Nuclear Theory·nucl-th

Monday·March 29, 2021

13 papers—7 primary·6 cross-listed

01
Variation of delta baryon mass and hybrid star properties in static and rotating conditions
Debashree Sen🇮🇳
The possible conditions for hadron-quark phase transition in hybrid star cores are investigated in the present work. For the hadronic matter part the effective chiral model is adopted. Exotic baryonic degrees like hyperons and the delta baryons are also taken into account. As $Δ$ s posses Breit-Wigner mass distribution ( $1232 \pm 120$ MeV), the hadronic equation of state is obtained by varying the mass of the delta baryons in this range. For the quark phase the MIT bag model is chosen with repulsive effects of the unpaired quarks. Phase transition is achieved using Gibbs construction and the gross properties of the resultant hybrid star are calculated in both static and rotating conditions and compared with the various constraints on them from different observational and empirical perspectives. The work presents a thorough study of the phase transition properties like the critical density of appearance of quarks, the density range for the persistence of the mixed phase and the population of different hadrons and quarks in hybrid star matter. The hybrid star properties, calculated in both static and rotating conditions, are found to be consistent with the bounds on them from different perspectives.
nucl-thPRC(2021)·19 citations
02
Memory effects in Langevin approach to the nuclear fission process
F.A. Ivanyuk · S.V. Radionov · C. Ishizuka · S. Chiba
We present the schematic calculations within the Langevin approach in order to investigate the dependence of fission width on the memory time and the excitation energy at low temperatures where the quantum fluctuations play an important role. For this we consider the simple one-dimensional case with the potential energy given by two parabolic potentials (Kramers potential). For friction and the mass parameters we use the deformation independent values fitted to the results obtained earlier within the microscopic linear response theory. We have found out that at small excitation energies (comparable with the fission barrier height) the memory effects in the friction and random force acts on the fission width in opposite direction. The total effect is not so large, but still quite noticeable (depending on the value of the relaxation time). The use of effective temperature in the diffusion coefficient turns out to be much more important compared with the memory effects. The calculated fission width at very low excitation energies is unrealistically too big.
nucl-th2 citations
03
On the microscopic origin of the Interacting Boson Model
Andriana Martinou🇬🇷
A microscopic interpretation of the s and d bosons of the Interacting Boson Model is being suggested: the s, d bosons can be interpreted as symmetric pairs of harmonic oscillator quanta of the valence nuclear shell. Within this interpretation, the SU(3) limit of the Interacting Boson Model results to the Elliott SU(3) symmetry.
nucl-th0 citations
04
Deuterium-tritium fusion process in strong laser fields: Semiclassical simulation
Shiwei Liu🇨🇳 · Hao Duan🇨🇳 · Difa Ye🇨🇳 · Jie Liu🇨🇳
In this paper, we investigate the deuterium-tritium (DT) fusion process in the presence of strong laser fields with a semiclassical (SC) method. In this model, two nuclei with a given incident kinetic energy that closely approach each other are simulated by tracing the classical Newtonian trajectories in the combined Coulomb repulsive potentials and laser fields. At the nearest position or classical turning point, quantum tunneling through the Coulomb barrier emerges, and its penetrability is estimated with the Wentzel-Kramers-Brillouin formula. Nuclear fusion occurs after the tunneling, and the total fusion cross section takes the Gamow form. We find that the tunneling penetrability can be enhanced dramatically because the nuclei can closely approach each other due to the quiver motion of the charged nuclei driven by the intense laser fields. We then calculate the DT fusion section for a wide range of laser parameters according to various incident nuclei kinetic energies and obtain the phase diagrams for the enhanced DT fusion. We compare our SC results with the quantum results of the Kramers-Henneberger approximation and the Volkov state approximation.
nucl-thPRC(2021)·19 citations
05
Nuclear energy density functionals grounded in ab initio calculations
F. Marino · C. Barbieri · G. Colò · A. Lovato · F. Pederiva · X. Roca-Maza · E. Vigezzi
We discuss the construction of a nuclear Energy Density Functional (EDF) from ab initio calculations, and we advocate the need of a methodical approach that is free from ad hoc assumptions. The equations of state (EoS) of symmetric nuclear and pure neutron matter are computed using the chiral NNLO $_{sat}$ and the phenomenological AV4 $^{'}$ +UIX $_{c}$ Hamiltonians as inputs in the Self-consistent Green's Function (SCGF) and Auxiliary Field Diffusion Monte Carlo (AFDMC) methods, respectively. We propose a convenient parametrization of the EoS as a function of the Fermi momentum and fit it on the SCGF and AFDMC calculations. We apply the ab initio-based EDF to carry out an analysis of the binding energies and charge radii of different nuclei in the local density approximation. The NNLO $_{sat}$ -based EDF produces encouraging results, whereas the AV4 $^{'}$ +UIX $_{c}$ -based one is farther from experiment. Possible explanations of these different behaviors are suggested, and the importance of gradient and spin-orbit terms is analyzed. Our work paves the way for a practical and systematic way to merge ab initio nuclear theory and DFT, while at the same time it sheds light on some of the critical aspects of this procedure.
nucl-thPRC(2021)·32 citations
06
Importance truncation in non-perturbative many-body techniques
Andrea Porro🇫🇷 · Vittorio Somà🇫🇷 · Alexander Tichai🇩🇪 · Thomas Duguet🇫🇷
Expansion many-body methods correspond to solving complex tensor networks. The (iterative) solving of the network and the (repeated) storage of the unknown tensors requires a computing power growing polynomially with the size of basis of the one-body Hilbert space one is working with. Thanks to current computer capabilities, ab initio calculations of nuclei up to mass $A \sim 100$ delivering a few percent accuracy are routinely feasible today. However, the runtime and memory costs become quickly prohibitive as one attempts (possibly at the same time) (i) to reach out to heavier nuclei, (ii) to employ symmetry-breaking reference states to access open-shell nuclei and (iii) to aim for yet a greater accuracy. The challenge is particularly exacerbated for non-perturbative methods involving the repeated storage of (high-rank) tensors obtained via iterative solutions of non-linear equations. The present work addresses the formal and numerical implementations of so-called importance truncation (IT) techniques within the frame of one particular non-perturbative expansion method, i.e., Gorkov Self-Consistent Green's Function (GSCGF) theory, with the goal to eventually overcome above-mentioned limitations. By a priori truncating irrelevant tensor entries, IT techniques are shown to reduce the storage to less than 1% of its original cost in realistic GSCGF calculations performed at the ADC(2) level while maintaining a 1% accuracy on the correlation energy. The future steps will be to extend the present development to the next, e.g., ADC(3), truncation level and to SCGF calculations applicable to doubly open-shell nuclei.
nucl-thEPJA(2021)·14 citations
07
Local polarization and isothermal local equilibrium in relativistic heavy ion collisions
F. Becattini (U. Florence)🇮🇹 · M. Buzzegoli (U. Florence)🇮🇹 · G. Inghirami (GSI, Darmstadt)🇩🇪 · I. Karpenko (U. Prague)🇨🇿 · A. Palermo (U. Florence)🇮🇹
We show that the inclusion of a recently found additional term of the spin polarization vector at local equilibrium which is linear in the symmetrized gradients of the velocity field, and the assumption of hadron production at constant temperature restore the quantitative agreement between hydrodynamic model predictions and local polarization measurements in relativistic heavy ion collisions at $s_{NN} = 200$ GeV. The longitudinal component of the spin polarization vector turns out to be very sensitive to the temperature value, with a good fit around 155 MeV. The implications of this finding are discussed.
nucl-thhep-phPRL(2021)·239 citations
08
How to build Hamiltonians that transport noncommuting charges in quantum thermodynamics
Nicole Yunger Halpern🇺🇸 · Shayan Majidy🇨🇦
Noncommuting conserved quantities have recently launched a subfield of quantum thermodynamics. In conventional thermodynamics, a system of interest and an environment exchange quantities -- energy, particles, electric charge, etc. -- that are globally conserved and are represented by Hermitian operators. These operators were implicitly assumed to commute with each other, until a few years ago. Freeing the operators to fail to commute has enabled many theoretical discoveries -- about reference frames, entropy production, resource-theory models, etc. Little work has bridged these results from abstract theory to experimental reality. This paper provides a methodology for building this bridge systematically: We present a prescription for constructing Hamiltonians that conserve noncommuting quantities globally while transporting the quantities locally. The Hamiltonians can couple arbitrarily many subsystems together and can be integrable or nonintegrable. Our Hamiltonians may be realized physically with superconducting qudits, with ultracold atoms, and with trapped ions.
↳ quant-phcond-mat.stat-mechhep-lathep-th+1npj Quantum Inf.(2022)·22 citations
09
Proton- $^{3} He$ elastic scattering at intermediate energies
A. Watanabe🇯🇵 · S. Nakai🇯🇵 · Y. Wada🇯🇵 · K. Sekiguchi🇯🇵 · A. Deltuva🇱🇹 · T. Akieda🇯🇵 · D. Etoh🇯🇵 · M. Inoue🇯🇵 · Y. Inoue🇯🇵 · K. Kawahara🇯🇵 · H. Kon🇯🇵 · K. Miki🇯🇵 and 33 other authors
We present a precise measurement of the cross section, proton and $^{3} He$ analyzing powers, and spin correlation coefficient $C_{y, y}$ for $p$ - $^{3} He$ elastic scattering near 65 MeV, and a comparison with rigorous four-nucleon scattering calculations based on realistic nuclear potentials and a model with $Δ$ -isobar excitation. Clear discrepancies are seen in some of the measured observables in the regime around the cross section minimum. Theoretical predictions using scaling relations between the calculated cross section and the $^{3} He$ binding energy are not successful in reproducing the data. Large sensitivity to the $N N$ potentials and rather small $Δ$ -isobar effects in the calculated cross section are noticed as different features from those in the deuteron-proton elastic scattering. The results obtained above indicate that $p$ - $^{3} He$ scattering at intermediate energies is an excellent tool to explore nuclear interactions not accessible by three-nucleon scattering.
↳ nucl-exnucl-thPRC(2021)·12 citations
10
Three loop correction in the formation of QGP droplet
M. Jena · K. K. Gupta · S. Somorendro Singh
Quark-gluon plasma (QGP) droplet formation is re-considered with the addition of three loop correction to the earlier loop factors in the mean field potential. The correction of the three loop factor increases stability in the droplet formations of QGP at different parametrization factors of the QGP fluid and it is in better agreement in comparison to the lattice results of pressure, energy density and other thermodynamic relations. This implies that the contribution of the three loop enhances in showing the characteristic features of the QGP fluid. It shows that increasing the loop increased the strength of parametrization value which we defined earlier as a number parameter of fluid dynamics. It indicates that the model with the loop correction boosts in explaining about the formation of QGP droplet in the expansion of early universe
↳ hep-phnucl-thIndian J.Phys.(2023)·0 citations
11
Numerical Study of Stellar Core Collapse and Neutrino Emission Using the Nuclear Equation of State Obtained by the Variational Method
Ken'ichiro Nakazato🇯🇵 · Kohsuke Sumiyoshi🇯🇵 · Hajime Togashi🇯🇵
Core-collapse simulations of massive stars are performed using the equation of state (EOS) based on the microscopic variational calculation with realistic nuclear forces. The progenitor models with the initial masses of $15 M_{⊙}$ , $9.6 M_{⊙}$ , and $30 M_{⊙}$ are adopted as examples of the ordinary core-collapse supernova with a shock stall, the low-mass supernova with a successful explosion, and the black hole formation, respectively. Moreover, the neutrinos emitted from the stellar collapse are assessed. Then, the variational EOS is confirmed to work well in all cases. The EOS dependences of the dynamics, thermal structure, and neutrino emission of the stellar collapse are also investigated.
↳ astro-ph.HEnucl-thPubl.Astron.Soc.Jap.(2021)·25 citations
12
Effect of magnetic field on jet transport coefficient $q^$
Debjani Banerjee🇮🇳 · Prottoy Das🇮🇳 · Souvik Paul🇮🇳 · Abhi Modak🇮🇳 · Ankita Budhraja🇮🇳 · Sabyasachi Ghosh🇮🇳 · Sidharth K. Prasad🇮🇳
We report the estimation of jet transport coefficient, $q^$ for quark- and gluon-initiated jets using a simple quasi-particle model in absence and presence of magnetic field. This model introduces a temperature and magnetic field-dependent degeneracy factor of partons, which is tuned by fitting the entropy density of lattice quantum chromodynamics data. At a finite magnetic field, $q^$ for quark jets splits into parallel and perpendicular components whose magnetic field dependence comes from two sources: the field-dependent degeneracy factor and the phase space part guided from the shear viscosity to entropy density ratio. Due to the electrically neutral nature of gluons, the estimation of $q^$ for gluon jets is affected only by the field-dependent degeneracy factor. In presence of a finite magnetic field, we find a significant enhancement in $q^$ for both quark- and gluon-initiated jets at low temperature, which gradually decreases towards high temperature. We compare the obtained results with the earlier calculations based on the anti-de Sitter/conformal field theory correspondence, and a qualitatively similar trend is observed. The change in $q^$ in presence of magnetic field is, however, quantitatively different for quark- and gluon-initiated jets. This is an interesting observation which can be explored experimentally to verify the effect of magnetic field on $q^$ .
↳ hep-phhep-exnucl-exnucl-thPramana(2023)·7 citations
13
Massive quarks in NLO dipole factorization for DIS: Longitudinal photon
G. Beuf🇵🇱 · T. Lappi🇫🇮 · R. Paatelainen🇫🇮
In this work, we will present the first complete calculation of the one-loop longitudinal photon-to-quark-antiquark light cone wave function, with massive quarks. The quark masses are renormalized in the pole mass scheme. The result is used to calculate the next-to-leading order correction to the high energy Deep Inelastic Scattering longitudinal structure function on a dense target in the dipole factorization framework. For massless quarks the next-to-leading order correction was already known to be sizeable, and our result makes it possible to evaluate it also for massive quarks.
↳ hep-phnucl-thPRD(2021)·61 citations

Affiliations

first authorsco-authorsvia INSPIRE