Nuclear Theory·nucl-th

Thursday·November 3, 2022

8 papers—5 primary·3 cross-listed

01
Nuclear Shape Transition, Triaxiality and Energy Staggering of gamma Band States for Even-Even Xenon Isotopic Chain
W.B.Elsharkawy · Abeer Mera · M.Kotb · A.M.Khalaf
The positive-parity states of even-even Xe nuclei are investigated within the framework of modified O(6) limit of the interacting boson model (IBM1). The effective three-body interaction [QQQ] where Q is the IBM O(6) quadrupole operator is introduced to exhibit the triaxiality nature. The shape of nuclear surface is described by the deformation parameters beta, gamma by using the intrinsic coherent state. The potential energy surfaces (PES) of the transition U(5)-Triaxiality-O(6) are calculated and analyzed and the critical phase transition points are identified. For each nucleus a fitting procedure is adopted to get the best model parameters by fitting some selected calculated energy levels and B(E2)transition rates ratios with experimental ones. These ratios are analyzed because they serve as effective order parameters in the shape phase transition. The nuclei in Xe isotopic chain evolve from spherical vibrator U(5) to gamma-soft rotor O(6) by increasing the boson number from N=3 (heavy isotope 132Xe) to N=10 (light isotope 120Xe) and the isotope 126Xe represent the critical nucleus. The nucleus 128Xe has triaxial nature. To deal with high spin states in gamma band in 118- 128Xe isotopic chain to investigate and exhibit the odd-even spin energy staggering, we introduce the two parameters collective nuclear softness rotor model (CNS2). Three different staggering indices depending on the dipole transitions linking the two families of spins and the quadrupole transitions within each spin family are considered. Strong odd-even spin energy staggering has been seen. As a link between the IBM and CNS2 models we observed that the energy difference between the gamma-band and ground state band normalized to decreases with increasing the mass number
nucl-thPhys.Atom.Nucl.(2023)·1 citation
02
Nuclei in Core-Collapse Supernovae Engine
Shun Furusawa · Hiroki Nagakura
Herein, we review the nuclear equations of state (EOSs) %for core-collapse supernova simulations and the constituent nuclei of core-collapse supernovae (CCSNe) and their roles in CCSN simulations. Various nuclei such as deuterons, iron, and extremely neutron-rich nuclei compose in the central engines of CCSNe. The center of a collapsing core is dominated by neutron-rich heavy nuclei prior to the occurrence of core bounce. Their weak interactions significantly affect the neutrino emission and the size of the produced proto-neutron star. After a core bounce, heavy nuclei are dissolved to protons, neutrons, and light nuclei between the expanding shock wave and the newly formed neutron star (NS). Some of the key components in determining the shock-wave dynamics and supernova explosion of outer envelopes are neutrino interactions of nucleons and light nuclei such as deuterons. An EOS provides the relations between thermodynamical properties and the nuclear composition, and is needed to simulate this explosion. Further investigations on uniform and non-uniform nuclear matter are needed to improve the understanding of the mechanism of CCSNe and the properties of supernova nuclei. The knowledge of the EOS for uniform nuclear matter is being continually improved by a combination of microscopic calculations, terrestrial experiments, and NS observations. With reference to various nuclear experiments and current theories, the finite temperature effects on heavy nuclei, formation of light nuclei in dilute nuclear matter, and transition to uniform nuclear matter should be improved in the model of the EOS for non-uniform nuclear matter.
nucl-thastro-ph.HEastro-ph.SRPPNP(2023)·17 citations
03
Towards a Unified Description of Isoscalar Giant Monopole Resonances in a Self-Consistent Quasiparticle-Vibration Coupling Approach
Z.Z. Li · Y.F. Niu · G. Colò
"Why is the EoS for tin so soft?" is a longstanding question, which prevents us from determining the nuclear incompressibility $K_{\infty}$ accurately. To solve this puzzle, a fully self-consistent quasiparticle random phase approximation (QRPA) plus quasiparticle-vibration coupling (QPVC) approach based on Skyrme-Hartree-Fock-Bogoliubov is developed. We show that the many-body correlations introduced by QPVC, which shift the ISGMR energy in Sn isotopes by about 0.4 MeV more than the energy in $^{208}$ Pb, play a crucial role in providing a unified description of the ISGMR in Sn and Pb isotopes. The best description of the experimental strength functions is given by SV-K226 and KDE0, which are characterized by incompressibility values $K_{\infty} =$ 226 MeV and 229 MeV, respectively, at mean field level.
nucl-thPRL(2023)·54 citations
04
Modewise Johnson-Lindenstrauss Embeddings for Nuclear Many-Body Theory
A. Zare · R. Wirth · C. A. Haselby · H. Hergert · M. Iwen
In this work, we explore modewise Johnson-Lindenstrauss embeddings (JLEs) as a tool to reduce the computational cost and memory requirements of nuclear many-body methods. JLEs are randomized projections of high-dimensional data tensors onto low-dimensional subspaces that preserve key structural features. Such embeddings allow for the oblivious and incremental compression of large tensors, e.g., the nuclear Hamiltonian, into significantly smaller random sketches that still allow for the accurate calculation of ground-state energies and other observables. Their oblivious character makes it possible to compress a tensor without knowing in advance exactly what observables one might want to approximate at a later time. This opens the door for the use of tensors that are much too large to store in memory, e.g., complete two-plus three-nucleon Hamiltonians in large, symmetry-unrestricted bases. Such compressed Hamiltonians can be stored and used later on with relative ease. As a first step, we analyze the JLE's impact on the second-order Many-Body Perturbation Theory (MBPT) corrections for nuclear ground-state observables. Numerical experiments for a wide range of closed-shell nuclei, model spaces and state-of-the-art nuclear interactions demonstrate the validity and potential of the proposed approach: We can compress nuclear Hamiltonians hundred- to thousand-fold while only incurring mean relative errors of 1\% or less in ground-state observables. Importantly, we show that JLEs capture the relevant physical information contained in the highly structured Hamiltonian tensor despite their random characteristics. In addition to the significant storage savings, the achieved compressions imply multiple order-of magnitude reductions in computational effort when the compressed Hamiltonians are used in higher-order MBPT or nonperturbative many-body methods.
nucl-thEPJA(2023)·4 citations
05
Equation of state of superfluid neutron matter with low-momentum interactions
Viswanathan Palaniappan🇮🇳 · S. Ramanan🇮🇳 · Michael Urban🇫🇷
In this work, we calculate the ground state energy of pure neutron matter using the renormalization group based low-momentum effective interaction $V_{low- k}$ in Bogoliubov many-body perturbation theory (BMBPT), which is a perturbative expansion around the Hartree-Fock-Bogoliubov (HFB) ground state. In order to capture the low-density behavior of neutron matter, it turns out to be better to use a density dependent cutoff in the $V_{low- k}$ interaction. Perturbative corrections to the HFB energy up to third order are included. We find that at low densities corresponding to the inner crust of neutron stars, the HFB state that includes pairing is a better starting point for perturbation expansion. It is observed that including the higher order perturbative corrections, the cutoff dependence of the ground state energy is reduced.
nucl-thPRC(2023)·13 citations
06
Faster spectral density calculation using energy moments
Jeremy Hartse🇺🇸 · Alessandro Roggero🇺🇸
Accurate predictions of inclusive scattering cross sections in the linear response regime require efficient and controllable methods to calculate the spectral density in a strongly-correlated many-body system. In this work we reformulate the recently proposed Gaussian Integral Transform technique in terms of Fourier moments of the system Hamiltonian which can be computed efficiently on a quantum computer. One of the main advantages of this framework is that it allows for an important reduction of the computational cost by exploiting previous knowledge about the energy moments of the spectral density. For a simple model of medium mass nucleus like $^{40}$ Ca and target energy resolution of $1$ MeV we find an expected speed-up of $\approx 125$ times for the calculation of the giant dipole response and of $\approx 50$ times for the simulation of quasi-elastic electron scattering at typical momentum transfers.
↳ quant-phnucl-thEPJA(2023)·9 citations
07
Determining the $C P$ Property of $h t t ˉ$ Coupling via a Novel Jet Substructure Observable
Zhite Yu🇺🇸 · Kirtimaan A. Mohan🇺🇸 · C.-P. Yuan🇺🇸
Determining the $C P$ property of the Higgs boson is important for a precision test of the Standard Model as well as for the search for new physics. We propose a novel jet substructure observable based on the azimuthal anisotropy in a linearly polarized gluon jet that is produced in association with a Higgs boson at hadron colliders, and demonstrate that it provides a new $C P$ -odd observable for determining the $C P$ property of the Higgs-top interaction. We introduce a factorization formalism to define a polarized gluon jet function with the insertion of an infrared-safe azimuthal observable to capture the linear polarization.
↳ hep-phhep-exhep-latnucl-thPLB(2024)·9 citations
08
Effects of electromagnetic fluctuations in plasmas on solar neutrino fluxes
Eunseok Hwang🇰🇷 · Dukjae Jang🇰🇷 · Kiwan Park🇰🇷 · Motohiko Kusakabe🇨🇳 · Toshitaka Kajino🇨🇳 · A. Baha Balantekin🇺🇸 · Tomoyuki Maruyama🇯🇵 · Youngshin Kwon🇰🇷 · Kyujin Kwak🇰🇷 · Myung-Ki Cheoun🇰🇷
We explore the effects of electromagnetic (EM) fluctuations in plasmas on solar neutrino fluxes exploiting the fluctuation-dissipation theorem. We find that the EM spectrum in the solar core is enhanced by the EM fluctuations due to the high density of the Sun, which increases the radiation energy density and pressure. By the EM fluctuations involving the modified radiation formula, the central temperature decreases when the central pressure of the Sun is fixed. With a help of the empirical relation between central temperature and neutrino fluxes deduced from the numerical solar models, we present the change in each of the solar neutrino fluxes by the EM fluctuations. We also discuss the enhanced radiation pressure and energy density by the EM fluctuations for other astronomical objects.
↳ astro-ph.SRastro-ph.HEnucl-thphysics.plasm-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE