Nuclear Theory·nucl-th

Wednesday·November 4, 2020

13 papers—6 primary·7 cross-listed

01
[Submitted on 2 Nov 2020]
Dark matter admixed neutron star properties in the light of gravitational wave observations: a two fluid approach
Arpan Das🇵🇱 · Tuhin Malik🇮🇳 · Alekha C. Nayak🇮🇳
We consider the effect of density dependent dark matter on the neutron star mass, radius, and tidal deformability. Nuclear matter (normal matter) as well as the fermionic dark matter sector is considered in a mean field model. We adopt the two fluid formalism to investigate the effect of dark matter on the neutron star properties. In the two fluid picture, there is no direct interaction between the dark matter and the nuclear matter. Rather these two sectors interact only through gravitational interaction. The nuclear matter sector is described by the $σ - ω - ρ$ meson interaction in the "FSU2R" parameterization. In the dark matter sector, we use the Bayesian parameter optimization technique to fix the unknown parameters in the dark matter equation of state. In the two fluid picture, we solve the coupled Tolman-Oppenheimer-Volkoff (TOV) equations to obtain the mass and radius of dark matter admixed neutron stars (DANSs). We also estimate the effect of the density dependent dark matter sector on the tidal deformability of dark matter admixed neutron stars (DANSs).
Comments:
17 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2011.01318 [pdf]
PRD(2022)·85 citations
02
[Submitted on 2 Nov 2020]
Complete and incomplete fusion of $^{7}$ Li projectiles on heavy targets
M.R. Cortes · J. Rangel · J.L. Ferreira · J. Lubian · L.F. Canto
We present a detailed discussion of a recently proposed method to evaluate complete and incomplete fusion cross sections for weakly bound systems. The method is applied to collisions of $^{7}$ Li projectiles on different heavy targets, and the results are compared with the available data. The overall agreement between experiment and theory is fairly good.
Comments:
18 pages, 18 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2011.01327 [pdf]
PRC(2020)·32 citations
03
[Submitted on 3 Nov 2020]
Relativistic non-resistive viscous magnetohydrodynamics from the kinetic theory:a relaxation time approach
Ankit Kumar Panda🇮🇳 · Ashutosh Dash🇮🇳 · Rajesh Biswas🇮🇳 · Victor Roy🇮🇳
We derive the relativistic non-resistive, viscous second-order magnetohydrodynamic equations for the dissipative quantities using the relaxation time approximation. The Boltzmann equation is solved for a system of particles and antiparticles using Chapman-Enskog like gradient expansion of the single-particle distribution function truncated at second order. In the first order, the transport coefficients are independent of the magnetic field. In the second-order, new transport coefficients that couple magnetic field and the dissipative quantities appear which are different from those obtained in the 14-moment approximation \cite{Denicol:2018rbw} in the presence of a magnetic field. However, in the limit of the weak magnetic field, the form of these equations are identical to the 14-moment approximation albeit with a different values of these coefficients. We also derive the anisotropic transport coefficients in the Navier-Stokes limit.
Comments:
20 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Fluid Dynamics (physics.flu-dyn); Plasma Physics (physics.plasm-ph)
arXiv:
2011.01606 [pdf]
JHEP(2021)·60 citations
04
[Submitted on 2 Nov 2020]
Wigner-Wilkins neutron/nucleus scattering kernel quantum-mechanically derived
J. A. Grzesik
We undertake herein to derive the Wigner-Wilkins [W-W] neutron/nucleus scattering kernel, a foundation stone in neutron thermalization theory, on the basis of a self-contained calculation in quantum mechanics. Indeed, a quantum-mechanical derivation of the W-W kernel is available in the literature, cited below, but it is, in our opinion, robbed of conviction by being couched in terms of an excessive generality. Here, by contrast, we proceed along a self-contained route relying on the Fermi pseudopotential and a first-order term in a time-dependent Born approximation series. Our calculations are fully explicit at every step and, in particular, we tackle in its every detail a final integration whose result is merely stated in the available literature. Furthermore, and perhaps the most important point of all, we demonstrate that the quantum-mechanical W-W kernel outcome is identical down to the last iota with its classical antecedent, classical not only by virtue of historical precedence but also by being based on classical Newtonian mechanics.
Comments:
v3--missing eq. no. (38) supplied; v2 eq. nos. (38) on, and all refs. thereto, advanced by 1; stray right parenth in 1st line args of eqs (35-40) (new enum) removed; 1st line args in eqs (37-38) (new enum) more perspicuously arranged; v4--ref. 10 framed in sharper focus; two minor textual infelicities repaired
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2011.01743 [pdf]
Nucl.Sci.Eng.(2023)·0 citations
05
[Submitted on 3 Nov 2020]
Potential roots of the deep sub-barrier heavy-ion fusion hindrance phenomenon
P.W. Wen🇷🇺 · C.J. Lin🇨🇳 · R.G. Nazmitdinov🇷🇺 · S.I. Vinitsky🇷🇺 · O. Chuluunbaatar🇷🇺 · A.A. Gusev🇷🇺 · A.K. Nasirov🇷🇺 · H.M. Jia🇨🇳 · A. Gozdz🇵🇱
We analyse the origin of the unexpected deep sub-barrier heavy-ion fusion hindrance in 64Ni+100Mo and 28Si+64Ni recations. Our analysis is based on the improved coupled-channels approach, implemented by means of the finite element method. With the aid of the Woods-Saxon potential the experimental cross sections and the S-factors of these reactions are remarkably well reproduced. We found that the account on the non-diagonal matrix elements of the coupling matrix, traditionally neglected in the conventional coupled-channels approaches in setting the left boundary conditions inside the potential pocket, and its minimal value are crucially important for the interpretation experimental data. Within our approach we found a good agreement with the experimental data for the S-factor of the fusion reaction 12C+12C, which has no a pronounced maximum for this system.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2011.01806 [pdf]
PRC(2021)·16 citations
06
[Submitted on 3 Nov 2020]
Electric dipole moments of three-nucleon systems in the pionless effective field theory
Zichao Yang🇺🇸 · Emanuele Mereghetti🇺🇸 · Lucas Platter🇺🇸 · Matthias R. Schindler🇺🇸 · Jared Vanasse🇺🇸
We calculate the electric dipole moments (EDMs) of three-nucleon systems at leading order in pionless effective field theory. The one-body contributions that arise from permanent proton and neutron EDMs and the two-body contributions that arise from CP-odd nucleon-nucleon interactions are taken into account. Neglecting the Coulomb interaction, we consider the triton and $^{3}$ He, and also investigate them in the Wigner-SU(4) symmetric limit. We also calculate the electric dipole form factor and find numerically that the momentum dependence of the electric dipole form factor in the Wigner limit is, up to an overall constant (and numerical accuracy), the same as the momentum dependence of the charge form factor.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2011.01885 [pdf]
PRC(2021)·10 citations
07
[Submitted on 2 Nov 2020] (cross-list from hep-th)
Geometry and entanglement in the scattering matrix
Silas R. Beane🇺🇸 · Roland C. Farrell🇺🇸
A formulation of nucleon-nucleon scattering is developed in which the S-matrix, rather than an effective-field theory (EFT) action, is the fundamental object. Spacetime plays no role in this description: the S-matrix is a trajectory that moves between RG fixed points in a compact theory space defined by unitarity. This theory space has a natural operator definition, and a geometric embedding of the unitarity constraints in four-dimensional Euclidean space yields a flat torus, which serves as the stage on which the S-matrix propagates. Trajectories with vanishing entanglement are special geodesics between RG fixed points on the flat torus, while entanglement is driven by an external potential. The system of equations describing S-matrix trajectories is in general complicated, however the very-low-energy S-matrix -- that appears at leading-order in the EFT description -- possesses a UV/IR conformal invariance which renders the system of equations integrable, and completely determines the potential. In this geometric viewpoint, inelasticity is in correspondence with the radius of a three-dimensional hyperbolic space whose two-dimensional boundary is the flat torus. This space has a singularity at vanishing radius, corresponding to maximal violation of unitarity. The trajectory on the flat torus boundary can be explicitly constructed from a bulk trajectory with a quantifiable error, providing a simple example of a holographic quantum error correcting code.
Comments:
44 pages, 18 figures. References and clarifications added in v2
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2011.01278 [pdf]
Annals Phys.(2021)·38 citations
08
[Submitted on 3 Nov 2020] (cross-list from hep-ph)
Multi-system Bayesian constraints on the transport coefficients of QCD matter
D. Everett🇺🇸 · W. Ke🇺🇸 · J.-F. Paquet🇺🇸 · G. Vujanovic🇺🇸 · S. A. Bass🇺🇸 · L. Du🇺🇸 · C. Gale🇨🇦 · M. Heffernan🇨🇦 · U. Heinz🇺🇸 · D. Liyanage🇺🇸 · M. Luzum🇧🇷 · A. Majumder🇺🇸 and 36 other authors
We study the properties of the strongly-coupled quark-gluon plasma with a multistage model of heavy ion collisions that combines the T $_{R}$ ENTo initial condition ansatz, free-streaming, viscous relativistic hydrodynamics, and a relativistic hadronic transport. A model-to-data comparison with Bayesian inference is performed, revisiting assumptions made in previous studies. The role of parameter priors is studied in light of their importance towards the interpretation of results. We emphasize the use of closure tests to perform extensive validation of the analysis workflow before comparison with observations. Our study combines measurements from the Large Hadron Collider and the Relativistic Heavy Ion Collider, achieving a good simultaneous description of a wide range of hadronic observables from both colliders. The selected experimental data provide reasonable constraints on the shear and the bulk viscosities of the quark-gluon plasma at $T \sim$ 150-250 MeV, but their constraining power degrades at higher temperatures $T ≳ 250$ MeV. Furthermore, these viscosity constraints are found to depend significantly on how viscous corrections are handled in the transition from hydrodynamics to the hadronic transport. Several other model parameters, including the free-streaming time, show similar model sensitivity while the initial condition parameters associated with the T $_{R}$ ENTo ansatz are quite robust against variations of the particlization prescription. We also report on the sensitivity of individual observables to the various model parameters. Finally, Bayesian model selection is used to quantitatively compare the agreement with measurements for different sets of model assumptions, including different particlization models and different choices for which parameters are allowed to vary between RHIC and LHC energies.
Comments:
51 pages, including 35 figures and 8 appendices, long companion paper to arXiv:2010.03928. A useful visualization tool to see the effect of varying individual model parameters on physical observables can be found at jetscape.org/sims-widget. Some references and discussion added. This version submitted for publication
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.01430 [pdf]
PRC(2021)·403 citations
09
[Submitted on 3 Nov 2020] (cross-list from hep-lat)
Deconfinement and Hadron Resonance Gas for Heavy Quarks
Peter Petreczky🇺🇸
I discuss the deconfinement transition in 2+1 flavor QCD in terms of Polyakov loops as well as the hadron resonance gas for hadrons containing static quarks and charm quarks.
Comments:
11 pages, LaTeX, 4 figures, Invited talk at Workshop on Criticality in QCD and Hadron Resonance Gas, July 29-31, 2020, Wroclaw, Poland, to be published in the proceedings, typos corrected
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2011.01466 [pdf]
Acta Phys.Polon.Supp.(2021)·2 citations
10
[Submitted on 31 Oct 2020] (cross-list from hep-ph)
Jet quenching with $T$ -dependent running coupling
B.G. Zakharov🇷🇺
We perform an analysis of jet quenching in heavy ion collisions at RHIC and LHC energies with the temperature dependent running QCD coupling. Our results show that the $T$ -dependent QCD coupling largely eliminates the difference between the optimal values of $α_{s}$ for the RHIC and LHC energies. It may be viewed as direct evidence of the increase of the thermal suppression of $α_{s}$ with rising temperature.
Comments:
7 pages, 3 figures, accepted for publication in JETP Letters. arXiv admin note: text overlap with arXiv:2007.09772
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2011.01526 [pdf]
JETP Lett.(2020)·5 citations
11
[Submitted on 3 Nov 2020] (cross-list from nucl-ex)
Nuclear Moments of Germanium Isotopes around $N$ = 40
A. Kanellakopoulos🇧🇪 · X. F. Yang🇨🇳 · M. L. Bissell🇬🇧 · M. L. Reitsma🇳🇱 · S. W. Bai🇨🇳 · J. Billowes🇬🇧 · K. Blaum🇩🇪 · A. Borschevsky🇳🇱 · B. Cheal🇬🇧 · C. S. Devlin🇬🇧 · R. F. Garcia Ruiz🇨🇭 · H. Heylen🇨🇭 and 15 other authors
Collinear laser spectroscopy measurements were performed on $^{69, 71, 73}$ Ge isotopes ( $Z = 32$ ) at ISOLDE-CERN. The hyperfine structure of the $4 s^{2} 4 p^{2}^{3} P_{1} \to 4 s^{2} 4 p 5 s^{3} P_{1}^{o}$ transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. The hyperfine fields for both atomic levels were calculated using state-of-the-art atomic relativistic Fock-space coupled-cluster calculations. A new $^{73}$ Ge quadrupole moment was determined from these calculations and previously measured precision hyperfine parameters, yielding $Q_{s}$ = $-$ 0.198(4) b, in excellent agreement with the literature value from molecular calculations. The moments of $^{69}$ Ge have been revised: $μ$ = +0.920(5) $μ_{N}$ and $Q_{s}$ = +0.114(8) b, and those of $^{71}$ Ge have been confirmed. The experimental moments around $N = 40$ are interpreted with large-scale shell-model calculations using the JUN45 interaction, revealing rather mixed wave function configurations, although their $g$ -factors are lying close to the effective single-particle values. Through a comparison with neighboring isotones, the structural change from the single-particle nature of nickel to deformation in germanium is further investigated around $N = 40$ .
Comments:
accepted in Phys. Rev. C., in production
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.01659 [pdf]
PRC(2020)·15 citations
12
[Submitted on 3 Nov 2020] (cross-list from physics.data-an)
Accuracy and precision of the estimation of the number of missing levels in chaotic spectra using long-range correlations
I. Casal🇪🇸 · L. Muñoz🇪🇸 · R.A. Molina🇪🇸
We study the accuracy and precision for estimating the fraction of observed levels $φ$ in quantum chaotic spectra through long-range correlations. We focus on the main statistics where theoretical formulas for the fraction of missing levels have been derived, the $Δ_{3}$ of Dyson and Mehta and the power spectrum of the $δ_{n}$ statistic. We use Monte Carlo simulations of the spectra from the diagonalization of Gaussian Orthogonal Ensemble matrices with a definite number of levels randomly taken out to fit the formulas and calculate the distribution of the estimators for different sizes of the spectrum and values of $φ$ . A proper averaging of the power spectrum of the $δ_{n}$ statistic needs to be performed for avoiding systematic errors in the estimation. Once the proper averaging is made the estimation of the fraction of observed levels has quite good accuracy for the two methods even for the lowest dimensions we consider $d = 100$ . However, the precision is generally better for the estimation using the power spectrum of the $δ_{n}$ as compared to the estimation using the $Δ_{3}$ statistic. This difference is clearly bigger for larger dimensions. Our results show that a careful analysis of the value of the fit in view of the ensemble distribution of the estimations is mandatory for understanding its actual significance and give a realistic error interval.
Comments:
10 pages, 9 figures
Subjects:
Data Analysis, Statistics and Probability (physics.data-an); cond-mat.other (cond-mat.other); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2011.01667 [pdf]
Eur.Phys.J.Plus(2021)·4 citations
13
[Submitted on 3 Nov 2020] (cross-list from hep-ph)
The $P_{cs} (4459)$ pentaquark from a combined effective field theory and phenomenological perspective
Fang-Zheng Peng🇨🇳 · Mao-Jun Yan🇨🇳 · Mario Sánchez Sánchez🇫🇷 · Manuel Pavon Valderrama🇨🇳
The observation of the $P_{cs} (4459)$ by the LHCb collaboration adds a new member to the set of known hidden-charm pentaquarks, which includes the $P_{c} (4312)$ , $P_{c} (4440)$ and $P_{c} (4457)$ . The $P_{cs} (4459)$ is expected to have the light-quark content of a $Λ$ baryon ( $I = 0$ , $S = - 1$ ), but its spin is unknown. Its closeness to the $D ˉ^{*} Ξ_{c}$ threshold -- $4478 MeV$ in the isospin-symmetric limit -- suggests the molecular hypothesis as a plausible explanation for the $P_{cs} (4459)$ . While in the absence of coupled-channel dynamics heavy-quark spin symmetry predicts the two spin-states of the $D ˉ^{*} Ξ_{c}$ to be degenerate, power counting arguments indicate that the coupling with the nearby $D ˉ Ξ_{c}^{'}$ and $D ˉ Ξ_{c}^{*}$ channels might be a leading order effect. This generates a hyperfine splitting in which the $J = \frac{3}{2}$ $D ˉ^{*} Ξ_{c}$ pentaquark will be lighter than the $J = \frac{1}{2}$ configuration, which we estimate to be of the order of $5 - 15 MeV$ . We also point out an accidental symmetry between the $P_{cs} (4459)$ and $P_{c} (4440/4457)$ potentials. Finally, we argue that the spectroscopy and the $J / ψ Λ$ decays of the $P_{cs} (4459)$ might suggest a marginal preference for $J = \frac{3}{2}$ over $J = \frac{1}{2}$ .
Comments:
16 pages, 1 figure; includes discussions on power counting, the J=1/2,3/2 hyperfine splitting, saturation, phenomenological relation between the Pcs(4459) and Pc(4440/4457) potentials, decay to $J / ψ Λ$ , etc
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2011.01915 [pdf]
EPJC(2021)·101 citations

Affiliations

first authorsco-authorsvia INSPIRE