Nuclear Theory·nucl-th

Wednesday·April 11, 2018

8 papers—6 primary·2 cross-listed

01
On the origin of asymmetric fission of actinides
Guillaume Scamps · Cédric Simenel
Nuclear fission of heavy (actinide) nuclei results predominantly in asymmetric mass-splits. Without quantum shells, which can give extra binding energy to these mass-asymmetric shapes, the nuclei would fission symmetrically. The strongest shell effects are in spherical nuclei, so naturally the spherical "doubly-magic" $^{132}$ Sn nucleus ( $Z = 50$ protons), was expected to play a major role. However, a systematic study of fission has shown that the heavy fragments are distributed around $Z = 52$ to 56, indicating that $^{132}$ Sn is not the only driver. Reconciling the strong spherical shell effects at $Z = 50$ with the different $Z$ values of fission fragments observed in nature has been a longstanding puzzle. Here, we show that the final mass asymmetry of the fragments is also determined by the extra stability of octupole (pear-shaped) deformations which have been recently confirmed experimentally around $^{144}$ Ba ( $Z = 56$ ), one of very few nuclei with shell-stabilized octupole deformation. Using a modern quantum many-body model of superfluid fission dynamics, we found that heavy fission fragments are produced predominantly with $52 - 56$ protons, associated with significant octupole deformation acquired on the way to fission. These octupole shapes favouring asymmetric fission are induced by deformed shells at $Z = 52$ and 56. In contrast, spherical "magic" nuclei are very resistant to octupole deformation, which hinders their production as fission fragments. These findings may explain surprising observations of asymmetric fission of lighter than lead nuclei.
nucl-thNature(2018)·202 citations
02
Low-Energy Gamow-Teller Transitions in deformed $N = Z$ odd-odd Nuclei
Hiroyuki Morita · Yoshiko Kanada-En'yo
We have investigated the Gamow-Teller transitions from $^{22} Ne$ to $^{22} Na$ by applying the isospin projected antisymmetrized molecular dynamics combined with generator coordinate method. We have found that the GT strength from $^{A} Z (J^{π} T) =^{22} Ne (0_{1}^{+} 1)$ is fragmented into two final states $^{22} Na (1_{1, 2}^{+} 0)$ , which belong to $K = 0$ and $K = 1$ bands constructed by a prolately deformed $^{20}$ Ne core with a $S = 1$ proton-neutron ( $p n$ ) pair. Coupling of the intrinsic-spin of the $p n$ pair with the core deformation play an important role in the GT fragmentation. The symmetry breaking in the intrinsic-spin rotation leads to the $S U (4)$ -symmetry breaking of the $N N$ pair and causes the GT fragmentation. We have compared the features of the GT transitions with those for $^{10} Be \to^{10} B$ and discuss the link of the $S U (4)$ -symmetry and the GT fragmentation in the deformed systems.
nucl-thPRC(2018)·1 citation
03
The restriction of $σ^{*}$ and $ϕ$ on the protoneutron stars PSR J0348+0432
Bin Hong🇨🇳 · Zhong-Zhou Ren🇨🇳
The restriction of $σ^{*}$ and $ϕ$ on the protoneutron star (PNS) PSR J0348+0432 is described by the relativistic mean field theory (RMFT) through choosing the effective coupling constants. We use an entropy per baryon S=1 to describe thermal effect on PSR J0348+0432 in this work and compare the differences between PNS PSR J0348+0432 with $σ^{*}$ , $ϕ$ and without $σ^{*}$ , $ϕ$ . These effects include the particle number distribution, the mass-radius relation, the moment of inertia and the surface gravitational redshift. The PNS PSR J0348+0432 with $σ^{*}$ and $ϕ$ has more nucleons and will pushed forward the threshold for the appearance of the hyperons. The mass-radius relations are ( $2.010 M_{⊙}$ ,12.6520km) with $σ^{*}$ and $ϕ$ and ( $2.010 M_{⊙}$ ,12.6170km) without $σ^{*}$ and $ϕ$ respectively. The moment of inertia corresponding PNS PSR J0348+0432 are ( $2.010 M_{⊙}$ ,1.510 $\times 1 0^{45}$ g.cm $^{2}$ ) and ( $2.010 M_{⊙}$ ,1.559 $\times 1 0^{45}$ g.cm $^{2}$ ) respectively, the surface gravitational redshift corresponding PNS PSR J0348+0432 are ( $2.010 M_{⊙}$ ,0.3747) and ( $2.010 M_{⊙}$ ,0.3701) respectively. With the help of these calculations, we study the restriction of $σ^{*}$ and $ϕ$ on the interactions between baryons in PNS core.
nucl-thCPC(2018)·4 citations
04
Meson-exchange currents and quasielastic predictions for neutrino-nucleus scattering
M.B. Barbaro🇮🇹 · J.E. Amaro🇪🇸 · J.A. Caballero🇪🇸 · A. De Pace🇮🇹 · T.W. Donnelly🇺🇸 · G.D. Megias🇪🇸 · I. Ruiz Simo🇪🇸
We review some recent progress in the study of electroweak interactions in nuclei within the SuSAv2-MEC model. The model has the capability to predict (anti)neutrino scattering observables on different nuclei. The theoretical predictions are compared with the recent T2K $ν_{μ} -^{16}$ O data and good agreement is found at all kinematics. The results are very similar to those obtained for $ν_{μ} -^{12}$ C scattering, except at low energies, where some differences emerge. The role of meson-exchange currents in the two-particle two-hole channel is analyzed in some detail. In particular it is shown that the density dependence of these contributions is different from what is found for the quasielastic response.
nucl-thhep-phnucl-exPoS(2017)·0 citations
05
Fluctuating fluid dynamics for the QGP in the LHC and BES era
Marcus Bluhm (1, 2)🇵🇱 · Marlene Nahrgang (2)🇫🇷 · Thomas Schaefer (3)🇺🇸 · Steffen A. Bass (4) ((1) Wroclaw U., (2) SUBATECH, Nantes, (3) North Carolina State U., (4) Duke U.)🇬🇧
In an era of high-precision determinations of QGP properties a full incorporation of fluid dynamical fluctuations into our models has become crucial, in particular, when describing the dynamics of small systems or near the conjectured QCD critical point. In this talk we discuss some effects of the propagation of these fluctuations. For LHC physics we focus on fluctuations in the energy-momentum tensor, while the impact of fluctuations in the diffusive net-baryon density is studied to improve our knowledge on the formation of critical fluctuations being searched in current and future BES programs.
nucl-thEPJ Web Conf.(2018)·18 citations
06
Heavy-quark dynamics in a hydrodynamically evolving medium
Marlene Nahrgang🇫🇷 · Joerg Aichelin🇫🇷 · Pol Bernard Gossiaux🇫🇷 · Klaus Werner (SUBATECH, Nantes)🇫🇷
In this talk we will discuss the recent advances in describing heavy-quark dynamics in the quark-gluon plasma (QGP), which evolves hydrodynamically. Special emphasis is put on the collective flow of the heavy-quarks with the medium constituents, for which we present our latest results obtained within the MC@sHQ+EPOS2 model at $s = 5$ ~TeV.
nucl-thhep-phEPJ Web Conf.(2018)·2 citations
07
Momentum Sum Rule Violation in QCD at High Energy Colliders and Confinement
Gouranga C Nayak🇺🇸
Momentum sum rule in QCD is widely used at high energy colliders. Although the exact form of the confinement potential energy is not known but the confinement potential energy at large distance $r$ can not rise slower than $ln (r)$ . In this paper we find that if the confinement potential energy at large distance $r$ rises linearly with $r$ (or faster) then the momentum sum rule in QCD is violated at the high energy colliders if we consider the hadron size as infinite. For finite size hadron we find that the momentum sum rule in QCD is violated at the high energy colliders for any form of the confinement potential energy.
↳ hep-phhep-latnucl-th5 citations
08
Dilepton photoproduction on a deuteron target
Carl E. Carlson (William and Mary)🇺🇸 · Vladyslav Pauk🇩🇪 · Marc Vanderhaeghen (Johannes Gutenberg-University, Mainz)🇩🇪
We investigate the sensitivity of the cross section for lepton pair production off a deuteron target, $γ d \to l^{+} l^{-} d$ , to the deuteron charge radius. We show that for small momentum transfers the Bethe-Heitler process dominates, and that it is sensitive to the charge radius such that a cross section ratio measurement of about $0.1%$ relative accuracy could give a deuteron charge radius more accurate that the current electron scattering value and sufficiently accurate to distinguish between the electronic and muonic atomic values.
↳ hep-phnucl-thPLB(2019)·5 citations

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first authorsco-authorsvia INSPIRE