Nuclear Theory·nucl-th

Tuesday·April 9, 2019

11 papers—8 primary·3 cross-listed

01
[Submitted on 5 Apr 2019]
Transition form factors: $γ^{*} + p \to Δ (1232)$ , $Δ (1600)$
Ya Lu🇨🇳 · Chen Chen🇧🇷 · Zhu-Fang Cui🇨🇳 · Craig D. Roberts🇺🇸 · Sebastian M. Schmidt🇩🇪 · Jorge Segovia🇪🇸 · Hong-Shi Zong🇨🇳
Electroproduction form factors describing the $γ^{*} p \to Δ^{+} (1232), Δ^{+} (1600)$ transitions are computed using a fully-dynamical diquark-quark approximation to the Poincaré-covariant three-body bound-state problem in relativistic quantum field theory. In this approach, the $Δ (1600)$ is an analogue of the Roper resonance in the nucleon sector, appearing as the simplest radial excitation of the $Δ (1232)$ . Precise measurements of the $γ^{*} p \to Δ^{+} (1232)$ transition already exist on $0 \leq Q^{2} ≲ 8$ GeV $^{2}$ and the calculated results compare favourably with the data outside the meson-cloud domain. The predictions for the $γ^{*} p \to Δ^{+} (1600)$ magnetic dipole and electric quadrupole transition form factors are consistent with the empirical values at the real photon point, and extend to $Q^{2} \approx 6 m_{p}^{2}$ , enabling a meaningful direct comparison with experiment once analysis of existing data is completed. In both cases, the electric quadrupole form factor is particularly sensitive to deformation of the $Δ$ -baryons. Interestingly, whilst the $γ^{*} p \to Δ^{+} (1232)$ transition form factors are larger in magnitude than those for $γ^{*} p \to Δ^{+} (1600)$ in some neighbourhood of the real photon point, this ordering is reversed on $Q^{2} ≳ 2 m_{p}^{2}$ , suggesting that the $γ^{*} p \to Δ^{+} (1600)$ transition is more localised in configuration space.
Comments:
13 pages, 8 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1904.03205 [pdf]
PRD(2019)·51 citations
02
[Submitted on 6 Apr 2019]
The effect of strong electric field on the evolution of charmonium in quark gluon plasma
Wu Biaogang🇨🇳 · Chen Baoyi🇨🇳 · Zhao Xingbo🇨🇳
In ultra-relativistic heavy-ion collisions, the strong electric field can be produced by the colliding nuclei. The magnitude of the electric field $E$ is on the order of $e E \sim m_{π}^{2}$ at the early stage of the collision. In quark gluon plasma (QGP), such a strong electric field can have a significant impact on the evolution of charmonia. We employ the time-dependent Schrödinger equation to study the evolution of charmonium states in the strong electric field generated by the moving charges. The electric field can result in transitions between charmonium states with different angular momenta. In order to see this effect, we make comparisons between the yields of $J / ψ$ , $ψ^{'}$ and $χ_{c}$ with and without the electric field. The results show that in the early stage of the collision the electric field induces significant dissociation of $J / ψ$ . In the meantime, $χ_{c}$ is generated via the transition from $J / ψ$ by the electric field.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1904.03384 [pdf]
Nucl.Phys.Rev.(2019)·2 citations
03
[Submitted on 6 Apr 2019]
Charge asymmetry dependence of the elliptic flow splitting in relativistic heavy-ion collisions
Zhang-Zhu Han🇨🇳 · Jun Xu🇨🇳
The elliptic flow splitting $Δ v_{2}$ between $u ˉ$ and $u$ quarks as well as between $π^{-}$ and $π^{+}$ in midcentral Au+Au collisions at $s_{N N} = 200$ GeV has been studied, based on the framework of an extended multiphase transport model with the partonic evolution described by the chiral kinetic equations of motion. Within the available statistics, the slope of $Δ v_{2}$ between $u ˉ$ and $u$ quarks with respect to the electric charge asymmetry $A_{c h}$ from the linear fit is found to be negative, due to the correlation between the velocity and the coordinate in the initial parton phase-space distribution. Simulations with the magnetic field in QGP overestimate the splitting of the spin polarization between $Λ$ and $Λ ˉ$ observed experimentally, with the latter more consistent with results under the magnetic field in vacuum. Considering the uncertainties from the magnetic field, the quark-antiquark vector interaction, and the hadronization, as well as the hadronic evolution, our study shows that the experimentally observed positive slope of $Δ v_{2}$ with respect to $A_{c h}$ is not likely due to the chiral magnetic wave.
Comments:
9 pages, 7 figures, a few typos corrected. arXiv admin note: text overlap with arXiv:1707.07262
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
1904.03544 [pdf]
PRC(2019)·10 citations
04
[Submitted on 7 Apr 2019]
Skewness of nuclear matter and three-particle correlations
Wolfgang Bentz🇯🇵 · Ian C. Cloet🇺🇸
We present a study of the skewness of nuclear matter, which is proportional to the third derivative of the energy per nucleon with respect to the baryon density at the saturation point, in the framework of the Landau-Migdal theory. We derive an exact relation between the skewness, the nucleon effective mass, and two-particle and three-particle interaction parameters. We also present qualitative estimates, which indicate that three-particle correlations play an important role for the skewness.
Comments:
8 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1904.03588 [pdf]
PRC(2019)·4 citations
05
[Submitted on 7 Apr 2019]
Fission and the r-process nucleosynthesis of translead nuclei in neutron star mergers
Samuel A. Giuliani · Gabriel Martínez-Pinedo · Meng-Ru Wu · Luis M. Robledo
We study the impact of fission on the production and destruction of translead nuclei during the r-process nucleosynthesis occurring in neutron-star mergers. Abundance patterns and rates of nuclear energy production are obtained for different ejecta conditions using three sets of stellar reaction rates, one of which is based on microscopic and consistent calculations of nuclear masses, fission barriers, and collective inertias. We show that the accumulation of fissioning material during the r process can strongly affect the free neutron abundance after the r-process freeze-out. This leads to a significant impact on the abundances of heavy nuclei that undergo $α$ decay or spontaneous fission, affecting the radioactive energy production by the ejecta at timescales relevant for kilonova emission.
Comments:
10 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1904.03733 [pdf]
PRC(2020)·48 citations
06
[Submitted on 8 Apr 2019]
Isovector Effects in Neutron Stars, Radii and the GW170817 Constraint
T. F. Motta🇦🇺 · A. M. Kalaitzis🇦🇺 · S. Antić🇦🇺 · P. A. M. Guichon🇫🇷 · J. R. Stone🇬🇧 · A. W. Thomas🇦🇺
An isovector-scalar meson is incorporated self-consistently into the quark-meson coupling description of nuclear matter and its most prominent effects on the structure of neutron stars are investigated. The recent measurement of GW170817 is used to constrain the strength of the isovector-scalar channel. With the imminent measurements of the neutron star radii in the NICER mission it is particularly notable that the inclusion of the isovector-scalar force has a significant impact. Indeed, the effect of this interaction on the neutron star radii and masses is larger than the uncertainties introduced by variations in the parameters of symmetric nuclear matter at saturation, namely the density, binding energy per nucleon and the symmetry energy. In addition, since the analysis of GW170817 has provided constraints on the binary tidal deformability of merging neutron stars, the predictions for this parameter within the quark-meson coupling model are explored, as well as the moment of inertia and the quadrupole moment of slowly rotating neutron stars.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1904.03794 [pdf]
ApJ(2019)·39 citations
07
[Submitted on 8 Apr 2019]
First microscopic coupled-channel calculation of $α$ inelastic cross sections on $^{16}$ O
Yoshiko Kanada-En'yo · Kazuyuki Ogata
The $α$ inelastic scattering on $^{16}$ O is investigated with the coupled-channel calculation using the $α$ -nucleus coupled-channel potentials, which are microscopically derived by folding the the Melbourne $g$ -matrix $N N$ interaction with the $^{16}$ O and $α$ densities. The matter and transition densities of $^{16}$ O are calculated by a microscopic structure model of the variation after the spin-parity projections combined with the generator coordinate method of $^{12}$ C+ $α$ in the framework of the antisymmetrized molecular dynamics. The calculation reproduces the observed elastic and inelastic cross sections at incident energies of $E_{α}$ =104 MeV, 130 MeV, 146 MeV, and 386 MeV. The coupled-channel effect on the cross sections is also discussed.
Comments:
10 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1904.03811 [pdf]
PRC(2019)·16 citations
08
[Submitted on 8 Apr 2019]
Investigating the 10Li continuum through 9Li(d,p)10Li reactions
A.M. Moro · J. Casal · M. Gómez-Ramos
The continuum structure of the unbound system $^{10}$ Li, inferred from the $^{9}$ Li $(d, p)^{10}$ Li transfer reaction, is reexamined. Experimental data for this reaction, measured at two different energies, are analyzed with the same reaction framework and structure models. It is shown that the seemingly different features observed in the measured excitation energy spectra can be understood as due to the different incident energy and angular range covered by the two experiments. The present results support the persistence of the $N = 7$ parity inversion beyond the neutron dripline as well as the splitting of the well-known low-lying $p$ -wave resonance. Furthermore, they provide indirect evidence that most of the $ℓ = 2$ single-particle strength, including possible $d_{5/2}$ resonances, lies at relatively high excitations energies.
Comments:
accepted for publication in Physics Letters B
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1904.04224 [pdf]
PLB(2019)·12 citations
09
[Submitted on 8 Apr 2019] (cross-list from hep-ph)
Dynamical supersymmetry for strange quark and $u d$ antidiquark in hadron mass spectrum
Taiju Amano (1,2)🇯🇵 · Daisuke Jido (2,1) ((1) Tokyo Metropolitan University, (2) Tokyo Institute of Technology)🇯🇵
Speculating that the $u d$ diquark with spin 0 has a similar mass to the constituent $s$ quark, we introduce a symmetry between the $s$ quark and the $u d$ diquark. Constructing an algebra for this symmetry, we regard a triplet of the $s$ quarks with spin up and down and the $u d$ diquark with spin 0 as a fundamental representation of this algebra. We further build higher representations constructed by direct products of the fundamental representations. We propose assignments of hadrons to the multiples of this algebra. We find in particular that ${D_{s}, D_{s}^{*}, Λ_{c}}$ , ${η_{s}, ϕ, Λ, f_{0} (1370)}$ and ${Ω_{c}, T_{sc}}$ form a triplet, a nonet and a quintet, respectively, where $T_{sc}$ is a genuine tetraquark meson composed of $u d sc$ . We also find a mass relation between them by introducing the symmetry breaking due to the mass difference between the $s$ quark and the $u d$ diquark. The masses of possible tetraquarks $u d sc$ and $u d s b$ are estimated from the symmetry breaking and the masses of $Ω_{c}$ and $Ω_{b}$ to be 2.942 GeV and 6.261 GeV, respectively.
Comments:
22 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1904.03882 [pdf]
PTEP(2019)·3 citations
10
[Submitted on 8 Apr 2019] (cross-list from hep-lat)
A Lattice Story of Proton Spin
Yi-Bo Yang🇨🇳
In this contribution, I summarized the recent Lattice QCD consensuses on the quark helicity, plus the investigations on the gluon helicity and orbital angular momenta. The preliminary non-perturbative normalized and renormalized Ji quark and gluon angular momentum results are also reported and compared with the previous 1-loop perturbative renormalized results.
Comments:
14 pages, 10 figures, Proceedings for the 36th Annual International Symposium on Lattice Field Theory, 22-28 July 2018, Michigan State University, East Lansing, Michigan, USA. References are updated
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1904.04138 [pdf]
PoS(2019)·7 citations
11
[Submitted on 8 Apr 2019] (cross-list from astro-ph.HE)
Constraining the neutron-matter equation of state with gravitational waves
Michael McNeil Forbes🇺🇸 · Sukanta Bose🇺🇸 · Sanjay Reddy🇺🇸 · Dake Zhou🇺🇸 · Arunava Mukherjee🇩🇪 · Soumi De🇺🇸
We show how observations of gravitational waves from binary neutron star (BNS) mergers over the next few years can be combined with insights from nuclear physics to obtain useful constraints on the equation of state (EoS) of dense matter, in particular, constraining the neutron-matter EoS to within 20% between one and two times the nuclear saturation density $n_{0} \approx 0.16 fm^{- 3}$ . Using Fisher information methods, we combine observational constraints from simulated BNS merger events drawn from various population models with independent measurements of the neutron star radii expected from x-ray astronomy (the Neutron Star Interior Composition Explorer (NICER) observations in particular) to directly constrain nuclear physics parameters. To parameterize the nuclear EoS, we use a different approach, expanding from pure nuclear matter rather than from symmetric nuclear matter to make use of recent quantum Monte Carlo (QMC) calculations. This method eschews the need to invoke the so-called parabolic approximation to extrapolate from symmetric nuclear matter, allowing us to directly constrain the neutron-matter EoS. Using a principal component analysis, we identify the combination of parameters most tightly constrained by observational data. We discuss sensitivity to various effects such as different component masses through population-model sensitivity, phase transitions in the core EoS, and large deviations from the central parameter values.
Comments:
13 pages, 9 figures + supplement 11 pages
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1904.04233 [pdf]
PRD(2019)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE