Nuclear Theory·nucl-th

Wednesday·August 14, 2024

13 papers—7 primary·6 cross-listed

08
Production characteristics of light nuclei, hypertritons and $Ω$ -hypernuclei in Pb+Pb collisions at $s_{N N} = 5.02$ TeV
Rui-Qin Wang🇨🇳 · Xin-Lei Hou🇨🇳 · Yan-Hao Li🇨🇳 · Jun Song🇨🇳 · Feng-Lan Shao🇨🇳
We extend an analytical nucleon coalescence model with hyperons to study productions of light nuclei, hypertritons and $Ω$ -hypernuclei in Pb+Pb collisions at $s_{N N} = 5.02$ TeV. We derive the formula of the momentum distribution of two bodies coalescing into dibaryon states and that of three bodies coalescing into tribaryon states. We explain the available data of the coalescence factors $B_{2}$ and $B_{3}$ , the transverse momentum spectra, the averaged transverse momenta, the yield rapidity densities, yield ratios of the deuteron, antihelium-3, antitriton, hypertriton measured by the ALICE collaboration, and give predictions of different $Ω$ -hypernuclei, e.g., $H (p Ω^{-})$ , $H (n Ω^{-})$ and $H (p n Ω^{-})$ . We find two groups of interesting observables, the averaged transverse momentum ratios of light (hyper-)nuclei to protons (hyperons) and the centrality-dependent yield ratios of theirs. The former group exhibits a reverse-hierarchy of the nucleus size, and the latter is helpful for the judgements of the nucleus production mechanism as well as the nucleus own size.
↳ hep-phnucl-thNucl.Sci.Tech.(2025)·6 citations
09
Semi-automatic Calculations of Multi-loop Feynman Amplitudes with AmpRed
Wen Chen🇨🇳
We present a Mathematica package AmpRed for the semi-automatic calculations of multi-loop Feynman amplitudes with high efficiency and precision. AmpRed implements the methods of integration by parts and differential equations in the Feynman-parameter representation. It allows for the calculations of general parametric integrals (which may not have momentum-space correspondences). Various user-friendly tools for multi-loop calculations, such as those to construct and solve differential equations for Feynman integrals, are provided. It can also deal with tensor algebras in non-relativistic field theories. Interfaces to some packages, like QGRAF and FORM, are also provided.
↳ hep-phhep-thnucl-thComput.Phys.Commun.(2025)·33 citations
10
Renormalization-group consistent treatment of color superconductivity in the NJL model
Hosein Gholami🇩🇪 · Marco Hofmann🇩🇪 · Michael Buballa🇩🇪
The Nambu-Jona-Lasinio (NJL) model and specifically its extension to color superconductivity (CSC) is a popular effective model for investigating dense quark matter. However, the reliability of its results is challenged by cutoff artifacts, which emerge if temperature or chemical potential are of the order of the cutoff energy scales. In this work, we generalize an idea from [Braun et al. SciPost Phys., 6:056, 2019], which is based on the requirement of renormalization-group (RG) consistency and has successfully been applied to the two-flavor Quark-Meson-Diquark model, to the NJL model for electrically and color-neutral three-flavor color-superconducting quark matter. To this end, we analyze the medium divergences of the model and eliminate them by appropriate counterterms, introducing three different schemes. We show that the RG-consistent treatment removes the cutoff artifacts of the conventional regularization and enables the investigation of CSC matter at higher densities by the model. Our studies reveal the emergence of a so-called d-quark superconducting (dSC) phase within the melting pattern of the Color-Flavor Locked (CFL) phase at high chemical potentials, consistent with earlier Ginzburg-Landau analyses.
↳ hep-phhep-thnucl-thPRD(2025)·47 citations
11
Nuclear Excitation by Near-Resonant Electron Transition in $^{229}$ Th $^{39 +}$ Ions
Karol Kozioł · Jacek Rzadkiewicz
Theoretical considerations are made for the nuclear excitation from the ground state to the 8 eV $^{229 m}$ Th isomer via near-resonant electron transitions in Sb-like ( $q = 39 +$ ) thorium ions. The energy of the first excited atomic state ( $J = 7/2$ ) in the $^{229}$ Th $^{39 +}$ ion is estimated to be 8.308 $\pm$ 0.069 eV, which is very close to the new reference value for the $^{229 m}$ Th nuclear isomer energy, 8.356 eV [Zhang et al., Nature 633, 63 (2024)]. Therefore, the $^{229}$ Th $^{39 +}$ ion provides a unique opportunity to study the nuclear excitation by electron transition process under well-defined atomic conditions in the regime of extremely low nuclear excitation energy. Our results indicate that the upper theoretical limit for the $^{229 m}$ Th isomer excitation rate reaches an enormous value of $1.27 \times 1 0^{16}$ s $^{- 1}$ at resonance ( $Δ = 0$ meV), but drops many orders of magnitude for the value of electronic transition energy within its uncertainty interval. Additionally, it was shown that using an electron beam ion trap, the production of the $^{229}$ Th isomer can reach rates ranging from a few to approximately $7 \times 1 0^{19}$ $^{- 1}$ .
↳ physics.atom-phnucl-exnucl-thquant-phPRC(2025)·4 citations
12
Pion to photon transition form factor: Beyond valence quarks
Xiaoyi Wu🇨🇳 · Zhimin Zhu🇨🇳 · Ziyang Lin🇨🇳 · Chandan Mondal🇨🇳 · Jiangshan Lan🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸
We investigate the singly virtual transition form factor (TFF) for the $π^{0} \to γ^{*} γ$ process in the space-like region using the hard-scattering formalism within the Basis Light-Front Quantization (BLFQ) framework. This form factor is expressed in terms of the perturbatively calculable hard-scattering amplitudes (HSAs) and the light-front wave functions (LFWFs) of the pion. We obtain the pion LFWFs by diagonalizing the light-front QCD Hamiltonian, which is determined for its constituent quark-antiquark and quark-antiquark-gluon Fock sectors with a three-dimensional confinement. We employ the HSAs up to next-to-leading order (NLO) in the quark-antiquark Fock sector and leading order (LO) in the quark-antiquark-gluon Fock sector. The NLO correction to the TFF in the quark-antiquark Fock sector is of the same order as the LO contribution to the TFF in the quark-antiquark-gluon Fock sector. We find that while the quark-antiquark-gluon Fock sector has minimal effect in the large momentum transfer ( $Q^{2}$ ) region, it has a noteworthy impact in the low- $Q^{2}$ region. Our results show that, after accounting for both Fock sectors, the TFF within the BLFQ framework aligns well with existing experimental data, particularly in the low $Q^{2}$ region.
↳ hep-phnucl-thPRD(2025)·4 citations
13
Shape Coexistence in $^{94}$ Zr from a Model-Independent Analysis
N. Marchini (1 and 2)🇮🇹 · M. Rocchini (1)🇮🇹 · M. Zielinska (3)🇫🇷 · A. Nannini (1)🇮🇹 · D.T. Doherty (4)🇬🇧 · N. Gavrielov (5)🇫🇷 · P.E. Garrett (6)🇨🇦 · K. Hadynska-Klek (7)🇵🇱 · A. Goasduff (8 and 9)🇮🇹 · D. Testov (8)🇮🇹 · S.D. Bakes (4 and 9 and 10)🇬🇧 · D. Bazzacco (8 and 9)🇮🇹 and 24 other authors
Low-lying states of $^{94}$ Zr were investigated via low-energy multi-step Coulomb excitation. From the measured $γ$ -ray yields, \textcolor{black}{16} reduced \textcolor{black}{E2} transition probabilities between low-spin states were determined, together with the spectroscopic quadrupole moments of the $2_{1, 2}^{+}$ states. Based on this information, for the first time in the Zr isotopic chain, the shapes of the $0_{1, 2}^{+}$ states including their deformation softness were inferred in a model-independent way using the quadrupole sum rules approach. The ground state of $^{94}$ Zr possesses a rather diffuse shape associated with a spherical configuration, while the $0_{2}^{+}$ state is \textcolor{black}{triaxial tending towards} oblate and more strongly deformed. {\color{black}The observed features of shape coexistence in $^{94}$ Zr are consistent with both Monte-Carlo shell-model predictions and IBM-CM calculations, and provide model-independent constraints on the shape character assigned in the IBM-CM to the intruder configuration in $^{92 - 96}$ Zr.}
↳ nucl-exnucl-thPLB(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Production characteristics of light nuclei, hypertritons and Ω-hypernuclei in Pb+Pb collisions at sNN​​=5.02 TeV

Semi-automatic Calculations of Multi-loop Feynman Amplitudes with AmpRed

Renormalization-group consistent treatment of color superconductivity in the NJL model

Nuclear Excitation by Near-Resonant Electron Transition in 229Th39+ Ions

Pion to photon transition form factor: Beyond valence quarks

Shape Coexistence in 94Zr from a Model-Independent Analysis

Affiliations

Production characteristics of light nuclei, hypertritons and $Ω$ -hypernuclei in Pb+Pb collisions at $s_{N N} = 5.02$ TeV

Nuclear Excitation by Near-Resonant Electron Transition in $^{229}$ Th $^{39 +}$ Ions

Shape Coexistence in $^{94}$ Zr from a Model-Independent Analysis