Search

We perform a parameter-free calculation for the high-energy proton-nucleus scattering based on the Glauber theory. A complete evaluation of the so-called Glauber amplitude is made by using the factorization of the single-particle wave functions. The multiple-scattering or multistep processes are fully taken into account within the Glauber theory. We demonstrate that proton- $^{12}$C, $^{20}$Ne, and $^{28}$Si elastic and inelastic scattering ($J^\pi=0^+ \to 2^+$ and $0^+ \to 4^+$) processes are very well described in a wide range of the incident energies from $\sim$50 MeV to $\sim$ 1 GeV. We evaluate the validity of a simple one-step approximation andfind that the approximation works fairly well for the inelastic $0^+ \to 2^+$ processes but not for $0^+ \to 4^+$ where the multistep processes become more important. As an application, we quantify the difference between the total reaction and interaction cross sections of proton-$^{12}$C, $^{20}$Ne, and $^{28}$Si collisions., Comment: 29 pages, 6 figures, to appear in Nucl. Phys. A

Geometric configurations of three-$\alpha$ particles in the ground- and first-excited $J^\pi=0^+$ states of $^{12}$C are discussed within two types of $\alpha$-cluster models which treat the Pauli principle differently. Though there are some quantitative differences especially in the internal region of the wave functions, equilateral triangle configurations are dominant in the ground state, while in the first excited $0^+$ state isosceles triangle configurations dominate, originating from $^8{\rm Be}+\alpha$ configurations., Comment: 7 pages, 4 figures, contribution to the 8th Asia-Pacific Conference on Few-Body Problems in Physics (APFB2020), 1-5 March 2021, Kanazawa, Japan

Background: A newly identified drip-line nucleus $^{31}\mathrm{F}$ offers a unique opportunity to study the two-neutron ($2n$) correlation at the east shore of the island of inversion where the $N=28$ shell closure is lost.Purpose: We aim to present the first three-body theoretical results for the radius and total reaction cross sections of $^{31}\mathrm{F}$. This will further help to investigate how the pairing and the breakdown of the $N=28$ shell closure influence the formation of the $2n$-halo structure and the antihalo effect in this mass region.Methods: A $^{29}\mathrm{F}+n+n$ three-body system is described by the cluster orbital shell model, and its total reaction cross section is calculated by the Glauber theory.Results: Our three-body calculations predict 3.48--3.70 fm for the root-mean-square radius of $^{31}\mathrm{F}$, which corresponds to the total reaction cross section of 1530 (1410) to 1640 (1500) mb for a carbon target at 240 (900) MeV/nucleon. The binding mechanism and halo formation in $^{31}\mathrm{F}$ are discussed.Conclusions: The present study suggests a novel antihalo effect in this mass region: When the pairing overcomes the energy gap between the ${p}_{3/2}$ and ${f}_{7/2}$ orbits, the inversion of the occupation number of these orbits takes place, and it diminishes the $2n$-halo structure.

Interaction cross sections for ^{42-51}Ca on a carbon target at 280 MeV/nucleon have been measured for the first time. The neutron number dependence of derived root-mean-square matter radii shows a significant increase beyond the neutron magic number N=28. Furthermore, this enhancement of matter radii is much larger than that of the previously measured charge radii, indicating a novel growth in neutron skin thickness. A simple examination based on the Fermi-type distribution, and mean field calculations point out that this anomalous enhancement of the nuclear size beyond N=28 results from an enlargement of the core by a sudden increase in the surface diffuseness of the neutron density distribution, which implies the swelling of the bare ^{48}Ca core in Ca isotopes beyond N=28.

Background: The $^{29}\mathrm{F}$ system is located at the lower-$N$ boundary of the ``island of inversion'' and is an exotic, weakly bound system. Little is known about this system beyond its two-neutron separation energy (${S}_{2n}$) with large uncertainties. A similar situation is found for the low-lying spectrum of its unbound binary subsystem $^{28}\mathrm{F}$.Purpose: We investigate the configuration mixing, matter radius, and neutron-neutron correlations in the ground-state of $^{29}\mathrm{F}$ within a three-body model, exploring the possibility of $^{29}\mathrm{F}$ to be a two-neutron halo nucleus.Method: The $^{29}\mathrm{F}$ ground-state wave function is built within the hyperspherical formalism by using an analytical transformed harmonic oscillator basis. The Gogny-Pires-Tourreil (GPT) $nn$ interaction with central, spin-orbit, and tensor terms is employed in the present calculations, together with different $\text{core}+n$ potentials constrained by the available experimental information on $^{28}\mathrm{F}$.Results: The $^{29}\mathrm{F}$ ground-state configuration mixing and its matter radius are computed for different choices of the $^{28}\mathrm{F}$ structure and ${S}_{2n}$ value. The admixture of $d$ waves with $pf$ components is found to play an important role, favoring the dominance of dineutron configurations in the wave function. Our computed radii show a mild sensitivity to the $^{27}\mathrm{F}+n$ potential and ${S}_{2n}$ values. The relative increase of the matter radius with respect to the $^{27}\mathrm{F}$ core lies in the range 0.1--0.4 fm depending upon these choices.Conclusions: Our three-body results for $^{29}\mathrm{F}$ indicate the presence of a moderate halo structure in its ground state, which is enhanced by larger intruder components. This finding calls for an experimental confirmation.

We investigate the spin-flip charge-exchange type nuclear excitations, that are, Gamow-Teller (GT) and isovector-spin-monopole (IVSM) transitions, to explore a possible probe to study the two-neutron correlations in the halo nuclei. A typical light halo nucleus, \(^6\)He, is studied with \(^4\)He (\(\alpha \)) \(+\) two-nucleon (N) three-body model. We show that the IVSM transitions are superior to the GT ones to obtain the information on the structure of \(^{6}\)He: The strong IVSM strengths, which are sensitive to the binding energy of \(^6\)He, are found in the low-lying region below the \(\alpha +\)deuteron (d) threshold, whereas the GT strengths have almost no peak due to small overlap between the wave functions of the ground state of \(^6\)He and the \(\alpha +d\) continuum of \(^6\)Li.

We report the measurement of reaction cross sections ($\sigma_R^{\rm ex}$) of $^{27,29}$F with a carbon target at RIKEN. The unexpectedly large $\sigma_R^{\rm ex}$ and derived matter radius identify $^{29}$F as the heaviest two-neutron Borromean halo to date. The halo is attributed to neutrons occupying the $2p_{3/2}$ orbital, thereby vanishing the shell closure associated with the neutron number $N = 20$. The results are explained by state-of-the-art shell model calculations. Coupled-cluster computations based on effective field theories of the strong nuclear force describe the matter radius of $^{27}$F but are challenged for $^{29}$F., Comment: 8 pages, 4 figures

Towards applications to multi-cluster systems involving heavy clusters, we study properties of a shallow-singular potential generated by supersymmetric transformations from an original deep potential. Changes of the relative wave functions by the transformations are quantified with electric-multipole transitions which give a different radial sensitivity to the wave function depending on their multipolarity. Despite the fact that the original and transformed potentials give exactly the same phase shift, some observables are unfavorably modified. We propose another possible way to obtain a desired supersymmetric potential.

Background: The neutron-rich $^{28,29}\mathrm{F}$ isotopes have been recently studied via knockout and interaction cross-section measurements. The two-neutron halo in $^{29}\mathrm{F}$ has been linked to the occupancy of $pf$ intruder configurations.Purpose: We investigate the bound spectrum and continuum states in $^{29}\mathrm{F}$, focusing on the electric dipole $(E1)$ response of low-lying excitations and the effect of dipole couplings on nuclear reactions.Method: $^{29}\mathrm{F}$ $(^{27}\mathrm{F}+n+n)$ wave functions are built within the hyperspherical harmonics expansion formalism, and total reaction cross sections are calculated using the Glauber theory. Continuum states and $B(E1)$ transition probabilities are described in a pseudostate approach using the analytical transformed harmonic oscillator basis. The corresponding structure form factors are used in continuum-discretized coupled-channels (CDCC) calculations to describe low-energy scattering.Results: Parity inversion in $^{28}\mathrm{F}$ leads to a $^{29}\mathrm{F}$ ground state characterized by 57.5% of ${({p}_{3/2})}^{2}$ intruder components, a strong dineutron configuration, and an increase of the matter radius with respect to the core radius of $\mathrm{\ensuremath{\Delta}}R=0.20$ fm. Glauber-model calculations for a carbon target at 240 MeV/nucleon provide a total reaction cross section of 1370 mb, in agreement with recent data. The model produces also a barely bound excited state corresponding to a quadrupole excitation. $B(E1)$ calculations into the continuum yield a total strength of 1.59 ${e}^{2}$ ${\mathrm{fm}}^{2}$ up to 6 MeV, and the $E1$ distribution exhibits a resonance at $\ensuremath{\approx}0.85$ MeV. Results using a standard shell-model order for $^{28}\mathrm{F}$ lead to a considerable reduction of the $B(E1)$ distribution. The four-body CDCC calculations for $^{29}\mathrm{F}+^{120}\mathrm{Sn}$ around the Coulomb barrier are dominated by dipole couplings, which totally cancel the Fresnel peak in the elastic-scattering cross section.Conclusions: Our three-body calculations for $^{29}\mathrm{F}$, using the most recent experimental information on $^{28}\mathrm{F}$, are consistent with a two-neutron halo. Our predictions show the low-lying enhancement of the $E1$ response expected for halo nuclei and the relevance of dipole couplings for low-energy reactions on heavy targets. These findings may guide future experimental campaigns.

In this contribution, we report our recent analysis of the nuclear radius of \(^{22}\)C with total reaction cross sections on \(^{12}\)C and \(^1\)H targets. The total reaction cross sections are calculated consistently for both the targets within a reliable microscopic framework, the Glauber theory. The multiple-scattering processes within the Glauber theory is fully taken into account using a Monte Carlo technique. We show that the simultaneous reproduction of the two recent cross section data are not feasible within the error bar and unlikely to obtain the huge matter radius \(\sim \)5 fm.

We propose formulas of the nuclear beta-decay rate that are useful in a practical calculation. The decay rate is determined by the product of the lepton and hadron current densities. A widely used formula relies upon the fact that the low-energy lepton wave functions in a nucleus can be well approximated by a constant and are linear to the radius for the $s$-wave and $p$-wave wave functions, respectively. We find, however, that the deviation from such a simple approximation is evident for heavy nuclei with large $Z$ by numerically solving the Dirac equation. In our proposed formulas, the neutrino wave function is treated exactly as a plane wave, while the electron wave function is obtained by iteratively solving the integral equation, thus we can control the uncertainty of the approximate wave function. The leading-order approximation gives a formula equivalent to the conventional one and overestimates the decay rate. We demonstrate that the next-to-leading-order formula reproduces well the exact result for a schematic transition density as well as a microscopic one obtained by a nuclear energy-density functional method.

Alpha($^{4}$He)-cluster models have often been used to describe light nuclei. Towards the application to multi-cluster systems involving heavy clusters, we study the relative wave functions of the $\alpha+^{16}$O and $\alpha+^{40}$Ca systems generated from phase-shift-equivalent potentials. In general, a potential between clusters is deep accommodating several redundant bound states which should be removed in an appropriate way. To avoid such a complicated computation, we generate a shallow-singular potential by using supersymmetric transformations from the original deep potential. Changes in the relative wave functions by the transformations are quantified with electric-multipole transitions which give a different radial sensitivity to the wave function depending on their multipolarity. Despite the fact that the original and transformed potentials give exactly the same phase shift, some observables are unfavorably modified. A possible way to obtain a desired supersymmetric potential is proposed., Comment: 30 pages, 9 figures, to appear in Nucl. Phys. A

Nuclear dipole excitation has been used as a probe of nuclear structure. To unveil the structure of various excitation modes proposed up to date, a study of isoscalar (IS) and isovector (IV) dipole excitations has been of particular importance. In this paper, we discuss the possibility of separating the dipole excitation cross sections into the IS and IV contributions using heavy-ion collisions at high-incident energies from 100 to 400 MeV/nucleon. We examine the dipole transitions of 6Li and 6He on carbon and lead targets and quantify the nuclear, Coulomb, and their interference contributions. We show that the IS and IV separation can be made in a certain degree of accuracy when appropriate target and incident energies are chosen for each case of 6Li and 6He.

Nuclear clustering plays an important role, especially in the dynamics of light nuclei. The importance of the emergence of the nuclear clustering was discussed in the recent measurement of the photoabsorption cross sections as it offered the possibility of the coexistence of various excitation modes which are closely related to the nuclear clustering. To understand the excitation mechanism, we study the electric-dipole ($E1$) responses of $^6$Li with a fully microscopic six-body calculation. The ground-state wave function is accurately described with a superposition of correlated Gaussian (CG) functions with the aid of the stochastic variational method. The final-state wave functions are also expressed by a number of the CG functions including important configurations to describe the six-body continuum states excited by the $E1$ field. We found that the out-of-phase transitions occur due to the oscillations of the valence nucleons against the $^4$He cluster at the low energies around 10 MeV indicating ``soft'' giant-dipole-resonance(GDR)-type excitations, which are very unique in the $^6$Li system but could be found in other nuclear systems. At the high energies beyond $\sim 30$ MeV typical GDR-type transitions occur. The $^3$He-$^3$H clustering plays an important role to the GDR phenomena in the intermediate energy regions around 20 MeV., Comment: 13 pages, 10 figures

The structure of $$^{22}$$ C plays a vital role in the new physics at subshell closure of $$N=16$$ in the neutron-rich region. We study the two-neutron correlations in the ground state of the weakly-bound Borromean nucleus $$^{22}$$ C sitting at the edge of the neutron-drip line and its sensitivity to $$\mathrm{core}$$ -n potential. For the present study, we employ a three-body ( $$\mathrm{core}+n+n$$ ) structure model designed for describing the Borromean system by explicit coupling of unbound continuum states of the subsystem ( $$\mathrm{core}+n$$ ). We use a density-independent contact-delta interaction to describe the neutron-neutron interaction and its strength is varied to fix the binding energy. Along with the ground-state properties of $$^{22}$$ C, we investigate its electric-dipole and monopole responses, discussing the contribution of various configurations. Our results indicate more configuration mixing as compared to the previous studies in the ground state of $$^{22}$$ C. However, they strongly depend upon the choice of the $$^{20}\mathrm{C}$$ -n potential as well as the binding energy of $$^{22}$$ C, which call for new precise measurements for the low-lying continuum structure of the binary system ( $$^{20}\mathrm{C}+n$$ ) and the mass of $$^{22}$$ C. These measurements will be essential to understand the Borromean three-body system $$^{22}$$ C with more accuracy.

A thick neutron skin emerges from the first determination of root mean square radii of the proton distributions for $^{17-22}$N from charge changing cross section measurements around 900$A$ MeV at GSI. Neutron halo effects are signaled for $^{22}$N from an increase in the proton and matter radii. The radii suggest an unconventional shell gap at $N$ = 14 arising from the attractive proton-neutron tensor interaction, in good agreement with shell model calculations. $Ab$ $initio$, in-medium similarity re-normalization group, calculations with a state-of-the-art chiral nucleon-nucleon and three-nucleon interaction reproduce well the data approaching the neutron drip-line isotopes but are challenged in explaining the complete isotopic trend of the radii., 18 pages, 3 figures

The European physical journal / Web of Conferences 223, 01003 (2019). doi:10.1051/epjconf/201922301003, Published by EDP Sciences, Les Ulis

Three-body correlations in three-body exotic atoms are studied with simple models that consist of three bosons interacting through a superposition of long- and short-range potentials. We discuss the correlations among particles by comparing the energy shifts given by precise three-body calculations and by the Deser-Trueman formula, in which the long- and short-range contributions are factorized. By varying the coupling of the short-range potential, we evaluate the ranges of the strength where the two-body correlations dominate and where the three-body correlations cannot be neglected., Comment: Submission to SciPost, Proceedings for the 24th edition of European Few Body Conference, Surrey, UK, 10 pages, 4 figures

Recently, the energy spectrum of $^{10}$Li was measured upto 4.6 MeV, via one-neutron transfer reaction d($^{9}$Li, p)$^{10}$Li. Considering the ambiguities on the $^{10}$Li continuum spectrum with reference to new data, we report the configuration mixing in the ground state of the two-neutron halo nucleus $^{11}$Li for two different choices of the $^{9}$Li$+$n potential. For the present study, we employ a three-body (core$+$n$+$n) structure model developed for describing the two-neutron halo system by explicit coupling of unbound continuum states of the subsystem (core$+$n), and discuss the two-neutron correlations in the ground state of $^{11}$Li., Comment: Submission to SciPost, Proceedings of the 24th European Conference of Few-Body Problems in Physics (EFB24), Surrey, UK, 2-4 September 2019, 10 pages, 4 figures

The 3He(α,γα,γ)7Be and 3H(α,γα,γ)7Li astrophysical S factors are calculated within the no-core shell model with continuum using a renormalized chiral nucleon–nucleon interaction. The 3He(α,γα,γ)7Be astrophysical S factors agree reasonably well with the experimental data while the 3H(α,γα,γ)7Li ones are overestimated. The seven-nucleon bound and resonance states and the α + 3He/3H elastic scattering are also studied and compared with experiment. The low-lying resonance properties are rather well reproduced by our approach. At low energies, the s-wave phase shift, which is non-resonant, is overestimated.

We study the configuration mixing in the ground state of the neutron-rich exotic nuclei. The results for weakly-bound two-neutron halo nuclei 11Li and 22C, and the two-neutron unbound nucleus 26O are reported. For the present study, we use a three-body (core + n + n) structure model developed for describing the two-neutron halo system by explicit coupling of unbound continuum states of the subsystem (core + n). We use a density-dependent contact-delta interaction to describe the neutron-neutron interaction and its strength is varied to fix the binding energy. We report the two-neutron correlations in the ground state of these systems.

A nuclear radius of $^{22}\mathrm{C}$ is investigated with the total reaction cross sections at medium- to high-incident energies in order to resolve the radius puzzle in which two recent interaction cross-section measurements using $^{1}\mathrm{H}$ and $^{12}\mathrm{C}$ targets show the quite different radii. The cross sections of $^{22}\mathrm{C}$ are calculated consistently for these target nuclei within a reliable microscopic framework, the Glauber theory. To describe appropriately such a reaction involving a spatially extended nucleus, the multiple scattering processes within the Glauber theory are fully taken into account, that is, the multidimensional integration in the Glauber amplitude is evaluated using a Monte Carlo technique without recourse to the optical-limit approximation. We discuss the sensitivity of the spatially extended halo tail to the total reaction cross sections. The root-mean-square matter radius obtained in this study is consistent with that extracted from the recent cross-section measurement on $^{12}\mathrm{C}$ target. We show that the simultaneous reproduction of the two recent measured cross sections is not feasible within this framework.

We present our recent study on the structure of kaonic nuclear systems with a modern antikaon-nucleon (K¯N) interaction. Strong short-range correlations due to the NN and K¯N interactions in three- to seven-body kaonic nuclear systems are systematically described with the correlated Gaussian method. Selecting specific three-, five- and seven-body systems involving K¯=K− or K¯0, we show that the competition between nucleon- and K¯NN-cluster correlations is a key to the understanding of the structure of the kaonic nuclei. While the K¯N interaction with isospin I = 0 is known to be strongly attractive, alpha-cluster correlations are further strong and determine the structure of the K¯NNNN system as observed in ordinary nuclear systems. In the K¯NNNNNN system, the K¯NN-cluster correlation becomes important due to the strong K¯NN correlation: The spin of its ground state can be changed depending on the strength of the K¯N interaction.We present our recent study on the structure of kaonic nuclear systems with a modern antikaon-nucleon (K¯N) interaction. Strong short-range correlations due to the NN and K¯N interactions in three- to seven-body kaonic nuclear systems are systematically described with the correlated Gaussian method. Selecting specific three-, five- and seven-body systems involving K¯=K− or K¯0, we show that the competition between nucleon- and K¯NN-cluster correlations is a key to the understanding of the structure of the kaonic nuclei. While the K¯N interaction with isospin I = 0 is known to be strongly attractive, alpha-cluster correlations are further strong and determine the structure of the K¯NNNN system as observed in ordinary nuclear systems. In the K¯NNNNNN system, the K¯NN-cluster correlation becomes important due to the strong K¯NN correlation: The spin of its ground state can be changed depending on the strength of the K¯N interaction.

Nuclear surface provides useful information on nuclear radius, nuclear structure as well as properties of nuclear matter. We discuss the relationship between the nuclear surface diffuseness and elastic scattering differential cross section at the first diffraction peak of high-energy nucleon-nucleus scattering as an efficient tool in order to extract the nuclear surface information from limited experimental data involving short-lived unstable nuclei. The high-energy reaction is described by a reliable microscopic reaction theory, the Glauber model. Extending the idea of the black sphere model, we find one-to-one correspondence between the nuclear bulk structure information and proton elastic scattering diffraction peak. This implies that we can extract both the nuclear radius and diffuseness simultaneously, using the position of the first diffraction peak and its magnitude of the elastic scattering differential cross section. We confirm the reliability of this approach by using realistic density distributions obtained by a mean-field model., Comment: 12 pages, 12 figures, to appear in Phys. Rev. C

We systematically investigate the neutron-skin thickness of neutron-rich nuclei within a compressible droplet model, which includes several parameters characterizing the surface tension and the equation of state (EOS) of asymmetric nuclear matter as well as corrections due to the surface diffuseness. Such a systematic analysis helps towards constraining the EOS parameters of asymmetric nuclear matter and the poorly known density dependence of the surface tension; the latter is estimated with help of available experimental data for the neutron and proton density distributions and the nuclear masses. Validity of the present approach is confirmed by calculating realistic density distributions of Ca, Ni, Zr, Sn, Yb, and Pb isotopes within a microscopic Skyrme-Hartree-Fock+BCS method for various sets of the effective nuclear force. Our macroscopic model accompanied by the diffuseness corrections works well in the sense that it well reproduces the evolution of the microscopically deduced neutron-skin thickness with respect to the neutron number for selected sets of the effective nuclear force. We find that the surface tension of the compressible nuclear droplet is a key to bridging a gap between microscopic and macroscopic approaches., 11 pages, 7 figures

Low-lying electric-dipole ($E1$) strength of a neutron-rich nucleus contains information on neutron-skin thickness, deformation, and shell evolution. We discuss the possibility of making use of total reaction cross sections on $^{40}$Ca, $^{120}$Sn, and $^{208}$Pb targets to probe the $E1$ strength of neutron-rich Ca, Ni, and Sn isotopes. They exhibit large enhancement of the $E1$ strength at neutron number $N > 28$, $50$, and $82$, respectively, due to a change of the single-particle orbits near the Fermi surface participating in the transitions. The density distributions and the electric-multipole strength functions of those isotopes are calculated by the Hartree-Fock+BCS and the canonical-basis-time-dependent-Hartree-Fock-Bogoliubov methods, respectively, using three kinds of Skyrme-type effective interaction. The nuclear and Coulomb breakup processes are respectively described with the Glauber model and the equivalent photon method in which the effect of finite-charge distribution is taken into account. The three Skyrme interactions give different results for the total reaction cross sections because of different Coulomb breakup contributions. The contribution of the low-lying $E1$ strength is amplified when the low-incident energy is chosen. With an appropriate choice of the incident energy and target nucleus, the total reaction cross section can be complementary to the Coulomb excitation for analysing the low-lying $E1$ strength of unstable nuclei., 12 pages, 6 figures, to appear in Phys. Rev. C

The structure of light antikaon-nuclear quasibound states, which consist of an antikaon $(\overline{K}={K}^{\ensuremath{-}},{\overline{K}}^{0})$ and a few nucleons $(N=p,n)$, such as $\overline{K}NN$, $\overline{K}NNN$, $\overline{K}NNNN$, and $\overline{K}NNNNNN$ systems, is studied with full three- to seven-body calculations. Employing a realistic $\overline{K}N$ potential based on the chiral SU(3) effective field theory with the SIDDHARTA constraint, we show that the central nucleon densities of these systems increase when the antikaon is injected, by about factor of 2 at maximum. The $\overline{K}NNNN$ system shows the largest central density, about 0.74 ${\mathrm{fm}}^{\ensuremath{-}3}$ even with the phenomenological $\overline{K}N$ potential, which is not as high as those suggested in previous studies with approximate treatments of the few-body systems. We find that the spin of the ground state of the $\overline{K}NNNNNN$ system depends on the strength of the $\overline{K}N$ attraction. Thus, the quantum number of the ground state can be another constraint on the $\overline{K}N$ interaction.

Nuclear responses involve the information on nuclear dynamics as well as underlying interactions. To describe them theoretically, one faces the difficulty in treating many-body continuum states. A newly developed time-dependent correlated Gaussian basis allows us to describe the response function without explicit construction of the many-body continuum states. As simple examples, the photoabsorption reactions of \(^2\)H and \(^3\)He are presented. In both cases, the calculations are remarkably improved compared to those with time-independent correlated Gaussian.

We formulate a core plus few-nucleon model allowing for a rotational excitation of the core. Three and four-body systems including a 12C core nucleus are studied using an explicitly correlated Gaussian basis. Effects of the core excitation are tested by investigating energy levels and electric quadrupole transition probabilities. Though some improvements are obtained, we realize that the Pauli principle for the nucleon-deformable core motion has to be appropriately defined for better understanding.

We provide a microscopic global optical potential (MGOP) for nucleon-nucleus (NA) systems in a wide range of nuclear mass numbers (A = 10-276) and incident energies (E = 50-400 MeV). The potential is microscopically constructed based on a single-folding (SF) model with the complex G-matrix interaction. The nuclear densities used in the SF model are generated, in a non-empirical way, from two kinds of microscopic mean-field models: the relativistic-mean-field (RMF) and Skyrme-Hartree-Fock BCS (HF-PBCS) models. We calculate the NA potentials for more than 1000 even-even nuclei with atomic number Z = 6-92, involving proton- and neutron-rich unstable nuclei. We confirm that both the MGOP models well reproduce the available experimental data of the total reaction cross sections, the total neutron cross sections, the elastic-scattering cross sections, the analyzing power, and the spin-rotation function Q. We also calculate the proton scattering cross sections of O-22, O-24, and Ni-56 targets to compare the experimental data and then the cross sections for unknown S-48, Zr-100, and Zr-110 are presented for future measurements. For the sake of convenience, the real and imaginary parts of the central and spin-orbit components of the NA potentials are respectively represented in a linear combination of 12-range Gaussians. They are provided on the website [http://www2.yukawa.kyoto-u.ac.jp/similar to takenori.furumoto/] with a program source file for reconstructing the MGOP.

We present precise three-body calculations for the spectrum of kaonic deuterium with a realistic antikaon-nucleon interaction. Thanks to the precise measurement of kaonic hydrogen, it is now possible to construct realistic $\bar KN$ interactions which reproduce the whole set of experimental data in the threshold region. Employing such realistic interactions, the energy of the three-body system of kaonic deuterium is determined with the accuracy of eV, by expanding its wave function with a large number of correlated Gaussian basis functions. The level shift and width of the 1S state are found to be 670 eV and 1016 eV, respectively. The improved Deser formulas work reasonably well to estimate the shift and width of kaonic hydrogen, but their application to kaonic deuterium does not give an accurate estimation. It is shown that the result is sensitive to the I = 1 component of the $\bar KN$ interaction, which will be further constrained in future experiments.

In this contribution, we discuss the electroweak responses of 4He based on a full four-body calculation. The wave function of the ground state is obtained accurately using an explicitly correlated basis. Four-body final states are expressed in a superposition of many basis functions including configurations which have 3+1 and 2+1+1 cluster partitions of four-nucleon system explicitly. The continuum is properly treated by taking the two approaches: one is the complex scaling method and the other is the microscopic R-matrix method. The calculated photoabsorption cross sections agree up to the rest energy of a pion. The spin–dipole strength function is also presented and its relationship between the spectrum of 4He is discussed.

A precise description of neutrino-nucleus reactions will play a key role in addressing fundamental questions such as the leptonic CP violation and the neutrino mass hierarchy through analyzing data from next-generation neutrino oscillation experiments. The neutrino energy relevant to the neutrino-nucleus reactions spans a broad range and, accordingly, the dominant reaction mechanism varies across the energy region from quasi-elastic scattering through nucleon resonance excitations to deep inelastic scattering. This corresponds to transitions of the effective degree of freedom for theoretical description from nucleons through meson-baryon to quarks. The main purpose of this review is to report our recent efforts towards a unified description of the neutrino-nucleus reactions over the wide energy range; recent overall progress in the field is also sketched. Starting with an overview of the current status of neutrino-nucleus scattering experiments, we formulate the cross section to be commonly used for the reactions over all the energy regions. A description of the neutrino-nucleon reactions follows and, in particular, a dynamical coupled-channels model for meson productions in and beyond the $\Delta$(1232) region is discussed in detail. We then discuss the neutrino-nucleus reactions, putting emphasis on our theoretical approaches. We start the discussion with electroweak processes in few-nucleon systems studied with the correlated Gaussian method. Then we describe quasi-elastic scattering with nuclear spectral functions, and meson productions with a $\Delta$-hole model. Nuclear modifications of the parton distribution functions determined through a global analysis are also discussed. Finally, we discuss issues to be addressed for future developments., Comment: 68 pages, 33 figures; (v2) reference added, author name in metadata corrected; (v3) Discussion extended in Sec. I and IV, Fig. 10 added to compare with a previous result on two-pion productions, Table I extended to include a comparison with a recent T2K result on coherent pion production

We report proton radii of 12-19C densities derived from first accurate charge changing cross section measurements at 900A MeV with a carbon target. A thick neutron surface evolves from ~0.5 fm in 15C to ~1 fm in 19C. Also, the halo radius in 19C is found to be 6.4±0.7 fm as large as 11Li. Ab initio calculations based on chiral nucleon-nucleon and three-nucleon forces reproduce the radii well.

Charge-changing cross sections at high energies are expected to provide useful information on nuclear charge radii. No reliable theory to calculate the cross section has yet been available. We develop a formula using Glauber and eikonal approximations and test its validity with recent new data on carbon isotopes measured at around $900A$ MeV. We first confirm that our theory reproduces the cross sections of $^{12,13,14}\mathrm{C}+^{12}\mathrm{C}$ consistently with the known charge radii. Next we show that the cross sections of $^{12\ensuremath{-}19}\mathrm{C}$ on a proton target are all well reproduced provided the role of neutrons is accounted for. We also discuss the energy dependence of the charge-changing cross sections.

The maximum entropy method is examined as a new tool for solving the ill-posed inversion problem involved in the Lorentz integral transformation (LIT) method. As an example, we apply the method to the spin-dipole strength function of 4He. We show that the method can be successfully used for inversion of LIT, provided the LIT function is available with a sufficient accuracy., 5 pages, 2 figures. Poster presented by TM at the International Workshop on Neutrino-Nucleus Interaction in the Few-GeV Region (NuInt15), Novenber 16-21 2015, Osaka, Japan

Resonances and continuum states of 4He are studied using correlated Gaussians. Applicability of the square-integrable functions is tested with use of a complex scaling method. All the known levels of 4He up to the excitation energy of 26 MeV are well understood with a realistic nucleon-nucleon potential. The importance of the tensor force is stressed. Strength functions for isoscalar monopole and spin-dipole tensor operators are investigated.

We investigate the short-range correlations in light nuclei. The highly correlated many-body states are obtained with an explicitly correlated basis which enables us to get a precise solution of a many-body Schrodinger equation for a realistic interaction. We show two-body density distributions for the different spin-isospin channels calculated from three- and four-body states to investigate the short-range correlations between nucleon pairs. At distances below 1 fm a universal behavior is found which does not depend on the many-body states. The universality is also seen in high momentum components of the two-body momentum distributions.

The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. In addition to the complex nature of nuclear forces, one faces the quantum-mechanical many-nucleon problem governed by an interplay between bound and continuum states. In recent years, significant progress has been made in ab initio nuclear structure and reaction calculations based on input from QCD employing Hamiltonians constructed within chiral effective field theory. In this contribution, we present one of such promising techniques capable of describing simultaneously both bound and scattering states in light nuclei. By combining the resonating-group method (RGM) with the ab initio no-core shell model (NCSM), we complement a microscopic cluster approach with the use of realistic interactions and a microscopic and consistent description of the clusters. We discuss applications to light nuclei scattering, radiative capture and fusion reactions.

We investigate the 6He dipole distribution in a three-body α+n+n model. Two approaches are used to describe the three-body 1− continuum: the discretized-continuum method, where the scattering wave functions are approximated by square-integrable functions, and the R-matrix formalism, where their asymptotic behaviour is taken into account. We show that some ambiguity exists in the pseudostate method, owing to the smoothing technique, necessary to derive continuous distributions. We show evidence for the important role of the halo structure in the E1 dipole strength. We also address the treatment of Pauli forbidden states in the three-body wave functions.