Nuclear Theory·nucl-th

Wednesday·January 16, 2019

17 papers—11 primary·6 cross-listed

01
GLISSANDO 3: GLauber Initial-State Simulation AND mOre..., ver. 3
Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱 · Maciej Rybczynski🇵🇱 · Grzegorz Stefanek🇵🇱
We present ver. 3 of GLISSANDO, a versatile Monte-Carlo generator for Glauber-like models of the initial stages of ultra-relativistic heavy-ion collisions. The present version incorporates the wounded quark model, which is phenomenologically successful in reproducing multiplicities of particle production at RHIC and the LHC. Within this model, one can study the nucleon substructure fluctuation effects, recently explored in p-A collisions. In addition, the code includes the possibility of investigating collisions of light nuclei, such as $^{3}$ He and $^{3}$ H, or the $α$ -clustered $^{7, 9}$ Be, $^{12}$ C, and $^{16}$ O, where the deformation of the intrinsic wave function influences the transverse shape of the initial state. The current version, being down-compatible, retains the functionality of the previous releases, such as incorporation of various variants of Glauber-like models, a smooth $N N$ inelasticity profile in the impact parameter obtained from a parametrization of experimental data, fluctuating strength of the entropy deposition, or realistic nuclear distributions of heavy nuclei with deformation. The code can provide output in the format containing the event-by-event source location, which may be further used in modeling the intermediate evolution phase, e.g., with hydrodynamics or transport models. The interface is simplified, such that in the control input file the user may supply only the very basic information, such as the collision energy, the mass numbers of the colliding nuclei, and the model type. GLISSANDO 3 is integrated with the CERN ROOT platform. The package includes numerous illustrative and useful ROOT scripts to compute and plot various results.
nucl-thComput.Phys.Commun.(2019)·49 citations
02
Consistent Skyrme parametrizations constrained by GW170817
O. Lourenço🇧🇷 · M. Dutra🇧🇷 · C. H. Lenzi🇧🇷 · S. K. Biswal🇨🇳 · M. Bhuyan🇧🇷 · D. P. Menezes🇧🇷
The high-density behavior of the stellar matter composed of nucleons and leptons under $β$ ~equilibrium and charge neutrality conditions is studied with the Skyrme parametrizations shown to be consistent (CSkP) with the nuclear matter, pure neutron matter, symmetry energy and its derivatives in a set of $11$ constraints [Dutra {\it et al.}, Phys. Rev. C 85, 035201 (2012)]. The predictions of these parametrizations on the tidal deformabilities related to the GW170817 event are also examined. The CSkP that produce massive neutron stars give a range of $11.86 \mbox k m ⩽ R_{1.4} ⩽ 12.55 \mbox k m$ for the canonical star radius, in agreement with other theoretical predictions. It is shown that the CSkP are compatible with the region of masses and radii obtained from the analysis of recent data from LIGO and Virgo Collaboration (LVC). A correlation between dimensionless tidal deformability and radius of the canonical star is found, namely, $Λ_{1.4} \approx 3.16 \times 1 0^{- 6} R_{1.4}^{7.35}$ , with results for the CSkP compatible with the recent range of $Λ_{1.4} = 19 0_{- 120}^{+ 390}$ from LVC. An analysis of the $Λ_{1} \times Λ_{2}$ graph shows that all the CSkP are compatible with the recent bounds obtained by LVC. Finally, the universal correlation between the moment of inertia and the deformability of a neutron star, named as the \mbox{ $I$ -Love} relation, is verified for the CSkP, that are also shown to be consistent with the prediction for the moment of inertia of the \mbox{PSR J0737-3039} primary component pulsar.
nucl-thEPJA(2020)·35 citations
03
Transmission coefficients in compound-nucleus reaction theory
Y. Alhassid · G.F. Bertsch · P. Fanto · T. Kawano
A recent article (D.A. Brown, et al., Phys. Rev. C98 024616 (2018)) rproposed a modification of the cross section formula used in practical calculations of compound nucleus reactions. We discuss the main concepts and approximations of statistical reaction theory and conclude that the standard practical implementations of the cross section formula remain the preferred choice.
nucl-thPRC(2019)·0 citations
04
Chiral vortices and pseudoscalar condensation due to rotation
Lingxiao Wang🇨🇳 · Yin Jiang🇨🇳 · Lianyi He🇨🇳 · Pengfei Zhuang🇨🇳
We investigate the influence of rotation on the dynamical chiral symmetry breaking in strongly interacting matter. We develop a self-consistent Bogoliubov-de Gennes-like theoretical framework to study the inhomogeneous chiral condensate and the possible chiral vortex state in rotating finite-size matter in four-fermion interacting theories. We show that for sufficiently rapid rotation in $2 + 1$ dimensions, the ground state can be a chiral vortex state, a type of topological defect in analogy to superfluids and superconductors. The vortex state exhibits pion condensation, providing a new mechanism to realize pseudoscalar condensation in strongly interacting matter.
nucl-thcond-mat.quant-gascond-mat.supr-conhep-phPRD(2019)·22 citations
05
Order, Chaos and (Quasi-) Dynamical Symmetries across 1st-order Quantum Phase Transitions in Nuclei
Michal Macek · Pavel Cejnar · Pavel Stránský · Jan Dobeš · Amiram Leviatan
First order quantum phase transition (QPT) between spherical and axially deformed nuclei shows coexisting, but well-separated regions of regular and chaotic dynamics. We employ a Hamiltonian of the Arima-Iachello Interacting Boson Model (IBM) with an arbitrarily high potential barrier separating the phases. Classical and quantum analyses reveal markedly distinct behavior of the two phases: Deformed phase is completely regular, while the spherical phase shows highly chaotic dynamics, similar to the Hénon-Heiles system. Rotational bands with quasi-SU(3) characteristics built upon the regular vibrational spectrum of beta- and gamma-vibrations are observed in the deformed phase up to very high excitation energies.
nucl-thAIP Conf.Proc.(2019)·1 citation
06
Continuum damping effects in nuclear collisions associated with twisted boundary conditions
C.Q.He · J.C.Pei · Yu Qiang · Na Fei
The time-dependent Skyrme Hartree-Fock calculations have been performed to study $^{24}$ Mg + $^{24}$ Mg collisions. The twisted boundary conditions, which can avoid finite box-size effects of the employed 3D coordinate space, have been implemented. The prolate deformed $^{24}$ Mg has been set to different orientations to study vibrations and rotations of the compound nucleus $^{48}$ Cr. Our time evolution results show continuum damping effects associated with the twist-averaged boundary condition play a persistent role after the fusion stage. In particular, a rotational damping in continuum is presented in calculations of both twist-averaged and absorbing boundary conditions, in which damping widths can be clearly extracted. It is unusual that the rotating compound nucleus in continuum evolves towards spherical but still has a considerable angular momentum.
nucl-thPRC(2019)·2 citations
07
Analytical approach for the Quartet Condensation Model
V.V. Baran · D.S. Delion
Within the Quartet Condensation Model (QCM), the isovector pairing correlations for $N = Z$ nuclei are described with a very high accuracy by a condensate of $α$ -like quartets. The usual approach involves cumbersome recurrence relations in order to compute numerically the relevant quantities of the model: the norm of the quartet states and the mean value of the isovector pairing Hamiltonian as functions of the pair mixing amplitudes. We present the final analytical expressions for the above mentioned quantities, for all cases up to four quartets in the valence shell. The analytical QCM expressions were obtained by a straightforward implementation of the SO(5) algebra in the symbolic computer algebra system Cadabra2. The norm of the quartet states and the mean value of the Hamiltonian are polynomial functions of the mixing amplitudes. The numerical implementation of the QCM model is thus made trivial as matter of copying and pasting the presented formulas. We introduce in this work the method of computer aided analytical calculus for a many body setting. In particular, we provide precise and easy to use tools for the description of isovector pairing correlations.
nucl-thPRC(2019)·11 citations
08
Thermonuclear fusion rates for tritium + deuterium using Bayesian methods
Rafael S. de Souza🇺🇸 · S. Reece Boston🇺🇸 · Alain Coc🇫🇷 · Christian Iliadis🇺🇸
The $^{3}$ H(d,n) $^{4}$ He reaction has a large low-energy cross section and will likely be utilized in future commercial fusion reactors. This reaction also takes place during big bang nucleosynthesis. Studies of both scenarios require accurate and precise fusion rates. To this end, we implement a one-level, two-channel R-matrix approximation into a Bayesian model. Our main goals are to predict reliable astrophysical S-factors and to estimate R-matrix parameters using the Bayesian approach. All relevant parameters are sampled in our study, including the channel radii, boundary condition parameters, and data set normalization factors. In addition, we take uncertainties in both measured bombarding energies and S-factors rigorously into account. Thermonuclear rates and reactivities of the $^{3}$ H(d,n) $^{4}$ He reaction are derived by numerically integrating the Bayesian S-factor samples. The present reaction rate uncertainties at temperatures between $1.0$ MK and $1.0$ GK are in the range of 0.2% to 0.6%. Our reaction rates differ from previous results by 2.9% near 1.0 GK. Our reactivities are smaller than previous results, with a maximum deviation of 2.9% near a thermal energy of $4$ keV. The present rate or reactivity uncertainties are more reliable compared to previous studies that did not include the channel radii, boundary condition parameters, and data set normalization factors in the fitting. Finally, we investigate previous claims of electron screening effects in the published $^{3}$ H(d,n) $^{4}$ He data. No such effects are evident and only an upper limit for the electron screening potential can be obtained.
nucl-thastro-ph.IMnucl-exphysics.data-anPRC(2019)·27 citations
09
Quantum Monte Carlo Methods in Nuclear Physics: Recent Advances
J. E. Lynn🇩🇪 · I. Tews🇺🇸 · S. Gandolfi🇺🇸 · A. Lovato🇺🇸
In recent years, the combination of precise quantum Monte Carlo (QMC) methods with realistic nuclear interactions and consistent electroweak currents, in particular those constructed within effective field theories (EFTs), has lead to new insights in light and medium-mass nuclei, neutron matter, and electroweak reactions. This compelling new body of work has been made possible both by advances in QMC methods for nuclear physics, which push the bounds of applicability to heavier nuclei and to asymmetric nuclear matter and by the development of local chiral EFT interactions up to next-to-next-to-leading order and minimally nonlocal interactions including $Δ$ degrees of freedom. In this review, we discuss these recent developments and give an overview of the exciting results for nuclei, neutron matter and neutron stars, and electroweak reactions.
nucl-thnucl-exAnn.Rev.Nucl.Part.Sci.(2019)·128 citations
10
16O within the Semimicroscopic Algebraic Cluster Model and the importance of the Pauli Exclusion Principle
P. O. Hess · J. R. M. Berriel-Aguayo · L. J. Chavez-Nuñez
The Semimicroscopic Algebraic Cluster Model (SACM) is applied to 16O, assumed to consist of a system of four alpha-clusters. For the 4-alpha cluster system a microscopic model space is constructed, which observes the Pauli-Exclusion-Principle (PEP) and is symmetric under permutation of the 4-alpha-particles. A phenomenological Hamiltonian is used, justifying the name Semi in the SACM. The spectrum and transition values are determined. One of the main objectives is to test the importance of the Pauli Exclusion Principle (PEP), comparing the results with the Algebraic Cluster Model (ACM), which does not include the PEP, and claims that the 16O shows evidence of a tetrahedral structure, which can be explained easily by symmetry arguments. We show that PEP is very important and cannot be neglected, otherwise it leads to a wrong interpretation of the band structure and to too many states at low energy.
nucl-thEPJA(2019)·6 citations
11
Directed flow of photons in Cu+Au collisions at RHIC
Pingal Dasgupta🇮🇳 · Rupa Chatterjee🇮🇳 · Dinesh K. Srivastava🇮🇳
Event-by-event fluctuations in the positions of nucleons in two colliding identical nuclei can lead to non-uniform initial energy density distribution on the transverse plane. In addition to initial state fluctuations, the difference in the number of participating nucleons in collision of two non-identical nuclei can also result in significant anisotropy in the initial geometry and energy density distributions. Thus, Cu+Au collisions are expected to provide interesting new aspects in the understanding of anisotropic flow in heavy ion collisions. We calculate directed flow co-efficient $v_{1}$ of thermal photons using a hydrodynamic model with fluctuating initial conditions at 200A GeV Cu+Au collisions at RHIC and compare it with the elliptic and triangular flow parameters obtained at same initial conditions. The photon $v_{1}$ as a function of transverse momentum is found to be non-zero and significantly large. However, it shows a different nature compared to the elliptic and triangular flow parameters. The $v_{1}$ is found to be completely dominated by QGP radiation in the region $1 < p_{T} < 6$ GeV and contribution from the hadronic phase to photon $v_{1}$ is only marginal. At $p_{T} < 2$ GeV, it is negative and it decreases further with smaller values of $p_{T}$ . However, at $p_{T} > 2$ GeV, $v_{1}$ is positive and rises slowly with $p_{T}$ . In addition, the photon $v_{1}$ is found to be more sensitive to the initial formation time of the plasma compared to the elliptic and triangular flow parameters. We suggest that a simultaneous measurements of photon $v_{n}$ co-efficients, (n=1, 2, 3) can provide valuable information about the initial state produced in heavy ion collisions as well as help us understanding the direct photon puzzle.
nucl-thJ.Phys.G(2020)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE