PaperPanorama

Nuclear Theory·nucl-th

Friday·September 9, 2022

12 papers5 primary·7 cross-listed

  1. 01

    Rooting the EDF method into the ab initio framework. PGCM-PT formalism based on MR-IMSRG pre-processed Hamiltonians

    T. Duguet · J.-P. Ebran · M. Frosini · H. Hergert · V. Somà

    Recently, ab initio techniques have been successfully connected to the traditional valence-space shell model. In doing so, they can either explicitly provide ab initio shell-model effective Hamiltonians or constrain the construction of empirical ones. In the present work, the possibility to follow a similar path for the nuclear energy density functional (EDF) method is analyzed. For this connection to be actualized, two theoretical techniques are instrumental: the recently proposed ab initio PGCM-PT many-body formalism and the MR-IMSRG pre-processing of the nuclear Hamiltonian. Based on both formal arguments and numerical results, possible new lines of research are briefly discussed, namely to compute ab initio EDF effective Hamiltonians at low computational cost, to constrain empirical ones or to produce them directly via an effective field theory that remains to be invented.

    nucl-thEPJA(2023)·23 citations
  2. 02

    Cold dense quark matter with phenomenological medium effects: a self-consistent formulation of the quark-mass density-dependent model

    G. Lugones🇧🇷 · A. G. Grunfeld🇦🇷

    We revisit the quark-mass density-dependent model -- a phenomenological equation of state for deconfined quark matter in the high-density low-temperature regime -- and show that thermodynamic inconsistencies that have plagued the model for decades, can be solved if the model is formulated in the canonical ensemble instead of the grand canonical one. Within the new formulation, the minimum of the energy per baryon occurs at zero pressure, and the Euler's relation is verified. Adopting a typical mass-formula, we first analyze in detail a simple model with one particle species. We show that a ``bag'' term that produces quark confinement naturally appears in the pressure (and not in the energy density) due to density dependence of the quark masses. Additionally, the chemical potential gains a new term as in other models with quark repulsive interactions. Then, we extend the formalism to the astrophysically realistic case of charge-neutral three-flavor quark matter in equilibrium under weak interactions, focusing on two different mass formulae: a flavor dependent and a flavor blind one. For these two models, we derive the equation of state and analyze its behavior for several parameter choices. We systematically analyze the parameter space and identify the regions corresponding to self-bound 2-flavor and 3-flavor quark matter, hybrid matter and causal behavior.

    nucl-thastro-ph.SRhep-phPRD(2023)·20 citations
  3. 03

    Deuteron Structure and Form Factors: Using Inverse Potentials for S-waves

    Anil Khachi · Lalit Kumar · M.R. Ganesh Kumar · O.S.K.S Sastri

    In this paper, we determine deuteron's static properties, low energy scattering parameters, total cross-section and form factors from inverse S-wave potentials constructed using Morse function. The scattering phase shifts (SPS) at different lab energies are determined using phase function method. The model parameters are optimised using both machine learning algorithm and traditional data analysis by choosing mean squared error as cost function. The mean absolute error between experimental and obtained SPS for states 3S1 and 1S0 are found to be 0.35 and 0.70 respectively. The low energy scattering parameters are matching well with expected values. The contribution due to S-waves SPS towards total cross-section at various energies have been obtained and are matching well with experimental values. The analytical ground state deuteron wave-function (DWF) is obtained by utilizing the experimental value for Quadrupole moment. Other static properties and form factors determined from obtained DWF are found to be in close agreement with experimental ones.

    nucl-th1 citation
  4. 04

    Shake-off in the 164Er neutrinoless double electronic capture and the dark matter puzzle

    F. F. Karpeshin🇷🇺 · M. B. Trzhaskovskaya🇷🇺

    Traditionally double neutrinoless electronic capture is considered as a resonance process. We have fulfilled shake-off probability calculations, leading to ionization of the electron shell, in the case of 164Er. Allowance for the shake-off removes the requirement of resonance, leading to a radical increase of the capture rate. In the case of 164Er, the contribution of the new mechanism increases the capture rate by a factor of 5.6 as compared to the conventional resonance fluorescence mechanism. It also increases the probability of electron capture from higher shells, which must be foreseen in the experimental studies. Moreover, the effect of the shake-off can expand the list of candidate nuclei for experimental research. The influence of the shake-off is also expected to manifest itself in the other beta processes which are used in the studies of the neutrino nature, its mass and role in the dark matter puzzle.

    nucl-thPRC(2023)·8 citations
  5. 05

    Investigation of the freeze-out parameters in B-B, O-O, Ca-Ca and Au-Au collisions at 39 GeV

    Muhammad Waqas🇨🇳 · Guang Xiong Peng🇨🇳 · Fu-Hu Liu🇨🇳 · Muhammad Ajaz🇵🇰 · Abd Al Karim Haj Ismail🇦🇪

    We analyzed the transverse momentum spectra of proton, deuteron and triton in Boron-Boron (B-B), Oxygen-Oxygen (O-O), and Calcium-Calcium (Ca-Ca) central collisions, as well as in several centrality bins in Gold-Gold (Au-Au) collisions at 39 GeV by using the blast wave model with Tsallis statistics. The bulk properties in terms of kinetic freeze-out temperature, transverse flow velocity and kinetic freeze-out volume are extracted from the model by the least square method. We observed that with increasing the rest mass of the particle, the kinetic freeze-out temperature becomes larger, while transverse flow velocity and the kinetic freeze-out volume reduces. These parameters are also found to depend on the size of the system. Larger the size of the system, the larger they are. Furthermore, the kinetic freeze-out temperature in peripheral Au-Au collisions is close to the central O-O collisions. We also observed that the above parameters depend on the centrality, and they decrease from central to peripheral collisions. Besides, we also extracted the entropy-index parameter , and the parameter which shows the multiplicity. Both of them depend on the size of interacting the system, rest mass of the particle and centrality. Both and are larger for lighter particles, and the former is smaller for large systems while the latter is larger, and the former decrease with increasing centrality while the latter increase.

    nucl-thhep-phEur.Phys.J.Plus(2022)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE