Quartet structure in atomic nuclei

Abstract

A quartet is a tightly bound cluster of two protons and two neutrons, similar to the α particle but occasionally with nonzero spin and/or isospin. If the interaction between two quartets is weak in given states, such states are concluded to be well represented by a quartet structure. In this paper, we study the quartet structure of eight valence nucleons in two cases. The first is a single j shell, demonstrating that the so-called stretch scheme [M. Danos and V. Gillet, Phys. Rev. Lett. 17, 703 (1966)] is very good for low-spin states with a quadruplequadruple interaction, and is reasonably good under realistic interactions. The second case is the ground state of 92 Pd in the p 1/2 p 3/2 f 5/2 g 9/2 shell with the JUN45 effective interaction. We show that the quartet correlation is essential in the ground state of 92 Pd.The α particle (namely, 4 He) is a very tightly bound system of two protons and two neutrons. Therefore α correlation in low-lying states of atomic nuclei has been conjectured and studied extensively [1]. One of the most famous examples is the Hoyle state [2] (weak coupling of the α particle and 8 Be in the 12 C nucleus). The work in Ref. [3] suggests that the Hoyle state has a deformed shape accompanied by a rotational band. Similar structure was also studied in 8 Be, 16 O, 20 Ne, and 24 Mg.There has been much work done towards quartet correlations in N = Z nuclei [4][5][6][7][8][9][10][11]. In the literature a cluster with two protons and two neutrons coupled to a given spin and isospin is usually called a quartet. It is a tightly bound cluster, similar to the α particle but occasionally with nonzero spin and/or isospin. If the interaction between two quartets is weak in given states, such states are concluded to be well represented by quartet structure. Among various efforts along this line, here we mention work involving antisymmetrized molecular dynamics (AMD) [12][13][14] and "quartet truncation" models [6,[15][16][17][18][19]. In AMD, the wave function is constructed by using multicenter configurations, similar to the idea in molecular physics. Not only the quartet structure but also other types of clustering structures are taken into account in the configuration space of the AMD. The quartet truncation models are based on the quartet truncation scheme of the nuclear shell model. In the quartet truncation models, the building blocks of wave functions are quartets. It has been shown that pairing correlation energies in the full shell model space and those in the quartet-truncated space are very close to each other under a simple phenomenological interaction [15][16][17][18][19]. The connection between the AMD and the quartet (or many-body cluster) truncation scheme is discussed in Refs. [20,21].In this paper we study structures consisting of two quartets (namely, eight valence nucleons). The framework we use here is a quartet truncation model similar to that in Refs. [6,15]. Our formalism is based on the nucleon-pair approximation of the shell model with isospin symmetry [22][23][24]. The bu...

Gate control of the spin mobility through the modification of the spin-orbit interaction in two-dimensional systems

“…A two-dimensional electron gas (2DEG) hosted in a quantum well (QW) with two occupied subbands offers unexplored opportunities for the study of spin transport [33,34]. Theoretically, the inter-and intra-subband spinorbit couplings (SOCs) have been extensively studied [35][36][37][38]. In terms of a random walk model (RWM) [39], the spin drift and diffusion was recently developed for these systems displaying two possible scenarios regarding the intersubband scattering (ISS) rate [40].…”

“…plus corrections due to the intersubband SOCs [23,[35][36][37][38]41]. Above, g = −0.44 is the electron g-factor for GaAs and µ B is the Bohr magneton.…”

Unified description of pairing and quarteting correlations within the particle-hole-boson approach

“…Indeed, it can be seen by combining Eqs. (33) and (34) that the average level occupation fraction satisfies , e.g. for hole states…”

Active Particles Powered by Quincke Rotation in a Bulk Fluid

“…For the sake of completeness, we provide all the elements of the resistance matrix R relevant for resistive-force theory of a slender helix in viscous flow [22],…”