Nuclear Theory·nucl-th

Thursday·September 26, 2019

10 papers—7 primary·3 cross-listed

01
Resonance Electroproduction and the Origin of Mass
Craig D. Roberts🇨🇳
One of the greatest challenges within the Standard Model is to discover the source of visible mass. Indeed, this is the focus of a "Millennium Problem", posed by the Clay Mathematics Institute. The answer is hidden within quantum chromodynamics (QCD); and it is probable that revealing the origin of mass will also explain the nature of confinement. In connection with these issues, this perspective describes insights that have recently been drawn using contemporary methods for solving the continuum bound-state problem in relativistic quantum field theory and how they have been informed and enabled by modern experiments on nucleon-resonance electroproduction.
nucl-thhep-lathep-phnucl-exEPJ Web Conf.(2020)·8 citations
02
Simple Woods-Saxon type form for $Ω α$ and $Ξ α$ interactions using Folding Model
Faisal Etminan🇮🇷 · Mohammad Mehdi Firoozabadi🇮🇷
We derive a simple Woods-Saxon type form for the potentials between $Y = Ξ, Ω$ and $α$ by using a single-folding potential method, based on a separable $Y$ -nucleon potential. Accordingly, the potentials $Ξ + α$ and $Ω + α$ are obtained using the ESC08c Nijmegens $Ξ N$ potential (in $^{3} S_{1}$ channel) and HAL QCD Collaboration $Ω N$ interactions (in lattice QCD), respectively. In deriving the potential between $Y$ and $α$ , the same potential between $Y$ and $N$ is used. Binding energy, scattering length and effective range of $Y$ particle on the alpha particle are approximated by the resultant potentials. The depths of the potentials in $Ω α$ and $Ξ α$ systems are obtained $- 61$ and $- 24.4$ MeV, respectively. In the case of $Ξ α$ potential, a fairly good agreement is observed between the single-folding potential method and the phenomenological potential of Dover-Gal model. These potentials can be used in 3-,4- and 5-body cluster structures of $Ω$ and $Ξ$ hypernuclei.
nucl-thCPC(2020)·13 citations
03
Three-body Description of $2 n$ -Halo and Unbound $2 n$ -Systems: $^{22}$ C and $^{26}$ O
Jagjit Singh · W. Horiuchi · L. Fortunato · A. Vitturi
We study the two-neutron correlations in the ground state of the weakly-bound two-neutron halo nucleus $^{22}$ C sitting at the edge of the neutron-drip line and also in the unbound nucleus $^{26}$ O sitting beyond the neutron dripline. For the present study, we employ a three-body (core $+ n + n$ ) structure model designed for describing the two-neutron halo system by explicit inclusion of unbound continuum states of the subsystem (core $+ n$ ). We use either a density-independent or a density-dependent contact-delta interaction to describe the neutron-neutron interaction and its strength is varied to fix the binding energy. We report the configuration mixing in the ground state of these systems for different choices of pairing interactions.
nucl-thJPS Conf.Proc.(2020)·1 citation
04
Recent progress on hypernuclei
Avraham Gal🇮🇱
Some of last year's progress made in hypernuclear physics is reviewed as follows: (i) resolving the $_{Λ}^{5}$ He overbinding problem in single- $Λ$ hypernuclei [1]; (ii) arguing that the onset of binding double- $Λ$ hypernuclei is most likely at $A$ =5, with the neutral systems $_{ΛΛ}^{3}$ n and $_{ΛΛ}^{4}$ n unbound by a large margin [2]; and (iii) revising the calculated value of the loosely bound $_{Λ}^{3}$ H lifetime to a level of $\sim$ 20% shorter than the free $Λ$ lifetime [3], given recent claims from relativistic heavy ion experiments that $τ (_{Λ}^{3}$ H) is shorter than $τ_{Λ}$ by as much as $\approx$ (30 $\pm$ 8)%. Also discussed briefly in this context is the lifetime expected for the questionable $_{Λ}^{3}$ n hypernucleus.
nucl-thhep-phnucl-exJ.Phys.Conf.Ser.(2020)·3 citations
05
Impact of error analysis on the composition the outer crust of a neutron star
D Neill · K Medler · A Pastore · C Barton
By means of bootstrap technique, we perform a full error analysis on the Duflo-Zucker mass model. We illustrate the impact of such study on the predicted chemical composition of the outer crust of a non-accreting neutron star. We define an existence probability for each nuclear species as a function of the depth of the crust. We observe that, due to statistical uncertainties, instead of having a well defined transition between two successive layers, we have a mixture of two species.
nucl-thastro-ph.HEJ.Phys.Conf.Ser.(2020)·1 citation
06
Chiral kinetic theory from Landau level basis
Shu Lin🇨🇳 · Lixin Yang🇨🇳
We derive a chiral kinetic theory with Landau level basis, which is valid for slow-varying magnetic field with arbitrary magnitude. We apply the new chiral kinetic theory to calculate the electric conductivity transverse to the magnetic field in a magnetized QED and QCD plasma. Under the lowest Landau level approximation and relaxation time approximation, we find the transverse conductivity approaches a constant in the large magnetic field limit and is inversely proportional to the relaxation time. We also obtain a frequency-dependent transverse conductivity in response to a time-dependent electric field. We find a high frequency enhancement in this conductivity.
nucl-thcond-mat.mes-hallhep-phPRD(2020)·39 citations
07
The mean transverse momentum of ultracentral heavy-ion collisions: A new probe of hydrodynamics
Fernando G. Gardim🇧🇷 · Giuliano Giacalone🇫🇷 · Jean-Yves Ollitrault🇫🇷
We predict that the mean transverse momentum of charged hadrons $⟨ p_{t} ⟩$ rises as a function of the charged-particle multiplicity in ultracentral nucleus-nucleus collisions. We explain that this phenomenon has a simple physical origin and represents an unambiguous prediction of the hydrodynamic framework of heavy-ion collisions. We argue that the relative increase of $⟨ p_{t} ⟩$ is proportional to the speed of sound squared $c_{s}^{2}$ of the quark-gluon plasma. Based on the value of $c_{s}^{2}$ from lattice QCD, we expect $⟨ p_{t} ⟩$ to increase by approximately $18$ MeV between 1\% and 0.001\% centrality in Pb+Pb collisions at $s_{NN} = 5.02$ TeV.
nucl-thhep-phnucl-exPLB(2020)·64 citations
08
Radial dose distribution and effective delta ray radius (Penumbra radius): Determination for some ions passing through water
E. M. Awad a · M. Abu-Shady
An analytical equation for calculating radial dose of heavy ions in water is introduced by Awad et al. (Applied Radiation and Isotopes, 142 (2018) 135-142. It is simple alternative to Monte Carlo code and is a promising code, however, still needs refinement. Refinement was added through adjusting radial dose integration upper limit which gives the effective delta-ray range, rmax and ions penumbra radius in water as well. Radial dose distributions for 85 ions forming fifteen energy groups from 0.25 to 24 MeV/n were studied. By employing the effective delta-ray range, it was possible to get more consistent radial dose distribution in comparison to experimental and Monte Carlo simulation data. The corresponding LET values of those ions were estimated and compared with SRIM program. Penumbra radii for 85 ions were determined. Good description for the penumbra radii was obtained using a proposed new equation which fits experimental data as well.
↳ physics.ins-detnucl-thphysics.med-phNucl.Instrum.Meth.B(2020)·2 citations
09
Energy, angular momentum and pressure force distributions inside nucleons
Cédric Lorcé (Ecole Polytechnique and CNRS)🇫🇷
We review some of the recent developments regarding mass, angular momentum and pressure forces inside hadrons. These properties are all encoded in the energy-momentum tensor of the system, which is described at the non-perturbative level in terms of gravitational form factors. Similarly to electromagnetic form factors, Fourier transforms of gravitational form factors allow one to map out the distribution of the above mechanical properties in position space, providing a whole new way of studying in detail the internal structure of hadrons.
↳ hep-phnucl-thJ.Phys.Conf.Ser.(2020)·1 citation
10
Spin-dipole mode in a trapped Fermi gas near unitarity
Hiroyuki Tajima · Alessio Recati · Yoji Ohashi
We theoretically investigate the spin-dipole oscillation of a strongly interacting Fermi gas in a harmonic trap. By using a combined diagrammatic strong-coupling theory with a local density approximation and a sum rule approach, we clarify the temperature dependence of the spin-dipole frequency near the unitarity, which is deeply related to the spin susceptibility, as well as pairing correlations. While the spin-dipole frequency exactly coincides with the trap frequency in a non-interacting Fermi gas, it is shown to remarkably be enhanced in the superfluid state, because of the suppression of the spin degree of freedom due to the spin-singlet Cooper-pair formation. In strongly interacting Fermi gases, this enhancement occurs even above the superfluid phase transition temperature, due to the strong pairing correlations.
↳ cond-mat.quant-gasnucl-thPRA(2020)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE