Nuclear Theory·nucl-th

Monday·November 16, 2020

8 papers—5 primary·3 cross-listed

01
Phase transitions and critical behavior in hadronic transport with a relativistic density functional equation of state
Agnieszka Sorensen🇺🇸 · Volker Koch🇺🇸
We develop a flexible, relativistically covariant parameterization of dense nuclear matter equation of state suited for inclusion in computationally demanding hadronic transport simulations. Within an implementation in the hadronic transport code SMASH, we show that effects due to bulk thermodynamic behavior are reproduced in dynamic hadronic systems, demonstrating that hadronic transport can be used to study critical behavior in dense nuclear matter, both at and away from equilibrium. We also show that two-particle correlations calculated from hadronic transport simulation data follow theoretical expectations based on the second order cumulant ratio, and constitute a clear signature of crossing the phase diagram above the critical point.
nucl-thhep-phPRC(2021)·55 citations
02
Calculable microscopic theory for $^{12}$ C( $α, γ$ ) $^{16}$ O cross section near Gamow window
Y. Suzuki
$^{12}$ C $(α, γ)^{16}$ O radiative-capture process is a key reaction to produce the element of oxygen in stars. Measuring the cross section near the Gamow window is extremely hard because it is too small. To make a theoretical contribution towards resolving the long-standing problem, I present a microscopic formulation that aims at providing all materials needed to calculate the cross section. The states of $^{12}$ C and $^{16}$ O relevant to the reaction are respectively described with fully microscopic 3 $α$ -particle and 4 $α$ -particle configurations, in which the relative motion among the $α$ particles is expanded in terms of correlated Gaussian basis functions. The configuration space has the advantage of being able to well describe the reduced $α$ -width amplitudes of the states of $^{16}$ O. Both electric dipole and electric quadrupole transitions are responsible for the radiative-capture process. The $α$ particle is described with a $(0 s)^{4}$ configuration admixed with a small amount of an isospin $T = 1$ impurity component, which is crucially important to account for the isovector electric dipole transition. The isoscalar electric dipole operators are also taken into account up to the first order beyond the long-wavelength approximation. All the necessary ingredients are provided to make the paper self-contained and ready for numerical computations.
nucl-thastro-ph.SRnucl-exFew Body Syst.(2021)·4 citations
03
Gaussian characterization of the unitary window for $N = 3$ : bound, scattering and virtual states
A. Deltuva. A. Kievsky · M. Gattobigio · M. Viviani
The three-body system inside the unitary window is studied for three equal bosons and three equal fermions having $1/2$ spin-isospin symmetry. We perform a gaussian characterization of the window using a gaussian potential to define trajectories for low-energy quantities as binding energies and phase shifts. On top of this trajectories experimental values are placed or, when not available, quantities calculated using realistic potentials that are known to reproduce experimental values. The intention is to show that the gaussian characterization of the window, thought as a contact interaction plus range corrections, captures the main low-energy properties of real systems as for example three helium atoms or three nucleons. The mapping of real systems on the gaussian trajectories is taken as indication of universal behavior. The trajectories continuously link the physical points to the unitary limit allowing for the explanation of strong correlations between observables appearing in real systems and which are known to exist in that limit. In the present study we focus on low-energy bound, scattering and virtual states.
nucl-thcond-mat.quant-gas3 citations
04
Hyperon electromagnetic form factors in the timelike region
Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪 · Ling-Yun Dai🇨🇳
Electromagnetic form factors of hyperons ( $Λ$ , $Σ$ , $Ξ$ ) in the timelike region, accessible in the reaction $e^{+} e^{-} \to Y ˉ Y$ , are studied. The focus is on energies close to the reaction thresholds, where the properties of these form factors are significantly influenced by the interaction in the final $Y ˉ Y$ system. This interaction is taken into account in the calculation, utilizing $Y ˉ Y$ potential models that have been constructed by the Jülich group for the analysis of data from the reaction $p ˉ p \to Y ˉ Y$ in the past. The enhancement of the effective form factor for energies close to the threshold, seen in experiments of $e^{+} e^{-} \to Λ ˉ Λ$ and $e^{+} e^{-} \to Σ ˉ^{0} Λ$ , is reproduced. With regard to the reactions $e^{+} e^{-} \to Σ ˉ^{-} Σ^{+}, Σ ˉ^{0} Σ^{0}, Σ ˉ^{+} Σ^{-}$ a delicate interplay between the three channels is observed in the results at low energies, caused by the $Σ ˉ Σ$ interaction. Predictions for the electromagnetic form factors $G_{M}$ and $G_{E}$ in the timelike region are presented for the $Λ$ , $Σ$ , and $Ξ$ hyperons.
nucl-thhep-exhep-phPRD(2021)·45 citations
05
Benchmarking Faddeev and transfer-to-the-continuum calculations for (p, pN ) reactions
M. Gomez-Ramos · A. Deltuva · A. M. Moro
Nucleon-knockout reactions on proton targets (p, pN ) have experienced a renewed interest due to the availability of inverse-kinematics experiment with exotic nuclei. Various theoretical descriptions have been used to describe these reactions, such as the Distorted-Wave Impulse Approximation (DWIA), the Faddeev-type formalism and the Transfer to the Continuum method. Our goal is to benchmark the observables computed with the Faddeev and Transfer to the Continuum formalisms in the intermediate energy regime relevant for the experimental (p, pn) and (p, 2p) studies. In this paper, we analyze the 11 Be(p,pn)10Be reaction for different beam energies, binding energies and orbital quantum numbers with both formalisms to assess their agreement for different observables. We obtain a good agreement in all cases considered, within 10%, when the input potentials are taken consistently and realistically.
nucl-thnucl-exPRC(2020)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Phase transitions and critical behavior in hadronic transport with a relativistic density functional equation of state

Calculable microscopic theory for 12C(α,γ)16O cross section near Gamow window

Gaussian characterization of the unitary window for N=3: bound, scattering and virtual states

Hyperon electromagnetic form factors in the timelike region

Benchmarking Faddeev and transfer-to-the-continuum calculations for (p, pN ) reactions

Affiliations

Calculable microscopic theory for $^{12}$ C( $α, γ$ ) $^{16}$ O cross section near Gamow window

Gaussian characterization of the unitary window for $N = 3$ : bound, scattering and virtual states