:40 New methods for quantum control of polar molecules for symmetry-violation searches

"Precision measurements of time-reversal symmetry violation in molecular systems provide stringent tests of new physics beyond the Standard Model. I will report our experimental progress towards measuring the nuclear magnetic quadrupole moment using polyatomic 173YbOH molecules. In addition, I will present our recent proposals for advancing the quantum control of molecules and thus improving the T-violation searches. These new methods include Rydberg atom-assisted sympathetic slowing and cooling [1], Rydberg atom-assisted quantum logic control and entanglement generation [2], as well as a new quantum entanglement-enhanced measurement protocol [3].

[1] CZ et al., Sympathetic cooling and slowing of molecules with Rydberg atoms, Phys. Rev. Lett. 132, 033001 (2024)
[2] CZ and M. R. Tarbutt, Quantum Computation in a Hybrid Array of Molecules and Rydberg Atoms, PRX Quantum 3, 030340 (2022)
[3] CZ et al., Quantum-Enhanced Metrology for Molecular Symmetry Violation using Decoherence-Free Subspaces, Phys. Rev. Lett. 131, 193602 (2023)"

Speaker: Chi Zhang (California Institute of Technology)

FPUA_ChiZhang.pdf

10:10 Current status of laser and optical system for EDM search using cold francium atoms at RIKEN/CNS

"A laser and optical system for magneto-optical trapping (MOT) of radioactive francium (Fr) atoms has been developed at RIKEN/CNS. The wavelength meter stabilized the laser frequencies involved in MOT, and the 400 m fiber link overcame the challenge of spatial separation of the laser and Fr atoms. MOT was successfully demonstrated in test experiments using stable rubidium. This achievement is not only a benchmark for Fr experiments but also provides valuable insights for experimental designers who need to move the light source away from the atomic source for various reasons. The current status and outlook of the EDM search project will also be presented at the event."

Speaker: Keisuke Nakamura (CNS, the University of Tokyo)

FPUA_20240314.pdf

10:35 → 11:00 Coffee

11:00 → 12:30 Oral: Session 2

Convener: Akira Ishida (The University of Tokyo)

11:00 Three-particles Aharonov-Bohm effect

"The setup of the Einstein-Podolsky-Rosen (EPR) paradox leads to provide the observer-depedent description of the quantum state from quantum information perspectives. While this problem is based on the single-particle system, the problem can be extended to the many identical particle system. We provide the experimental proposal to clarify the quantum state description to the identical particle. This experimental proposal is used in the three-particles Aharonov Bohm effect."

Speaker: Yutaka Shikano (University of Tsukuba)

fpua_YS.pdf

11:30 Control of equilibrium and non-equilibrium Casimir forces

"Following a brief overview of Casimir forces, our recent theoretical works on Casimir forces are presented. Feedback control is introduced for manipulating non-equilibrium Casimir forces. In addition, fundamental properties of equilibrium and non-equilibrium Casimir forces are discussed for systems consisting of reciprocal and non-reciprocal materials."

Speaker: Hideo IIzuka (KEK / Tyota Central RandD Lab)

FPUA 2024 iizuka.pdf

12:00 Towards quantum gravity: Test of Gravitational Inverse Square Law and Lorentz Invariance

"Tabletop experiments searching violation of gravitational inverse square law and the muLV experiment at J-PARC, aiming Lorentz violation using muon decay, will be introduced. Motivations will also be discussed based on opening the window to quantum gravitational theories."

Speaker: Jiro Murata (Rikkyo University)

FPUA2024-murata4share.pdf

12:30 → 14:30 Poster: Lunch Break

12:30 Development of the Mx magnetometer toward the search for dark matter (#1)

"Dark matter is one of the mystery of modern particle physics and cosmology. We have studied the method to search for dark matter using ultracold atoms. Recently, we developed the Mx magnetometer to estimate the magnetic field around the trap region. In this poster, we report our current status and experimental results."

Speaker: Takatoshi Aoki (The University of Tokyo)

12:40 Search for parity and time reversal symmetry violation using neutron absorption reaction by nuclei (#2)

"The fundamental parity violation caused by the hadronic weak interaction is enhanced by up to 10^6 times in neutron absorption reactions of 139La, 131Xe, 117Sn, and other nuclei. This enhancement can be explained by the mixing between s-wave and p-wave amplitudes of the compound nuclear state (s-p mixing model). Similarly, T-violation can also be enhanced in these systems through the same mechanism, suggesting the possibility of conducting a sensitive search for T-violation using compound nucleus reactions. The NOPTREX collaboration is planning an experiment to explore unknown T-violation by measuring the T-odd cross-section between a polarized neutron beam and a polarized target. Recently, fundamental studies for the T-violation search experiment have been conducted, including the measurement of the angular correlation of (n,gamma) reactions, enhanced P-violation, and the spin-dependent cross-section between polarized neutrons and a polarized target. In our presentation, we will provide an overview of these experiments and present several new results."

Speaker: Takuya Okudaira (Nagoya University, J-PARC)

FPUA2024.pdf

12:50 Dark Matter Search with Coherent Atoms (#3)

"Axion and Dark Photon (DP) have been considered as well-motivated dark matter candidates. Axion was originally introduced as the solution to the Strong CP problem, while DP is a massive vector particle predicted by any extension of the Standard Model. Both particles should experience coupling or mixing with normal photons, this characteristic renders them viable for direct dark matter detection.
Here a new experimental approach is proposed to search both particles. This approach uses collective and coherent Cs atoms as a target, Axion/DP inducing resonant atomic transition along with signal photon emission to be detected. The key feature of this method is the “coherent amplification mechanism” . That is, when the process occurs coherently in an N-atom system, its transition amplitude interferes constructively, and the rate becomes proportional to N2 instead of N.
In this regard, we focus on the coherence measurement experiment by investigating the cesium 8p-6p electric-dipole forbidden transition. We first determined the spontaneous emission rate of the forbidden transition, then generate coherence between the 8p and 6p states of cesium., the forbidden transition is expected to be amplified by the established coherence, and the amplification factor of the forbidden transition serves as a quantitative indicator of the achieved level of coherence.
In this talk, we explain the Cs coherence measurement experiment along with the dark matter detection principle."

Speaker: Jing Wang (Okayama University)

FPUA Poster.pdf

13:00 Enhancement of the parity-violating energy in chiral molecules (#4)

"The parity-violating energy difference (PVED) between the enantiomers of a chiral molecule is caused by the Z boson exchange between electrons and nucleons. PVED is proportional to the difference in electron chirality density between the enantiomers at the nuclear positions. PVED has not yet been observed experimentally.

The integral value of the electron chirality density generally has a non-zero value in chiral molecules (Electron Chirality in Chiral Molecules; ECCM). A theory focusing on ECCM has been proposed for the origin of homochirality, which is an excess of enantiomers in nature.

We found by relativistic quantum chemical calculations that the PVED and ECCM can be significantly enhanced in some electronic excited states for chiral molecules, H2X2 (X=O, S, Se, Te), CHFClBr, CHFClI, and CHFBrI. This may provide new hints for observing undiscovered PVED in experiments. The behavior of ECCM was significantly different from that of PVED. Contributions from each molecular orbital to PVED and ECCM cancel each other out and become very small in the ground state. Focusing on this cancellation mechanism, we explained that PVED and ECCM are enhanced due to the cancellation breaking by electron excitation (Cancellation Breaking Enhancement; CBE)."

Speaker: Naoya Kuroda (Kyoto University)

13:10 Analytical Study of Birefringence Effects in an Optical Cavity for Axion-Like Particle Search (#5)

"If cold dark matter is light pseudo scalar particles, herein referred to as Axion-Like Particles (ALPs), it rotates the polarization of linearly polarized light. Several experimental schemes using an optical cavity have been proposed to detect this effect. Birefringence at the mirrors, however, would degrade the sensitivity. We have studied the effect of the birefringence on the sensitivity analytically. The birefringent mirrors are treated as mirrors covered by wave plates. We have found that degradation of the sensitivity exists in the region where the axion mass is smaller than the inverse of the averaged round-trip time of the cavity when the phase retardations of the wave plates are larger than the inverse of the finesse. On the contrary, the sensitivity with birefringence is higher than that without birefringence in a special mass region where both carrier light and signal light are resonant simultaneously."

Speaker: Tadashi Kuramoto (Okayama University)

13:20 Pulsed laser spectroscopy of Muonium 1S-2S transition in J-PARC (#6)

"Our purpose is precision measurement of the 1S-2S energy interval in Muonium, which is an exotic hydrogen-like atom consists of a positive muon and an electron. This purely leptonic system enables a precise calculation of the energy interval with the Standard Model without any concerns of the uncertainty from the charge radius of the nucleus, unlike the hydrogen atom. This advantage motivates us to measure the precise 1S-2S energy interval in Muonium with technology of laser spectroscopy and to determine the muon mass with the highest accuracy of 10 ppb. The improvement of muon mass accuracy has an impact on verification of the Standard Model, muon g-2/EDM experiment, for example.

We will report a recent result of Muonium 1S-2S energy interval measurement at J-PARC. The event rate of 1S→2S in our experiment is 50 times higher than the previous experiment[1]. This improvement gives promising prospect for higher accuracy of 1S-2S energy interval and the muon mass accuracy in the future.

1,Meyer, V. et al. Measurement of the 1s-2s energy interval in muonium. Phys. Rev. Lett. 84, 1136
(2000)."

Speaker: Shinsuke Yamamoto (Okayama University)

FPUA2024_poster_yama_ver3.pdf

13:30 K+ ID detector and Time Projection Chamber to study K+N interaction at DAΦNE (#7)

"Chiral symmetry is thought to be partially restored in the finite density such as nucleus thus, quark condensation should be decreased. To investigate wether the chiral symmetry is surly restored and how much of the chiral symmetry will be restored, embedding hadrons in the nucleus is effective methods. As systematic studies of deeply bound pionic atoms and the low-energy π−-nucleus elastic scattering experiment have conducted. The result revealed that the chiral symmetry was about 30% restored in both bounded and scattered state. However it is not trivial that how dose the effect on the restoration of chiral symmetry appears in other nucleus-hadron systems. Therefor, from the systematic aspects, it is necessary to investigate the effect of restoration of the chiral symmetry breaking in other nucleus-hadron systems.
We are going to conduct elastic scattering experiment by using K+ mesons. Considering elastic scattering of K+ and nucleus, because the mean free path of the K+ is comparatively long in the nuclear medium, it is possible to expect that K+ will scatter with each nucleons. Therefor it is expected that the linear-density approximation; σ (K + A ) ≃ A σ (K + N ) will be hold. However, the scattering cross section ratio for one nucleon as target as Carbon 12C and deuteron d is know to be
{σ(12C)/12}/{σ(K+d)/2} >1
from experiment. Thus, the linear-density approximation is broken and it can be said the K+N interaction in nuclear medium is larger than that in the vacuum. Although the interpretation of this phenomenon is still uncertain. One of the reason for this is the lack of experimental data in the low-energy region. We would like to show that such nontrivial behavior of the scattering cross section ration can be explained in terms of partial restoration of chiral symmetry."

Speaker: Kairo Toho (ELPH, Tohoku Universtiy)

13:40 Characterization of Thorium-229 doped crystals using synchrotron radiation X-rays toward an understanding the Thorium-229 isomer in solids (#8)

"Nuclear clocks based on the ultra-low isomeric state of thorium-229 are expected as the next-generation clocks. Solid-state nuclear clocks in which thorium-229 nuclei are doped in crystals excite a large number of nuclei simultaneously. Toward the development of solid-state nuclear clocks, direct excitation experiments to the isomeric state using thorium-229 doped crystals are currently being performed at many institutions. Studying crystal properties is crucial to understanding the transition properties of the Thorium-229 isomeric state under solid-state environments. Okayama group, in collaboration with TU Wien, is working on characterizing Thorium-229 doped crystals. In this presentation, we will introduce the current status of characterization experiments of Thorium-229 doped crystals using synchrotron radiation X-rays."

Speaker: Sayuri Takatori (Okayama University)

13:50 The development of Delay Cable-Free signal readout circuit (#9)

"ADC is commonly used in the nuclear and elementary particle fields as a method of measuring electric charge.
The conventional method for obtaining charge information is to digitize the analog signal from the detector by integrating the electric charge.
Therefore, existing data acquisition systems needs trigger system, which causes a dead time, as well as a delay of the analog signal by coaxial cable.
Therefore, we aim to obtain wave height information using a waveform digitizer. In this method, it is difficult to obtain wave height information from a large number of detectors using high frequencies and with large number of bits due to data volume and cost.
Therefore, it is difficult to obtain high energy resolution. However, it has been found that the use of a filter circuit inside the circuit can prevent deterioration of resolution.
In this presentation, we report on the performance of an evaluation board that combines a filter circuit and a flash ADC (FADC), which is a waveform digitizer type ADC, aiming at an QDC that does not require a delay cable."

Speaker: Ginga Kojima (ELPH, Tohoku University)

14:00 Observation of the VUV signal from the 229Th isomer in a Th doped CaF2 crystal toward realizing the nuclear clock (#10)

"The first excited state of the Th-229 nucleus has an exceptionally low energy of 8 eV, with laser excitability, and is an isomer state with a lifetime of about 10^3 seconds. As such, it is expected to be the only level that can be applied to nuclear clocks. Nuclear clocks are considered to achieve higher accuracy than atomic clocks and are expected to be used to explore physics beyond the Standard Model. This poster presents our work on deexcitation light observations of Th-229 isomers using high-brilliance synchrotron radiation X-rays."

Speaker: Ryoichiro Ogake (Okayama University)

14:10 Development of second Yb+ ion trap for frequency comparison (#11)

"To evaluate frequency shifts including isotope shifts, we are developing a second ion trap system for ytterbium ions with three dimensional cooling. We will present a current status of the development."

Speaker: Kazuhiko Sugiyama (Kyoto University)

(24_03)FPUA2024_posterA0.pdf

14:20 Development of Vacuum Ultraviolet Laser Towards Th-229 Nuclear Clock (#12)

"The Th-229 nucleus possesses the exceptionally low-energy first excited state (isomeric state) of approximately 8 eV, making it the only nucleus capable of being excited by lasers, and thus, it is expected to serve as a candidate for a nuclear clock. Last year, vacuum ultraviolet light with a wavelength of about 150 nm by the de-excitation from the isomeric state was observed for the first time, sparking research worldwide into laser excitation of the nucleus. Currently, our group is advancing research on the development of a vacuum ultraviolet laser for the direct excitation of the isomeric state, and in this presentation, we will discuss an overview of the laser development and its progress."

Speaker: Kotaro Shimizu (Okayama University)

FPUA2024poster_KotaroSHIMIZU_3.pdf

14:30 → 15:50 Oral: Session 3

Convener: Kazuhiko Sugiyama (Kyoto University)

14:30 Nuclear and particle physics with cold ytterbium and Rydberg atoms

"Precision spectroscopy of atoms has reached as high accuracy as 18 digit precision. This remarkable accuracy has opened avenues for investigating nuclear and particle physics, which were conventionally explored with high energy accelerators. Such high precision measurements are sensitive to subtle effects of high energy phenomena that may manifest in the low energy system. Alternatively, atoms can serve as a sensor with high sensitivity beyond existing detectors.
In this talk, I will describe two examples of such applications of atomic physics to nuclear and particle physics. First, I discuss our recent experimental work on the precision spectroscopy of the new clock transition at 431 nm in Yb. We completed the table of isotope shifts for stable isotopes and performed various analyses based on it, including the assessment of nuclear charge radii and a search for new bosons mediating the force between an electron and a neutron. In the second half, I will describe my recent theoretical proposal to improve the position resolution of a charged particle tracker by two orders of magnitude using an array of Rydberg atoms."

Speaker: Akio Kawasaki (NMIJ/AIST)

20240314FPUA2024_share.pdf

15:00 Production-decay dynamics of Th-229 nuclear clock isomeric state in crystal

"Thorium-229 has the lowest nuclear excited level (229mTh), around 8 eV, which provides many applications from practical usage to fundamental research. In 2019, our group succeeded in producing 229mTh states via X-ray pumping and in 2023, we observed the vacuum-ultraviolet (VUV) photons stemmed from the radiative decay of 229mTh. The lifetime of 229mTh is measured, by counting the VUV photons, to be around 10^3 seconds after pumping. On the other hand, the lifetime of 229mTh seems quite reduced during the X-ray irradiation. Therefore, the accelerated decay channels of 229mTh during X-ray irradiation exist; isomer quenching."

Speaker: Ming Guan (Okayama University)

Th FPUA guan 20240319.pdf

15:25 Progress of a Neutron Electric Dipole Search by the TUCAN Collaboration

"To explain the asymmetry between matter and antimatter in the universe, a new source of CP violation is necessary. The presence of a non-zero permanent electric dipole moment (EDM) in a fundamental particle, such as a neutron, breaks the time-reversal symmetry and implies CP violation if we assume CPT conservation.

A neutron EDM measurement is performed using ultra-cold neutrons (UCNs), that have a kinetic energy of less than 300 neV. The UCNs are confined in a material container placed in an electromagnetic field, and the neutron EDM (nEDM) is measured by precisely observing the spin precession caused by the interaction with the electromagnetic field. Since the current experimental sensitivity is limited by statistical precision, a high-intensity UCN source development is essential.

The TRIUMF Ultra-Cold Advanced Neutron (TUCAN) collaboration aims to construct a high-intensity UCN source to perform an nEDM measurement at 10-27 ecm. High-intensity UCN production is possible by using an accelerator neutron source with spallation reactions and a super-thermal method with superfluid helium. The TUCAN collaboration has successfully demonstrated UCN production using a prototype UCN source developed in Japan. Currently, efforts are underway to upgrade the UCN source to establish a world-leading UCN facility.

The nEDM measurement requires a highly uniform and stable magnetic field environment. A magnetic shielding room is under construction at TRIUMF. Other equipment necessary for nEDM experiments is also under development.

In this presentation, the progress made in the TUCAN collaboration and capabilities of nEDM search are discussed."

Speaker: Shinsuke Kawasaki (KEK)

nEDM_kawasaki_FPUA2024.pdf

15:50 → 16:10 Coffee

16:10 → 17:45 Oral: Session 4

Convener: Hirohiko Shimizu (Nagoya University)

16:10 Light Dark Matter Search with Nitrogen-Vacancy Centers in Diamonds

"We propose new ideas to directly search for light dark matter, such as the axion or the dark photon, by using magnetometry with nitrogen-vacancy centers in diamonds. If the dark matter couples to the electron spin, it affects the evolution of the Bloch vectors consisting of the spin triplet states, which may be detected through several magnetometry techniques. We give several concrete examples with the use of dc and ac magnetometry and estimate the sensitivity on dark matter couplings."

Speaker: Kazunori Nakayama (Tohoku University / QUP)

Nakayama_FPUA2024.pdf

16:40 Directional Detection of Cosmic Ray Boosted Dark Matter

"Dark matter with MeV scale mass is difficult to detect with standard direct search detectors. However, they can be searched for by considering the up-scattering of kinetic energies by cosmic rays. Because the dark matter density is higher in the central region of the Galaxy, the up-scattered dark matter will arrive at Earth from the direction of the Galactic center. Once the dark matter is detected, we can expect to recognize this feature by directional direct detection experiments. In this study, we simulate the nuclear recoils of the up-scattered dark matter and quantitatively reveal that a large amount of this type of dark matter is arriving from the direction of the Galactic center."

Speaker: Keiko Nagao (Okayama University of Science)

nagao_20240314FPUA.pdf

17:05 Quantum entanglement of ions for light dark matter detection

"We explore a detection scheme for light dark matter, such as axion dark matter or dark photon dark matter, using a Paul ion trap system. It turns out that the sensitivities of the Paul ion trap system to axion-photon coupling and gauge kinetic mixing can reach previously unexplored parameter space. Furthermore, we illustrate that an entangled qubit system involving N ions can enhance the dark matter signal by a factor of N^2 rather than N.
The talk is based on arXiv: 2311.11632 [hep-ph]."

Speaker: Asuka Ito (QUP/KEK)

Asuka Ito.pdf

17:25 Research and development towards an axion search experiment using quantum sensing of magnons

"We plan to search for axion dark matter through their interactions with electron spins. Axion wind from the dark matter halo in our galaxy creates an effective magnetic field that induces quanta of collective electron spin wave excitations called magnons in ferromagnetic crystals like Yttrium Iron Garnet (YIG). We plan to observe these axion-induced magnons using a hybrid magnon - photon - superconducting qubit system to perform search for axions and axion-like particles at ultra-cryogenic temperature. As a part of our R&D, we are currently building a hybrid magnon - photon system with improved YIG volume to increase the axion induced magnon signal. At ultracryogenic temperature, axion search is ultimately limited by the Standard Quantum Limit (SQL) arising due to the Heisenberg's uncertainty principle. To overcome this limit, we plan to perform magnon - counting using superconducting qubit in contrast to the conventional microwave cavity based magnon readout. Thus, with improved detector volume and the use of superconducting qubit based quantum sensing techniques, we hope to reach unprecedented sensitivity in magnon-based axion search."

Speaker: Yaman Singh Shrestha (The University of Tokyo)

Yaman_FPUA2024.pdf

18:30 → 20:30 Evening session

Free Discussion

Friday, 15 March

09:00 → 10:00 Oral: Sesseion 5

Convener: Noboru Sasao (Okayama University)

09:00 Study of Gravitational Wave by LIGO : past, present and future

"Sincere the prediction of the gravitation wave (GW) by Einstein 100 years go, scientists all over the world have been looking for the GW signal.
The first GW signal was detected by US-based LIGO GW detectors using laser interferometry on September 14, 2015. The source of the signal was a merger of two black holes at 1.3 billion light year away.
Another epoch making observation was done on August 17, 2017, by LIGO and European GW detector Virgo. The source of the signal was a merger of two neutron stars. Using the location information by the GW signal, world wide telescopes collaborated to study the event, using wide range of spectrums over many months of observation period. This was the start of the multi messenger astronomy.
After the first qualitative phase of detecting GW signals, now is a second phase to study signals more qualitatively. Over the coming decade, the sensitivity will be dramatically improved. Challenging projects to go further have started, trying to reach to the end of the universe."

Speaker: Hiroaki Yamamoto (California Institute of Technology)

LIGO-G2400461

10:00 → 10:25 Coffee

10:25 → 11:30 Oral: Session 6

Convener: Yasuhiro Sakemi (CNS, the university of Tokyo)

10:25 Fundamental Physics Using (Anti)hydrogen Atoms: ALPHA at CERN and HAICU at TRIUMF

"Precision comparisons between antihydrogen and its well-studied counterpart, hydrogen, enable tests of fundamental symmetries and principles, such as CPT invariance and Einstein's Equivalence Principle. Over the past 25 years, experiments at CERN's antiproton facility have achieved significant progress. In this talk, I will discuss recent developments by the ALPHA experiment at CERN. Additionally, I will introduce our new project, HAICU (俳句), at TRIUMF, which aims to develop anti-atomic fountains and anti-atom interferometers, using hydrogen as a proxy for its antimatter counterpart."

Speaker: Makoto Fujiwara (TRIUMF)

FPUA2024_Fujiwara.pdf

11:05 Magnetic field studies using electron plasmas for gravitational experiments with antihydrogen

"The hydrogen atom has been studied extensively throughout history and provides the most precisely measured systems in physics. Antihydrogen has a significantly shorter history of study but no less potential for precision physics measurements. Comparisons between hydrogen and antihydrogen then offer the possibility to test fundamental symmetries such as charge, parity, time (CPT) invariance at high precision.

The antihydrogen laser physics apparatus (ALPHA) at CERN produces and traps antihydrogen atoms in a magnetic minimum for study and testing of fundamental symmetries. The latest venture for the ALPHA collaboration has been a new experiment, ALPHAg, aiming to observe the motion of antimatter in Earth’s gravitational field for the first time. As CPT makes no assertion about the motion of antimatter in Earth’s gravitational field this is a test of the equivalence principle.

Antihydrogen atoms are confined in a vertical magnetic minimum trap, the trapping potential is then different between the top and bottom of the trap by -mgΔh, where m is the antihydrogen mass, g is the gravitational acceleration and h is the height. When the vertical confining field is then removed during a slow magnetic release, antihydrogen escape in a direction favouring the gravitational acceleration. The difference in trapping potential is equivalent to a magnetic field difference of approximately 4× 10^(-4) T. The magnetic field is changed from 1.7 T to 1 T over 20 seconds during the release, it is therefore necessary to control and measure the magnetic fields at the ends of the magnetic trap to a higher precision than the gravitational potential difference.

I will discuss the systematic studies of these magnetic fields using electron plasmas [1] in ALPHAg that enabled the first determination of the gravitational acceleration of antihydrogen, a_g ̅ = (0,75 ± 0,13 (stat. + syst.) ± 0,16 (simulation))g where g = 9.81 m/s2 [2].

[1] Electron cyclotron resonance (ECR) magnetometry with a plasma reservoir, E. D. Hunter ; A. Christensen ; J. Fajans ; T. Friesen ; E. Kur ; J. S. Wurtele Phys. Plasmas 27, 032106 (2020)

[2] Observation of the effect of gravity on the motion of antimatter, The ALPHA collaboration, Nature volume 621, pages716–722 (2023)"

Speaker: Adam Powell (University of Calgary)

Powell_FPUA2024.pdf

11:30 → 13:00 Lab Tour: Lunch Break

11:30 2 or 3 parties of tours

13:00 → 14:20 Oral: Session 7

Convener: Koichiro Shimomura (KEK IMSS)

13:00 Fundamental physics using exotic atoms at J-PARC

"The HEATES collaboration has been studying exotic atoms using an innovative X-ray detector known as “an array of superconducting Transition-Edge Sensor (TES) microcalorimeter” which has both excellent energy resolution and collection efficiency. Three experimental results on the kaonic and muonic atom studies have been published over the past few years [1-3], and a new challenging experiment on muonic molecules was conducted recently. Here we present these recent progresses.

Exotic atoms are atomic systems in which negatively-charged particles other than the usual electrons orbit the nucleus. We especially focused on negatively-charged muons (μ-) and kaons (K-), which have the longest lifetimes among the second-generation particles and composite particles in the Standard Model of particle physics. The atomic systems bound by these particles are used to perform precision spectroscopies on the following four types of X-rays:
(a) X-rays from kaonic atoms [1]
(b) X-rays from muonic atoms [2]
(c) Characteristic X-rays from electrons bound to muonic atoms [3]
(d) X-rays from muonic “molecules”
In these experiments, we have studied fundamental physics as follows: (a) the strong interaction between a kaon and a nucleus working at short distances [1], (b) testing quantum electrodynamics (QED) under an ultra-strong electric field environment between a muon and a nucleus [2,4], (c) the femtosecond dynamics of negative muon and bound electrons in the muonic atom formation process [3], and (d) the complex quantum mechanical dynamics process of muon-catalyzed fusion (μCF) process [5].

All these experiments make the most of the advantages of the TES detector, which can cover a wide energy range with both high energy resolution and detection efficiency. Very recently (February 2024), new TES detectors capable of measuring high-energy X-rays above 40 keV and 100 keV have been introduced to the J-PARC muon facility, which will cover a region that cannot be covered by a crystal spectrometer and is expected to be a successor to the experiment (b) for more precise QED verification. In this talk, we would like to review these four studies and discuss future developments.

[1] T. Hashimoto et al., Phys. Rev. Lett. 128, 112503 (2022).
[2] T. Okumura et al., Phys. Rev. Lett. 130, 173001 (2023).
[3] T. Okumura et al., Phys. Rev. Lett. 127, 053001 (2021).
[4] N. Paul et al., Phys. Rev. Lett., 126, 173001 (2021).
[5] T. Yamashita et al., Scientific Reports 12, 6393 (2022)."

Speaker: Shinji Okada (Chubu University)

Okada_FPUA2024.pdf

13:30 Muon Penning Trap Experiment at J-PARC

"Muon precision measurements are one of the powerful probes in the search for new physics beyond the Standard Model of particle physics. As an example, muon anomalous magnetic moment (g-2) measurements show a discrepancy between the Standard Model prediction and experimental values, which is considered to be a sign of new physics. In standard muon precision measurements, muons were either accelerated or in muonium state. We propose a new method to precisely measure slow free muons by trapping them in an electromagnetic field, applying the Penning trap technique. This is the first time in the world that a penning trap has been used to trap particles as short-lived as muons (2.2 micro s), and will be realized using the high-intensity pulsed muon beam at J-PARC H-Line. The final goal is to measure the muon mass and magnetic moment with a precision of 1 ppb and the muon lifetime with a precision of 1 ppm.
Ultra-slow muons producing target in a 3 T superconducting magnet. The ultra-slow muons are transported to the trap region by the electric field. During the transport, an RF magnetic field is irradiated to rotate the spin direction by Pi/2 to be perpendicular to the magnetic field, and the Larmor precession is observed. The muon spins and positions are precisely controlled by the electromagnetic field, and their oscillation frequencies are measured with upper and lower detectors through decaying electrons or positrons. Currently, we are developing electrodes, which are important in the trap, and detectors to measure the fast spin rotation. We will report on the status of these developments."

Speaker: Shoichiro Nishimura (KEK IMSS)

20240315_FPUA2024_Nishimura.pdf

13:55 Mu-antiMu conversion search in J-PARC

"The conversion from muonium (Mu, μ+e-) to anti-muonium (antiMu, μ-e+) is strongly suppressed in the Standard Model (SM) of particle physics because it violates the conservation of the leptonic family number. In many theories of SM extension, leptonic family numbers (lepton flavors) are not conserved and then the Mu-antiMu conversion can become observable level, just below the current experimental upper limit of 8.3×10^{-11}. Though the search for the Mu-antiMu conversion is strongly motivated in this way, a new experimental method is required to go beyond the current limit which is determined by beam-related background.

We propose to search for the Mu-antiMu conversion with a new method; Mu is produced by injecting muon into a muonium production target such as silica aerogel. Converted antiMu is ionized by laser and μ- is transported by electric and magnetic components. Because there is no source of μ- in such an experimental setup, background-free search can be conducted. This method needs an intense pulsed muon beam and a laser system, both of which could be available in MLF J-PARC.
We will present the details of this new Mu-antiMu search concept and the result of the feasibility study performed in D line, MLF to confirm the background level is low enough."

Speaker: Naritoshi Kawamura (KEK/J-PARC)

FPUA2024 20240314 Kawamura.pdf

14:20 → 14:45 Coffee

14:45 → 16:00 Oral: Session 8

Convener: Minoru Tanaka (Osaka University)

14:45 Space time evolution of the lepton number densities including the momentum distribution

"We investigate the Space time evolution of the lepton number densities.
The formulation is constructed as the time evolution of a lepton family number density operator.
The expectation value of the density operator is evaluated for the initial state with a Gaussian distribution for the momentum amplitude.
This enables us to study wave-packet-like decoherence effects.
We show in the non-relativistic regime, the type of neutrino mass (Dirac or Majorana) are distinguishable even under the presence of wave-packet-like decoherence effects."

Speaker: Takuya Morozumi (Hiroshima University)

FPUA2024TMorozumi0317.pdf

15:10 Coherence amplification using atoms (ions) for fundamental physics

"Coherent phenomena have potential applications in fundamental physics. We have proposed neutrino mass spectroscopy using atomic targets, by utilizing the “coherence-amplification” of the weak neutrino-emission process. I will mainly report on recent activity on coherence-related proposals and experiments using the doped ion in crystals [1,2], and some related topics.

[1] H. Hara, J. Han et al. “Periodic superradiance in an Er:YSO crystal”, Phys. Rev. Res. 6, 013005 (2024).
[2] H. Hara, A. Yoshimi, M. Yoshimura, “Parity violating magnetization at neutrino pair emission using trivalent lanthanoid ions”, Phys. Rev. D 104, 115006 (2021)."

Speaker: Akihiro Yoshimi (Okayama University)

AYoshimi_FPUA2024_span.pdf

15:35 Disentangle neutrino electromagnetic properties with atomic radiative pair emission

"We elaborate the possibility of using the atomic radiative emission of neutrino pair (RENP) to probe the neutrino electromagnetic properties, including magnetic and electric dipole moments, charge radius, and anapole. With the typical O(eV) momentum transfer, the atomic RENP is sensitive to not just the tiny neutrino masses but also very light mediators to which the massless photon belongs. The neutrino EM properties introduce extra contribution besides the SM one induced by the heavy W/Z gauge bosons. Since the associated photon spectrum is divided into several sections whose boundaries are determined by the final-state neutrino masses, it is possible to identify the individual neutrino EM form factor elements. Most importantly, scanning the photon spectrum inside the particular section with deviation from the SM prediction once observed allows identification of the neutrino EM form factor type. The RENP provides an ultimate way of disentangling the neutrino EM properties to go beyond the current experimental searches or observations."

Speaker: Shao-Feng Ge (TDLI/SJTU)

240315_FPUA.pdf

16:00 → 16:10 Summary