Nuclear Theory·nucl-th

Friday·December 30, 2016

14 papers—10 primary·4 cross-listed

01
Time-dependent mean field determination of the excitation energy in transfer reactions: application to the reaction $^{238}$ U on $^{12}$ C at 6.14 MeV/A
G. Scamps🇯🇵 · C. Rodríguez-Tajes🇫🇷 · D. Lacroix🇫🇷 · F. Farget🇫🇷
The internal excitation of nuclei after multi-nucleon transfer is estimated by using the time-dependent mean-field theory. Transfer probabilities for each channel as well as the energy loss after re-separation are calculated. By combining these two informations, we show that the excitation energy distribution of the transfer fragments can be obtained separately for the different transfer channels. The method is applied to the reaction involving a $^{238}$ U beam on a $^{12}$ C target, which has recently been measured at GANIL. It is shown that the excitation energy calculated with the microscopic theory compares well with the experimental observation, provided that the competition with fusion is properly taken into account. The reliability of the excitation energy is further confirmed by the comparison with the phenomenological HIPSE model at higher center of mass energies.
nucl-thnucl-exPRC(2017)·5 citations
02
Using TDHF to study quasifission dynamics
A.S. Umar · C. Simenel
We show that the microscopic TDHF approach provides an important tool to shed some light on the nuclear dynamics leading to the formation of superheavy elements. In particular, we discuss studying quasifission dynamics and calculating ingredients for compound nucleus formation probability calculations.
nucl-th0 citations
03
Mesic nuclei with a heavy antiquark
Yasuhiro Yamaguchi🇮🇹 · Shigehiro Yasui🇯🇵
The binding system of a hadron and a nucleus is a topic of great interest for investigating the hadron properties. In the heavy-flavor region, the attraction between a $P (= D ˉ, B)$ meson and a nucleon $N$ can appear, where the $P N - P^{*} N$ mixing plays an important role in relation to the heavy-quark spin symmetry. The attraction can produce exotic heavy mesic nuclei that are stable against the strong decay. We study an exotic system where the $D ˉ$ ( $B$ ) meson and nucleus are bound. The meson-nucleus interaction is given by a folding potential with single-channel $P N$ interaction and the nucleon number distribution function. By solving the Schrödinger equations of the heavy meson and the nucleus, we obtain several bound and resonant states for nucleon number $A = 16, \dots, 208$ . The results indicate the possible existence of exotic mesic nuclei with a heavy antiquark.
nucl-thhep-phPTEP(2017)·3 citations
04
Radiative 3He-alpha reaction in Halo Effective Field Theory
Renato Higa🇧🇷 · Gautam Rupak🇺🇸 · Akshay Vaghani🇺🇸
In this work we study the radiative capture of $^{3} He$ on $^{4} He$ within the halo effective field theory (EFT) framework. At leading order the capture amplitude comprises the initial state $s$ -wave strong and Coulomb interactions summed to all orders. At the same order in the expansion, leading two-body currents contribute as well. We find delicate cancelations between the various contributions, and the two-body current contributions can be replaced by appropriately enhancing the asymptotic normalizations of the $^{7}$ Be ground and first excited state wave functions. The next-to-leading order corrections come from the $s$ -wave shape parameter and the pure Coulomb $d$ -wave initial state interactions. We fit the EFT parameters to available scattering data and most recent capture data. Our zero-energy astrophysical $S$ -factor estimate, $S_{34} \sim 0.55$ keV b, is consistent within error bars with the average in the literature.
nucl-thastro-ph.SRhep-phnucl-exEPJA(2018)·46 citations
05
Relating Measurable Correlations in Heavy Ion Collisions to Bulk Properties of Equilibrated QCD Matter
Scott Pratt🇺🇸 · Clint Young🇺🇸
In order to compare theoretical calculations of thermal fluctuations of conserved quantities, such as charge susceptibilities or the specific heat, to experimentally measured correlations and fluctuations in heavy ion collisions, one must confront the reality of changing conditions within the collision environment, and transport of conserved quantities within the finite duration of the expansion and dissolution of the reaction. In previous work, fluctuations of conserved charges from lattice calculations, where charge is allowed to fluctuate within the designated volume consistent with the grand canonical ensemble, was linked to correlations in heavy-ion collisions, which accounted for the finite time with which to transport absolutely conserved quanatities. In this case details of the correlations were related to the evolution of the susceptibility. In this work, this paradigm is extended to compare fluctuations of momentum or energy to transverse energy correlations that can be measured in heavy-ion collisions. The sensitivity of these correlations to the equation of state, viscosity and diffusion is illustrated by considering simple models without transverse expansion. Only correlations in relative spatial rapidity are discussed here, but the prospects for extending these ideas to realistic calculations and for making realistic connections with experiment are discussed.
nucl-thPRC(2017)·13 citations
06
Generalized density functional equation of state for astrophysical simulations with 3-body forces and quark gluon plasma
J. Pocahontas Olson🇺🇸 · MacKenzie Warren🇺🇸 · Matthew Meixner🇺🇸 · Grant J. Mathews🇺🇸 · N.Q. Lan🇺🇸 · H.E. Dalhed🇺🇸
We present an updated general purpose nuclear equation of state (EoS) for use in simulations of core-collapse supernovae, neutron star mergers and black hole collapse. This EoS is formulated in the context of Density Functional Theory (DFT) and is generalized to include all DFT EoSs consistent with known nuclear and astrophysical constraints. This EoS also allows for the possibility of the formation of material with a net proton excess ( $Y_{p} > 0.5$ ) and has an improved treatment of the nuclear statistical equilibrium and the transition to heavy nuclei as the density approaches nuclear matter density. We include the effects of pions in the regime above nuclear matter density and incorporate all of the known mesonic and baryonic states at high temperature. We analyze how a 3-body nuclear force term in the DFT at high densities stiffens the EoS to satisfy the maximum neutron star constraint, however the density dependence of the symmetry anergy and the formation of pions at high temperatures allows for a softening of the central core in supernova collapse calculations leading to a robust explosion. We also add the possibility of a transition to a QCD chiral-symmetry-restoration and deconfinement phase at densities above nuclear matter density. This paper details the physics, and constraints on, this new EoS and presents an illustration of its implementation in both neutron stars and core-collapse supernova simulations. We present the first results from core-collapse supernova simulations with this EoS.
nucl-thastro-ph.HE15 citations
07
$α$ -decay properties of $^{296} 118$ from double-folding potentials
Peter Mohr
$α$ -decay properties of the yet unknown nucleus $^{296}$ 118 are predicted using the systematic behavior of parameters of $α$ -nucleus double-folding potentials. The results are $Q_{α} = 11.655 \pm 0.095$ MeV and $T_{1/2} = 0.825$ ms with an uncertainty of about a factor of 4.
nucl-thPRC(2017)·34 citations
08
Triton and Neutron-Deuteron Scattering up to Next-to-Leading Order in Chiral EFT
Young-Ho Song🇰🇷 · Rimantas Lazauskas🇫🇷 · U. van Kolck🇫🇷
Determination of the proper power-counting scheme is an important issue for the systematic application of Chiral Effective Field Theory in nuclear physics. We analyze the cutoff dependence of three-nucleon observables (the neutron-deuteron scattering lengths and the triton binding energy) at the leading and next-to-leading orders of a power counting that ensures order-by-order renormalization in the two-nucleon system. Our results imply that three-body forces are not needed for renormalization of the three-nucleon system up to next-to-leading order, as usually assumed in the literature. (Erratum to the original article is included)
nucl-thPRC(2017)·39 citations
09
Spectral and Transport Properties of Quark-Gluon Plasma in a Nonperturbative Approach
Shuai Y.F. Liu🇺🇸 · Ralf Rapp🇺🇸
Nonperturbative methods play an important role in quantum many-body systems, especially in situations with an interplay of continuum and bound states and/or large coupling strengths between the constituents. Employing the Luttinger-Ward functional (LWF) we have computed the equation of state (EoS) of the quark-gluon plasma (QGP) using fully dressed selfconsistent 1- and 2-body propagators. We first give an alternative derivation of our previously reported results for resumming the ladder diagram series of the LWF using a "matrix log" technique which accounts for dynamically formed bound and resonant states. Two types of solutions were found in selfconsistent fits to lattice-QCD data for the EoS, heavy-quark free energy and quarkonium correlators: a strongly coupled scenario (SCS) with broad parton spectral functions and strong meson resonances near the transition temperature vs. a weakly coupled scenario (WCS) with well-defined parton quasiparticles and weak meson resonances. Here, we discuss how these solutions can be distinguished by analyzing the pertinent transport properties. We focus on the specific shear viscosity, $(4 π) η / s$ , and the heavy-quark diffusion coefficient, $(2 π T) D_{s}$ , including its mass dependence. At low temperatures, in the SCS, they turn out to be a factor of 2 within their conjectured quantum lower bound, while they are a factor of 2-5 larger in the WCS. At higher temperatures, the transport parameters of the two scenarios approach each other. We propose the ratio $(4 π η / s) / (2 π T D_{s})$ as a measure to distinguish the perturbative and strong-coupling limits of 5/2 and 1, respectively.
nucl-thcond-mat.quant-gascond-mat.stat-mechhep-ph+1EPJA(2020)·66 citations
10
Soft modes in the proton-neutron pairing channel as precursors of deuteron condensate in N=Z nuclei
Elena Litvinova🇺🇸 · Caroline Robin🇺🇸 · Irina A. Egorova🇷🇺
Relativistic nuclear response theory is formulated for the proton-neutron pairing, or deuteron transfer, channel. The approach is based on the meson-nucleon Lagrangian of Quantum Hadrodynamics (QHD) and advances the relativistic field theory to connect consistently the high-energy scale of heavy mesons, the medium-energy range of the pion and the low-energy domain of emergent collective vibrations (phonons) in a parameter-free way. Mesons and phonons build up the in-medium nucleon-nucleon interaction in spin-isospin transfer channels, in particular, the phonon-exchange part takes care of the leading-order retardation effects. In this framework, we explore $J^{π} = 0^{+}$ and $J^{π} = 1^{+}$ channels of the nuclear response to the proton-neutron pair removal and addition in $^{56}$ Ni and $^{100}$ Sn with a special focus on the lowest (soft) modes as precursors of deuteron condensate and candidates for being the mediators of the proton-neutron pairing interaction.
nucl-thPLB(2018)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE