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
12
[Submitted on 31 Aug 2020] (cross-list from hep-ph)
The Strangest Proton?
Ferran Faura🇳🇱 · Shayan Iranipour🇬🇧 · Emanuele R. Nocera🇳🇱 · Juan Rojo🇳🇱 · Maria Ubiali🇬🇧
We present an improved determination of the strange quark and anti-quark parton distribution functions of the proton by means of a global QCD analysis that takes into account a comprehensive set of strangeness-sensitive measurements: charm-tagged cross sections for fixed-target neutrino-nucleus deep-inelastic scattering, and cross sections for inclusive gauge-boson production and $W$ -boson production in association with light jets or charm quarks at hadron colliders. Our analysis is accurate to next-to-next-to leading order in perturbative QCD where available, and specifically includes charm-quark mass corrections to neutrino-nucleus structure functions. We find that a good overall description of the input dataset can be achieved and that a strangeness moderately suppressed in comparison to the rest of the light sea quarks is strongly favored by the global analysis.
Comments:
Version accepted for publication in EPJC. PDF sets available from http://nnpdf.mi.infn.it/nnpdf3-1strangeness/. v3: fixed typos
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2009.00014 [pdf]
EPJC(2020)·90 citations
13
[Submitted on 31 Aug 2020] (cross-list from hep-ph)
Open charm and dileptons from relativistic heavy-ion collisions
Elena Bratkovskaya🇩🇪 · Taesoo Song🇩🇪 · Pierre Moreau🇺🇸 · Carsten Greiner🇩🇪
We study the dynamics of open charm production and the dilepton radiation of the semi-leptonic decays of correlated $D D ˉ$ pairs versus the quark-gluon plasma (QGP) radiation and hadronic sources in relativistic heavy-ion collisions. Our study is based on the Parton-Hadron-String Dynamics (PHSD) transport approach employing a non-perturbative QCD description of the strongly interacting quark-gluon plasma (sQGP) in terms of dynamical quasiparticles and the EoS based on lattice QCD. We compare the PHSD results for charm observables with the calculations from BAMPS (Boltzmann Approach to Multi-Parton Scatterings) which is based on perturbative QCD with massless partons and interaction cross sections calculated in leading order of the QCD coupling. We compare the $p_{T}$ dependence of the ratio $R_{AA}$ of $D$ -mesons in $A + A$ over $p + p$ collisions scaled by the number of binary collisions $N_{bin}$ as well as the elliptic flow $v_{2}$ of $D$ -mesons calculated within the PHSD and BAMPS at LHC energies. In other study, based on the PHSD calculations we find that the dileptons from correlated $D -$ meson semi-leptonic decays dominate the 'thermal' radiation from the QGP in central Pb+Pb collisions at the intermediate masses ( $1.2 < M < 3$ GeV) for higher invariant energies However, for invariant energies $s_{N N} < 40$ GeV the QGP radiation overshines the contribution from $D, D ˉ$ decays such that one should observe a rather clear signal from the partonic dilepton radiation. This finding provides promising perspectives to measure the QGP radiation in the dilepton experiments at RHIC BES and the future FAIR/NICA facilities.
Comments:
5 pages, 3 figures, Contribution to the "Hard Probe-2020" Proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2009.00040 [pdf]
1 citation
14
[Submitted on 1 Sept 2020] (cross-list from astro-ph.SR)
Enhancement of Lithium in Red Clump Stars by the Additional Energy Loss Induced by New Physics
Kanji Mori🇯🇵 · Motohiko Kusakabe🇨🇳 · A. Baha Balantekin🇺🇸 · Toshitaka Kajino🇯🇵 · Michael A. Famiano🇺🇸
Since 7Li is easily destroyed in low temperatures, the surface lithium abundance decreases as stars evolve. This is supported by the lithium depletion observed in the atmosphere of most red giants. However, recent studies show that almost all of red clump stars have high lithium abundances A(Li)>-0.9, which are not predicted by the standard theory of the low-mass stellar evolution. In order to reconcile the discrepancy between the observations and the model, we consider additional energy loss channels which may come from physics beyond the Standard Model. A(Li) slightly increases near the tip of the red giant branch even in the standard model with thermohaline mixing because of the 7Be production by the Cameron-Fowler mechanism, but the resultant 7Li abundance is much lower than the observed values. We find that the production of 7Be becomes more active if there are additional energy loss channels, because themohaline mixing becomes more efficient and a heavier helium core is formed.
Comments:
8 pages, 11 figures, accepted by MNRAS
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.00293 [pdf]
MNRAS(2021)·10 citations
15
[Submitted on 1 Sept 2020] (cross-list from hep-lat)
New method for calculating electromagnetic effects in semileptonic beta-decays of mesons
Chien-Yeah Seng🇩🇪 · Xu Feng🇨🇳 · Mikhail Gorchtein🇩🇪 · Lu-Chang Jin🇺🇸 · Ulf-G. Meißner🇩🇪
We construct several classes of hadronic matrix elements and relate them to the low-energy constants in Chiral Perturbation Theory that describe the electromagnetic effects in the semileptonic beta decay of the pion and the kaon. We propose to calculate them using lattice QCD, and argue that such a calculation will make an immediate impact to a number of interesting topics at the precision frontier, including the outstanding anomalies in $∣ V_{u s} ∣$ and the top-row Cabibbo-Kobayashi-Maskawa matrix unitarity.
Comments:
Version to appear in JHEP
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2009.00459 [pdf]
JHEP(2020)·38 citations
16
[Submitted on 30 Aug 2020] (cross-list from hep-ph)
Heavy Quark Radiation in the Quark-Gluon Plasma in the Moliere Theory: Angular Distribution of the Radiation
B. Blok (Technion)🇮🇱
We study the effects of adding the Coulomb interactions to the harmonic oscillator (HO) approximation of the heavy parton propagating through the quark-gluon plasma (the extension to QCD of the Molliere theory). We explicitly find the expression for the transverse momentum distribution of the gluon radiation of the heavy quark propagating in the quark gluon plasma in the framework of the Moliere theory, taking into account the BDMPSZ radiation in the harmonic oscillator (HO) approximation, and the Coulomb logarithms described by the additional logarithmic terms in the effective potential. We show that these Coulomb logarithms significantly influence the HO distribution, derived in the BDMPSZ works, especially for the small transverse momenta, filling the dead cone, and reducing the dead cone suppression of the heavy quark radiation (dead cone effect). In addition we study the effect of the phase space constraints on the heavy quark energy loss, and argue that taking into account of both the phase space constraints and of the Coulomb gluons reduces the dependence of the heavy quark energy loss on its mas in the HO approximation.
Comments:
26 pages, 7 figures 2 tables. arXiv admin note: text overlap with arXiv:2002.11233, references added,a mistake in the numerical code for angular distributions leading to unphysical oscillations corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2009.00465 [pdf]
EPJC(2021)·8 citations
17
[Submitted on 1 Sept 2020] (cross-list from physics.data-an)
Conception and software implementation of a nuclear data evaluation pipeline
Georg Schnabel · Henrik Sjöstrand · Joachim Hansson · Dimitri Rochman · Arjan Koning · Roberto Capote
We discuss the design and software implementation of a nuclear data evaluation pipeline applied for a fully reproducible evaluation of neutron-induced cross sections of $^{56}$ Fe above the resolved resonance region using the nuclear model code TALYS combined with relevant experimental data. The emphasis is on the mathematical and technical aspects of the pipeline and not on the evaluation of $^{56}$ Fe, which is tentative. The mathematical building blocks combined and employed in the pipeline are discussed in detail. A unified representation of experimental data, systematic and statistical errors, model parameters and defects enables the application of the Generalized Least Squares (GLS) and its natural extension, the Levenberg-Marquardt (LM) algorithm, on a large collection of experimental data. The LM algorithm tailored to nuclear data evaluation accounts for the exact non-linear physics model to determine best estimates of nuclear quantities. Associated uncertainty information is derived from a Taylor expansion at the maximum of the posterior distribution. We also discuss the pipeline in terms of its IT (=information technology) building blocks, such as those to efficiently manage and retrieve experimental data of the EXFOR library and to distribute computations on a scientific cluster. Relying on the mathematical and IT building blocks, we elaborate on the sequence of steps in the pipeline to perform the evaluation, such as the retrieval of experimental data, the correction of experimental uncertainties using marginal likelihood optimization (MLO) and after a screening of thousand TALYS parameters -- including Gaussian process priors on energy dependent parameters -- the fitting of about 150 parameters using the LM algorithm. The code of the pipeline including a manual and a Dockerfile for a simplified installation is available at www.nucleardata.com.
Comments:
45 pages
Subjects:
Data Analysis, Statistics and Probability (physics.data-an); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2009.00521 [pdf]
Nucl.Data Sheets(2021)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE