Seminar

2024年度

Title: ミュオン触媒核融合研究の新展開

Abstract: ミュオンは 2.2 μs の自然崩壊寿命をもち、質量が電子の 207 倍である以外は電子 と同じ性質をもつ素粒子である。物質中では電子と入れ替わりミュオン原子を形 成する。核融合材料となる重水素と三重水素中にミュオンを打ち込むと、ミュオン 分子イオン(dtμ)を形成する。電子より 207 倍重いミュオンは強く d と t を引き 寄せ、dtμ 分子内で核融合反応が引き起こす。ミュオンは核融合後自由になり、再 び dtμ を形成し、自身の寿命が尽きるまで核融合反応を次々に引き起こす。これは ミュオンがあたかも核融合反応を触媒しているように見えるため、「ミュオン触媒 核融合(muon catalyzed fusion、以降 μCF と略す。)」と呼ばれている。1990 年代 に盛んに研究されていたが、核融合で得られるエネルギーがミュオンを作るため に必要なエネルギーの半分程度に留まり、2000 年以降、研究はあまり行われなく なった。我々は最新の量子多少数体系理論に基づく精密計算により、新しい μCF の反応サイクル模型を提案し、μCF の諸問題を解決した。この模型により、高温領 域での μCF 効率の増加が見込まれる。さらに、高エネルギー分解能カロリーメー タを用い、この新しい模型を裏付けるミュオン分子共鳴状態からの X 線の検出に 成功した。μCF は学術研究に重点が置かれていたが、熱エネルギー、核融合中性子、低速ミュオンの取り出しについても研究を進めている。

2023年度

Title: 陽子中性子対相関を取り入れた生成座標法による N = Z 奇々核の M1 遷移 の解析

Abstract: 同種核子間の場合と比べ陽子中性子間の対相関の理解には未解明な点が多い。特にアイソスカラー(IS)型対相関と呼ばれる(S=1,T=0)に組んだ対の凝縮については現実の原子核内で起こる可能性自体が議論の対象になっている。そのため、我々はN=Z奇々核のM1遷移におけるIS対の役割に着目することで、IS対凝縮の兆候を引き出すことが可能かを議論する。その目的のために、我々は生成座標法という手法を用いる。生成座標法では集団的なパラメータでラベルされた平均場波動関数の重ね合わせを行うが、我々は生成座標としてIV型とIS型の陽子中性子対振幅を用いる。それによりN=Z奇々核の磁気遷移を効果的に記述可能であることを明らかにするとともに、18Fを例に実験との比較を行う。得られた結果から、換算遷移確率B(M1)はIS対凝縮について敏感でないが、そのSpin成分B(M1)_SpinはIS対間相互作用に大きく依存することが明らかになった。また、集団波動関数の振る舞いから、必ずしも対凝縮が起こる必要はなく、IS対振幅方向の揺らぎの増大がB(M1)_Spinを上昇させることが明らかになった。


Title: The Molybdenum Puzzle

Abstract: The creation of the chemical elements in various astrophysical sites is reviewed by example of the element Molybdenum. Its stable isotopes originate from different nucleosynthesis processes, which are not known equally well. Especially the explanation of the origin of the light Mo isotopes proves difficult. To fully understand the abundance of Mo on Earth and in stars it is necessary to combine many puzzle pieces, comprising astrophysical simulations as well as improvements in nuclear physics treatments. An overview of the nucleosynthesis processes as well as the required knowledge of nuclear reaction physics is given.


Title: Neutron skin of 208Pb from ab initio calculations

Abstract: The neutron skin thickness could be a crucial observable to constrain the neutron star equation of state (EoS). According to the mean-field type studies, the neutron skin of 208Pb is known to be strongly correlated with the slope parameter of the EoS, motivating neutron skin thickness measurements. From this background, an ab initio study can provide a good test of the correlation. Furthermore, it is interesting to see if the ab initio calculations can narrow down and predict the neutron skin. With the recent progress in the nuclear ab initio theory, such as underlying nuclear interaction, uncertainty quantification, and emulator technique, predicting the neutron skin of 208Pb becomes feasible. In this seminar, I will introduce the recent progress and show the prediction for the neutron skin of 208Pb. If time allows, I will briefly introduce some recent results of the medium- and heavy-mass nuclei.


Title: The neutron time-of-flight facility n_TOF at CERN

Abstract: Based on an idea by Carlo Rubbia, the n_TOF facility at CERN has been built and has been operating for over 20 years. It is a neutron spallation source, driven by the 20 GeV/c proton beam from the CERN PS accelerator. Neutrons in a very wide energy range (from GeV, down to sub-eV kinetic energy) are generated by a massive Lead spallation target feeding two experimental areas. EAR1, horizonal with respect to the proton beam direction is set at 185 meters from the spallation target. EAR2, on the vertical line from the spallation source, is placed at 20 m. Neutron energies for experiments are selected by the time-of-flight technique (hence the name n_TOF), while the long flight paths ensure a very good energy resolution. Over one hundred experiments have been performed by the n_TOF Collaboration at CERN, with applications ranging from nuclear astrophysics (synthesis of the heavy elements in stars, big bang nucleosynthesis, nuclear cosmo-chronology), to advanced nuclear technologies (nuclear data for applications, nuclear safety) to basic nuclear science (structure and decay of highly excited compound states).
During the planned shutdown of the CERN accelerator complex between 2019 and 2021, the facility went through a substantial upgrade with a new target-moderator assembly, refurbishing of the neutron beam lines and experimental areas. An additional measuring and irradiation station (the NEAR Station) has been envisaged and its capabilities for performing material test studies and new physics opportunities are presently explored. An overview of the facility and of the activities performed at CERN will be presented, with a particular emphasis on the most relevant experiments for nuclear astrophysics and advanced nuclear technologies.


Title: 核子物質における新奇超流動探索

Abstract: 原子核は核子の多体系ではあるが、いわゆる物質よりもより量子的な振る舞いが強く現れる。一方で対相関は非常に大きな役割を果たしており、フェルミオン対凝縮相としての超流動的性質を持っているとされる。フェルミオン対凝縮相は電子クーパー対による超伝導相に始まり、原子系でも確認されているほか、クオーク系での存在が示唆されるなど質量階層によらず普遍的な物質相であると考えられており、核子物質における対凝縮相の解明は重要な課題である。中性子星では冷却過程やパルサーグリッチの発現機構において超流動相の存在が仮定されているものの、その起源についての微視的な根拠は未確立である。また、原子核を構成する陽子・中性子という二種類のフェルミオンの存在が核子物質においてどのような超流動相を引き起こすかは興味深い課題である。本講演ではPHANESプロジェクトの一環として進めている、核子階層における対凝縮相の解明を目指した近年の超流動探索計画と現状について報告する。

2022年度

Title: 核子多体系における 3核子力の役割 ―殻構造の微視的起源に迫る―

Abstract: 原子核の微視的記述、すなわち核子多体系の諸現象を核力の観点から理解しようという試みは、近年の核力理論の発展と相まって、原子核物理の大きな潮流の一つである。私は、核力のうち3核子力に注目し、これが3核子以上から成る多体系にどのように寄与しているのかに興味を持っている。現時点で、3核子力が引き起こす核子多体系の現象やそのメカニズムは理解が不十分である。例えば、よく知られている原子核の殻構造は、核力がどのように作用してそれが発現するのかが十分には分かっていない。そこで我々は、3核子力が殻構造(より具体的にはスピン・軌道分離)の発達にどのように寄与するのかに着目し、これを理論的に調べた。理論的手法として、カイラル有効場理論によって導出された核力(2核子力および3核子力)と殻模型を採用した。我々は3核子力をテンソル分解することにより、2核子力からは決して生じなかった新奇なメカニズムが3核子力によって誘起され、これがスピン・軌道分離に決定的な役割を果たしていることを明らかにした。講演ではこのことを紹介した後、自身の考える3核子力研究の展望についても述べる。


Title: Shell effects in non-axial-shape excitations

Abstract: With divergence from the magic numbers, nuclei exhibit a spheroidal shape. Searching for a non-axial equilibrium shape has been a long issue. The gamma vibrational mode of excitation is an acknowledged collective mode in deformed nuclei and can be considered a precursory phenomenon breaking axial symmetry. Since the collectivity depends sensitively on the shell structure around the Fermi levels, a detailed study of the gamma vibration can lead to an understanding of the shell structure in deformed nuclei. In this seminar, I take examples of two regions of deformation: rare earth nuclei in a doubly-mid shell between N=82 and 126 and Z=50 and 82, and heavy actinides around Z=100. I discuss a microscopic mechanism for the strongest collectivity measured so far and a perspective of nuclear density-functional theory for the island of stability, respectively.


Title: A unified framework for nuclear single-particle states and collective vibrations

Abstract: In this seminar, I will discuss our recent implementation of a fully self-consistent QuasiParticle-Vibration Coupling (QPVC) model. This is based on a Skyrme functional plus pairing terms, and can be applied to both closed-shell and open-shell spherical nuclei. I will present some applications to the evolution of single-proton states, as a function of neutron excess. I will also discuss Giant Resonances, focusing in particular on new results for the so-called "breathing mode" and the nuclear incompressibility.


Title: ノックアウト反応で探るアルファクラスター構造（PDF）

Abstract: 核子多体系である原子核において、いかにアルファ粒子が形成されるかは原子核物理の長年の興味である。ラザフォードらによるアルファ崩壊の発見とそれが4He原子核であることの同定や、アルファ粒子がクーロンバリアをトンネル効果によって通り抜けるというガモフによるアルファ崩壊の理解は、まさに原子核物理黎明期に成された。また、軽い原子核領域においては池田ダイアグラムが提唱され、アルファ閾値近傍に多彩なアルファクラスター構造が発現することが示唆された。これらはすでに一世紀近く続く原子核物理の主要な研究テーマのひとつである。一方、上述のような原子核や励起状態に限らず、軽い原子核から中重核、重い原子核の基底状態の表面にも普遍的にアルファ粒子が形成されていることが近年明らかになりつつある。このようなアルファ粒子形成を定量的に明らかにする方法として有力なのが、アルファノックアウト反応である。本セミナーでは、近年の成果を中心に、アルファノックアウト反応による定量的なクラスター振幅の理解[1]、中重核であるスズ同位体核表面でのアルファ粒子形成の発見[2-4]、無偏極陽子ビームによるアルファノックアウト反応を用いた偏極残留核の生成[5]、ノックアウト反応を用いたアルファ崩壊核におけるアルファ換算振幅の決定可能性[6]等について紹介し、アルファノックアウト反応の現状と今後を俯瞰する。

References

[1] "Quantitative description of the 20Ne(p,pα)16O as a means of probing the surface α amplitude", K. Yoshida, Y. Chiba, M. Kimura, Y. Taniguchi, Y. Kanada-En'yo, and K. Ogata, Phys. Rev. C. 100, 044601 (2019).

[2] "Neutron skin thickness of heavy nuclei with α-particle correlations and the slope of the nuclear symmetry energy", S. Typel,Phys. Rev. C 89, 064321 (2014).

[3] "Investigating the α clustering on the surface of 120Sn via (p,pα) reaction, and the validity of the factorization approximation",K. Yoshida, K. Minomo, and K. Ogata, Phys. Rev. C 94, 044604 (2016).

[4] "Formation of α clusters in dilute neutron-rich matter", Junki Tanaka, Zaihong Yang, et al., Science 371, 260 (2021).

[5] "Effective polarization in proton-induced α knockout reactions", Tomoatsu Edagawa, Kazuki Yoshida, Yoshiki Chazono, Kazuyuki Ogata, arXiv:2202.00225.

[6] "α knockout reaction as a new probe for α formation in α-decay nuclei", Kazuki Yoshida and Junki Tanaka, Phys. Rev. C 106, 014621 (2022).


Title: New results on decay spectroscopy of 254No with GABRIELA@SHELS

Abstract: The structure of the 254No nucleus has been studied for more than 20 years: the last publications on the decay spectroscopy are from four experiments performed at LBNL [1], GSI [2], JYFL [3] and ANL [4]. Four decay schemes featuring two isomers have been published. These are interpreted as 2 and 4qp states. Unfortunately, while the authors agree on the excitation energy and decay scheme of the 2-qp ∼ 260 ms 8-isomer, they disagree on the configuration assignment for both the 8- and the shorter-lived ∼180 μs 4-qp isomer and differ considerably on the excitation energy and decay scheme of the 4qp isomer. These discrepancies have triggered new experiments worldwide, for example the combined prompt and decay spectroscopy performed using SAGE and GREAT [5]. We report here on an experiment performed with the GABRIELA [6] array, at the focal plane of the SHELS [7] separator at the FLNR, Dubna.
   The 254No nucleus was produced using the cold fusion-evaporation reaction 48Ca(208Pb, 2n)254No. The first part of this talk will present the experimental setup and the analysis techniques used to reveal the electromagnetic decay of the known isomers in 254No. The second part will focus on the new results obtained. Due to the combination of a higher transmission of the separator (as compared to VASSILISSA [8]) and an increased efficiency of the upgraded GABRIELA array [9], more than 1.5 million 254No nuclei were implanted in the focal plane detector enabling the electromagnetic decay of the short and long-lived isomers to be studied in more detail. In particular, the internal conversion electron spectrum observed in decay of the 8- isomer has revealed the presence of a strong transition, possibly E0, suggesting low-lying shape coexistence in this nucleus as predicted in [10]. The gamma spectrum obtained from the decay of the short-lived isomer has revealed new gamma peaks leading to new interpretations about this isomer decay. The spectroscopic information extracted from alpha, gamma and electron correlations will be presented and discussed in terms of the likely underlying single-particle structure.

References
[1] R.M Clark et al., Phys. Lett. B 690, 19 (2010).
[2] F.P. Hessberger et al., Eur. Phys. J. A 43, 55 (2010).
[3] R.-D. Herzberg et al., Nature 442, 896 (2006).
[4] S.K. Tandel et al., Phys. Rev. Lett. 97, 082502 (2006).
[5] A. Ward PhD, University of Liverpool (2016).
[6] K. Hauschild et al., Nucl. Instr. Methods A 560, 388-394 (2006).
[7] A.G. Popeko et al., NIM B 376, 140-143 (2016).
[8] O.N. Malyshev et al., Nucl. Instrum. Methods Phys. Res. A 440, 86 (2000).
[9] R. Chakma et al., Eur. Phys. J. A 56, 245 (2020).
[10] J.-P. Delaroche et al., Nucl. Phys. A 771, 103-168 (2006).

2021年度

title : 冷却原子量子シミュレーションで探る高密度物質の性質

Abstract : 中性子星合体による重力波の観測は、星内部の高密度物質の状態方程式について有用な知見をもたらしたが、その他の物性については、観測的知見が非常に限られるのが現状である。ここでは、冷却原子系を用いた量子シミュレーションにより、核物質やクォーク物質の性質をよりよく知ろうという試みを紹介する。


title : 冷却原子と原子核をつなぐ量子少数多体系の普遍性

Abstract : 相互作用する量子系を理解することは、原子物理や原子核物理から物性物理まで、幅広い物理系において重要な課題である。これらの全く異なる物理系における量子現象は多彩だが、普遍性（ユニバーサリティ）という概念によって、統一的に理解できることがある。熱・統計力学で学ぶ、量子多体系の相転移・臨界現象のユニバーサリティクラスがその典型である。実は、３粒子や４粒子などの少数粒子系においても、原子、原子核、固体電子系などが全く同じ量子少数現象を示すことがある。その代表例であるエフィモフ状態と呼ばれる3 粒子現象をこのセミナーでは解説する。エフィモフ状態は2006年に冷却原子で観測され、冷却原子分野で盛んに研究されている。それと同時に中性子過剰原子核などの原子核現象をエフィモフ状態と解釈する研究も多く行われている。これら両分野における発展を解説したのち、原子と原子核がどの程度同じとみなせるのか、どの程度普遍性（ユニバーサリティ）が成立しているのかを探る研究を紹介する。


title : rプロセス元素の起源と進化：連星中性子星合体の重力波・キロノヴァ観測以後

Abstract : rプロセスは、鉄より重い元素（trans iron）の合成過程の一つであり、特に、金やプラチナ、超寿命アクチノイド元素（ThとU）の主要な起源である。自然界におけるrプロセスは、中性子星が関与する爆発的な天体環境において、中性子捕獲が爆発的に速く進むことで起こる。rプロセスにまつわる様々な謎を解明するには、関連する宇宙物理と原子核物理の精密な理解が必要である。rプロセスが起こりうる天体現象は、超新星爆発や連星中性子星の合体であるが、それらの天体モデルは確立されてない。さらに、rプロセスの元素合成「経路」は、核図表において安定核から遠く離れた中性子過剰側になるが、これらは最新の原子核実験でも未到達の領域である。天体現象と原子核のともに理論の不確定性も大きい。天文学においては、さらに、rプロセス元素は、銀河宇宙の進化史に特徴的な痕跡を刻むため、銀河進化の研究においても重要な対象でもある。
    本講演では、まず、GW170817とキロノヴァ観測について簡単にまとめ、連星中性子星合体でのrプロセス元素合成シナリオが観測と整合的であることを示し、銀河の化学進化において中心的な役割を担うことを紹介する。加えて、それにもかかわらず、銀河の化学進化などに未解明問題が残されていることを指摘する。天体モデル、銀河科学進化に関する研究について、講演者らの研究を中心にいくつか紹介しつつ、天文学におけるrプロセスの理解の進展が原子核物理の研究にどう影響を与えるのかも議論する。

2020年度

title : Nuclear “pasta” structures and symmetry energy

Abstract : In the framework of the relativistic mean field model with Thomas-Fermi approximation, we study the structures of low density nuclear matter in a fully three-dimensional geometry. Typical pasta structures (droplet, rod, slab, tube, and bubble) arranged in various crystalline configurations are obtained for both fixed proton fraction and cold catalyzed matter. By introducing an ω-ρ cross coupling term, we further examine the pasta structures with smaller symmetry energy slope L = 41.34 MeV, which is consistent with various constrains from nuclear physics and pulsar observations.


title : Lambda(1405) as a hadronic molecule

Abstract : Hadronic molecules are the new form of matter induced by the strong interaction. However, identification of the hadronic molecules involves several subtle difficulties such as the model dependence and the interpretation of the resonance wave function. To overcome these difficulties, we use the compositeness to characterize the internal structure of hadrons, and generalize the weak-binding relation for unstable resonances. It is quantitatively shown that the structure of the $\Lambda(1405)$ resonance is dominated by the molecular state of an antikaon and a nucleon.


title : 原子核におけるパイ中間子の役割と私が描く核物理

Abstract : パイ中間子は核子間の相互作用の中長距離を支配している。カイラル対称性の破れから生じるパイ中間子は擬スカラー粒子であり、核子間に強いテンソル力を生じる。桁違いに大きなテンソル力は強いテンソル相関を生み出し、大きく束縛エネルギーに寄与する。テンソル最適化した反対称化分子動力学法(TOAMD)による計算結果で核物理における重要さを定量的に議論する。さらに、パイ中間子はバリオンの励起状態であるデルタ粒子と強く結合する。核子間の３体力を生み出す原動力になっているが、３体力でとどまる保証はない。次のステップではデルタを陽に含む可能性を考える。私の描く将来の核物理である。


title : QCD Casimir effect for exploring chiral partners of hadrons

Abstract : The original Casimir effect is a zero-point energy shift induced by two parallel plates, which is a perturbative phenomenon in the QED vacuum (essentially, photon fields). On the other hand, in the QCD vacuum including quarks and gluons (and also hadrons), the Casimir effect should be affected by the nonperturbative properties such as the spontaneous chiral symmetry breaking, color confinement, and instantons. The "Casimir effect" in QCD is still not experimentally observed, but recently similar phenomena were observed from lattice pure Yang-Mills simulations.

In this talk, I will discuss our recent studies about the relation between the Casimir effect in QCD and the chiral partner structures of hadrons such as nucleons [1] and D mesons [2]. In addition, I will discuss the Casimir effect for lattice fermions [3], which will be measured in lattice simulations and strongly correlated electron systems.


[1] T. Ishikawa, K. Nakayama, and K. Suzuki, Phys. Rev. D 99, 054010 (2019).

[2] T. Ishikawa, K. Nakayama, D. Suenaga, and K. Suzuki, Phys. Rev. D 100, 034016 (2019).

[3] T. Ishikawa, K. Nakayama, and K. Suzuki, arXiv:2005.10758.


title : Properties of neutron star from ab initio calculation to machine learning 

Abstract : The golden age of neutron-star physics has come with rapid developments of astronomical techniques. The observation of gravitational wave as GW170817 event from binary neutron-star merger opens the multi-messenger astronomy. But, a 2.6 solar mass compact object in GW190814 observed recently also took a great challenge to present nuclear many-body theory. We investigated the properties of neutron star in the frame work of a relativistic ab initio method, i.e. relativistic Brueckner-Hartree-Fock (RBHF) theory with high-precision charge-dependent relativistic nucleon-nucleon (NN) potentials. All of the results obtained from present calculations only with two-body NN potentials completely satisfy various constraints from recent astronomical observations of massive neutron stars, gravitational wave detection (GW170817), and mass-radius simultaneous measurement (NICER).

Furthermore, we also try to produce a complete equations of state (EOS) of neutron star from crust to core with machine learning method and the mass-radius observations of available 14 neutron stars. A five layer artificial neural network (ANN) system was designed, where the observations of neutron star and EOS are regarded as the input and output of ANN system, respectively. 100 EOSs were obtained with millions of training data. These EOSs cannot only generate reasonable mass-radius relations of neutron star at intermediate mass region but also generate massive compact stars more than 2.6 solar mass.


title : QCD-like phase diagram of resonantly interacting SU(3) Fermi gases

Abstract : Systems of fermions with two components (such as spin-1/2 electrons) are well-known to lead the phenomenon of Cooper pairing of different components, leading to fermionic superfluidity. Pair formation and superfluidity also occurs in fermionic systems with 3 components, leading to the so-called "colour superfluidity" where each of three different components (regarded as colours) can pair with one of the two others. However, another phenomenon can occur in these systems: the formation of trimers of three different components, due to the Efimov effect.

The interplay between Cooper pairing and the Efimov effect makes the phase diagram of such systems non trivial. Using an in-medium three-body equation and a non-self-consistent T-matrix approximation, we obtain a first insight into the temperature-density phase diagram of an SU(3)-symmetric unitary Fermi, that is to say a three-component fermionic system where all the scattering lengths between different components are infinite. The obtained phase diagram consists of three phases (trimer, normal, and colour superfluid phases) and bears some similarities with the conjectured phase diagram of quantum chromodynamics (QCD) at finite density and temperature.


title : A simple quantum many-body system – neutron drop

Abstract : A neutron drop is a system composed only of neutrons trapped by artificial external fields [1]. This simple system can be easily calculated by both the ab initio approach and energy-density functional theory. Therefore, the ab initio solutions for a neutron drop can be used as pseudo-data to calibrate and improve the effective Hamiltonians and density functionals in nuclear physics [2,3]. In this seminar, I will introduce our investigation on neutron drop by using the energy- density functional theories, including the following aspects: the origin of the spin- orbit and pseudospin-orbit splittings ’evolution in neutron drop; the pairing [4] and the deformation effects on the neutron drop.


[1] B. S. Pudliner, A. Smerzi, J. Carlson, V. R. Pandharipande, S. C. Pieper, D. G. Ravenhall, Neutron drops and skyrme energy-density functionals, Phys. Rev. Lett. 76 (1996) 2416-2419.

[2] S. Gandolfi, J. Carlson, S. C. Pieper, Cold neutrons trapped in external elds, Phys. Rev. Lett. 106 (2011) 012501.

[3] S. K. Bogner, R. J. Furnstahl, H. Hergert, M. Kortelainen, P. Maris, M. Stoitsov, J. P. Vary, Testing the density matrix expansion against ab initio calculations of trapped neutron drops, Phys. Rev. C 84 (2011) 044306.

[4] Y. H. Ge, Y. Zhang, J. N. Hu, Effects of pairing correlation on neutron drop, Sci. China Physics, Mech. Astron. 63 (2020) 242011.


title : Structure of Be9-Lambda with alpha-alpha-Lambda microscopic cluster mode

Abstract : We study the structure of Be9-Lambda in the framework of three body alpha+alpha+Lambda cluster model by using the realistic NN and YN interaction. With applying the complex scaling method into Gaussian expansion method, we obtain both the energy and decay width of the resonances of Be9-Lambda(T=0). The three particular structures of Be9-Lambda: Be8 analogue states, Be9-Lambda genuine states and Be9 analogue states are confirmed with calculating the overlap probability with the SU(3) shell model configurations. We find several resonances which are pointed out by the previous studies of Be9-Lambda, are missing. The new states of Be9-Lambda are also found at a high energy region and there might appear new structures.


title : Extracting each component from discretized breakup cross sections in multi-breakup-channel reactions

Abstract : The continuum-discretized coupled-channel method (CDCC) proposed in Kyushu University is still one of the most powerful methods of describing breakup reactions. As a dramatic development in the last fifteen years, CDCC can treat multi-breakup-channel reactions beyond simple three-body scattering, i.e., four-body CDCC and three-body scattering with core excitation. For example, in 6Li scattering (n+p+α+T, T is a target), the four-body-breakup channel (n+p+α+T) and the three-body-breakup channel (d+α+T) coexist, and they are coupled to each other during the scattering. In CDCC, those two channels are precisely taken into account on an equal footing but the corresponding breakup cross sections (BUXs) are obtained as an admixture of these channels because of its discretization. It is desired to separately calculate those BUXs. In this talk, we propose an approximate method of extracting each component from the discretized breakup cross sections. We show the validity of the approximation method and discuss reaction dynamics beyond simple three-body scattering.


title : Nuclear electric dipole moment and new physics beyond the standard model

Abstract : The electric dipole moment (EDM) of light nuclei is a very sensitive probe of CP violation beyond the standard model which may be measured in future experiments. Nuclei are particularly interesting since the nuclear level CP violation is not suppressed by the atomic screening effect pointed by Schiff. However, their sensitivity on hadronic CP violation strongly depends on the nuclear structure due to the many-body effect. In this talk, we present the results of our theoretical evaluations of the EDM of light nuclei using few-body methods, and show the prospect for the discovery of new physics beyond the standard model.