Nuclear Theory·nucl-th

Monday·December 23, 2019

10 papers—6 primary·4 cross-listed

01
[Submitted on 20 Dec 2019]
Quantum statistical effects in warm nuclear matter with light and heavy clusters
Shun Furusawa · Igor Mishustin
We have investigated the compositions of hot and dense nuclear matter with the focus on the quantum-statistical effects for light clusters. Our main observation is that the formation of heavy nuclei in stellar matter leads to the reduction of the number densities of light clusters. As a result, the quantum statistical effects such as Bose-Einstein condensation of deuterons and $α$ -particles are suppressed. The deviations in number densities of light clusters between Boltzmann and quantum statistics at sub-nuclear densities and temperatures 1-3 MeV are $\sim$ 0.2 $%$ at most. The condensation of $α$ -particles in iso-symmetric nuclear matter is predicted only under the assumptions that it is composed only of nucleons and light clusters and no heavy nuclei are present. We also found that the Coulomb screening effects hardly affect the critical baryon densities for alpha condensation, although mass and chemical potential of $α$ -particles are modified.
Comments:
15 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.09606 [pdf]
1 citation
02
[Submitted on 20 Dec 2019]
$Σ_{c} N$ interaction in chiral perturbation theory
Lu Meng🇨🇳 · Bo Wang🇨🇳 · Shi-Lin Zhu🇨🇳
We adopt the heavy baryon chiral perturbation theory to calculate the $Σ_{c} N$ interaction to the next-to-leading order. We consider the contact interactions, one-pion-exchange contributions, two-pion-exchange diagrams, and renormalization effects of the vertices, masses and wave functions. With the pion mass dependent expression, we fit the $Σ_{c} N$ interaction from HAL QCD calculation with $m_{π} \approx 410$ MeV and $m_{π} \approx 570$ MeV, and then extrapolate it to the physical pion mass. The $^{3} S_{1} (I = 1/2)$ $Σ_{c} N$ interaction is weakly attractive but no bound solution is found. We also propose a quark model to estimate the leading order $Σ_{c} N$ contact interaction with the $N N$ interaction as input. This approach combining the quark model and the chiral effective field theory predicts a very attractive interaction in $^{1} S_{0} (I = 3/2)$ $Σ_{c} N$ channel and a two-body bound state.
Comments:
11 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1912.09661 [pdf]
PRC(2020)·25 citations
03
[Submitted on 20 Dec 2019]
The Hyperspherical Harmonics method: a tool for testing and improving nuclear interaction models
L.E. Marcucci · J. Dohet-Eraly · L. Girlanda · A. Gnech · A. Kievsky · M. Viviani
The Hyperspherical Harmonics (HH) method is one of the most accurate techniques to solve the quantum mechanical problem for nuclear systems with $A \leq 4$ . In particular, by applying the Rayleigh-Ritz or Kohn variational principle, both bound and scattering states can be addressed, using either local or non-local interactions. Thanks to this versatility, the method can be used to test the two- and three-nucleon components of the nuclear interaction. In the present review we introduce the formalism of the HH method, both for bound and scattering states. In particular, we describe the implementation of the method to study the $A = 3$ and $4$ scattering problem. Second, we present a selected choice of results of the last decade, most representative of the latest achievements. Finally, we conclude with a discussion of what we believe will be the most significant developments within the HH method for the next five-to-ten years.
Comments:
25 pages, 9 figures, 4 tables, submitted to Frontiers in Physics (Research Topic) "The Long-Lasting Quest for Nuclear Interactions: The Past, the Present and the Future"
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.09751 [pdf]
Front.in Phys.(2020)·78 citations
04
[Submitted on 20 Dec 2019]
Constraining resonance properties through kaon production in pion-nucleus collisions at low energies
Vinzent Steinberg🇩🇪 · Jan Steinheimer🇩🇪 · Hannah Elfner🇩🇪 · Marcus Bleicher🇩🇪
Hadronic interactions are crucial for the dynamical description of heavy-ion reactions at low collision energies and in the late dilute stages at high collision energies. In particular, the properties and decay channels of resonances are an essential ingredient of hadronic transport approaches. The HADES collaboration measured particle production in collisions of pions with carbon and tungsten nuclei at $E_{kin} = 1.7 GeV$ . Such reactions are of high interest, because they allow to probe the properties of baryonic resonances produced in a much cleaner environment than the usual nucleus-nucleus collisions. We study these reactions with two transport approaches: SMASH (Simulating Many Accelerated Strongly-interacting Hadrons) and UrQMD (Ultra relativistic Quantum Molecular Dynamics) which follow the same underlying concept but with different implementations. The differential spectra in rapidity and transverse momentum are used to show how model parameters, as the decay channels of high mass resonances and angular distributions of kaon elastic scattering, can be constrained. It is found that the data favor the production of more particles with lower momentum over the production of few particles with higher momentum in these decays. In addition, the shape of the rapidity distribution of the kaons strongly depends on the angular distribution of the elastic kaon-nucleon cross section.
Comments:
15 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1912.09895 [pdf]
J.Phys.G(2021)·10 citations
05
[Submitted on 20 Dec 2019]
Isobaric-multiplet mass equation in a macroscopic-microscopic approach
Oleg Klochko · Nadezda A. Smirnova🇫🇷
We study the a, b and c coefficients of the isobaric-multiplet mass equation using a macroscopic-microscopic approach developed by P. Moeller and his collaborators in ADNDT 59, 185 (1995) and ADNDT 109-110, 1 (2016). We show that already the macroscopic part of the finite-range liquid-drop model (FRLDM) describes the general trend of the a and b coefficients relatively well, while the staggering behavior of b coefficients for doublets and quartets can be understood in terms of the difference of average proton and neutron pairing energies. The sets of isobaric masses, predicted by the full macroscopic-microscopic approaches, are used to explore the general trends of IMME coefficients up to A=100. We conclude that while the agreement for a coefficients is quite satisfactory, the global approaches have less sensitivity to predict the staggering pattern observed for b coefficients of doublets and quartets. The best set of theoretical b coefficients for multiplets up to about A=100 is used to predict masses of proton-rich nuclei based on the known experimental masses of neutron-rich mirror partners, and subsequently to investigate their one- and two-proton separation energies. The estimated position of the proton-drip line is in fair agreement with known experimental data. These masses are important for simulations of the astrophysical rp-process.
Comments:
13 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1912.09915 [pdf]
PRC(2021)·12 citations
06
[Submitted on 20 Dec 2019]
Helical massive fermions under rotation
Victor E. Ambrus🇷🇴
The properties of a massive fermion field undergoing rigid rotation at finite temperature and chemical potential are discussed. The polarisation imbalance is taken into account by considering a helicity chemical potential, which is dual to the helicity charge operator. The advantage of the proposed approach is that, as opposed to the axial current, the helicity charge current remains conserved at finite mass. A computation of thermal expectation values of the vector, helicity and axial charge currents, as well as of the fermion condensate and stress-energy tensor is provided. In all cases, analytic constitutive equations are derived for the non-equilibrium transport terms, as well as for the quantum corrections to the equilibrium terms (which are derived using an effective relativistic kinetic theory model for fermions with helicity imbalance) in the limit of small masses. In the context of the parameters which are relevant to relativistic heavy ion collisions, the expressions derived in the massless limit are shown to remain valid for masses up to the thermal energy, except for the axial charge conductivity in the azimuthal direction, which presents strong variations with the particle mass.
Comments:
68 pages, 13 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
1912.09977 [pdf]
JHEP(2020)·42 citations
07
[Submitted on 19 Dec 2019] (cross-list from hep-ph)
$π π$ scattering in a renormalized Hamiltonian matrix
María Gómez-Rocha🇪🇸 · Enrique Ruiz Arriola🇪🇸
A Wilsonian approach to $π π$ scattering based in the Glazek-Wilson Similarity Renormalization Group (SRG) for Hamiltonians is analyzed in momentum space up to a maximal CM energy of $s = 1.4$ GeV. To this end, we identify the corresponding relativistic Hamiltonian by means of the 3D reduction of the Bethe-Salpeter equation in the Kadyshevsky scheme, introduce a momentum grid and provide an isospectral definition of the phase-shift based on a spectral shift of a Chebyshev angle. We also propose a new method to integrate the SRG equations based on the Crank-Nicolson algorithm with a single step finite difference so that isospectrality is preserved at any step of the calculations. We discuss issues on the unnatural high momentum tails present in the fitted interactions and reaching far beyond the maximal CM energy of $s = 1.4$ GeV and how these tails can be integrated out explicitly by using Block-Diagonal generators of the SRG.
Comments:
5 pages, 4 figures, presented by María Gómez-Rocha at Light Cone 2019, 16-20 September 2016, Palaiseau, France
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1912.09248 [pdf]
PoS(2020)·0 citations
08
[Submitted on 20 Dec 2019] (cross-list from nucl-ex)
Early signal of emerging nuclear collectivity in neutron-rich $^{129}$ Sb
T.J. Gray · J.M. Allmond · A.E. Stuchbery · C.-H. Yu · C. Baktash · A. Gargano · A. Galindo-Uribarri · D.C. Radford · J.C. Batchelder · J.R. Beene · C.R. Bingham · L. Coraggio and 11 other authors
Radioactive $^{129}$ Sb, which can be treated as a proton plus semi-magic $^{128}$ Sn core within the particle-core coupling scheme, was studied by Coulomb excitation. Reduced electric quadrupole transition probabilities, $B (E 2)$ , for the $2^{+}$ $\times$ $π g_{7/2}$ multiplet members and candidate $π d_{5/2}$ state were measured. The results indicate that the total electric quadrupole strength of $^{129}$ Sb is a factor of 1.39(11) larger than the $^{128}$ Sn core, which is in stark contrast to the expectations of the empirically successful particle-core coupling scheme. Shell-model calculations performed with two different sets of nucleon-nucleon interactions suggest that this enhanced collectivity is due to constructive quadrupole coherence in the wavefunctions stemming from the proton-neutron residual interactions, where adding one nucleon to a core near a double-shell closure can have a pronounced effect. The enhanced electric quadrupole strength is an early signal of the emerging nuclear collectivity that becomes dominant away from the shell closure.
Comments:
Accepted, Physical Review Letters
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1912.09612 [pdf]
PRL(2020)·22 citations
09
[Submitted on 20 Dec 2019] (cross-list from hep-ph)
Isospin violating decay $D_{s}^{*} \to D_{s} π^{0}$ in chiral perturbation theory
Bin Yang🇨🇳 · Bo Wang🇨🇳 · Lu Meng🇨🇳 · Shi-Lin Zhu🇨🇳
We systematically calculate the isospin violating decay, $D_{s}^{*} \to D_{s} π^{0}$ , with the heavy meson chiral perturbation theory up to $O (p^{3})$ including the loop diagrams. The $O (p^{3})$ tree level amplitudes contain four undetermined LECs. We use two strategies to estimate them. With the nonanalytic dominance approximation, we get $Γ [D_{s}^{*} \to D_{s} π^{0}] = (3.38 \pm 0.12)$ eV. With the naturalness assumption, we give a possible range of the isospin violating decay width, $[1.11 - 6.88]$ eV. We find that the contribution of the $O (p^{3})$ corrections might be significant.
Comments:
8 pages,5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1912.09616 [pdf]
PRD(2020)·10 citations
10
[Submitted on 20 Dec 2019] (cross-list from astro-ph.HE)
Twin stars and the stiffness of the nuclear equation of state: ruling out strong phase transitions below $1.7 n_{0}$ with the new NICER radius measurements
Jan-Erik Christian · Jürgen Schaffner-Bielich
We explore the connection between the stiffness of an hadronic equation of state (EoS) with a sharp phase transition to quark matter to its tidal deformability. For this we employ a hadronic relativistic mean field model with a parameterized effective nucleon mass to vary the stiffness in conjunction with a constant speed of sound EoS for quark matter. We compute multiple scenarios with phase transitions according to the four possible cases of a hybrid star EoS with a stable second branch. We demonstrate at the example of GW170817 how the effective nucleon mass can be constrained by using gravitational wave data. We find, that certain values of the effective nucleon mass are incompatible with GW170817 and a phase transition simultaneously. By using the recent NICER measurements of J0030+0451 at the $1 σ$ level we constrain our results further and find that strong phase transitions with a visible jump in the mass-radius relation are ruled out at densities below 1.7 times saturation density.
Comments:
7 pages, 6 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1912.09809 [pdf]
ApJL(2020)·78 citations

Affiliations

first authorsco-authorsvia INSPIRE