Nuclear Theory·nucl-th

Tuesday·July 20, 2021

18 papers—8 primary·10 cross-listed

01
Description of the shape of medium and heavy nuclei using a finite deformed one-particle potential with deformation-dependent diffuseness
G. I. Bykhalo · V. N. Orlin · K. A. Stopani
Adjustment of the behavior of the potential energy of nuclear deformation, defined as the sum of the energies of lowest-lying occupied single-particle levels in a deformed finite potential with a pairing correction, is considered by taking into account the dependence of the diffuseness of the surface of the potential on deformation. To verify this approach we construct a non-axial ellipsoidally-deformed potential with a slight (of the order of 1\%) variation of the surface diffuseness at moderate deformations. Parameters of the variation are determined from a calculation for a group of 36 deformed, transitional, and spherical nuclei in the range $50 \leq A \leq 241$ using existing experimental data on static quadrupole moments. In order to test the performed parameter choice, we applied the model to description of the ground-state deformation of the isotopic chains $^{95 - 132}$ Cd and $^{74 - 106}$ Sr. The obtained description of the ground state deformation of the considered nuclei is in agreement with experimental data and results of macro-microscopic models and calculations using the Hartree-Fock-Bogoliubov method.
nucl-th7 citations
02
Microscopic self-consistent description of induced fission: dynamical pairing degree of freedom
Jie Zhao · Tamara Nikšić · Dario Vretenar
The role of dynamical pairing in induced fission dynamics is investigated using the time-dependent generator coordinate method in the Gaussian overlap approximation, based on the microscopic framework of nuclear energy density functionals. A calculation of fragment charge yields for induced fission of $^{228}$ Th is performed in a three-dimensional space of collective coordinates that, in addition to the axial quadrupole and octupole intrinsic deformations of the nuclear density, also includes an isoscalar pairing degree of freedom. It is shown that the inclusion of dynamical pairing has a pronounced effect on the collective inertia, the collective flux through the scission hyper-surface, and the resulting fission yields, reducing the asymmetric peaks and enhancing the contribution of symmetric fission, in better agreement with the empirical trend.
nucl-thnucl-exPRC(2021)·22 citations
03
Hydrodynamic description of the baryon-charged quark-gluon plasma
Lipei Du (Ohio State U.)🇺🇸
One of the primary goals of nuclear physics is studying the phase diagram of Quantum Chromodynamics, where a hypothetical critical point serves as a landmark. A systematic model-data comparison of heavy-ion collisions at center-of-mass energies between 1 and 100 GeV per nucleon is essential for locating the critical point and the phase boundary between the deconfined quark-gluon plasma and the confined hadron resonance gas. At these energies the net baryon density of the system can be high and critical fluctuations can become essential in the presence of the critical point. Simulating their dynamical evolution thus becomes an indispensable part of theoretical modeling. In this thesis we first present the (3+1)-dimensional relativistic hydrodynamic code BEShydro, which solves the equations of motion of second-order Denicol-Niemi-Molnar-Rischke theory, including bulk and shear viscous components as well as baryon diffusion current. We then study the effects caused by the baryon diffusion on the longitudinal dynamics and on the phase diagram trajectories of fluid cells at different space-time rapidities of the system, and how they are affected by critical dynamics near the critical point. We finally explore the evolution of non-hydrodynamic slow processes describing long wavelength critical fluctuations near the critical point, by extending the conventional hydrodynamic description by coupling it to additional explicitly evolving slow modes, and their back-reaction to the bulk matter properties.
nucl-thhep-phnucl-ex5 citations
04
Prospects for study of the effect of the electronic screening on the $α$ decay in the storage rings
F. F. Karpeshin · M. B. Trzhaskovskaya · L. F. Vitushkin
Study of the role of the electron screening in the $α$ decay is advanced, aimed at the experimental test in the storage rings. To this end, systematic calculation of the effect in heavy ions of the nuclei within the Ra to Po domain of the $α$ emitters is conducted within the adiabatic approach. The obtained effect is to slow down the decay by an amount within the percent value. It is of the opposite sign comparing to what is predicted within the conventional frozen shell model. The reason for this divergence is demonstrated. Testing this difference experimentally in storage ring facilities is proposed. It is of great interest for advancing the astrophysical fundamental research.
nucl-thPRC(2022)·3 citations
05
Two-neutrino double-beta decay matrix elements based on relativistic nuclear energy density functional
N. Popara🇭🇷 · A. Ravlić🇭🇷 · N. Paar🇭🇷
Nuclear matrix elements (NMEs) for two-neutrino double-beta decay ( $2 ν β β$ ) are studied in the framework of relativistic nuclear energy density functional (REDF). The properties of nuclei involved in the decay are obtained using the relativistic Hartree-Bardeen-Cooper-Schrieffer theory and relevant nuclear transitions are described using the relativistic proton-neutron quasiparticle random phase approximation based on relativistic energy density functional (REDF-QRPA). Three effective interactions have been employed, including density-dependent meson-exchange (DD-ME2) and point coupling interactions (DD-PC1 and DD-PCX), and pairing correlations are described consistently both in $T = 1$ and $T = 0$ channels using a separable pairing interaction. The optimal values of $T = 0$ pairing strength parameter $V_{0 pp}$ are constrained by the experimental data on $β$ -decay half lives. The $2 ν β β$ matrix elements and half-lives are calculated for several nuclides experimentally known to undergo this kind of decay: $^{48}$ Ca, $^{76}$ Ge, $^{82}$ Se, $^{96}$ Zr, $^{100}$ Mo, $^{116}$ Cd, $^{124}$ Xe, $^{128}$ Te, $^{130}$ Te, $^{136}$ Xe and $^{150}$ Nd. The model dependence of the NMEs and their sensitivity on $V_{0 pp}$ is investigated, and the NMEs obtained using optimal values of $V_{0 pp}$ are discussed in comparison to previous studies. The results of the present work represent an important benchmark for the future applications of the relativistic framework in studies of neutrinoless double-beta decay.
nucl-thnucl-exPRC(2022)·13 citations
06
Highest weight irreducible representations favored by nuclear forces within SU(3)-symmetric fermionic systems
Andriana Martinou · S. Sarantopoulou · K.E. Karakatsanis · Dennis Bonatsos
The consequences of the attractive, short-range nucleon-nucleon (NN) interaction on the wave functions of nuclear models bearing the SU(3) symmetry are reviewed. The NN interaction favors the most symmetric spatial SU(3) irreducible representation (irrep), which corresponds to the maximal spatial overlap among the fermions. The consideration of the highest weight (hw) irreps in nuclei and in alkali metal clusters, leads to the prediction of a prolate to oblate shape transition beyond the mid-shell region. Subsequently, the consequences of the use of the hw irreps on the binding energies and two-neutron separation energies in the rare earth region are discussed within the proxy-SU(3) scheme, by considering a very simple Hamiltonian, containing only the three dimensional (3D) isotropic harmonic oscillator (HO) term and the quadrupole-quadrupole interaction. This Hamiltonian conserves the SU(3) symmetry and treats the nucleus as a rigid rotator.
nucl-thEPJ Web Conf.(2021)·5 citations
07
Properties of Hybrid Stars with Density Dependent Bag Model
Debashree Sen🇮🇳 · Naosad Alam🇮🇳 · Gargi Chaudhuri🇮🇳
The phenomena of deconfinement of hadronic matter into quark matter at high density, relevant to hybrid star (HS) cores, is studied in the present work. The effective chiral model describes the pure hadronic phase while for the quark phase the MIT bag model is chosen with density dependent bag pressure. Phase transition is achieved using Maxwell construction. The effect of variation of the asymptotic value of the bag pressure ( $B_{a s}$ ) is analyzed w.r.t to the mass and radius of the HSs. The presence of hyperons in the hadronic sector also has significant effect on the choice of the value of $B_{a s}$ . Both the hadronic composition and the choice of $B_{a s}$ significantly affect the stability of the star. The gross structural properties of the resultant HS are calculated in static condition and compared with the various constraints on them from different observational and empirical perspectives. The static properties like the maximum gravitational mass of the HS, obtained with $B_{a s}$ =80 MeV fm $^{- 3}$ , is consistent with the limits imposed from the observational analysis of PSR J0348+0432 and PSR J0740+6620. The estimates of $R_{1.4}$ and $R_{1.6}$ of HSs are found to be within the range prescribed from GW170817 analysis. Also the $M - R$ solutions of the HSs are in excellent agreement with the recently obtained NICER data for PSR J0030+0451. The results of maximum surface redshift, obtained with hybrid equation of state, satisfy the constraints from 1E 1207.4-5209 and RX J0720.4-3125. The work is also extended to obtain the tidal deformation properties of the HSs. The obtained value of $Λ_{1.4}$ is consistent with the bound obtained from GW170817 data analysis.
nucl-thJ.Phys.G(2021)·27 citations
08
Connecting the proxy-SU(3) symmetry to the shell model
Dennis Bonatsos · Andriana Martinou · I. E. Assimakis · S.K. Peroulis · S. Sarantopoulou · N. Minkov
Proxy-SU(3) symmetry is an approximation scheme extending the Elliott SU(3) algebra of the sd shell to heavier shells. When introduced in 2017, the approximation had been justified by calculations carried out within the Nilsson model. Recently our group managed to map the cartesian basis of the Elliott SU(3) model onto the spherical shell model basis, proving that the proxy-SU(3) approximation corresponds to the replacement of the intruder orbitals by their de Shalit-Goldhaber partners, paving the way for using the proxy-SU(3) approximation in shell model calculations. The connection between the proxy-SU(3) scheme and the spherical shell model has also been worked out in the original framework of the Nilsson model, with identical results.
nucl-thEPJ Web Conf.(2021)·6 citations
09
On the moment of inertia of PSR J0737-3039 A from LIGO/Virgo and NICER
Zhiqiang Miao · Ang Li · Zi-Gao Dai
We perform a Bayesian analysis of neutrons star moment of inertia by utilizing the available gravitational-wave data from LIGO/Virgo (GW170817 and GW190425) and mass-radius measurements from the Neutron Star Interior Composition Explorer (PSR J0030+0415 and PSR J0740+6620), incorporating the possible phase transition in the pulsar inner core. We find that the moment of inertia of pulsar A in the double pulsar binary J0737-3039 is $\sim 1.30 \times 1 0^{45} g c m^{2}$ , which only slightly depends on the employed hadronic equation of states. We also demonstrate how a moment of inertia measurement would improve our knowledge of the equation of state and the mass-radius relation for neutron stars and discuss whether a quark deconfinement phase transition is supported by the available data and forthcoming data that could be consistent with this hypothesis. We find that if pulsar A is a quark star, that its moment of inertia is a large value of $\sim 1.55 \times 1 0^{45} g c m^{2}$ suggesting the possibility of distinguishing it from (hybrid-)neutron stars with measurements of PSR J0737-3039A moment of inertia. We finally demonstrate the moment-of-inertia-compactness universal relations and provide analytical fits for both (hybrid-)neutron star and quark star results based on our analysis.
↳ astro-ph.HEastro-ph.SRnucl-thMNRAS(2022)·38 citations
10
Ultracold spin-balanced fermionic quantum liquids with renormalized $P$ -wave interactions
J. M. Alarcón🇪🇸 · J. A. Oller🇪🇸
We consider a spin-balanced degenerate gas of spin-1/2 fermions whose dynamics is governed by low-energy $P$ -wave interactions, characterized by the scattering volume $a_{1}$ and effective momentum $r_{1}$ . The energy per particle $E ˉ$ in the many-body system is calculated by resumming the ladder diagrams comprising both particle-particle and hole-hole intermediate states, following the novel advances recently developed by us in Ann.Phys. 437,168741(2022). This allows to obtain a renormalized result for $E ˉ$ within generic cutoff regularization schemes, with $E ˉ$ directly expressed in terms of the scattering parameters $a_{1}$ and $r_{1}$ , once the cut off is sent to infinity. The whole set of possible values of $a_{1}$ and $r_{1}$ is explored for the first time in the literature looking for minima in the energy per particle with $E ˉ$ given as described. They are actually found, but a further inspection reveals that the associated scattering parameters give rise to resonance poles in the complex momentum-plane with positive imaginary part, which is at odds with the Hermiticity of the Hamiltonian. We also determine that these conflictive poles, with a pole-position momentum that is smaller in absolute value than the Fermi momentum of the system, clearly impact the calculation of $E ˉ$ . As a result, we conclude that unpolarized spin-1/2 fermionic normal matter interacting in $P$ -wave is not stable. We also study three universal parameters around the unitary limit. Finally, the whole set of values for the parameters $a_{1}$ , $r_{1}$ is characterized according to whether they give rise to unallowed poles and, if so, by attending to their pole positions relative to the Fermi momentum of the system explored.
↳ cond-mat.quant-gashep-phnucl-thquant-phPRC(2022)·5 citations
11
X-ray bounds on cooling, composition, and magnetic field of the Cassiopeia A neutron star and young central compact objects
Wynn C. G. Ho (Haverford)🇺🇸 · Yue Zhao (Alberta)🇨🇦 · Craig O. Heinke (Alberta)🇨🇦 · D. L. Kaplan (Wisconsin-Milwaukee)🇺🇸 · Peter S. Shternin (Ioffe Institute)🇷🇺 · M. J. P. Wijngaarden (Southampton)🇬🇧
We present analysis of multiple Chandra and XMM-Newton spectra, separated by 9-19 years, of four of the youngest central compact objects (CCOs) with ages < 2500 yr: CXOU J232327.9+584842 (Cassiopeia A), CXOU J160103.1-513353 (G330.2+1.0), 1WGA J1713.4-3949 (G347.3-0.5), and XMMU J172054.5-372652 (G350.1-0.3). By fitting these spectra with thermal models, we attempt to constrain each CCO's long-term cooling rate, composition, and magnetic field. For the CCO in Cassiopeia A, 14 measurements over 19 years indicate a decreasing temperature at a ten-year rate of 2.2+/-0.2 or 2.8+/-0.3 percent (1sigma error) for a constant or changing X-ray absorption, respectively. We obtain cooling rate upper limits of 17 percent for CXOU J160103.1-513353 and 6 percent for XMMU J172054.5-372652. For the oldest CCO, 1WGA J1713.4-3949, its temperature seems to have increased by 4+/-2 percent over a ten year period. Assuming each CCO's preferred distance and an emission area that is a large fraction of the total stellar surface, a non-magnetic carbon atmosphere spectrum is a good fit to spectra of all four CCOs. If distances are larger and emission areas are somewhat smaller, then equally good spectral fits are obtained using a hydrogen atmosphere with B <= 7x10^10 G or B >= 10^12 G for CXOU J160103.1-513353, B <= 10^10 G or B >= 10^12 G for XMMU J172054.5-372652, and non-magnetic hydrogen atmosphere for 1WGA J1713.4-3949. In a unified picture of CCO evolution, our results suggest most CCOs, and hence a sizable fraction of young neutron stars, have a surface magnetic field that is low early in their life but builds up over several thousand years.
↳ astro-ph.HEastro-ph.SRhep-phnucl-thMNRAS(2021)·30 citations
12
Collective modes in anisotropic plasmas
Margaret E. Carrington🇨🇦 · Bailey M. Forster🇨🇦 · Sofiya Makar🇨🇦
We study collective modes in anisotropic plasmas of quarks and gluons using a quasi-particle picture and a hard loop approximation. We use a general class of anisotropic distribution functions, and we consider chirally asymmetric systems. We introduce a complete tensor basis to decompose the gluon polarization tensor into a set of nine scalar functions. We derive and solve the corresponding dispersion equations. Imaginary modes are particularly important because of their potential influence on plasma dynamics. We explore in detail their dependence on the chiral chemical potential and the parameters that characterise the anisotropy of the system. We show that our generalized distributions produce dispersion relations that are much richer in structure than those obtained with a simple one parameter deformation of an isotropic distribution. In addition, the size and domain of the imaginary solutions are enhanced, relative to those obtained with a one parameter deformation. Finally, we show that the influence of even a very small chiral chemical potential is significantly magnified when anisotropy is present.
↳ hep-phnucl-thPRC(2021)·14 citations
13
ERLC (Twin LC) and LHC/FCC Based eA Colliders
A. N. Akay🇹🇷 · B. Dagli🇹🇷 · B. Ketenoglu🇹🇷 · S. Sultansoy🇹🇷
Construction of the ERLC (twin LC) collider tangential to LHC or FCC will give opportunity to realize eA collisions at multi-TeV center-of-mass energies. Luminosity estimations show that values comparable with that of ERL60 based eA colliders are achievable while center of mass energies are essentially higher. Certainly, proposed eA colliders have great potential for clarifying QCD basics and nuclear structure.
↳ physics.acc-phhep-exhep-phnucl-ex+11 citation
14
Hidden charm pentaquark states in a diquark model
Pan-Pan Shi🇨🇳 · Fei Huang🇨🇳 · Wen-Ling Wang🇨🇳
The mass spectrum of hidden charm pentaquark states composed of two diquarks and an antiquark are calculated by use of an effective Hamiltonian which includes explicitly the spin, color, and flavor dependent interactions. The results show that the $P_{c} (4312)^{+}$ and $P_{c} (4440)^{+}$ states could be explained as hidden charm pentaquark states with isospin and spin-parity $I J^{P} = 1/2 (3/ 2^{-})$ , the $P_{c} (4457)^{+}$ state could be explained as a hidden charm pentaquark state with $I J^{P} = 1/2 (5/ 2^{-})$ , and the $P_{cs} (4459)^{+}$ state could be explained as a hidden charm pentaquark state with $I J^{P} = 0 (1/ 2^{-})$ or $0 (3/ 2^{-})$ . Predications for the masses of other possible pentaquark states are also given, and the possible decay channels of these hidden charm pentaquark states are discussed.
↳ hep-phnucl-thEPJA(2021)·37 citations
15
Hydrodynamical attractor and thermal particle production in heavy-ion collision
Lakshmi J. Naik🇮🇳 · Sunil Jaiswal🇮🇳 · K. Sreelakshmi🇮🇳 · Amaresh Jaiswal🇮🇳 · V. Sreekanth🇮🇳
Study of thermal particle production is crucial to understand the space-time evolution of the fireball produced in high energy heavy-ion collisions. We consider thermal particle production within the framework of relativistic viscous hydrodynamics and employ recently obtained analytical solutions of higher-order viscous hydrodynamics with longitudinal Bjorken expansion to calculate the spectra of dileptons and photons. Using these analytical solutions, we constrain the allowed initial states by demanding positivity and reality of energy density throughout the evolution. Further, we compute thermal particle spectra and study the particle yield in context of hydrodynamic attractors. We find that, of all allowed solutions, the evolution corresponding to attractor solution leads to maximum production of thermal particles.
↳ hep-phhep-thnucl-th11 citations
16
The role of proton-antiproton regeneration in the late stages of heavy-ion collisions
Oscar Garcia-Montero🇩🇪 · Jan Staudenmaier🇩🇪 · Anna Schäfer🇩🇪 · Juan M. Torres-Rincon🇩🇪 · Hannah Elfner🇩🇪
We investigate the long-standing question of the effect of proton-antiproton annihilation on the (anti-)proton yield, while respecting detailed balance for the 5-body back-reaction for the first time in a full microscopic description of the late stages of heavy-ion collisions. This is achieved by employing a stochastic collision criterion in a hadronic transport approach (SMASH), which allows to treat arbitrary multi-particle reactions. It is used to account for the regeneration of (anti-)protons via $5 π \to p p ˉ$ . Our results show that a back-reaction happens for a fraction of 15-20\% of all annihilations. Within a viscous hybrid approach Au+Au/Pb+Pb collisions from $s_{N N} = 17.3$ GeV $- 5.02$ TeV are investigated and the quoted fraction is independent of the beam energy or centrality of the collision. Taking the back-reaction into account results in regeneration of half of the (anti-)proton yield that is lost due to annihilations at midrapidity. We also find that, concerning the multiplicities, treating the back-reaction as a chain of 2-body reactions is equivalent to a single 5-to-2 reaction.
↳ hep-phnucl-thPRC(2022)·28 citations
17
Unpolarized gluon distribution in the nucleon from lattice quantum chromodynamics
Tanjib Khan🇺🇸 · Raza Sabbir Sufian🇺🇸 · Joseph Karpie🇺🇸 · Christopher J. Monahan🇺🇸 · Colin Egerer🇺🇸 · Bálint Joó🇺🇸 · Wayne Morris🇺🇸 · Kostas Orginos🇺🇸 · Anatoly Radyushkin🇺🇸 · David G. Richards🇺🇸 · Eloy Romero🇺🇸 · Savvas Zafeiropoulos🇫🇷
In this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a $3 2^{3} \times 64$ ensemble with a pion mass of $358$ MeV and lattice spacing of $0.094$ fm. We construct the nucleon interpolating fields using the distillation technique, flow the gauge fields using the gradient flow, and solve the summed generalized eigenvalue problem to determine the glounic matrix elements. Combining these techniques allows us to provide a statistically well-controlled Ioffe-time distribution and unpolarized gluon PDF. We obtain the flow time independent reduced Ioffe-time pseudo-distribution, and calculate the light-cone Ioffe-time distribution and unpolarized gluon distribution function in the $MS$ scheme at $μ = 2$ GeV, neglecting the mixing of the gluon operator with the quark singlet sector. Finally, we compare our results to phenomenological determinations.
↳ hep-lathep-exhep-phnucl-ex+1PRD(2021)·80 citations
18
Heavy Flavor and Jet Studies for the Future Electron-Ion Collider to Explore the Hadronization Process
Xuan Li🇺🇸
Heavy flavor production at the future Electron-Ion Collider (EIC) will allow us to precisely determine the quark/gluon fragmentation processes in vacuum and the nuclear medium especially within the poorly constrained kinematic region. Heavy flavor hadron and jet reconstruction with the recent EIC detector design have been studies in simulation. Results of corresponding physics projections such as the flavor dependent hadron nuclear modification factor $R_{e A}$ in electron+nucleus collisions will be shown. The statistical precision obtained by these proposed heavy flavor measurements for the future EIC provides a strong discriminating power in separating different theoretical predictions.
↳ nucl-exhep-exhep-phnucl-thSciPost Phys.Proc.(2022)·6 citations

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