Naoyuki Itagaki (Yukawa Institute for Theoretical Physics, Kyoto University)
Cluster structure comprised of shell model states

Essential role of the noncentral interactions is one of the most characteristic features of our research field. For instance, the spinorbit interaction is the key ingredient that enables to explain the observed magic numbers of 28, 50, 82, and 126. Furthermore, the tensor interaction has been found to contribute to the large binding energy of 4He, which can be treated as clusters in many nuclei. The nuclear systems thus show different features, shell aspects and cluster aspects, owing to the decisive effects of these two noncentral interactions. The idea of combining the shell and cluster models has been fascinating the theoreticians for decades. Here, the big obstacle comes from the fact that the contribution of the spinorbit interaction, quite important in the shell model, vanishes when we introduce simple alpha cluster wave functions. The spinorbit interaction is the driving force which breaks the alpha cluster structure and restores the symmetry of the jjcoupling shell model. Consisting description of two pictures on the same footing is of special importance.
Theoretically speaking, the wave functions of the alpha cluster model indeed have some overlap with the jjcoupling shell model. If we take the smalldistancelimit between the alpha clusters, the lowest configuration of the threedimensional harmonic oscillator is described, but this is still different from the jjcoupling shell model wave function, where the spinorbit interaction strongly acts. We have developed antisymmetrized quasi cluster model (AQCM), which allows the smooth transformation of the alpha cluster model wave functions to the jjcoupling shell model ones [1]. By adding only one parameter to the Brinktype alpha cluster model, the wave functions are continuously transformed to the jjcoupling shell model ones, which we call the transformation to the quasi clusters.
As the next step of the study, we prepare plural jjcoupling shell model wave functions. Until now, most of the clusters introduced as subsystems have been limited to the closure of the threedimensional harmonic oscillator, such as 4He, 16O, and 40Ca. However, with the increase of mass number, the symmetry of the jjcoupling shell model gets more important, which might exist as subsystems of the nuclear structure. Such studies are easily performed using AQCM. The first example is 14C, and we discuss the possibility of two and three14C cluster configurations [2]. Here each 14C cluster is jjcoupling shell model wave function. We also discuss the cases of a few 8He and/or 9Li clusters [3]. Until now, the halo structure of 11Li has been extensively investigated, and it is intriguing to see how the halo neutrons outside the 9Li core play molecularorbital motion when another 9Li cluster approaches.
Hiro Ejiri (RCNP Osaka Univ. Osaka and CTU, Prague)
Delta isobar (\(\Delta\)) contribution to neutrino nuclear response for double beta decay

Neutrinoless double beta decays (DBD) are of current interest for studying the neutrino nature (Majorana/Dirac), the absolute mass scale and others beyond the standard model. Here, the nuclear matrix elements NMEs are crucial for extracting the neutrino properties of the particle physics interests.
Axialvector (\(\sigma\tau , J^\pi=1+,2, 3+\)) NMEs in the large q (~ 100 MeV/c) region associated with DBD NMEs were studied for the first time by using nuclear and lepton chargeexchange reactions of the 0.4 GeV (^{3}He,t) and the muon induced \((\mu,\nu_\mu)\). The obtained \(\sigma\tau\) NMEs are found to be much smaller than the NMEs based on the QRPA model with the nucleonic \(\sigma\tau\) correlations. These results suggest nonnucleonic \(\sigma\tau\) effects. One of them is the coherent \(\Delta\) isobar (quark \(\sigma\tau\) flip) contribution, where many \(\Delta\)particle nucleonhole pairs affect coherently the DBD NME. This is incorporated by using the quenched axialvector coupling of gAeff/gA~0.50.7 with gAeff and gA being the effective and bare coupling constants.
We note that the \(\Delta\)DBD with \(\nu\)exchange between 2 quarks in the \(\Delta\) plays a important role in the 2+ state transition with the large \(\Delta\) NME if the \(\Delta\) probability in the initial ground state is of the order of \(10^{2}\).
Impact of the present work on DBD neutrino studies and weakdecay NMEs in a few nucleon system and light nuclei are discussed.
Li Sheng Geng (Beihang University)
Understanding of the LHCb pentaquark states as hadronic molecules, from masses, spinparities to production yields

Xiaoling Cui (Chinese Academy of Science)
Stability of quantum droplet against confinement and multicomponent

Yifei Niu (Lanzhou University)
Beyond Meanfield Description of Nuclear Weak Interaction Processes in Stars

Yusuke Tanimura (Tohoku University)
How to visualize nuclear manybody correlations?

Shimpei Endo (Tohoku University)
Are atoms spherical?

Tokuro Fukui (Kyoto University)
Manybody effective models with chiral interaction

Shin Inouye (Osaka City University)
Measurement of the Variation of ElectrontoProton Mass Ratio Using Ultracold Molecules Produced from LaserCooled Atoms

Watch 
A rovibrationally pure sample of ultracold KRb molecules was used to improve the measurement on the stability of electrontoproton mass ratio ( \(\mu = m_e/M_p \) ). The measurement was based upon a large sensitivity coefficient of the molecular spectroscopy, which utilizes a transition between nearly degenerate pair of vibrational levels each associated with a different electronic potential. Observed limit on temporal variation of \(\mu\) was \( \frac{1}{\mu} \frac{d\mu}{dt}=\) (0.30±1.0)×10^{−14}/year, which was better by a factor of five compared with the most stringent laboratory molecular limits to date.
Shun Uchino (JAEA)
Atomtronics

Servaas Kokkelmans (Eindhoven University of Technology)
Elastic fewbody interactions in dilute Bose gases

14:00 Ying Zhang (Tianjin University and RIKEN)
Lambda halo structure of C, B and Zr isotopes
The halo nuclei are characterized by its extended density profile far beyond the nuclear surface region [13]. Very much enhanced electric dipole transitions have been also observed in several halo nuclei as a unique phenomenon associated with the extended halo wave function [4]. For hypernuclei consisting nuclei and a Lambda hyperon, there is also possibility to have Lambda halo states in lighter systems [5,6]. In this work, we study the Lambda hypernuclei of C, B [7] and Zr isotopes by HartreeFock and HartreeFockBogoliubov model with Skyrmetype nucleonnucleon and nucleonhyperon interactions. The calculated binding energies agree well with the available experiment data for C and B hypernuclei. We found halo structures with extended wave function beyond the nuclear surface in the Lambda 1pstate in the light C and B isotopes. We also found the enhanced electric dipole transition between 1p and 1sLambda states, which could be the evidence for this hyperon halo structure. The Lambda hyperon in the Zr isotopes which were predicted to have giant neutron halo, has more halo orbits near the threshold, such as 3s, 2d, and 1gstates. They are almost degenerate. Especially, the 3sstate could have even more extended wave function than that of the giant neutron halo.
[1] I. Tanihata, et al., Phys. Rev. Lett. 55, 2676 (1985).
[2] B. Jonson, Phys. Rep. 389, 1(2004).
[3] J. Meng and S. G. Zhou, J. Phys. G 42, 093101 (2015).
[4] T. Nakamura et al., Phys. Rev. Lett. 96, 252502 (2006).
[5] K. Miyagawa, H. Kamada, W. Glockle, and V. Stoks, Phys. Rev. C 51, 2905 (1995).
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14:45 Jinniu Hu (Nankai University and RIKEN)
The mass limit of a neutron star
The rapid progresses of the astronomical observable techniques provide not only great challenges but also many opportunities in the investigations of neutron star. In the past decade, the measurements of massive neutron stars above \(2.0M_\odot\) successively broke through our recognition of their maximum masses. In 2019, a compact object was observed with a mass of \(2.502.67~M_\odot\) by LIGO Scientific and Virgo collaborations (LVC) in GW19081. In this talk, I will show our results about properties of neutron star, including its mass, radius, tidal deformabilities, and so on with different density functional theories and ab initio methods obtained during the past year, when I visited SNP laboratory. We found these theoretical frameworks can describe various constraints of neutron star from the massive neutron star observations, the massradius simultaneous measurements (NICER), and gravitational wave detections. The maximum masses of neutron star, composed of pure hadron matter can be around \(2.55M_\odot\), the dimensionless tidal deformabilities at \(1.4M_\odot\) are less than \(800\), and the radius of \(1.4M_\odot\) are smaller than \(13.0\) km.
[1] Y. Zhang, P. Liu, and J. Hu, Int. J. Mod. Phys. E, 28, 1950094 (2019)
[2] J. Hu, S. Bao, Y. Zhang, K. Nakazato, K. Sumiyoshi, and H. Shen, Prog. Theo. Exp. Phys., 2020, 043D01 (2020)
[3] C. Wang, J. Hu, Y. Zhang, and H. Shen, Astrophys. J., 897, 96 (2020).
[4] K. Huang, J. Hu, Y. Zhang, and H. Shen, Astrophys. J., in press, arXiv: 2008.04491
Tetsuo Hyodo (Tokyo Metropolitan University)
Lambda(1405) as a hadronic molecule

HansWerner Hammer (TU Darmstadt)
The lifetime of the hypertriton

We investigate the lifetime of the hypertriton as a function of the Lambda separation energy B_{Λ} in an effective field theory with Lambda and deuteron degrees of freedom. We also consider the impact of new measurements of the weak decay parameter of the Lambda. While the sensitivity of the total width to B_{Λ} is small, the partial widths for decays into individual final states and the experimentally measured ratio R=Γ_{3He}/(Γ_{3He}+Γ_{pd}) show a strong dependence. We comment on recent measurements of hypertriton properties in heavy ion collisions.
Peng Zhang (Renmin University, Beijing)
Laser control of twobody processes in nuclear and coldatom systems

In this talk I will introduce two of our recent works. (1) Laser control of lowenergy neutronproton collisions. Recently the control of nuclear processes with strong laser (power density 10^{19}10^{22} W/cm^{2}) has attracted a lot of attention. In this work we study the lowenergy elastic and inelastic scattering between neutron and proton in such a strong laser, and find that in such a system there can be extremely strong multiphoton absorption effect (i.e., the inverse bremsstrahlung effect). In some cases the neutron and proton may absorb 10^{4}10^{5} photons in one collision. In addition, the inelastic scattering (absorption) rate can also be manipulated by the laser. (2) Molecular electric dipole moment of alkalineearth (like) atoms in ^{1}S_{0} and ^{3}P_{0} states. We study the molecule states of two alkalineearth (like) atoms in ^{1}S_{0} and ^{3}P_{0} states respectively, and show that there is an interorbit electric transition dipole moment between two such states in spin singlet and triplet manifolds. For two ^{173}Yb atoms the peak value of this electric dipole close to one Debye for ^{173}Yb atoms. With such a dipole moment one can dress these two molecule states with electricdipole transition induced by, e.g., a microwave, and form a dressed ``dipolar” molecule.
Chris Greene (Purdue University)
Linking Efimov physics, fewfermion universality, and the 3n and 4n systems

This seminar will present our recent unpublished results [1] based on an adiabatic hyperspherical coordinate treatment of the 3neutron and 4neutron systems. This study finds a totally repulsive hyperradial potential energy versus the hyperradius, which immediately and visually makes it clear that there cannot be any low energy resonance in either the 3n or the 4n system. Our calculations utilize several state of the art nucleonnucleon potentials, while also testing the importance of 3body nuclear force terms, and multichannel coupling effects. One major conclusion is that there is a 1/sqrt(E) zeroenergy divergence of the 3fermion and 4fermion density of states, which might play a role in explaining the excess lowenergy 4n events in the recent experiment by Kisamori et al.[2] This talk will also demonstrate the linkage between the divergent low energy density of states (or WignerSmith time delay), the Efimov effect, and fewfermion universality. Additional preliminary studies of some fewfermion systems occurring in ultracold atomic physics experiments will also be discussed. [1] M. D. Higgins, C. H. Greene, A. Kievsky, and M. Viviani, arXiv:2005.04714 (2020). [2] K. Kisamori et al., Phys. Rev. Lett. 116, 052501 (2016)
Munekazu Horikoshi (Osaka City University)
Ultracold AMO experiment for quantum fewbody and manybody

Ultracold atomic gases can mimic various quantum systems due to their characteristic of short range interactions, dilute density, and tunable interactions using Feshbach resonances. Since they basically show the universal physics which does not depend on detail of particle and the absolute energy scale, we can simulate various quantum systems experimentally, namely quantum simulation. In this seminar, I will introduce recent our cold atom experiments using lithium atoms from basic of the cold atomic system to application to the neutron star equation of state. Also I will show you our recent study toward studying quantum manybody cluster physics.
Yuta Sekino (RIKEN)
Mesoscopic spin transport between strongly interacting Fermi gases

Ultracold atomic gases are pure and highly controllable systems, providing us an ideal platform to examine physical properties of quantum manybody systems with strong interparticle interactions. In this talk, we report our theoretical study on mesoscopic spin transport for strongly interacting Fermi gases through a quantum point contact [1], which can be realized in ultracold atom experiments. By employing the linear response theory and manybody Tmatrix approximation, we investigate how a strong interaction affects the spin current. For a small spinbias regime, the current in the vicinity of the superfluid transition temperature is strongly suppressed due to the formation of pseudogaps, which are dip structures in singleparticle densities of states. For a large spinbias regime where the gases become highly polarized, on the other hand, the current is enhanced by the appearance of Fermi polarons, which are quasiparticles consisting of minority atoms dressed by majority atoms. These results suggest that the spin transport measurement in our setup becomes a novel probe to examine pseudogap and polaronic phenomena in ultracold atom experiments. [1] Y. Sekino, H. Tajima, and S. Uchino, Phys. Rev. Research 2, 023152 (2020)
The nucleon vector and axial elastic form factors are good probes to investigate the internal structure of the nucleon. Although great theoretical and experimental efforts have been devoted to improving our knowledge of the nucleon structure, there are several unsolved problems associated with fundamental properties of the proton and neutron. The proton radius puzzle, where highprecision measurements of the proton's electric charge radius from the muonic hydrogen ($(J\mu H$) Lamb shift disagree with well established(B results of both electronproton scattering and hydrogen spectroscopy, is currently one of the most intriguing problems in this field. The neutron lifetime puzzle, where the discrepancy between the results of beam experiments and storage experiments remains unsolved, is another open question that deserves further investigation in terms of the nucleon axialvector coupling ($g_A$). In this talk, we report our recent results of the nucleon isovector form factors measured on a largevolume lattice $(10.8~{(J\rm fm})^4$ at the physical point in 2+1(B flavor QCD. The configurations are generated with the stoutsmeared $O(a)$ improved Wilson quark action and Iwasaki gauge action at $(J\beta=6/g^2=1.82$,(B which corresponds to the lattice spacing of 0.085 fm. The pion mass at the simulation point is about 135 MeV. A large spatial volume of $(10.8~{(J\rm fm})^3$(B allows us to investigate the form factors at small momentum transfer region. We obtain the electric and magnetic form factors and their RMS radii which are evaluated from the slope of the respective form factor at the zero momentum transfer. We find that our results for the electric RMS charge radius seem to favor the experimental result of the $(J\mu H$ spectroscopy within 1sigma(B error, though it is still too early to draw any definitive conclusion. We also obtain the axialvector coupling and the axial RMS radius from the axialvector form factor. Although the 2% precision of our $g_A$ value is an orderofmagnitude larger than the experimental one, our result of the axial RMS radius that achieves the 7% precision is comparable with the experimental one.
In this talk, I will talk about the strong decay patterns of the Zc and Zb states. They are assumed to be hadronic molecules composed of openflavor heavy mesons. Employing the relativized quark model and the quarkinterchange model, we investigate the charged heavy quarkoniumlike states Zc(3900), Zc(4020), Zc (4430), Zb(10610) and Zb(10650) decaying into the ground and radially excited heavy quarkonia via emitting a pion meson. The calculated decay ratios can be compared with the experimental data, which are useful in judging whether the molecule state assignment for the corresponding Zc and Zb state is reasonable or not. The theoretical framework constructed in this work will be helpful in revealing the underlying structures of some exotic hadrons.
In this talk, I will summarize our recent results from radiative transitions of singly and doublycharmed baryons in lattice QCD. I will summarize the spin3/2 to spin1/2 electromagnetic transitions of the Omega_cc, Xi_cc and Omega_c baryons as well as the spin1/2 to spin1/2 transitions of Xi_c and Xi_c^prime baryons studied on 2+1 flavor lattices with a pion mass of ~156 MeV. In these works, we extracted the transition form factors and computed the decay widths and lifetimes of spin3/2 Xi_cc, Omega_cc and Omega_c baryons and spin1/2 Xi_c^prime baryon. We also used two different heavyquark actions to study the discretization effects. A comparison has ben made between two actions in the case of the Omega_c baryon.
Recently, the interest on establishing the existence of low energy three and four neutron resonances has been renewed. The possible existence of a four neutron resonance has been recently reported experimentally, but different theoretical groups find conflicting solutions on that problem. In this talk, this issue is studied solving the 3n→3n and 4n→4n scattering problems using the adiabatic Hyperspherical Harmonic approach. The preliminary results of this investigation will be shown and discussed.
Understanding of the internal structure of exotic hadrons is an important topic of the current hadron physics. Particularly in recent years, precise data on the hadron scattering have been accumulated from the experimental analysis, and it is becoming possible to extract detailed information on the scattering amplitude. This enables us to study the hadron structure from the properties of the scattering amplitude. In this seminar, the modelindependent approaches to study the hadron structure from the scattering amplitude are discussed. In the first part, the weakbinding relation between the experimental observables and compositeness, defined as the probability of finding the composite component, is introduced [1, 2]. While the compositeness is in general modeldependent quantity, this can be calculated in a modelindependent manner using the experimental observables when the hadron is weaklybinding swave state. Here, I mainly explain the reasoning of small model dependence of the compositeness in the weakbinding limit. In the second part, we see the qualitative method using the position of the CastillejoDalitzDyson (CDD) zero defined as the zero of the amplitude [3]. For the eigenstate that originates in the hidden channel, the existence of the CDD zero close to the pole is indicated by the topological nature of the phase of the amplitude. At the end of each part, the applications to Lambda(1405) baryon are discussed. [1] S. Weinberg, Phys. Rev. 137, B672 (1965). [2] Y. Kamiya and T. Hyodo, Phys. Rev. C 93, 035203 (2016), Y. Kamiya and T. Hyodo, Prog. Theor. Exp. Phys. (2017) 023D02. [3] Y. Kamiya and T. Hyodo, Phys. Rev. D 97, 054019 (2018).
Fixedtarget experiments using the high energy beam of the LHC can unveil various aspects of quantum chromodynamics (QCD) thanks to the ALICE and LHCb detectors, the high luminosity typical of high energy accelerators, and the versatility of the target with the possibility to polarize it. One of the most important topics to be studied is the nucleon structure when the constituents (partons) have a high momentum fraction. In the first part of this seminar, we will present the experimental project of A Fixed Target ExpeRiment (AFTER@LHC) [1], with an emphasis on the precise determination of the parton distribution functions (PDFs) of nucleons and nuclei. In the second part, we will report on the gluon and charm PDFs of the deuteron using lightfront quantization together with the impulse approximation [2]. We use a nuclear wave function obtained by solving the nonrelativistic Schrödinger equation using the Gaussian expansion method [3] with the realistic Argonne v18 nuclear force; it is then convoluted with the proton PDF. As a result, we found that the gluon distribution in the deuteron (per nucleon) is smaller than that of the proton by a few percent close to x = 0.4, whereas it is enhanced at x larger than 0.6. We will discuss the applicability of our computation and will comment on how to extend it to x as large as two. We will also present the charm distribution of the deuteron within the same approach by considering perturbatively and nonperturbatively (intrinsic) generated charm inside the deuteron. In particular, we note that the intrinsic charm content in the deuteron may be enhanced for 6quark configurations. [1] S. J. Brodsky, F. Fleuret, C. Hadjidakis, and J.P. Lansberg, Phys. Rep. 522, 239 (2013). [2] S. J. Brodsky, K.Y.J. Chiu, J.P. Lansberg, NY, arXiv:1805.03173 [hepph]. [3] E. Hiyama, Y. Kino, and M. Kamimura, Prog. Part. Nucl. Phys. 51, 223 (2003).
I will present our results of charmed hadrons, with emphasis on our successful prediction to the doubly charmed baryon Ξ_{cc} . I also explain our new attempt on twohadron interaction by lattice QCD.
The lowenergy dipole excitations in neutronrich nuclei are attracting a great interest in physics of unstable nuclei. A particular attention is paid on isoscalar and isovector natures of dipole excitations. We studied dipole excitations in Be isotopes with an extended version of the antisymmetrized molecular dynamics, which are designed to describe 1p1h excitations and large amplitude cluster modes. Two dipole modes were obtained in the lowenergy dipole excitations in 10Be. In this talk, I will briefly overview our recent researches on nuclear clustering, and then discuss the dipole excitations in light nuclei.
In ordinary nuclei, chiral NN and NNN interactions in chiral effective field theory (ChEFT) are now standard for ab initio studies. The description of baryonbaryon interactions in the strangeness sector has also been developed. After a brief introduction to the construction of baryonbaryon interactions in ChEFT, hyperon singleparticle potentials calculated in nuclear matter with NLO hyperonnucleon (YN) and NNLO hyperonnucleonnucleon (YNN) interactions parametrized in ChEFT are presented. The NLO YN interactions bear strong lambdasigma coupling. The interesting result is that the lambda potential becomes shallower beyond the normal density. Together with the repulsion from the YNN interactions, the ChEFT description provides the possibility to solve the hyperon puzzle without introducing ad hoc assumptions.
We have extended the conventional ab initio methods, such as molecular orbital and quantum Monte Carlo methods, to the multicomponent systems, which composed of electrons, a positron, and nuclei. We have carried out the accurate calculation of positron affinity and pair annihilation rate for positronic compounds by using these multicomponent methods including vibrational effect, and found that these values are in reasonable agreement with the corresponding experimental ones. [14] The positronic orbital is much more delocalized than the highest occupied electronic orbital, and the correlation between positron affinity and both permanent dipole moment and dipolepolarizability is clearly shown.
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[2] M. Tachikawa, Y. Kita, and R. J. Buenker: New J. Phys. 14 (2012) 035004.
[3] Y. Yamada, Y. Kita, M. Tachikawa: Phys. Rev. A 89 (2014) 062711.
[4] K. Suzuki, T. Takayanagi, Y. Kita, M. Tachikawa, and T. Oyamada: Comp. Theo. Chem. 1123 (2018) 135.
Nuclear quantum effects of hydrogen nuclei such as zeropoint energy and nuclear delocalization significantly influence dynamical and structural properties of condensed hydrogen systems. I will report the first computational study on realtime dynamics of hydrogen molecular liquids, solids, and supercooled liquids exhibiting strong nuclear quantum effects which have been hardly accessible by use of previous computational and theoretical methods like density functional theory and semiquantum molecular dynamics simulations with path integrals. [16] All the physical insights and information we obtained will provide a milestone for identifying and characterizing various unknown hydrogen phases, which will open a new avenue of hydrogen material research.
[1] K. Abe and K. HyeonDeuk, J. Phys. Chem. Lett., 8, 3595 (2017)
[2] K. HyeonDeuk, and K. Ando, Phys. Chem. Chem. Phys. (Communication), 18, 2314 (2016)
[3] K. HyeonDeuk, and K. Ando, J. Chem. Phys. (Communication), 143, 171102 (2015)
[4] K. HyeonDeuk, and K. Ando, Phys. Rev. B, 90, 165132 (2014)
[5] K. HyeonDeuk, and K. Ando, J. Chem. Phys. (Communication), 140, 171101 (2014)
[6] K. HyeonDeuk, and K. Ando, Chem. Phys. Lett., 532, 124 (2012)
The baryonbaryon (BB) interaction is one of the central topics in hadron and nuclear physics. Especially for the strangeness sector, in spite of lack of experimental data, detailed properties of it is required to understand the hypernuclear structures and deep inside of neutron stars. We investigate BB interactions via the timedependent HAL QCD method which enables us to derive potentials from NambuBetheSalpeter (NBS) wave function simulated on the lattice. We report the latest results of BB potentials and their scattering observables especially focusing on the strangeness S=2 sector. We also discuss the possibility of Hdibaryon state through the LambdaLambda and NXi scatterings.
We study the Lambda_c  nucleon interaction faithful to Smatrix in QCD on the basis of the HAL QCD method. In HAL QCD method, NambuBetheSalpeter wave functions are calculated on the lattice, and potentials are extracted form them. I will present our results on the 1S0 and 3S1 Lambda_c  nucleon potentials and scattering observables such as phase shifts. The scattering observables show that the Lambda_c  nucleon interaction is attractive and its spin dependence is weak. Using the extracted potentials, we also examine possible Lambda_c nuclei by constructing a singlefolding potential, which can be studied at JPARC and FAIR in the future.
We have been developing a method to deduce proton, neutron, and nucleondensity distributions in a nucleus via the reaction cross section that stands for a possibility of nuclear collision. Using this prescription, we can now discuss halo and skinstructures, or nuclear deformations based on the experimental reaction cross section data. In this talk, I would like to show recent results of experiments at NIRSHIMAC* and RIKEN. Especially, the latest preliminary result from the experiment carried out at RIBF last autumn on Ca and Ni isotopes will be introduced to discuss neutronskin thickness and the equation of state for asymmetric nuclear matter.
A corecollapse supernova is a generation site of a neutron star as well as one of the largest explosions in the universe. In this talk, I will show our recent results of supernova simulations with multidimensional neutrinoradiation hydrodynamics, especially focusing on neutron star formations.
In this talk some examples of the applications of instantons and skyrmions in describing the properties of strongly interacting systems will be discussed. In particular, first we discuss the contributions of nonperturbative effects in the heavy quark sector starting from the instanton induces quarkantiquark potential. The second, we start from the effective skyrmionskyrmion interactions in a many body systems and discuss the properties of the manynucleonic systems.
An ordinary heavy baryon consists of one heavy quark and two light quarks. In the present seminar, we review a recent work on the mass splitting of the lowestlying heavy baryons, based on the chiral quarksoliton model. The dynamical variables were fixed in the lightbaryon sector, the experimental data being used. The results were in remarkable agreement with the experimental data. We also predict the mass of the Omega_b. Within the same framework, we also analyze recent experimental results for excited Omega_c from the LHCb experiment. We suggest possible scenarios on them. As a second part of the talk, we will discuss a recent study on excited baryons, based on the extended chiral quarksoliton model. Since the confinement plays an essential role in describing the excited baryons, we consider the confining background field in addition to the pion mean field. To avoid the divergence in the quark level, we chop off the linearlyrising confining field at a certain value that is comparable to the quark mass. We discuss the mass spectra of the first excited baryons. We also discuss the theoretical puzzles on the mass ordering of N*(1440) and N*(1535) as well as N*(1535) and N*(1520).
I will discuss about the possibility for a four neutron system to posses a narrow resonance as suggested by a recent experimental result in RIKEN. Before discussing my own development, a short overview of the experimental and theoretical results concerning pure neutron systems will be presented.
Since any sensitive modification of the nucleonnucleon (NN) potentials or on the leading contributions of the threenucelon (NNN) forces affect strongly the nuclear chart, in our recent work we have introduced a phenomenological T = 3/2 three neutron force, in addition to a realistic NN interaction, as an artefact to accommodate a 4n nearthreshold states. We inquired what would be the strength of such a 3n force in order to generate a resonance compatible with the experimental findings. The reliability of the resulting threeneutron force in the T = 3/2 channel is examined, by analyzing its consistency with the lowlying T = 1 states of 4H, 4He and 4Li and the 3H + n scattering. Two independent configuration space methods are used in solving the fourbody problem: the Gaussian expansion method to solve the Schrodinger equation and the Lagrangemesh technique applied to solve the FadeevYakubowsky equation. The boundary conditions related to the fourbody problem in the continuum are implemented by using the complex scaling method and the position of the 4n resonances in the complex energyplane are determined.
The solution of the scattering problem in configuration space is a very difficult task both from formal (theoretical) as well as from computational points of view. The principal difficulties are related with the complex structure of the systems wave function in the asymptotes, being result of either presence of multiple scattering channels or the systems breakup into three or more clusters. One is obliged to seek for the exact methods enabling to treat the multiparticle scattering problem by avoiding the explicit treatment of the systems wavefunction at the boundaries.
Complexscaling method, proposed in the late sixties by Nuttal and Cohen, offers very accurate and elegant formalism to treat diverse scattering problems for short range potentials. Within the last fewyears I have applied this method in handling very different scattering problems: 2body collisions including Coulomb interaction, Optical potentials; scattering including the 3body breakup for real and Optical shortranged interactions; 3body and 4body scattering for the systems, where twoparticles (clusters) are charged; 3body breakup amplitude for nd as well as pd scattering. Finally, I have demonstrated that the conventional smooth complex scaling technique might be also used in describing collisions in pure Coulombic 3body systems. These recent achievements will be overviewed and discussed.
Neutrons decay into a proton after several minutes, and they can only escape their fate inside nuclei with the help of other protons. Do they really need protons to survive? Experimental programs try to provide a final answer to this question since the 1960s, but forming a nucleus with neutrons only is not an easy task, even theoretically! We will pass in review the different techniques that have been used, discuss a few key issues about the subject of neutral nuclei, and describe the present and future plans that should answer this question at RIKEN.
In recent years the family of nucleonnucleon interactions has been expanded by new models arising from different assumptions and motivations. In this talk I will focus on such forces as the improved chiral interaction of the BochumBonn group, the JISP16 force and lowmomentum interaction arising from the CDBonn force via the unitary transformation. While all models describe twonucleon systems very well, their behaviour changes when applied to threenucleon reactions. I will briefly overview applications of this forces to elastic nucleondeuteron scattering and/or weak muon capture processes at energies below the pion production threshold.
We study the mechanism for the hypertriton hadronic weak decay and provide an explanation for its significantly shortened lifetime which was observed recently by GSI, ALICE and STAR.
Enormous effort of generations of physicists has been devoted to understanding low energy nuclear structure since the discovery of the atomic nucleus in 1911. Properties of nuclei in their ground state, including their mass, building energy and shape provide a vital input to many areas of subatomic physics as well as astrophysics and cosmology. Low energy excited states are equally important for understanding nuclear dynamics. Yet, no consensun exis as to what is the best path to a theory, which would not only consistently reproduce a wide variety of experimental data but also have enough predictive power to yield credible predictions in area where data are still missing. In this talk I will give a basic outline of some of the main obstacles preventing us building such a theory. These include the change between the nucleonnucleon force in free space and in nuclear environment, the saturation property of the nuclear force and effects of the subnucleon (quark) structure of the nucleon. Selected classes of nuclear models, shell models, mean field models, microscopicmicroscopic and abinitio models, will be discussed with emphasis on their regions of applicability. Finally, suggestions will be made for, at least partial, progress that can be made with the quarkmeson coupling model, as reported in the recent publication.
We investigate fourbody breakup dynamics of 6Li elastic scattering on heavy targets (n+p+α+T; T=target). Since the n+p subsystem of 6Li has a bound state as deuteron (d), there exist not only fourbody breakup processes (6Li+T→n+p+α+T) but also threebody breakup processes (6Li+T→d+α+T). This makes reaction dynamics more complex in 6Li scattering than in scattering of Borromean systems such as 6He (n+n+α+T). In order to take into account both the breakup processes explicitly, 6Li is constructed by the Gaussian expansion method and the scattering process is then described with the fourbody version of continuumdiscretized coupledchannels method (fourbody CDCC). Fourbody CDCC reproduces measured elastic cross sections without introducing any adjustable parameter. In this seminar, we will discuss which of four and threebody breakup processes is favored in 6Li scattering and clarify the dynamic properties of 6Li scattering.
Motivated by the recently observed hypernucleus (Kiso event) Xi15C (14N+Xi^), we identify the state of this system theoretically within the framework of the relativisticmeanfield model. The XiN interactions are constructed to reproduce the two possibly observed \Xi^ removal energies, 4.38\pm 0.25 MeV or 1.11\pm 0.25 MeV. The preferred interpretation of the event is 14N(g.s.)+Xi^(1p), which is consistent with previous data on the hypernucleus Xi12Be (11B+Xi^).
We discuss the structure of the nucleon in free space and its structure changes in nuclear environment in the framework of inmedium modified chiral soliton model. The influence of surrounding nuclear environment to the inmedium nucleon properties is taken into account by means of the pionnucleus optic potential in the mesonic sector. The parameters of the optic potential are related to the pionic atoms data at low densities and to the nuclear matter matter properties at the saturation density. Then the properties of symmetric and asymmetric nuclear matter are discussed. Further, considering the extrapolations to extreme high densities, the structure and properties of neutron stars are also discussed.
Recently, threebody decays of the ground state charmed baryons like Lambda_c and Xi_c have been measured by Belle and BESIII collaborations. These decays lead to the analysis of interesting baryon resonances with strangeness such as Lambda(1405) and Xi(1690) through the final state interaction of the mesonbaryon pair. In this work, we study the weak decay processes theoretically, and find that these are ideal to analyze the properties of resonances. For instance, these decays can filter the isospin of the mesonbaryon pair and provide clear resonance signal compared with other production reactions. With the decay processes, we calculate the spectra of Lambda and Xi resonances and conclude that these decays are quite useful to clarify the nature of the baryon resonances with strangeness S=1 and 2.
Positron (e^{+}), an antiparticle of an electron, can be bound to some kinds of atoms and forms positronic atoms. Since the positron has the same but an opposite sign of charge, the positron lies far away from the nucleus by Coulombic repulsion. A positron and an electron form a hydrogenlike bound state which is called a positronium (Ps). Because of the same mass as an electron, the wavefunction of the positron spreads widely. Positron can be an alternative and a unique probe to electronic states of atoms/molecules by analyzing annihilation gamma rays. Recently, a low energy and high resolution positron beam has been developed, and the search for resonance states of positronic noble gas atoms is becoming possible [1]. Since the positronic atoms are expected to show many different faces from ordinary atoms, many theoretical and experimental attempts have been made to open a new aspect of atomic physics. Positronic alkali atoms (APs^{+}) have a minimum necessary to describe the positronic and electronic states of positronic atoms and have been the best testing grounds. We can regard the alkali atom (A) as a twobody model consisting of a valence electron and residual closedshell ion core (A^{+}). Both positronvalence electron active correlation and polarization of the ion core/atom can be described effectively. Since the ionization energy of an alkali atom is smaller than that of a Ps, the structure of the loosely bound state of APs^{+} shows Ps cloud which exists as Ps halo [2]. In this work, we precisely calculate bound and resonance states of LiPs^{+}, NaPs^{+}, KPs^{+}, RbPs^{+} and CsPs^{+} as a threebody system {A^{+}, e^{}, e^{+}} with a Gaussian Expansion Method, and find unique and exotic features of positronic alkali atoms. Relativistic effects based on the BreitPauli interactions to loosely bound states of LiPs^{+} and NaPs^{+} are investigated [3] by comparing with normal atoms. Structures and mechanisms of resonance states caused by weak longrange forces are also investigated. [1] J. R. Machacek, R. Boadle, S. J. Buckman, and J. P. Sullivan, Phys. Rev. Lett. 86, 064702 (2012). [2] J. Mitroy, Phys. Rev. Lett. 94, 033402 (2005). [3] T. Yamashita, and Y. Kino, J. Phys. Conf. Ser., 635, 052086 (2015).
The quantum mechanical threebody problem has been studied extensively for about a century. The helium atom (two electrons and a nuclues) and the molecular hydrogen ion (two protons and one electron) are textbook examples that illustrate the organization of the periodic table and molecular binding mechanisms, respectively. In 1970 Vitaly Efimov predicted a rather different and counterintuive quantum mechanical threebody binding mechanism that leads to an infinite series of stable threebody states of enormous spatial extents. These Efimov states are predicted to exist for shortrange interactions like the van der Waals force between atoms or the strong force between nucleons. When the potential becomes so shallow that the last twobody bound state is at the verge of becoming unbound or is unbound, then three particles stick together to form Efimov states. This talk will review recent theoretical and experimental advances in this field. The observation of the helium trimer (three neutral helium atoms) Efimov state and extensions of the Efimov scenario to four and higherbody systems will be discussed.
「メタマテリアル」は，電磁波の波長より小さな構造を用いて物質の電磁気学特性を操作した人工物質である．メタマテリアルは，マイクロ波から光波まで幅広い周波数領域で研究されているが，我々は特に光の領域で動作する「光メタマテリアル」の実現とその応用展開を目指して研究を進めている．これまで我々は，この光メタマテリアルを作るために必要な加工技術を中心に，レーザーを用いたトップダウン的な手法や，DNAや磁場を用いたボトムアップ的な手段，さらに最近では，トップダウンとボトムアップを融合させた新しい手法を開発・提案してきた．講演では，これらの内容とともに，メタマテリアルのサイエンスとテクノロジーについて紹介する．
The seminar will review two related developments in the abinitio study of mediummass exotic nuclei. The selfconsistent Green’s function theory method is used to learn about the characteristics of single nucleon correlations along several full spectroscopic chains. In the first case, chiral EFT interactions have been used to obtain the nuclear spectral function of the oxygen isotopes. This confirmed from the abinitio perspective the mechanism by which three nucleon forces generate the anomalous dripline at O24 and also affect nearby fluorine isotopes. We will also discuss implication of 3NFs for the Ca chain and its neighbours. Very neutron rich Ca and K isotopes have recently been measured and suggest the necessity for improved chiral interactions. In the second part, we will discuss the structure of closed shell isotopes as generated by nuclear forces from Lattice QCD simulations. For pion mass of 470 MeV (now getting closer to the physics limit) 4He and 40Ca are finally bound. However, the 16O could be still unstable under breakup onto four alpha particles.
In the first part of talk I will introduce the calculations of (ordinary) nuclei based on the selfconsistent HFB method, solved with the realistic NN interactions, and subsequent Equation of Motion Phonon Model (EMPM). The EMPM model is used for the calculations of the excitation spectra within multi particlehole configuration space. Such configurations are important to incorporate the beyond mean field correlations into the description of nuclear spectra. In the second part of the talk I will speak about the modification of this model which allows to describe the spectra of medium and heavy hypernuclei.
Heavy flavor physics has played an essential role in testing the CKM paradigm of the Standard Model and in searching for new physics. CP violation and rare decays of K and B meson and EDM can be good probe for new physics such as supersymmetry. In our work, taking account of the recent LHC results for the Higgs discovery and the SUSY searches we consider the highscale SUSY scenario in the framework of the nonminimal flavor violation. We discuss the effect of the high scale SUSY on FCNC of K, B0 and Bs mesons. References: M. Tanimoto and K. Yamamoto, "Sensitivity of HighScale SUSY in Low Energy Hadronic FCNC”, Symmetry 7 (2015) 689 [arXiv:1506.01850 [hepph]]. M.Tanimoto and K.Yamamoto, "Probing the high scale SUSY in CP violations of K, B0 and Bs mesons", Phys. Lett. B 735 (2014) 426 [arXiv:1404.0520 [hepph]].
The neutrinonucleus reactions play an important role for the heating and cooling mechanism in the core collapse supernova explosion. In addition to neutrons, protons and one representative nuclei line iron, ^{4}He has been considered in the equation of state of supernovae. In ref. [1], light nuclei such as deuteron, triton and 3He are taken into account. ^{4}He has been considered as a significant component and the importance of neutrino4He reactions has been studied in the accelerating shockwave [2] and nucleosynthesis [3]. The neutrino^{4}He reaction cross sections are evaluated in shellmodel approach[4] and an approach using Lorentz Integral Transformation method [5]. In this presentation, we will report on our analysis of cross sections and temperature averaged cross sections for CC and NC (anti)neutrino induced ^{4}He break up reactions: ν_{e} + ^{4}He → e^{} + X(A=4, Z=3) \bar{ν_{e}} + ^{4}He → e^{} + X(A=4, Z=1) ν_{e} / \bar{ν_{e}} + ^{4}He → ν_{e} / \bar{ν_{e}} + X(A=4, Z=2). For this analysis, we have employed the spindipole and dipole strength functions of ^{4}He calculated in the Complex Scaling Method (CSM) [6]. Comparison with the previous works will be discussed. [1] K. Sumiyoshi and G. Ropke, Phys. Rev. C77, 055804 (2008). [2] W. C. Haxton, Phys. Rev. Lett. 60, 1999 (1988). [3] G. M. Fuller and B. S. Meyer, Astrophys. J. 453, 792 (1995). [4] T. Suzuki, S. Chiba, T. Yoshida, T. Kajino and T. Otsuka, Phys. Rev. C74, 034307 (2006). [5] D. Gazit and N. Barnea, Phys. Rev. Lett. 98, 192501 (2007). [6] W. Horiuchi and Y. Suzuki, Phys. Rev. C87, 034001 (2013).
In the present talk, we review series of recent works on the charge and spin structure of the nucleon and the pion. We emphasize the new concept of the transverse charge and spin densities of hadrons. The corresponding results are discussed.
See here (PDF file).
多体系の物理学は特定の分科を超えた物理学共通の研究課題の一つである。なかでも、平衡から離れた系の統計物理学を構成することは現代物理学の挑戦的な重要課題である。本講演では、この問題にAdS/CFT対応を応用し、従来とは異なる視点から非平衡物理学を記述する試みについて解説する。AdS/CFT対応とは、ある種の量子ゲージ理論とある種の古典重力理論の間の対応関係である。この対応を用いると、非閉じ込め相にあるゲージ粒子の多体系はブラックホール時空にマップされる。通常、温度やエントロピーといった巨視的物理量は微視的自由度の粗視化で得られるが、ブラックホール時空の場合、微視的理論と巨視的物理量をつなぐのは重力の古典方程式であり、具体的な統計分布の知識は顕わに必要とされない。この性質は、統計分布が明らかでない非平衡系の記述には強力な武器となり得る。本講演では、この重力の不思議な性質を利用し、非平衡系の統計的性質を探ってゆく。いったん平衡系が重力理論で準備されれば、外力でドライブすることで非平衡統計系を準備できるが、AdS/CFT対応では、外力の線形応答を超えた領域の計算が、比較的平易な古典方程式を解くことで遂行可能となる。当日の講演は２部に分け、前半はAdS/CFT対応一般の導入的解説を、後半は講演者らが最近精力的に行っている、非平衡定常系の物理学へのAdS/CFT対応の応用に関して解説する予定である。
link: http://www.th.phys.titech.ac.jp/Nuclth/cafe/cafe.html
See here (PDF file).
希ガス等の中性の原子間にはファンデルワールス的な引力相互作用が働くために、通常、十分低温まで冷却すれば原子気体は凝縮をおこし液体や固体を形成する。しかし、ヘリウム原子のような量子性の高い原子においては、これは必ずしも自明ではない。特に2次元面内に閉じ込めたヘリウム3は、凝縮による引力相互作用からの利得と零点エネルギー等による損失が拮抗していることが知られており、その基底状態が気体であるか液体であるかについては主に理論計算によっていくつもの研究が行われてきた。しかし、その多くは基底状態が気体であることを示唆するものであった。 最近、私は原子レベルで平坦なグラファイト基板上に単原子相ヘリウム3を吸着させ、フェルミ縮退温度域（2 < T < 80 mK）での熱容量測定によってその基底状態が気体であるか液体であるかを調べたところ、ヘリウム3が1 nm^2以下の非常に希薄な密度の液体を形成していると考えられる結果を得た[1]。さらに、この液体は2次元面内への閉じ込めポテンシャルが大きく異なるグラファイト上1層目・2層目・3層目においても同程度の密度で現れており、このことから、ここで得られた結果は、厳密な2次元系においてもヘリウム3の基底状態が液体状態であることを示唆するものではないかと考えている。 [1] D. Sato, K. Naruse, T. Matsui, and H. Fukuyama, Phys. Rev. Lett.109, 235306 (2012); D. Sato et al., J. Low Temp. Phys. 158, 201 (2010).
The transverse charge and spin densties provide a novel aspect on the structure of the nucleon, since they reveal internal quarkgluon structures of the nucleon. We review a series of recent works on the transverse charge and spin densities of the pion and the nucleon, based on the chiral quark(soliton) model. We first discuss the transverse spin densities of the pion, which can be obtained from the electromagnetic and tensor form factors. We then discuss the transverse charge and spin structures of the nucleon. In particular, we report the first results of the transverse strange charge and spin densities. Finally, we also show how the transverse charge densities undergo changes in nuclear matter based on the Skyrme model.
近年重いフレーバーの領域(チャーム・ボトム領域)では、KEKBelleやSLACBabarを中心に「XYZ」と呼ばれる新粒子の発見が相次いでいる。 これらは単純なクォーク模型では説明することが難しいエキゾチックな構造を持っているが、なかでもメソン反メソンの閾値近傍では、そのメソン反メソンが緩く束縛した「ハドロン分子状態」とよばれる構造を持った粒子の存在が議論されている。 重いフレーバー領域でこのようなハドロン分子状態が形成される大きな要因として、この領域に現れるヘビークォークスピン対称性とそれにより強調されるパイオン交換力による重要な働きが考えられる。ヘビークォークスピン対称性はヘビークォークの質量m_Qが無限大の極限で現れる。このとき、クォーク間のスピンスピン力は1/m_Qで抑制されてしまうため、ヘビー擬スカラーメソンとヘビーベクターメソンの質量の縮退が起こる。実際にストレンジネス領域のK*メソンとKメソンの質量差に比べて、ボトム領域のB*とB、チャーム領域のD*とDの質量差は非常に小さい。そのため、ヘビーフレーバー領域では、DD*pi vertexを通して働くパイオン交換力が強調される。 パイオン交換力の中でも特にテンソル力と呼ばれる力が強い引力を生み出す事はすでに原子核物理で知られており、ヘビーメソン系でも同様にハドロン分子状態を形成する原動力となることが期待される。 本研究では、パイオン交換力による強い引力に着目し、ヘビーメソンとバリオン(核子)による新たなハドロン分子状態の存在可能性について議論する。ヘビーメソンとして、反DメソンとBメソンを取り扱い、核子との間でクォーク反クォーク対消滅が起こらない真にエキゾチックな状態(ペンタクォーク状態)を考える。2体系として反DN(BN)状態、そして3体系である反DNN(BNN)状態について束縛・共鳴状態の解析を行い、結果として閾値近傍に多くの状態が現れることを予言した。
See here (PDF file).
Structures of deformed states in sdshell nuclei are discussed focusing on cluster correlations. Recently, rotational bands of largely deformed states have been observed by \gammaspectroscopy experiments in A \sim 40 region such as 36,40Ar, 40Ca and 44Ti. Some of the deformed states are strongly populated by clustertransfer reactions. In order to understand those properties, both of clustering and deformations should be taken into account. I will briefly introduce basics of clustering and deformations in nuclei, and discuss cluster correlations in largely deformed states of A \sim 3040 nuclei such as Si, S, and Ca isotopes.
The details of this workshop: program and photo
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The electric dipole moment (EDM) is an observable sensitive to the CP violation, with very small standard model prediction, and it is a very good probe of new physics beyond the standard model. In this talk, we will present the physics of the EDM from the elementary to nuclear level together with our works, by focusing on the supersymmetry as the leading candidate of new physics. We will also discuss the possibility to constrain the supersymmetric CP phases with prospective experiments.
We study charmedhadron coupling constants based on 2+1flavor lattice QCD. By computing hadronic form factors, coupling constants between charmedhadrons and mesons (D*D\pi, DD\rho, DD*\rho) are evaluated. We discuss the flavorSU(4) symmetry breaking in coupling constants, and evaluate electromagnetic radii of light and charm quarks in charmed mesons. (If possible) We will show our preliminary results of charmedbaryon couplings.
The operation of JPARC opens a new window for studying hyperons. In this talk, several interesting problems in hyperon spectrum which can be investigated at JPARC will be discussed. We first discuss the strong modeldependence of Xi and Omega hyperon spectrum and the issue on the structure of several hyperon resonances. Then the question on the determination of spinparity quantum numbers of Xi hyperons will be shortly mentioned.
Modern experiments require sophisticated analysis tools for interpreting and extracting interesting physics from their data. For hadronic and/or nuclear reactions, such analysis tools are often theoretical models constructed with hadronic degrees of freedom. As such, I discuss a dynamical coupledchannels model developed for analyzing mesonbaryon reaction data, thereby extracting baryon resonances. This dynamical model also has a great potential, with some extensions, for analyzing JPARC data, and studying strange nuclear physics. I will discuss our ongoing effort towards this direction.
Achieving high accuracy in both electronic and nuclear structure computations is a priority when developing a structure method. The full configuration interaction (FullCI) method achieves the highest accuracy within a model space, but is very computationally expensive (exponential scaling). FullCI is a robust method that can be used with any Hamiltonian. It does not take advantage of the inherent smoothness associated with the solutions to the electronic and nuclear structure Hamiltonians. In the nuclear structure problem simplicity arises from every nucleon being identical (in the isospin formalism), and that the Hamiltonian only contains one and twobody symmetric operators (though threebody operators are becoming more prominent). The same is true in the electronic structure problem. Our approach takes into account these symmetries that are neglected in the FullCI approach. Results from Griebel[1] and others[24] in the mathematics of complexity literature show how one may construct a truncated FullCI that has polynomial scaling but maintains FullCI accuracy (at least within the large model space limit). We refer to this approach as GKCI.[5] A special case of the method is similar to the nocore shell model. In this presentation the mechanics of the approach will be explained as well as preliminary results. References 1. M. Griebel and S. Knapek, Constr. Approx. 16, 525 (2000). 2. H. Bungartz and M. Griebel, Acta Numer. 13, 147 (2001). 3. G.W. Wasilkowski and H. Wozniakowski, Found. Comput. Math., 5, 240 (2005) 4. S.A. Smolyak, Dokl. Akad. Nauk 4, 240 (1963) 5. J.S.M. and P.W. Ayers, J. Chem. Phys., J. Chem. Phys. Submitted (2011).
Investigation of fermion spectrum in a bosonfermion system such as QED/QCD at high temperature (T) or chemical potential (μ) is very important because it gives us the information on the basic building block of the system. In contrast to the case that the energy scale is of order gT or gμ (g: coupling constant), in which the method for perturbative analysis called "hard thermal/dense loop approximation" has been established, perturbative analysis in p<< g^2T region is difficult because of the infrared singularity. In this seminar, we find a novel fermionic excitation and obtain the expression of the dispersion relation, the decay width, and the strength, using the resummed perturbation theory regularizing that singularity in a hot QED/QCD plasma. We also find that the excitation disappears in the high density case, and discuss the reason of the disappearnce. Finally we derive the new generalized Boltzmann equation which is equivalent to the resummed perturbation from KadanoffBaym equation. By using that equivalence, we discuss kinetic interpretation of the resummed perturbation scheme, and show that the terms whose origin is different from those in the Boltzmann equation, appear in that kinetic equation.
Since the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) started its operation in 2000, a lot of discovery has been made and a lot of insight related to quantum chromodynamics (QCD) phase transition and the QuarkGluon Plasma (QGP) has been gained. One of the most physically interesting and surprising outcomes at RHIC is the production of the strongly interacting QGP (sQGP). Besides, at Large Hadron Collider (LHC) heavy ion collision experiments started in 2010. To understand experimental data at RHIC and LHC comprehensively, construction of realistic dynamical model for description of relativistic hydrodynamic model is indispensable. First I outline the modeling of a realistic dynamical model based on relativistic hydrodynamics for comprehensive description of high energy heavy ion collisions. Comparing theoretical calculations and experimental data at RHIC and LHC, I will give brief explanation of the key ingredients for the construction of a multimodule model: initial condition, hydrodynamical expansion, hadronization, and freezeout processes. Then I will discuss our recent development of stateof theart relativistic viscous hydrodynamic model and its application to relativistic heavy ion collisions.
One of the most promising possibilities may be the appearance of quark matter in astrophysical phenomena in the light of recent progress in observations. The properties of deconfinement is not well understood, but the thermodynamical aspects of hadronquark (HQ) phase transition have been extensively studied in recent years. Then the mixed phase of hadron and quark matter becomes important; the proper treatment is needed to describe the HQ phase transition and derive the equation of state (EOS) for hadronquark matter, based on the Gibbs conditions for phase equilibrium. We here use a realistic EOS for hyperonic matter in the hadron phase. For quark matter we further try to improve the previous EOS by considering other effective models of QCD. One of the interesting consequences may be the appearance of the inhomogeneous structures called ”pasta”, which are brought about by the surface and the Coulomb interaction effects. We present here a comprehensive review of our recent works about the HQ phase transition in various astrophysical situations: cold catalyzed matter, hot matter and neutrino trapped matter. We show how the pasta structure becomes unstable by the charge screening of the Coulomb interaction, thermal effect or the neutrino trapping effect. Such inhomogeneous structure may affect astrophysical phenomena through its elasticity or thermal properties. Here we also discuss some implications on supernova explosion, gravitational wave and cooling of compact stars.
About a decade ago, the THSR (Tohsaki, Horiuchi, Schuck, Ropke) wave function was proposed, which has been quite successful in describing the dilute gaslike states in light nuclei and indeed leads us to have a new perspective for the n alpha cluster structure in light 4n nuclei. Now, we propose a generalized wave function based on the flexible original THSR wave function , which is applicable to studies of general cluster structures in nuclei. The groundstate band in 20Ne is investigated by using this generalized wave function and the energies obtained agree well with the experimental values. Moreover, it is found that the single generalized THSR wave functions almost completely coincide with the exact solutions of alpha+16O resonating group method for the groundstate band in 20Ne. For the ground state, for instance, the squared overlap between them is 99.3%. Therefore we have a new concept for understanding the compact structure of the groundstate band in 20Ne, which provides a more exact picture than the Brink cluster model. On the other hand, we can conclude that the THSR model wave function can also be extended to study more compact cluster states in nuclei such as, e.g., the groundstate band in 20Ne.
A halo structure with an extended density distribution is one of the characteristic features of weakly bound neutronrich nuclei. For the neutronrich nucleus ^{31}Ne, the halo structure has been recently suggested by the experimental data of Coulomb breakup and interaction cross sections measured at RIKEN RIBF facility. Assuming that ^{31}Ne consists of the strongly deformed core nucleus ^{30}Ne and one valence neutron, we calculate Coulomb breakup and reaction cross sections of ^{31}Ne taking into account the rotational excitation energy of the core nucleus ^{30}Ne with particlerotor model (PRM). We will discuss the structure of ^{31}Ne deduced from these calculations.
In this talk, we will discuss the structure of several psd shell and neutronrich $\Lambda$ hypernuclei such as Be, Ne and Mg, based on the antisymmetrized molecular dynamics (AMD) calculation. Forthcoming experiments at JPARC will reveal the spectroscopy of sdshell and neutronrich $\Lambda$ hypernuclei. One of the unique and interesting aspects of hypernuclei is the structure change caused by hyperon. Through the interaction with surrounding nucleons, a hyperon in the atomic nucleus can affect and modify nuclear clustering and deformation. Especially, the structure changes of sdshell and neutronrich $\Lambda$ hypernuclei are of interest, since the various clustering and deformed structures coexist in the ground and lowlying excited states. To study such phenomena, we have extended the AMD for hypernuclei and applied it. By using the YNG and Gogny D1S as effective $\Lambda$N and NN interactions, we investigated the lowlying structure of Be, Ne and Mg $\Lambda$ hypernuclei without any assumption on the clustering and deformation. In this talk, we will show you the excitation spectra of such $\Lambda$ hypernuclei and discuss the structure changes caused by $\Lambda$ hyperon.
The nucleonnucleon (NN) interaction contains a strong tensor interaction due to pion exchange. The strong attraction of the tensor interaction contributes significantly to the binding energy of nuclei. Therefore it is natural to treat the tensor interaction explicitly in nuclear structure calculations. Such calculations are, however, limited in fewnucleon systems due to mainly technical difficulty. Thus the role of the tensor interaction, or tensor correlation, in nuclear structure has not been explicitly taken into account in conventional shellmodel and meanfield calculations, and has been hidden. Experimental trial for probing the effects of tensor correlation is one of hot topics. We have recently observed bulk contribution of the tensor correlation in the ground states of selfconjugate (N=Z) eveneven nuclei. The experiment was performed at the Research Center for Nuclear Physics (RCNP), employing a highresolution proton beam at 295 MeV and the Grand Raiden spectromter. SpinM1 transition strengths from the ground states of ^{12}C, ^{16}O, ^{20}Ne, ^{24}Mg, ^{28}Si, ^{32}S, ^{36}Ar, and ^{40}Ca nuclei have been determined for each of isoscalar and isovector transitions up to 16 MeV. The observed transition strengths are converted, by using a sumrule, to an expected value of the ground state wavefunction ＜S_p . S_n＞, where S_p(n) is the vectorsum of all the proton (neutron) spinoperators. The value is quite sensitive to the tensor correlation between protons and neutrons. The extracted number is ~0.1 and is more or less flat in sdshell region. The number is consistent with predictions for the 4He nucleus using realistic NN interactions. I will report on the experiment and discuss the results.
We investigate the charm quark system using the relativistic heavy quark action on 2+1 flavor PACSCS configurations. The dynamical updown and strange quark masses are set to the physical values by using the technique of reweighting to shift the quark hopping parameters from the values employed in the configuration generation. The charm quark mass is determined by the spinaveraged mass of the 1S charmonium state. We also calculated the CabibboKobayashiMaskawa matrix elements, V_{cd} and V_{cs}, extracted from the charmed and charmedstrange meson decay constants.
We discuss the probability distribution of a net conserved charge based on the Landau theory of phase transition. Statistical fluctuations of the net baryon number, especially of higher orders, have been regarded as diagnostics of the chiral phase transition in QCD. Normally they are discussed by calculating cumulants of the net baryon number through derivatives of the thermodynamic pressure with respect to the chemical potential in the grand canonical ensemble. Lattice QCD and effective model calculations have revealed their critical behaviors in the vicinity of the chiral phase transition. The purpose of this work is to characterize the critical behavior in terms of the probability distribution. We construct an analytically solvable model which respects relevant symmetries based on the Landau theory within mean field approximation. We clarify differences in the probability distribution originated from the singular part of the thermodynamic potential. Then, we consider an extension by implementing O(4) critical scaling in the model pressure such that higher order cumulants (c3 and c4) diverge at the phase transition. We emphasize the relationship of the probability distribution to the analytic structure of the grand canonical partition function in complex chemical potential. It is pointed out that the singular structure, which gives the divergent cumulants, leads to an anomalous oscillatory factor in the probability distribution through both numerical calculations and analytic consideration.
We perform BruecknerHartreeFock calculations of kaoncondensed matter, hypernuclear matter and hybird matter, and compute the structure of neutron stars within this approach. We conclude that kaon condensation may be totally suppressed in our model, but low maximum masses below 2 solar masses are found for hyperon stars and hybrid stars.
ユニタリー・フェルミ気体の熱力学関数が、３つのグループにより実験的に計測された[1]。これらの実験結果を解析する理論的なアプローチの一つとして、フガシティz=exp(βμ)による展開（クラスター展開）が注目されている。多くの先行研究により、3次や4次の低次の係数が数値的に求められた[2]。しかし、相転移を扱うには、高次の項を取り入れる必要がある。我々は、クラスター展開の高次の項を系統的に扱うために、LeeYangの量子クラスター展開法[3]を拡張した[4]。拡張された方法を用いれば、ボース系やフェルミ系の大分配関数とN 粒子還元密度行列が、ボルツマン統計で定義された同じ系のクラスター関数を用いて、系統的に計算できる。この方法は、展開を数学的に正当化でき、一様系でもトラップ系でも使える。今回の拡張により、ボース系やフェルミ系の「非対角長距離秩序（ODLRO）の発現」の有無を調べることができる。得られたODLROの判定条件は、収束する無限和で表される。セミナーでは、関連する最近の研究[5, 6]についても簡単に触れる予定である。 [1] M. Horikoshi et al., Science 327, 442 (2010); S. Nascimbne et al., Nature 463, 1057 (2010); M. J. H. Ku et al., Science, 335, 563 (2012). [2] G. Rupak, PRL 98, 090403 (2007); X.J. Liu et al., PRL 102, 160401 (2009); D. B. Kaplan and S. Sun, PRL 107, 030601 (2011). [3] T. D. Lee and C. N. Yang, Phys. Rev. 113, 1165 (1958); 117, 22 (1960). [4] N. Sakumichi, N. Kawakami and M. Ueda, Phys. Rev. A 85, 043601 (2012). [5] N. Sakumichi, N. Kawakami and M. Ueda, arXiv:1202.6532 (2012). [6] N. Sakumichi, Y. Nishida and M. Ueda, in preparation.
The XiN interaction is not wellknown, other than it could be weakly attractive. An experimental search of Xi^ hypernucleus via (K^, K^+) reaction on 12C target is planned at JPARC as E05. Many authors have theoretically performed the calculation of (K^, K^+) reaction spectra on 12C and the heavier targets with the closed shell, while none for the lighter target than 12C so far. On the other hand, Hiyama et al. have predicted the existence of Xi^ hypernuclear bound state for several light $p$shell nuclei by the fewbody structure calculation. Thus, our purpose is to calculate the (K^, K^+) reaction spectra on light pshell targets and examine their experimental feasibility. In this talk, we focus on the 7Li target case, which forms [Xi^ + 6He] bound state via (K^, K^+) reaction. The expected reaction spectrum is calculated within the framework of distorted wave impulse approximation (DWIA) using coupledchannel Green's function method considering [Xi^ + 6He(0+)][Xi^ + 6He(2+)] channel coupling.
GammaRay Bursts (GRBs) are the most powerful explosions in the Universe. Recently, it is found that some GRBs are born with peculiar supernova explosions. The explosion energy of the peculiar supernovae is about 10 times greater than that of normal supernovae. That is why it is believed that the central engine of GRBs is different from the one of normal supernovae. However, it is not known well how the engine of GRBs is working. In this talk, I would like to review the history of the study on the central engine of GRBs and I would like to present my recent numerical simulations (General Relativistic MagnetoHydrodynamic Simulations) of the engine. Also, I would like to show briefly some our recent works that are related with GRB phenomena.
One of recent interests in the hadron structure is whether hadrons are made up of quarks and gluons confined in a singleparticle potential as described in the conventional quark model, or rather develop subcomponents of quarkclusters inside hadrons. It has been suggested that some hadronic resonances could have substantially large components of hadronic composites. In view of the fact that hadronic resonant states are unavoidably mixture of hadronic and quarkcomposites, an important issue is to clarify how these components are mixed in a hadron. In this talk, we focus on hadron structure having two components of hadronic composite and elementary component, by taking the a1(1260) meson as an example. The problem is analyzed in a manner similar to a twolevel problem with mixing in quantum mechanics. We propose a method to disentangle their mixture appearing in the physically observed state.