Nuclear Theory·nucl-th

Friday·August 20, 2021

8 papers—3 primary·5 cross-listed

01
[Submitted on 18 Aug 2021]
Exploring an experimental route of synthesizing superheavy elements beyond Z > 118
H.C.Manjunatha · Y.S.Vidya · P.S.Damodara Gupta · N.Manjunatha · N.Sowmya · L.Seenappa · T. Nandi
Role of the Coulomb interaction, mean fissility, mass asymmetry, and charge asymmetry parameters on the synthesis of heavy and superheavy elements has been examined with respect to the deformation parameters of the projectile and target nuclei explicitly in light of the experimental results. The observed facts are classified into four categories and are then used to study several unsuccessful as well as planned reactions to synthesize the new superheavy elements $Z = 119, 120$ . Concrete inference is too difficult to draw from these results because of excessive deviations in evaporation residue cross-section data. It is found that the arbitrary choice of excitation energy for the experiments studied was the root cause of such large deviations. Such a complex issue can be resolved well by theoretical excitation function studies using the advanced statistical model or the dinuclear system model and choosing the excitation energy corresponding to the energy where the excitation function curve shows the maximum. We believe this method may help us to predict whether the estimated evaporation residue cross-section can be measurable within the experimental limit of the existing facilities for the future reactions planned.
Comments:
5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2108.08335 [pdf]
0 citations
02
[Submitted on 19 Aug 2021]
Dynamics of particle production in Pb--Pb collisions at $s_{N N}$ = 2.76 TeV using PYTHIA8 Angantyr model
Ravindra Singh🇮🇳 · Yoshini Bailung🇮🇳 · Ankhi Roy🇮🇳
We study the dynamics of identified, strange, and multi-strange particle production in Pb--Pb collisions at $s_{NN}$ = 2.76 TeV using the recently developed Angantyr model, incorporated within PYTHIA8. We show the interplay between multi-parton interactions (MPI) and color reconnection (CR) on the experimentally measured quantities. The charged-particle multiplicity ( $N_{ch}$ ) and mean transverse momentum ( $⟨ p_{T} ⟩$ ) distributions are well explained by PYTHIA8 Angantyr with proper tuning, as presented in this paper. Predictions of $p_{T}$ spectra, $⟨ p_{T} ⟩$ , $p_{T}$ integrated yields of the identified, strange and multi-strange particles are studied. To provide insight into the collective nature of the produced particles, we look into the ratio of particle yields to pions and kaons. PYTHIA8 Angantyr with CR and MPI mimic signs of collectivity and is possibly one of the suitable candidates to study ultra-relativistic heavy-ion collisions.
Comments:
11 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2108.08626 [pdf]
PRC(2022)·8 citations
03
[Submitted on 19 Aug 2021]
Finite-temperature linear response theory based on relativistic Hartree Bogoliubov model with point-coupling interaction
A. Ravlić · Y.F. Niu · T. Nikšić · N. Paar · P. Ring
The finite-temperature linear response theory based on the finite-temperature relativistic Hartree-Bogoliubov (FT-RHB) model is developed in the charge-exchange channel to study the temperature evolution of spin-isospin excitations. Calculations are performed self-consistently with relativistic point-coupling interactions DD-PC1 and DD-PCX. In the charge-exchange channel, the pairing interaction can be split into isovector ( $T = 1$ ) and isoscalar ( $T = 0$ ) parts. For the isovector component, the same separable form of the Gogny D1S pairing interaction is used both for the ground-state calculation as well as for the residual interaction, while the strength of the isoscalar pairing in the residual interaction is determined by comparison with experimental data on Gamow-Teller resonance (GTR) and Isobaric analog resonance (IAR) centroid energy differences in even-even tin isotopes. The temperature effects are introduced by treating Bogoliubov quasiparticles within a grand-canonical ensemble. Thus, unlike the conventional formulation of the quasiparticle random-phase approximation (QRPA) based on the Bardeen-Cooper-Schrieffer (BCS) basis, our model is formulated within the Hartree-Fock-Bogoliubov (HFB) quasiparticle basis. Implementing a relativistic point-coupling interaction and a separable pairing force allows for the reduction of complicated two-body residual interaction matrix elements, which considerably decreases the dimension of the problem in the coordinate space. The main advantage of this method is to avoid the diagonalization of a large QRPA matrix, especially at finite temperature where the size of configuration space is significantly increased. The implementation of the linear response code is used to study the temperature evolution of IAR, GTR, and spin-dipole resonance (SDR) in even-even tin isotopes in the temperature range $T = 0 - 1.5$ MeV.
Comments:
20 pages, 9 figures, submitted for publication
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2108.08702 [pdf]
14 citations
04
[Submitted on 18 Aug 2021] (cross-list from astro-ph.HE)
Resolving the fastest ejecta from binary Neutron Star mergers: implications for electromagnetic counterparts
Coleman Dean · Rodrigo Fernández · Brian D. Metzger
We examine the effect of spatial resolution on initial mass ejection in grid-based hydrodynamic simulations of binary neutron star mergers. The subset of the dynamical ejecta with velocities greater than $\sim 0.6$ c can generate an ultraviolet precursor to the kilonova on $\sim$ hr timescales and contribute to a years-long non-thermal afterglow. Previous work has found differing amounts of this fast ejecta, by one- to two orders of magnitude, when using particle-based or grid-based hydrodynamic methods. Here we carry out a numerical experiment that models the merger as an axisymmetric collision in a co-rotating frame, accounting for Newtonian self-gravity, inertial forces, and gravitational wave losses. The lower computational cost allows us to reach spatial resolutions as high as $4$ m, or $\sim 3 \times 1 0^{- 4}$ of the stellar radius. We find that fast ejecta production converges to within $10%$ for a cell size of $20$ m. This suggests that fast ejecta quantities found in existing grid-based merger simulations are unlikely to increase to the level needed to match particle-based results upon further resolution increases. The resulting neutron-powered precursors are in principle detectable out to distances $≲ 200$ Mpc with upcoming facilities. We also find that head-on collisions at the free-fall speed, relevant for eccentric mergers, yield fast and slow ejecta quantities of order $1 0^{- 2} M_{⊙}$ , with a kilonova signature distinct from that of quasi-circular mergers.
Comments:
Accepted by ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2108.08311 [pdf]
ApJ(2021)·23 citations
05
[Submitted on 19 Aug 2021] (cross-list from astro-ph.HE)
Comparison of simulated neutrino emission models with data on Supernova 1987A
Jackson Olsen🇺🇸 · Yong-Zhong Qian🇺🇸
We compare models of supernova (SN) neutrino emission with the Kamiokande II data on SN 1987A using the Bayesian approach. These models are taken from simulations and are representative of current 1D SN models. We find that models with a brief accretion phase of neutrino emission are the most favored. This result is not affected by varying the overall flux normalization or considering neutrino oscillations. We also check the compatibility of the best-fit models with the data.
Comments:
7 pages, 5 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2108.08463 [pdf]
PRD(2021)·11 citations
06
[Submitted on 19 Aug 2021] (cross-list from hep-lat)
Local correlation among the chiral condensate, monopoles, and color magnetic fields in Abelian projected QCD
Hideo Suganuma (Kyoto U.)🇯🇵 · Hiroki Ohata (YITP, Kyoto U.)🇯🇵
Using the lattice gauge field theory, we study the relation among the local chiral condensate, monopoles, and color magnetic fields in quantum chromodynamics (QCD). First, we investigate idealized Abelian gauge systems of 1) a static monopole-antimonopole pair and 2) a magnetic flux without monopoles, on a four-dimensional Euclidean lattice. In these systems, we calculate the local chiral condensate on quasi-massless fermions coupled to the Abelian gauge field, and find that the chiral condensate is localized in the vicinity of the magnetic field. Second, using SU(3) lattice QCD Monte Carlo calculations, we investigate Abelian projected QCD in the maximally Abelian gauge, and find clear correlation of distribution similarity among the local chiral condensate, monopoles, and color magnetic fields in the Abelianized gauge configuration. As a statistical indicator, we measure the correlation coefficient $r$ , and find a strong positive correlation of $r ≃ 0.8$ between the local chiral condensate and an Euclidean color-magnetic quantity $F$ in Abelian projected QCD. The correlation is also investigated for the deconfined phase in thermal QCD. As an interesting conjecture, like magnetic catalysis, the chiral condensate is locally enhanced by the strong color-magnetic field around the monopoles in QCD.
Comments:
15 pages, 7 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2108.08499 [pdf]
Universe(2021)·6 citations
07
[Submitted on 19 Aug 2021] (cross-list from hep-ph)
Transport properties and equation-of-state of hot and dense QGP matter near the critical end-point in the phenomenological dynamical quasi-particle model
Olga Soloveva🇩🇪 · Jörg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪
We extend the effective dynamical quasiparticle model (DQPM) - constructed for the description of non-perturbative QCD phenomena of the strongly interacting quark-gluon plasma (QGP) - to large baryon chemical potentials, $μ_{B}$ , including a critical end-point and a 1st order phase transition. The DQPM description of quarks and gluons is based on partonic propagators with complex selfenergies where the real part of the selfenergies is related to the quasiparticle mass and the imaginary part to a finite width of their spectral functions. In DQPM the determination of complex selfenergies for the partonic degrees of freedom at zero and finite $μ_{B}$ has been performed by adjusting the entropy density to the lQCD data. The temperature-dependent effective coupling (squared) $g^{2} (T / T_{c})$ , as well as the parton effective masses and widths are based on this adjustment. The novel extended dynamical quasiparticle model, named "DQPM-CP", makes it possible to describe thermodynamical and transport properties of quarks and gluons in a wide range of $T$ and $μ_{B}$ , and reproduces the equation-of-state (EoS) of lQCD calculations in the crossover region of finite $T, μ_{B}$ . We apply a scaling ansatz for the strong coupling constant near the CEP, located at ( $T^{C E P}$ , $μ_{B}^{C E P}) = (0.100, 0.960)$ GeV. We show the EoS as well as the speed of sound for $T > T_{c}$ and for a wide range of $μ_{B}$ , which can be of interest for hydrodynamical simulations. Furthermore, we consider two settings for the strange quark chemical potentials (I) $μ_{s} = μ_{B} /3$ and (II) $μ_{s} = 0$ . The isentropic trajectories of the QGP matter are compared for these two cases. The phase diagram of DQPM-CP is close to PNJL calculations. The leading order pQCD transport coefficients of both approaches differ. This elucidates that the knowledge of the phase diagram alone is not sufficient to describe the dynamical evolution of QGP.
Comments:
18 pages, 17 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2108.08561 [pdf]
PRD(2022)·32 citations
08
[Submitted on 19 Aug 2021] (cross-list from hep-ph)
Quantum information approach to high energy interactions
Dmitri E. Kharzeev🇺🇸
High energy hadron interactions are commonly described by using a probabilistic parton model that ignores quantum entanglement present in the light-cone wave functions. Here we argue that since a high energy interaction samples an instant snapshot of the hadron wave function, the phases of different Fock state wave functions cannot be measured - therefore the light-cone density matrix has to be traced over these unobservable phases. Performing this trace with the corresponding $U (1)$ Haar integration measure leads to "Haar scrambling" of the density matrix, and to the emergence of entanglement entropy. This entanglement entropy is determined by the Fock state probability distribution, and is thus directly related to the parton structure functions. As proposed earlier, at large rapidity $η$ the hadron state becomes maximally entangled, and the entanglement entropy is $S_{E} \sim η$ according to QCD evolution equations. When the phases of Fock state components are controlled, for example in spin asymmetry measurements, the Haar average cannot be performed, and the probabilistic parton description breaks down.
Comments:
9 pages; one typo corrected for archiving purposes, no other changes
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2108.08792 [pdf]
Phil.Trans.A.Math.Phys.Eng.Sci.(2021)·54 citations

Affiliations

first authorsco-authorsvia INSPIRE