Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session FA: Frontiers of Nuclear Theory |
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Chair: Takashi Abe, University of Tokyo Room: Hilton Kona 4 |
Friday, October 26, 2018 9:00AM - 9:45AM |
FA.00001: Quantum self-organization and nuclear collectivity Invited Speaker: Takaharu Otsuka The interplay between the single-particle states and the collective modes have been one of the central subjects of nuclear physics since the very beginning. If the single-particle aspect is too strong, for instance, with a large gap between relevant orbits, it certainly suppresses the collective mode. Thus, the single-particle states and the collective modes have been considered to be enemies each other, and the former behaves as the resistance power against the latter. However, an opposing idea has arisen recently. The nuclear force is characterized by a component driving a collective mode, like the quadrupole interaction for the ellipsoidal shape. Recently, the monopole component of nuclear forces has been shown to reduce this resistance power: energies of single-particle orbits can be optimized for a given mode by choosing favorable configurations. In fact, the monopole component of the central and tensor forces show strong orbital dependences, and can move single-particle energies depending on configurations of other nucleons. This mechanism is called the quantum self-organization, and is consistent with the general self-organization concept. Its effect can be seen in the quantum phase transition of Zr isotopes, while the same underlying mechanism promotes the shape evolution in Sm isotopes. These phenomena have been clarified quantitatively by state-of-the-art Monte Carlo Shell Model calculations with reasonable interactions, showing good agreements with experiment. Thus, single-particle states are not necessarily an enemy of the collectivity, but can be a good friend. One of the striking outcome is that contrary to the conventional idea, side bands of rotational nuclei may not be beta or gamma vibration of the ellipsoidal shape, but may be consequences of many-body correlations due to nuclear forces, beyond the liquid drop model. Some other manifestations and possible experimental challenges will be discussed. |
Friday, October 26, 2018 9:45AM - 10:30AM |
FA.00002: Emergent phenomena in nuclei: Collectivity and clustering within an ab initio framework Invited Speaker: Kristina D Launey Remarkable progress in {\it ab initio} nuclear theory has opened up new domains of the nuclear chart for study and prediction. In this talk, I will discuss two central questions, namely, understanding and predicting diverse nuclear properties from the underlying physics of only two or three nucleons, and the origin of emergent orderly patterns in the intricate nuclear dynamics. In particular, I will address a long-standing challenge, namely, the emergence from first principles of collectivity and clustering in light to medium-mass nuclei, with implications for reproducing enhanced E2 transitions without effective charges; for the formation of alpha clustering; as well as for the description of alpha-capture reactions of interest to nucleosynthesis. This is achieved by using physically relevant degrees of freedom including the symmetry-adapted basis framework, which exploits approximate symmetries that, we find, dominate the nuclear dynamics. These new developments, empowered by high performance computing, are key to further advancing our knowledge about astrophysical processes and fundamental symmetries in nature, as well as related reactions, providing complementary theory to experimental research at radioactive beam facilities. |
Friday, October 26, 2018 10:30AM - 11:15AM |
FA.00003: Nuclear structure problems solved by realistic nucleonic interaction Invited Speaker: Hitoshi Nakada I will present selected results of self-consistent mean-field (SCMF) calculations using semi-realistic interactions, aiming at disclosing roles of specific channels of the nucleonic interaction at qualitative and quantitative level. In practice, studies in this line seem to solve some puzzles in the nuclear structure physics. The semi-realistic interaction of the M3Y-type is applied, which are based on the G-matrix, and include the tensor force without any phenomenological modification. With such tensor force, the level inversion of $p0d_{3/2}$ and $p1s_{1/2}$ from $^{40}$Ca to $^{48}$Ca is nicely reproduced. The deformation of $^{80}$Zr is described well, with keeping nearly doubly magic nature of $^{90}$Zr, implying that the realistic tensor force operates with a good balance. Second, it has been pointed out that the three-nucleon LS interaction based on the chiral EFT could account for missing part of origin of the $\ell s$ splitting. Incorporating it into the SCMF calculations, long-standing puzzles with respect to charge radii of spherical nuclei can be solved. The kink in the isotope shifts in the Pb nuclei is reproduced reasonably well, without fictitious degeneracy of $n1g_{9/2}$ and $n0i_{11/2}$. Moreover, the same interaction accounts for almost equal charge radii between $^{40}$Ca and $^{48}$Ca. This seems consistent with the \textit{ab initio} result, and may anatomize it. The SCMF calculations with the same interaction also describe rapid increase of the charge radii from $^{48}$Ca to $^{52}$Ca, and predict a kink for the isotope shifts in the Sn chain at $N=82$. |
Friday, October 26, 2018 11:15AM - 12:00PM |
FA.00004: Nuclear structure and reactions from chiral two- and three-nucleon forces Invited Speaker: Petr Navratil In recent years, significant progress has been made in ab initionuclear structure and reaction calculations based on input from QCD employing Hamiltonians constructed within chiral effective field theory. One of the recently developed approaches is the No-Core Shell Model with Continuum (NCSMC) [1,2], capable of describing both bound and scattering states in light nuclei simultaneously. I will present latest NCSMC calculations of weakly bound states and resonances of exotic halo nuclei such as 6He and 11Be and discuss strong E1 transitions and photo-dissociation of 11Be. I will also present our results for unbound nuclei such as 7He, 9He and 11N and highlight the role of chiral NN and 3N interactions. Further, I will present our calculations of the 11C(p,p) scattering and the astrophysical relevant 11C(p,γ)12N radiative capture. Finally, I will discuss polarization effects in the 3H(d,n)4He fusion. [1] S. Baroni, P. Navratil, and S. Quaglioni, Phys. Rev. Lett.110, 022505 (2013); Phys. Rev. C 87, 034326 (2013). [2] P. Navratil, S. Quaglioni, G. Hupin, C. Romero-Redondo, A. Calci, Physica Scripta 91, 053002 (2016). |
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