九大原子核セミナー

2020年7月10日(金) 16:00〜17:30

講師：Pascal Naidon 氏 (理研仁科加速器科学研究センター)
演題：QCD-like phase diagram of resonantly interacting SU(3) Fermi gases
場所：※オンラインセミナー

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

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

2020年6月26日(金) 15:00〜

講師：Ying Zhang 氏 (天津大学)
演題：A simple quantum many-body system – neutron drop
場所：※オンラインセミナー

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

[1] B. S. Pudliner, A. Smerzi, J. Carlson, V. R. Pandharipande, S. C. Pieper, D. G. Ravenhall, Neutron drops and skyrme energy-density functionals, Phys. Rev. Lett. 76 (1996) 2416-2419.
[2] S. Gandolfi, J. Carlson, S. C. Pieper, Cold neutrons trapped in external elds, Phys. Rev. Lett. 106 (2011) 012501.
[3] S. K. Bogner, R. J. Furnstahl, H. Hergert, M. Kortelainen, P. Maris, M. Stoitsov, J. P. Vary, Testing the density matrix expansion against ab initio calcu-
lations of trapped neutron drops, Phys. Rev. C 84 (2011) 044306.
[4] Y. H. Ge, Y. Zhang, J. N. Hu, Effects of pairing correlation on neutron drop, Sci. China Physics, Mech. Astron. 63 (2020) 242011.