理化学研究所・仁科加速器科学研究センターが擁する重イオン加速器施設「RI ビームファクトリー（RIBF）」は2007年の稼働以来、世界最高の性能を誇り、 陽子、中性子で構成された原子核を研究する分野、「低エネルギー原子核物理 学」において、多くの新しい成果を生み出している、国際研究拠点・国際頭脳 循環拠点です。 本セミナーでは、低エネルギー原子核物理学分野のテーマ、RIBF施設、これま で得られた優れた研究成果を紹介し、RIBFの将来計画を議論します。

The Nuclear Incompressibility parameter is one of three important components characterizing the nuclear equation of state (EOS). It has crucial bearing on diverse nuclear and astrophysical phenomena, including radii of neutron stars, strength of supernova collapse, emission of neutrinos in supernova explosions, and collective flow in medium- and high-energy nuclear collisions. In this talk I will review current status of the research on direct experimental determination of nuclear incompressibility via the compressional-mode giant resonances. In particular, measurements on a series of Tin and Cadmium isotopes have provided an "experimental" value for the asymmetry term of nuclear incompressibility, which can provide constraints on the EOS of neutron stars.

Realistic nuclear reaction cross-section models are an essential ingredient of reliable heavy-ion transport codes. Such codes are used for risk evaluation of manned space exploration missions as well as for ion-beam therapy dose calculations and treatment planning [1]. Within the community of basic research in nuclear reactions, reaction cross section data compared to theoretical calculations, mostly performed within the Glauber model [2] with folded potentials (f.p.) [3,4], have been used for many years [5,6]. Also since the beginning of physics with RIBs the method has been applied to deduce density distributions of exotic nuclei as well as their root mean square radii (rms) [7,14]. Glauber formalism is also applied to study knockout reactions and deduce spectroscopic factors [15]. The accuracy of the n-target and core-target S-matrices, obtained from phase shifts calculated within the Optical Limit (OL) are key ingredients of the model [16]. In order to improve the calculations of nucleus-nucleus folded potentials, usually called double folded potentials (d.f) Satchler and Love [3] proposed to calculate single folded (s.f) potentials using projectile densities together with phenomenological nucleon-target (n-T) potentials. In this talk we will show that for 9Be and 12C very good agreement with experimental data can be found using (n-T) phenomenological potentials which we have obtained tting the (n-T) cross section in a very large energy range and also the nucleus-target (N-T) cross sections at high energy. We will discuss the dierence with d.f. method and results. The advantage of s.f. potentials is to avoid the dependence on the target density choice as well as the choice of the parameters to describe the free n-n-amplitude.
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[8] Isao Tanihata, Herve Savajols, Rituparna Kanungo, Prog. Part. Nucl. Phys. 68 (2013) 215, and references therein.
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[10] M. Tanaka et al. Phys. Rev. Lett. 124, 102501 (2020).
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[15] T. Aumann et al., Prog. Part. Nucl. Phys. 103847 (2021).
[16] A. Bonaccorso, Prog. Part. Nucl. Phys. 101 (2018) 154.

（このセミナーは、日本物理学会大阪支部の支部講演会の一環として開催します。）
問い合わせ先　：　福田　光順　（理学研究科物理学専攻）

It has been know that Quantum Mechanics allows a strong and bizarre correlation among particles, called entanglement, that is not possible in any alternative theories that are local and real. In those local-real theories, correlations among particles must satisfy Bell inequalities, while Quantum Mechanics can violate them. The entanglement and Bell inequalities are therefore thought of the key to understand Quantum Mechanics in a deeper level and play an important role in quantum information and computation theories. Violation of Bell inequalities has been observed in low energy experiments but it has not been tested at high-energy collider experiments with energy higher or around the weak scale. In this talk I will propose a collider measurement of various quantum properties in H->tau,tau at future lepton colliders and discuss its possible application to the CP measurements.

Nambu-Goldstone (NG) modes for 0-form and higher-form symmetries can become unstable in the presence of background fields. Examples include the instability of a photon with a time-dependent axion background or with a chirality imbalance, known as the chiral plasma instability, and the instability of a dynamical axion with a background electric field. We show that all these phenomena can be universally described by a symmetry algebra for 0-form and higher-form symmetries. We prove a counting rule for the number of unstable NG modes in terms of correlation functions of broken symmetry generators. Based on our unified description, we further give a simple new example where one of the NG modes associated with the spontaneous 0-form symmetry breaking U(1)×U(1)→{1} becomes unstable.

Neutrinos are the least constrained and are expected to shed new light on the state of dark matter detection. In particular, neutrino line spectra from MeV dark matter in our Galaxy are an important signal because they are detected in the inverse decay channel with little smearing effect. In this talk, I will discuss the possibility that JUNO, a future neutrino detector, will be able to detect neutrino lines from the annihilation and decay of MeV dark matter in a model-independent way. In addition, constraints from future neutrino detectors on a particular dark matter model motivated by a neutrino mass mechanism called the Majoron will be presented.

I review some properties of pure Yang-Mills theories and explain why color flux tubes can be cosmic strings. Their stability is explained by 1-form center symmetries.Their production in the thermal phase transition is explained by the qualitative picture coming from the electric-magnetic duality. Some of their further properties such as intercommutation probability in the large N limit can be understood by the theory of large N counting and holographic duality. Pure Yang-Mills theories are the simplest and natural models for cosmic strings, and may be observed by future gravitational wave experiments.

In this talk, we show that the AdS-Rindler reconstruction is incomplete. CFT operators naively given by the holographic dictionary for the AdS-Rindler reconstruction contain tachyonic modes, which are inconsistent with the spectrum in the CFT side defined on the associated subregion. Therefore, the subregion duality and the entanglement wedge reconstruction do not hold. In addition, we also show that the tachyonic modes are related to null geodesics connecting the past and future horizons.

A recently proposed order parameter, analogous to the Edwards-Anderson order parameter of the spin glass, was shown to detect a symmetry breaking transition between the Higgs and QCD like phases of an SU(2) gauge-Higgs in D=4. A stronger criterion for confinement termed "separation of charge" was proposed to distinguish phases with an unbroken global custodial symmetry. This order parameter has been shown to detect the breaking of this global custodial symmetry between the confinement and Higgs like regions, but has not been tested for additional phases which also maintain unbroken custodial symmetry. In this talk I will cover the SU(2) gauge-Higgs theory in D=5 which contains a massless phase and present the behavior of this order parameter with a massless phase present. I will also present the phase diagram associated with this field theory and discuss how this order parameter may be applied to lattice monte carlo simulations.

Baryon and lepton numbers are accidental symmetries in the standard model, while Peccei-Quinn symmetry is hypothetical symmetry which is introduced to solve the strong CP problem. We study the possible connections between Peccei-Quinn symmetry and baryon/lepton number symmetries. This framework identifies an axion as the Nambu-Goldstone boson of baryon/lepton number violations. As a result, characteristic baryon/lepton number violating processes are predicted. We developed the general method to determine the baryon number and lepton number of new scalar bosons in the axion model.

There is a famous puzzle in QED coupled to N massless Dirac fermions that the scattering of afermion off a monopole creates an out-state which cannot be any of the elementary particles in the theory. We give a new understanding of the s-wave reduced version of the phenomena by interpreting the magnetic defect as a Tambara-Yamagami line defect.

In this talk, we will discuss recent work on constructing an explicit example of dS3/CFT2 correspondence via analytic continuation, then we will use it to obtain the late time correlation functions in the three dimensional de Sitter spacetime from two dimensional CFT. We will also discuss how to reproduce them from the suitable holographic configurations, and future directions.

Recently, Hoshina, Fujii, and Kikukawa [1] pointed out that the naive lattice gauge theory action in Minkowski signature does not result in a unitary theory in the continuum limit, and Kanwar and Wagman [2] proposed alternative lattice actions to the Wilson action without divergences. We here show that the subtlety can be understood from the asymptotic expansion of the modified Bessel function, which has been discussed for path integral of compact variables in nonrelativistic quantum mechanics [3,4]. The essential ingredient for defining the appropriate continuum theory is the iε prescription, which we show is applicable also for the Wilson action. It is here important that the iε should be implemented for both timelike and spacelike plaquettes. We then argue that such iε can be given a physical meaning that they remove singular paths having nontrivial winding for an infinitesimal time evolution that do not have corresponding paths in the continuum. Such point of view is only apparent in systems with compact variables as lattice gauge theories. This talk is based on [5].

[1] H. Hoshina, H. Fujii and Y. Kikukawa, "Schwinger-Keldysh formalism for Lattice Gauge Theories," PoS LATTICE2019, 190 (2020)
[2] G. Kanwar and M. L. Wagman, "Real-time lattice gauge theory actions: Unitarity, convergence, and path integral contour deformations," Phys. Rev. D 104, no.1, 014513 (2021) [arXiv:2103.02602 [hep-lat]]
[3] W. Langguth and A. Inomata, "Remarks on the Hamiltonian path integral in polar coordinates," J. Math. Phys. 20, 499-504 (1979)
[4] M. Bohm and G. Junker, "Path integration over compact and noncompact rotation groups," J. Math. Phys. 28, 1978-1994 (1987)
[5] N. M. "Comment on the subtlety of defining real-time path integral in lattice gauge theories," [arXiv:2206.00865 [hep-lat]]

We study the phase structure of the CP(1) model by using several kinds of the tensor renormalization group. The phase structure of the CP(1) model is investigated by the strong coupling expansion, analytical continuation with the assumption, possibly sign problematic Monte Carlo simulation and the simple TRG. These predictions show the first-order transition at θ = π at the strong coupling region, but there are contradicted in the weak and intermediate coupling region because of the limitation of the systematic error. In this work, we extend the TRG method to the intermediate coupling region by carefully discussing the systematic error in TRG. We apply the recently developed TRG method, such as the anisotropic TRG and bond-weighted TRG, to reduce the systematic errors in the coarse-graining step. In order to show the importance of systematic error estimation, we start from the θ = 0 calculation as a demonstration.The larger bond size is strongly required for a reliable result, depending on the initial tensor size. After the demonstration, we calculate the CP(1) model with the theta term. With the controlled systematic error, the TRG method shows the first order transition at the θ = π up to β < 1.1.

We consider the relative entropy between two theories (or systems) described by heavy and light degrees of freedom. The non-negativity of the relative entropy gives inequalities for the difference between the two EFTs obtained by integrating the heavy degrees of freedom.　Using the inequalities, we consider the entropy constraint on higher-dimensional operators arising from integration over the heavy degrees of freedom.

Muonium is a bound state composed of an antimuon and an electron, which constitutes a hydrogen-like atom.The process of the muonium-to-antimuonium transition is considered to be effective to identify fundamental interactions which relate to the lepton flavor and lepton number violation.New experiments are being planned at J-PARC in Japan and CSNS in China, and it is expected to attract more attention in the near future.We have studied what kind of model can be verified in the next generation of the muonium-to-antimuonium transition search experiments while escaping the constraints by other experiments.Though the transition probability is strongly suppressed by the lepton flavor conservation in the standard model, it can be much larger by the exchanges of neutral and doubly charged bosons, and by box loop diagrams in new physics beyond the standard model. In this talk, I will show the analyses for some neutrino models which can be tested in the forthcoming experiments for the muonium to antimuonium transition.

We study lattice fermions from the viewpoint of spectral graph theory (SGT). We find that a fermion defined on a certain lattice is identified as a spectral graph. SGT helps us investigate the number of zero eigenvalues of lattice Dirac operators even on the non-torus and non-regular lattice, leading to understanding of the number of fermion species (doublers) on lattices with arbitrary topologies. We apply this idea to the known lattice fermion formulations including Naive fermions, Wilson fermions and Domain-wall fermions, and reproduce the known fact on the number of species. We also apply it to the lattice fermion on the discretized four-dimensional hyperball and discuss the number of fermion species on the bulk. In the end of the paper, we discuss the application of the analysis to lattice fermions on generic lattices with arbitrary topologies, leading to conjecturing a new theorem regarding the number of fermion species on the lattice.

To answer the question in the title is rather non-trivial. In a flat spacetime, as a consequence of Noether's 1st theorem, a time translation symmetry not only defines a corresponding energy density as the time component of the Noether current, but also tells that a total energy given by a volume integral of the energy density is conserved. This construction of a conserved energy does not work in general relativity, since a time translational symmetry is a part of local symmetries, general coordinate transformations, to which Noether's first theorem can not be directly applied. Recently we propose a general method to derive a conserved current associated with a global symmetry which is a part of local symmetries. We apply the method to general relativity and obtain the following answer to the question. “No, the matter energy is not conserved in general. However there always exist a more general conserved charge associated with matters.” In my talk, I will explain how this conclusion is derived.

Vortex strings are topological solitons in field theories and appear in various systems, such as superconductor, neutron star, early universe and so on. We clarify the nature of vortex strings in the Abelian-Higgs-like model with a Coleman-Weinberg type Higgs potential, which is inspired by the argument of the naturalness problem in particle physics. This model has the gauge U(1) symmetry and the classical scale invariance. The model has no vortex string solution at the classical level, while quantum corrections spontaneously break the U(1) symmetry and stable vortex strings exist. The interaction between the two vortex strings is found to be very different from that of the Abelian-Higgs model with the conventional second- and fourth-order type potentials. Implications for particle physics and cosmology are also discussed.

In this talk, I want to motivate a possible way to realise time as an emergent concept. I will introduce a general fermionic system and demonstrate how a modular flow can be interpreted as a physical time flow. I will provide support for this interpretation using the thermofield double state together with the relations between various quantum chaos diagnostic quantities. I will explain how these concepts can be linked together and realise an emergence of time. I will end by discussing some limitations of our example.

The CDF collaboration recently announced the most precise measurement of the W-boson mass by using the proton-antiproton collision data at the Fermilab Tevatron. This data provides a significant inconsistency between the measured mass and the Standard Model prediction. In this talk, first, I will summarize the current circumstances of the W-boson mass measurements and the Standard Model prediction. Next, I will present several explanations of this anomaly by the new physics beyond the Standard Model. Finally, a model with the vector-like quark will be introduced, based on our recent work arXiv:2204.05962.

In the last year, the Fermilab experiment has reported their first result on the measurement of the muon anomalous magnetic moment (g-2). The result was consistent with the Brookhaven E821 experiment, and the deviation from the standard model prediction becomes 4.2sigma, which is planned to be revised soon. In this talk, we will overview the status and prospect of the theoretical side of the muon g-2. I will first review the standard model prediction and explain the issues explored today. Then, new physics interpretations will be discussed, especially focusing on the supersymmetric models.

A Narain CFT is a conformal field theory (CFT) that describes a compactified spacetime. On the other hand, an error-correcting code is a concept in information theory for transmitting information correctly in spite of errors. In this talk, I will discuss the relation between Narain CFTs and error-correcting codes on finite fields through lattices. Using this correspondence, we can consider the spectrum and the symmetries of the CFT in the language of the code. In particular, the spectral gap of the CFT and the error correction capability of the code are roughly proportional, which helps to find CFTs with large spectral gaps.

Axion (or axion-like particle) is a prominent candidate of light dark matter (DM). It emerged as the pseudo Nambu-Goldstone boson originated from the breaking of global U(1) symmetry. If the mass scale is keV, axion usually suffers from the severe constraint from the X-ray bounds. However, a fascinating axion, which can evade such a severe constraint, was proposed as an anomaly-free axion. In this talk, I will discuss a three Higgs doublet model (3HDM) as a UV complete model where the anomaly-free axion is embodied. I will show the synergy between the anomaly-free axion and the heavy Higgs bosons predicted in this concrete model.

Symmetry protected topological (SPT) phases are one of the simplest, yet nontrivial, gapped systems that go beyond the Landau paradigm. In this work, we study the notion of SPT for critical systems, namely, symmetry protected topological criticality (SPTC). We discuss a systematic way of constructing a large class of SPTCs using decorated defect construction, study the physical observables that characterize the nontrivial topological signatures of SPTCs, and discuss the stability under symmetric perturbations. Our exploration of SPTC is mainly based on several previous studies of gapless SPT: gapless symmetry protected topological order, symmetry enriched quantum criticality and intrinsically gapless topological phases. We partially reinterpret these previous studies in terms of decorated defect construction, and discuss their generalizations.

We present a class of dS/CFT correspondence between two-dimensional CFTs and three-dimensional de Sitter spaces. We argue that such a CFT includes an SU(2) WZW model in the critical level limit k → −2, which corresponds to the classical gravity limit. We can generalize this dS/CFT by considering the SU(N) WZW model in the critical level limit k →−N, dual to the higher spin gravity on a three-dimensional de Sitter space. We confirm that under this proposed duality the classical partition function in the gravity side can be reproduced from CFT calculations.

I will talk about some phenomenological aspects of the two Higgs doublet model(2HDM). The 2HDM can explain the muon anomalous magnetic moment with a light pseudoscalar. I will discuss the prospect of discovering such particles at the lepton collider like ILC. Then I will discuss how an extension of 2HDM can connect neutrino mass and muon anomalous magnetic moment.

The Nuclear Incompressibility parameter is one of three important components characterizing the nuclear equation of state (EOS). It has crucial bearing on diverse nuclear and astrophysical phenomena, including radii of neutron stars, strength of supernova collapse, emission of neutrinos in supernova explosions, and collective flow in medium- and high-energy nuclear collisions. In this talk I will review current status of the research on direct experimental determination of nuclear incompressibility via the compressional-mode giant resonances. In particular, measurements on a series of Sn and Cd isotopes have provided an "experimental" value for the asymmetry term of the nuclear incompressibility; this term is important for the EOS of neutron stars. We also find that the GMR centroid energies of the in both Sn and Cd isotopes are significantly lower than the theoretical predictions, pointing to the possible role of superfluidity in nuclear incompressibility.
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IPC intensive lecture will be also given online by Prof. Umesh Garg during Feb 1-4.
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問い合わせ先：川畑　貴裕　（理学研究科物理学専攻）