Nuclear Theory·nucl-th

Wednesday·September 2, 2020

17 papers—11 primary·6 cross-listed

01
[Submitted on 1 Sept 2020]
Statistical and Dynamical Model Studies of Nuclear Multifragmentation Reactions at Intermediate Energies
S. Mallik🇮🇳
Nuclear multifragmentation is an important phenomenon, the study of which can throw light on reaction mechanism in heavy ion collisions at intermediate and high energies. Based on statistical and dynamical model studies, this thesis is concentrated mainly on, the following three aspects of nuclear multifragmentation reactions namely (i) production of exotic nuclei which are normally not available in the laboratory (ii) nuclear symmetry energy from heavy ion collisions at intermediate energies and (iii) Nuclear liquid-gas phase transition. In addition to these equivalence of statistical ensembles under different conditions is also studied in the framework of multifragmentation.
Comments:
PhD Thesis (Variable Energy Cyclotron Centre, Homi Bhabha National Institute)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2009.00283 [pdf]
1 citation
02
[Submitted on 1 Sept 2020]
Proxy-SU(3) symmetry in the shell model basis
Andriana Martinou · Dennis Bonatsos · N. Minkov · I.E. Assimakis · S. K. Peroulis · S. Sarantopoulou · J. Cseh
The proxy-SU(3) symmetry has been proposed for spin-orbit like nuclear shells using the asymptotic deformed oscillator basis for the single particle orbitals, in which the restoration of the symmetry of the harmonic oscillator shells is achieved by a change of the number of quanta in the z-direction by one unit for the intruder parity orbitals. The same definition suffices within the cartesian basis of the Elliott SU(3) model. Through a mapping of the cartesian Elliott basis onto the spherical shell model basis, we translate the proxy-SU(3) approximation into spherical coordinates, proving, that in the spherical shell model basis the proxy-SU(3) approximation corresponds to the replacement of the intruder parity orbitals by their de Shalit--Goldhaber partners. Furthermore it is shown, that the proxy-SU(3) approximation in the cartesian Elliott basis is equivalent to a unitary transformation in the z-coordinate, leaving the x-y plane intact, a result which in the asymptotic deformed oscillator coordinates implies, that the z-projections of angular momenta and spin remain unchanged. The present work offers a microscopic justification of the proxy-SU(3) approximation and in addition paves the way, for taking advantage of the proxy-SU(3) symmetry in shell model calculations.
Comments:
15 pages, 7 tables, 1 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.00307 [pdf]
EPJA(2020)·40 citations
03
[Submitted on 1 Sept 2020]
Nucleon momentum distribution extracted from the experimental scaling function
M. V. Ivanov · A. N. Antonov · J. A. Caballero
The connection between the scaling function, directly extracted from the analysis of electron scattering data, and the nuclear spectral function or nuclear momentum density is investigated at depth. The dependence of the scaling function on the two independent variables in the scattering process, the transfer momentum ( $q$ ) and the scaling variable ( $y$ ), is taken into account, and the analysis is extended to both, positive and negative $y$ -values, i.e., below and above the center of the quasielastic peak, respectively. Analytical expressions for the derivatives of the scaling function, evaluated at the finite limits of integration dealing with the kinematically allowed region, are connected with the spectral function. Here, contributions corresponding to zero and finite excitation energies are included. The scaling function is described by the Gumbel density distribution, whereas short-range correlations are incorporated in the spectral function by using some simple models. Also different parametrizations for the nucleon momentum distribution, that are compatible with the general properties of the scaling function, have been considered.
Comments:
26 pages, 16 figures, accepted for publication in Nuclear Physics, Section A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.00350 [pdf]
NPA(2020)·4 citations
04
[Submitted on 1 Sept 2020]
Light clusters in dilute heavy-baryon admixed nuclear matter
Armen Sedrakian
We study the composition of nuclear matter at sub-saturation densities, non-zero temperatures, and isospin asymmetry, under the conditions characteristic of binary neutron star mergers, stellar collapse, and low-energy heavy-ion collisions. The composition includes light clusters with mass number $A \leq 4$ , a heavy nucleus ( $\isotope [56] F e$ ), the $Δ$ -resonances, the isotriplet of pions, as well as the $Λ$ hyperon. The nucleonic mean-fields are computed from a zero-range density functional, whereas the pion-nucleon interactions are treated to leading order in chiral perturbation theory. We show that with increasing temperature and/or density the composition of matter shifts from light-cluster to heavy baryon dominated one, the transition taking place nearly independent of the magnitude of the isospin. Our findings highlight the importance of simultaneous treatment of light clusters and heavy baryons in the astrophysical and heavy-ion physics contexts.
Comments:
v3: matches published version; v2: version in print, some clarifications, corrections, and additional references, 8 page, 4 figures. v1: 6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2009.00357 [pdf]
EPJA(2020)·14 citations
05
[Submitted on 1 Sept 2020]
Effect of liquid drop model parameters on nuclear liquid gas phase transition
G. Chaudhuri · S. Mallik
The phenomenon of liquid-gas phase transition occurring in heavy ion collisions at intermediate energies is a subject of contemporary interest. In statistical models of fragmentation, the liquid drop model is generally used to calculate the ground state binding energies of the fragments. It is well known that the surface and symmetry energy of the hot fragments at the low density freeze out can be considerably modified. In addition to this, the level density parameter also has a wide variation. The effect of variation of these parameters is studied on fragmentation observables which are related to the nuclear liquid gas phase transition. The canonical thermodynamical model which has been very successful in describing the phenomenon of fragmentation is used for the study. The shift in transition temperature owing to the variation in liquid drop model parameters has been examined.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2009.00374 [pdf]
PRC(2019)·4 citations
06
[Submitted on 30 Aug 2020]
Constraining Nuclear Symmetry Energy parameters from Neutron skin thickness of $^{48}$ Ca
S. K. Tripathy · D. Behera · T. R. Routray · B. Behera
In the present work, we use a finite range effective interaction to calculate the neutron skin thickness in $^{48}$ Ca and correlate these quantities with the parameters of nuclear symmetry energy. Available experimental data on the neutron skin thickness in $^{48}$ Ca are used to deduce information on the density slope parameter and the curvature symmetry parameter of the nuclear symmetry energy at saturation and at subsaturation densities. We obtained the constraints such as $54.5 \leq L (ρ_{0}) \leq 97.5$ MeV and $47.3 \leq L (ρ_{c}) \leq 57.1$ MeV for the density slope parameter. The constraints on the curvature symmetry energy parameter are obtained as $- 170.7 \leq K_{sy m} (ρ_{0}) \leq - 43.4$ MeV and $- 80.8 \leq K_{sy m} (ρ_{c}) \leq 23.8$ MeV. A linear relation between the neutron skin thickness in $^{48}$ Ca and in $^{2088}$ Pb is obtained.
Comments:
10 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.00427 [pdf]
5 citations
07
[Submitted on 29 Aug 2020]
Isoscalar and isovector giant resonances in 44Ca, 54Fe, 64,68Zn and 56,58,60,68Ni
G. Bonasera · S. Shlomo · D.H. Youngblood · Y.-W. Lui · J. Button · X. Chen
We have studied the uncharacteristic behavior of the measured values of the isoscalar and isovector centroid energies, ECEN, of giant resonances with multipolarity L=0-3 in 44Ca, 54Fe, 64,68Zn and 56,58,60,68Ni. For this purpose, we carried out calculations of ECEN within the spherical Hartree-Fock (HF)-based random phase approximation (RPA) theory with 33 different Skyrme-type effective nucleon-nucleon interactions. We have also determined the Pearson linear correlation coefficients between the calculated centroid energies and the various nuclear matter (NM) properties associated with each interaction and determined the sensitivity of ECEN to NM properties. We compared the calculated centroid energies of the giant resonances with experimental data and discuss the results. We note in particular, that we obtain good agreement between the calculated ECEN of isovector giant dipole resonance and the available experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.00451 [pdf]
NPA(2021)·3 citations
08
[Submitted on 30 Aug 2020]
Parameter-free predictions for the collective deformation variables beta and gamma within the pseudo-SU(3) scheme
Dennis Bonatsos · Andriana Martinou · S. Sarantopoulou · I.E. Assimakis · S. K. Peroulis · N. Minkov
The consequences of the short range nature of the nucleon-nucleon interaction, which forces the spatial part of the nuclear wave function to be as symmetric as possible, on the pseudo-SU(3) scheme are examined through a study of the collective deformation parameters beta and gamma in the rare earth region. It turns out that beyond the middle of each harmonic oscillator shell possessing an SU(3) subalgebra, the highest weight irreducible representation (the hw irrep) of SU(3) has to be used, instead of the irrep with the highest eigenvalue of the second order Casimir operator of SU(3) (the hC irrep), while in the first half of each shell the two choices are identical. The choice of the hw irrep predicts a transition from prolate to oblate shapes just below the upper end of the rare earth region, between the neutron numbers N=114 and 116 in the W, Os, and Pt series of isotopes, in agreement with available experimental information, while the choice of the hC irrep leads to a prolate to oblate transition in the middle of the shell, which is not seen experimentally. The prolate over oblate dominance in the ground states of even-even nuclei is obtained as a by-product.
Comments:
18 pages, 4 tables, 8 figures. arXiv admin note: text overlap with arXiv:1909.01967
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.00468 [pdf]
Eur.Phys.J.ST(2020)·22 citations
09
[Submitted on 1 Sept 2020]
Isospin dependent hybrid model for studying isoscaling in heavy ion collisions around the Fermi energy domain
S. Mallik · G. Chaudhuri
Investigation of observables from nuclear multifragmentation reactions depending on isospin led to the development of a hybrid model. The mass and charge distribution as well as isotopic distribution was studied using this model for $^{112}$ Sn+ $^{112}$ Sn reaction as well as $^{124}$ Sn+ $^{124}$ Sn reactions at different energies. The agreement of the results obtained from the model with those from experimental data confirms the accuracy of the model. Isoscaling coefficients were extracted from these observables which can throw light on the symmetry energy coefficient. Another important facet of this model is that temperature of the studied reaction can be directly extracted using this model.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2009.00491 [pdf]
NPA(2020)·12 citations
10
[Submitted on 1 Sept 2020]
Energy Loss Versus Energy Gain of Heavy Quarks in a Hot Medium
Mohammad Yousuf Jamal🇮🇳 · Santosh K. Das🇮🇳 · Marco Ruggieri🇨🇳
We study the energy loss and the energy gain of heavy quarks in a hot thermal medium. These include the study of the energy change due to the polarization and to the interaction with the thermal fluctuations of the medium. The dynamics of the heavy quarks with the medium is described by the Wong equations, that allow for the inclusion of both the backreaction on the heavy quarks due to the polarization of the medium, and of the interaction with the thermal fluctuations of the gluon field. Both the momentum as well as the temperature dependence of the energy loss and gain of charm and bottom quark are studied. We find that heavy quark energy gain dominate the energy loss at high-temperature domain achievable at the early stage of the high energy collisions. This finding supports the recently observed heavy quarks results in Glasma and will have a significant impact on heavy quark observables at RHIC and LHC energies.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.00561 [pdf]
PRD(2021)·21 citations
11
[Submitted on 1 Sept 2020]
Equation of Motion Method to strongly correlated Fermi systems and Extended RPA approaches
P. Schuck🇫🇷 · D.S. Delion🇷🇴 · J. Dukelsky🇪🇸 · M. Jemai🇹🇳 · E. Litvinova🇺🇸 · G. Roepke🇩🇪 · M. Tohyama🇯🇵
The status of different extensions of the Random Phase Approximation (RPA) is reviewed. The general framework is given within the Equation of Motion Method and the equivalent Green's function approach for the so-called Self-Consistent RPA (SCRPA). The role of the Pauli principle is analyzed. A comparison among various approaches to include Pauli correlations, in particular, renormalized RPA (r-RPA), is performed. The thermodynamic properties of nuclear matter are studied with several cluster approximations for the self-energy of the single-particle Dyson equation. More particle RPA's are shortly discussed with a particular attention to the alpha-particle condensate. Results obtained concerning the Three-level Lipkin, Hubbard and Picket Fence Models, respectively, are outlined. Extended second RPA (ESRPA) is presented.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.00591 [pdf]
Phys.Rept.(2021)·32 citations

Affiliations

first authorsco-authorsvia INSPIRE