Nuclear Theory·nucl-th

Wednesday·September 21, 2022

9 papers—3 primary·6 cross-listed

01
Collective-model description of shape coexistence and intruder states in cadmium isotopes based on a relativistic energy density functional
K. Nomura · K.E. Karakatsanis
Low-energy structure of even-even $^{108 - 116}$ Cd isotopes is analyzed using a collective model that is based on the nuclear density functional theory. Spectroscopic properties are computed by solving the triaxial quadrupole collective Hamiltonian, with parameters determined by the constrained self-consistent mean-field calculations within the relativistic Hartree-Bogoliubov method employing a universal energy density functional and a pairing force. The collective Hamiltonian reproduces the observed quadrupole phonon states of vibrational character, which are based on the moderately deformed equilibrium minimum in the mean-field potential energy surface. In addition, the calculation yields a low-lying excited $0^{+}$ band and a $γ$ -vibrational band that are associated with a deformed local minimum close in energy to the ground state, consistently with the empirical interpretation of these bands as intruder bands. Observed energy spectra, $B (E 2)$ , and $ρ^{2} (E 0)$ values are, in general, reproduced reasonably well.
nucl-thnucl-exPRC(2022)·9 citations
02
Hyperonic equation of state at finite temperature for neutron stars
Hristijan Kochankovski · Angels Ramos · Laura Tolos
We review the composition and the equation of state of the hyperonic core of neutron stars at finite temperature within a relativistic mean-field approach. We make use of the new FSU2H* model, which is built upon the FSU2H scheme by improving on the Xi potential according to the recent analysis on the Xi atoms, and we extend it to include finite temperature corrections. The calculations are done for a wide range of densities, temperatures and charge fractions, thus exploring the different conditions that can be found in protoneutron stars, binary mergers remnants and supernovae explosions. The inclusion of hyperons has a strong effect on the composition and the equation of state at finite temperature, which consequently would lead to significant changes in the properties and evolution of hot neutron stars.
nucl-thastro-ph.HEEPJ Web Conf.(2022)·1 citation
03
Muon capture on deuteron using local chiral potentials
L. Ceccarelli🇮🇹 · A. Gnech🇺🇸 · L.E. Marcucci🇮🇹 · M. Piarulli🇺🇸 · M. Viviani🇮🇹
The muon capture reaction $μ^{-} + d \to n + n + ν_{μ}$ in the doublet hyperfine state is studied using nuclear potentials and consistent currents derived in chiral effective field theory, which are local and expressed in coordinate-space (the so-called Norfolk models). Only the largest contribution due to the $^{1} S_{0}$ $nn$ scattering state is considered. Particular attention is given to the estimate of the theoretical uncertainty, for which four sources have been identified: (i) the model dependence, (ii) the chiral order convergence for the weak nuclear current, (iii) the uncertainty in the single-nucleon axial form factor, and (iv) the numerical technique adopted to solve the bound and scattering $A = 2$ systems. This last source of uncertainty has turned out essentially negligible. The $^{1} S_{0}$ doublet muon capture rate $Γ^{D} (^{1} S_{0})$ has been found to be $Γ^{D} (^{1} S_{0}) = 255.8 (0.6) (4.4) (2.9)$ s $^{- 1}$ , where the three errors come from the first three sources of uncertainty. The value for $Γ^{D} (^{1} S_{0})$ obtained within this local chiral framework is compared with previous calculations and found in very good agreement.
nucl-thFront.Phys.(2023)·7 citations
04
Causal, stable first-order viscous relativistic hydrodynamics with ideal gas microphysics
Alex Pandya · Elias R. Most · Frans Pretorius
We present the first numerical analysis of causal, stable first-order relativistic hydrodynamics with ideal gas microphysics, based in the formalism developed by Bemfica, Disconzi, Noronha, and Kovtun (BDNK theory). The BDNK approach provides definitions for the conserved stress-energy tensor and baryon current, and rigorously proves causality, local well-posedness, strong hyperbolicity, and linear stability (about equilibrium) for the equations of motion, subject to a set of coupled nonlinear inequalities involving the undetermined model coefficients (the choice for which defines the "hydrodynamic frame"). We present a class of hydrodynamic frames derived from the relativistic ideal gas "gamma-law" equation of state which satisfy the BDNK constraints, and explore the properties of the resulting model for a series of (0+1)D and (1+1)D tests in 4D Minkowski spacetime. These tests include a comparison of the dissipation mechanisms in Eckart, BDNK, and Muller-Israel-Stewart theories, as well as investigations of the impact of hydrodynamic frame on the causality and stability properties of Bjorken flow, planar shockwave, and heat flow solutions.
↳ gr-qcastro-ph.HEnucl-thPRD(2022)·38 citations
05
$D^{*}$ and $D_{s}^{*}$ distribution amplitudes from Bethe-Salpeter wave functions
Fernando E. Serna🇧🇷 · Roberto Correa da Silveira🇧🇷 · Bruno El-Bennich🇧🇷
We report on the first calculation of the longitudinal and transverse light front distribution amplitudes of the $D^{*}$ and $D_{s}^{*}$ mesons and their first four moments. As a byproduct, we also obtain these distribution amplitudes for the $ρ$ , $ϕ$ , $K^{*}$ and $J /Ψ$ mesons and confirm a prediction of lattice QCD for the vector kaon: while the longitudinal distribution amplitude is almost symmetric, the transverse one is oblique implying that the strange quark carries more momentum.
↳ hep-phhep-latnucl-thPRD(2022)·16 citations
06
Large-Momentum Effective Theory vs. Short-Distance Operator Expansion: Contrast and Complementarity
Xiangdong Ji🇺🇸
Although equivalent in the infinite-momentum limit, large-momentum effective theory (LaMET) and short-distance operator product expansion (SD-OPE) are two different approaches to extract parton distribution functions (PDFs) from coordinate-space correlation functions in large-momentum hadrons. LaMET implements a momentum-space expansion in $Λ_{QCD} / [x (1 - x) P^{z}]$ to directly calculate PDFs $f (x)$ in a middle region of Bjorken $x \in [x_{min} \sim Λ_{QCD} / P^{z}, x_{max} \sim 1 - x_{m i n}]$ . SD-OPE applies perturbative QCD at small Euclidean distances $z$ to extract a range $[0, λ_{max}]$ of leading-twist correlations, $h (λ = z P^{z})$ , corresponding to the Fourier transformation of PDFs. Similar to the quantum mechanical uncertainty principle, an incomplete leading-twist correlation cannot be readily converted to a momentum-space local distribution, and the methods to solve the ``inverse problem'' involve essentially modelling of the missing information beyond $λ_{max}$ . On the other hand, short-distance correlations, along with the expected end-point asymptotics, can be used to phenomenologically fit the PDFs in the LaMET-complementary regions: $x \in [0, x_{min}]$ and $[x_{max}, 1]$ . We use the recent results of the pion valence quark distribution from the ANL/BNL collaboration to demonstrate this point.
↳ hep-lathep-phnucl-thResearch(2025)·35 citations
07
Further understanding the nature of $Ω (2012)$ within a chiral quark model
Hui-Hua Zhong🇨🇳 · Ru-Hui Ni🇨🇳 · Mu-Yang Chen🇨🇳 · Xian-Hui Zhong🇨🇳 · Ju-Jun Xie🇨🇳
In our previous works, we have analyzed the two-body strong decays of the low-lying $Ω$ baryon states within a chiral quark model. The results show that the $Ω (2012)$ resonance favors the three-quark state with $J^{P} = 3/ 2^{-}$ classified in the quark model. With this assignment, in the present work we further study the three-body strong decay $Ω (2012) \to Ξ^{*} (1530) K ˉ \to Ξ π K ˉ$ and coupled-channel effects on $Ω (2012)$ from nearby channels $Ξ K ˉ$ , $Ω η$ and $Ξ^{*} (1530) K ˉ$ within the chiral quark model as well. It is found that the $Ω (2012)$ resonance has a sizeable decay rate into the three-body final state $Ξ π K ˉ$ . The predicted ratio $R_{Ξ K ˉ}^{Ξ π K ˉ} = B [Ω (2012) \to Ξ^{*} (1530) K ˉ \to Ξ π K ˉ] / B [Ω (2012) \to Ξ K ˉ] ≃ 12%$ is close to the up limit $11%$ measured by the Belle Collaboration in 2019, however, our predicted ratio is too small to be comparable with the recent data $0.97 \pm 0.31$ . Furthermore, our results show that the coupled-channel effects on the $Ω (2012)$ is not large, its components should be dominated by the bare three-quark state, while the proportion of the molecular components is only $\sim 16%$ . To clarify the nature of $Ω (2012)$ , the ratio $R_{Ξ K ˉ}^{Ξ π K ˉ}$ is expected to be tested by other experiments.
↳ hep-phhep-exnucl-thCPC(2023)·19 citations
08
Systems Dominated by Exchange Particles
V.A. Karmanov🇷🇺
As well known, the spectrum of a non-relativistic two-body system interacting by the Coulomb potential is the Balmer series $E_{n} = \frac{α ^{2} m}{4 n ^{2}}$ produced by the Schrödinger equation. In 1954, Wick and Cutkosky have found, in the Bethe-Salpeter equation framework, that for $α > \frac{π}{4}$ the relativistic effects result in new levels (in addition to the Balmer series). However, the physical nature of these new states remained unclear and therefore their existence was being questioned. We have recently shown that these extra states are dominated by the exchange (massless) particles, moving with speed of light. That's why they did not appear in the non-relativistic (Schrödinger) framework.
↳ hep-phnucl-thNucl.Theor.(2022)·0 citations
09
Entanglement between Valence and Sea Quarks in Hadrons of 1+1 Dimensional QCD
Peter J. Ehlers🇺🇸
The conceptual interpretation of valence- and sea-quark separation, which is a key aspect of the parton model and of an intuitive picture of hadron structure, becomes obscured by quantum effects in QCD. This suggests that there may be measures of entanglement between quark degrees of freedom that are present in QCD, but absent in the intuitive picture with a clear valence-sea (VS) separation. In this paper, we define the first rigorous measure of VS entanglement in QCD in an attempt to bring conceptual clarity to this issue, and, potentially, to find a measure of the applicability of the parton model to QCD bound states. This VS entanglement vanishes in the large- $N_{c}$ limit, and it remains low when finite- $N_{c}$ states resemble their large- $N_{c}$ counterparts. We perform a numerical study of VS entanglement in 1+1 dimensional discrete light-cone quantized QCD, and in the process develop a method for building the color-singlet basis of 1+1d QCD that is manifestly complete and orthogonal by construction. We calculate this VS entanglement entropy for the first time and find that it is relatively low for the first few excited states of both mesons and baryons compared to all other states in the spectrum, with the VS entropy of ground state hadrons providing a minimum. We also see that for ground state mesons the entropy is well described in the $1/ N_{c}$ approximation. These results suggest that low energy hadrons may be the only QCD bound states for which the large- $N_{c}$ expansion, and perhaps the parton model, provide an accurate description. This work also provides the first evidence that the VS entanglement entropy of QCD in 3+1d, which would likely serve as an order parameter for the transition between quark and hadron degrees of freedom, may be perturbatively accessible through a large- $N_{c}$ expansion.
↳ hep-phnucl-thquant-phAnnals Phys.(2023)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE