Nuclear Theory·nucl-th

Tuesday·October 5, 2021

16 papers—8 primary·8 cross-listed

01
[Submitted on 1 Oct 2021]
Monte Carlo simulations of {\gamma}-directional correlations and their application on FIFRELIN cascades
A. Chalil (1) · T. Materna (1) · O. Litaize (2) · A. Chebboubi (2) · F. Gunsing (1) ( (1) IRFU, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France (2) CEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, France)
Angular distribution and correlation measurements are an essential part in nuclear structure experiments, especially when spectroscopic information of a specific nucleus is unknown. In most cases, the experimental determination of the spins, parities of the studied nuclear states, as well as the possible mixing between two electric/magnetic multipoles of a transition are determined using angular correlation measurements. In this work, the full effect of directional {\gamma}-correlations is simulated, by using the formal theory of angular distributions. The density matrix formalism along with its multipole expansions called statistical tensors is employed, enabling to perform a full simulation of the angular correlation effects in a cascade of an arbitrary number of {\gamma} transitions. A triple {\gamma} angular correlation simulation is demonstrated for the first time. The present approach was coupled with the Monte Carlo code FIFRELIN, which can simulate the de-excitation of fission fragments or of excited nuclei after neutron capture. It provides a complete description of the spatial distributions of all the {\gamma} rays in the cascade, that can be used for simulation purposes in various applications both in nuclear and particle physics. The potential for a novel approach in data analysis of angular correlation measurements is discussed thoroughly.
Comments:
12 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2110.00619 [pdf]
EPJA(2022)·7 citations
02
[Submitted on 1 Oct 2021]
Strangeness neutral equation of state with a critical point
Jamie M. Karthein🇺🇸 · Debora Mroczek🇺🇸 · Angel R. Nava Acuna🇺🇸 · Jacquelyn Noronha-Hostler🇩🇪 · Paolo Parotto🇺🇸 · Damien R. P. Price🇺🇸 · Claudia Ratti🇺🇸
We formulate a family of equations of state for Quantum Chromodynamics that exhibit critical features and obey the charge conservation conditions present in heavy-ion collisions (HICs). This construction utilizes the first-principle Lattice QCD (LQCD) results up to $O (μ_{B}^{4})$ by matching the Taylor coefficients at each order. The criticality of the equation of state (EoS) is implemented based on the well-established principle of universal scaling behavior, where QCD belongs to the 3D Ising Model universality class. The critical point can be placed in a range of temperature and baryonic chemical potential relevant for the Beam Energy Scan II at RHIC. Furthermore, the strength of the critical features can be varied as well. This flexibility is embedded in four free parameters, that could potentially be constrained by the experimental data. We will discuss the features and versatility of our EoS, as well as present the relevant thermodynamic quantities which are important for hydrodynamical simulations of HICs.
Comments:
6 pages, 4 figures, Proceedings of the International Conference on Critical Point and Onset of Deconfinement 2021
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2110.00622 [pdf]
PoS(2022)·2 citations
03
[Submitted on 4 Oct 2021]
Single-particle and collective structures in neutron-rich Sr isotopes
Kamila Sieja🇫🇷
Neutron-rich Sr nuclei around N=60 exhibit a sudden shape transition from spherical ground state to strongly prolate-deformed. Recently, a lot of new insight into the structure of Sr isotopes in this region was gained through experimental studies of excited levels, transitions strengths and spectroscopic factors. In this work, a "classic" shell-model description of strontium isotopes from N=50 to N=58 is provided, using a natural valence space outside the 78Ni core. Both even-even and even-odd isotopes are adressed. In particular, spectroscopic factors are computed to shed more light on the structure of low-energy excitations and their evolution along the Sr chain. The origin of deformation at N=60 is commented in the context of the present and previous shell-model and Monte-Carlo shell-model calculations.
Comments:
14 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2110.01298 [pdf]
Universe(2022)·9 citations
04
[Submitted on 4 Oct 2021]
Derivation of the M $_{n}$ /M $_{p}$ ratio in exotic nuclei
E. Khan🇫🇷
A generalized formula is provided, to calculate the M $_{n}$ /M $_{p}$ ratio of the multipole transition matrix elements, in the framework of the so-called phenomenological analysis. It takes into account the possible difference between the neutron and proton radii and diffuseness, which can occur, especially in exotic nuclei. The validity domain of the original Bernstein formula is discussed, in the case of the proton scattering probe at few tens of MeV. The largest discrepancies are obtained for very neutron-rich nuclei (N/Z $≳$ 1.6) or when the electromagnetic deformation parameter is larger than the proton scattering one. The reduction of the statistical error bars, and the study of very neutron-rich nuclei at facilities of exotic beams of new generation, should favor the use of the generalized Bernstein formula.
Comments:
8 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2110.01299 [pdf]
PRC(2022)·2 citations
05
[Submitted on 1 Oct 2021]
Utilization of Event Shape in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
Ryan Milton🇺🇸 · Gang Wang🇺🇸 · Maria Sergeeva🇺🇸 · Shuzhe Shi🇨🇦 · Jinfeng Liao🇺🇸 · Huan Zhong Huang🇺🇸
The search for the chiral magnetic effect (CME) has been a subject of great interest in the field of high-energy heavy-ion collision physics, and various observables have been proposed to probe the CME. Experimental observables are often contaminated with background contributions arising from collective motions (specifically elliptic flow) of the collision system. We present a method study of event-shape engineering (ESE) that projects the CME-sensitive $γ_{112}$ correlator and its variations ( $γ_{132}$ and $γ_{123}$ ) to a class of events with minimal flow. We discuss the realization of the zero-flow mode, the sensitivity on the CME signal, and the corresponding statistical significance for Au+Au, Ru+Ru, and Zr+Zr collisions at $s_{NN} = 200$ GeV with a multiphase transport (AMPT) model, as well as a new event generator, Event-By-Event Anomalous-Viscous Fluid Dynamics (EBE-AVFD).
Comments:
12 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
2110.01435 [pdf]
PRC(2021)·21 citations
06
[Submitted on 4 Oct 2021]
Effective Field Theory analysis of $^{3}$ He- $α$ scattering data
Maheshwor Poudel · Daniel R. Phillips
We treat low-energy $^{3}$ He- $α$ elastic scattering in an Effective Field Theory (EFT) that exploits the separation of scales in this reaction. We compute the amplitude up to Next-to-Next-to-Leading Order (NNLO), developing a hierarchy of the effective-range parameters that contribute at various orders. We use the resulting formalism to analyze data for recent measurements at center-of-mass energies of 0.38-3.12 MeV using the SONIK gas target at TRIUMF as well as older data in this energy regime. We employ a likelihood function that incorporates the theoretical uncertainty due to truncation of the EFT and use Markov Chain Monte Carlo sampling to obtain the resulting posterior probability distribution. We find that the inclusion of a small amount of data on the analysing power $A_{y}$ is crucial to determine the sign of the p-wave splitting in such an analysis. The combination of $A_{y}$ and SONIK data constrains all effective-range parameters up to $O (p^{4})$ in both s- and p-waves quite well. The ANCs and s-wave scattering length are consistent with a recent EFT analysis of the capture reaction $^{3}$ He( $α$ , $γ$ ) $^{7}$ Be.
Comments:
22 pages, 15 figures, Published and corrected version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2110.01451 [pdf]
J.Phys.G(2022)·12 citations
07
[Submitted on 4 Oct 2021]
Neutron star crustal properties from relativistic mean-field models and bulk parameters effects
M. Dutra · C. H. Lenzi · W. de Paula · O. Lourenço
We calculate crustal properties of neutron stars, namely, mass ( $M_{crust}$ ), radius ( $R_{crust}$ ) and fraction of moment of inertia ( $Δ I / I$ ) from parametrizations of hadronic relativistic mean-field (RMF) model consistent with symmetric and asymmetric nuclear matter constraints, as well as some stellar boundaries. We verify which one are also in agreement with restrictions of $Δ I / I ⩾ 1.4%$ and $Δ I / I ⩾ 7%$ related to the glitching mechanism observed in pulsars, such as the Vela one. The latter constraint explains the glitches phenomenon when entrainment effects are taken into account. Our findings indicate that these parametrizations pass in the glitching limit for a neutron star mass range of $M ⩽ 1.82 M_{⊙}$ ( $Δ I / I ⩾ 1.4%$ ), and $M ⩽ 1.16 M_{⊙}$ ( $Δ I / I ⩾ 7%$ ). We also investigate the influence of nuclear matter bulk parameters on crustal properties and find that symmetry energy is the quantity that produces the higher variations on $M_{crust}$ , $R_{crust}$ , and~ $Δ I / I$ . Based on the results, we construct a particular RMF parametrization able to satisfy $Δ I / I ⩾ 7%$ even at $M = 1.4 M_{⊙}$ , the mass value used to fit data from the softer component of the Vela pulsar X-ray spectrum. The model also presents compatibility with observational data from PSR J1614-2230, PSR J0348+0432, and MSP J0740+6620 pulsars, as well as, with data from the Neutron Star Interior Composition Explorer (NICER) mission.
Comments:
11 pages, 8 figures, published in European Physical Journal A Topical Issue 'CompOSE: a repository for Neutron Star Equations of State and Transport Properties'
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2110.01461 [pdf]
EPJA(2021)·5 citations
08
[Submitted on 4 Oct 2021]
DREENA-A framework as a QGP tomography tool
Dusan Zigic🇷🇸 · Igor Salom🇷🇸 · Jussi Auvinen🇷🇸 · Pasi Huovinen🇷🇸 · Magdalena Djordjevic🇷🇸
We present a fully optimised framework DREENA-A based on a state-of-the-art energy loss model. The framework can include any, in principle arbitrary, temperature profile within the dynamical energy loss formalism. Thus, 'DREENA' stands for Dynamical Radiative and Elastic ENergy loss Approach, while 'A' stands for Adaptive. DREENA-A does not use fitting parameters within the energy loss model, allowing it to fully exploit differences in temperature profiles which are the only input in the framework. The framework applies to light and heavy flavor observables, different collision energies, and large and smaller systems. This, together with the ability to systematically compare data and predictions within the same formalism and parameter set, makes DREENA-A a unique multipurpose QGP tomography tool.
Comments:
21 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2110.01544 [pdf]
Front.in Phys.(2022)·43 citations
09
[Submitted on 30 Sept 2021] (cross-list from hep-lat)
Parton physics from a heavy-quark operator product expansion: Lattice QCD calculation of the second moment of the pion distribution amplitude
William Detmold🇺🇸 · Anthony Grebe🇺🇸 · Issaku Kanamori🇯🇵 · C.-J. David Lin🇹🇼 · Santanu Mondal🇺🇸 · Robert Perry🇹🇼 · Yong Zhao🇺🇸
The pion light-cone distribution amplitude (LCDA) is a central non-perturbative object of interest for high-energy exclusive processes in quantum chromodynamics. In this article, the second Mellin moment of the pion LCDA is determined as a proof-of-concept calculation for the first numerical implementation of the heavy-quark operator product expansion (HOPE) method. The resulting value for the second Mellin moment, determined in quenched QCD at a pion mass of $m_{π} = 550$ MeV at a factorization scale of 2 GeV is $⟨ ξ^{2} ⟩ = 0.210 \pm 0.013 (stat.) \pm 0.034 (sys.)$ . This result is compatible with those from previous determinations of this quantity.
Comments:
30 pages, 16 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2109.15241 [pdf]
PRD(2022)·40 citations
10
[Submitted on 30 Sept 2021] (cross-list from hep-ph)
Collinear factorization of diphoton photoproduction at next to leading order
Oskar Grocholski🇵🇱 · Bernard Pire🇫🇷 · Paweł Sznajder🇵🇱 · Lech Szymanowski🇵🇱 · Jakub Wagner🇵🇱
We calculate in the framework of collinear factorization the amplitude for the photoproduction of a near forward large mass diphoton at leading twist and next to leading order (NLO) in $α_{s}$ . We demonstrate the validity of factorization at this order, which was never achieved for such a reaction where the coefficient function describes a $2 \to 3$ hard process. While the Born order amplitude was purely imaginary and only probed the $x = \pm ξ$ cross-over line of generalized parton distributions (GPD) domain, the NLO result contains both a real and an imaginary part and probes the whole domain of definition of quark GPDs. The phenomenology of our results for medium (JLab) and higher energy (EIC) experiments will be developed in a future study.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.00048 [pdf]
PRD(2021)·35 citations
11
[Submitted on 2 Oct 2021] (cross-list from astro-ph.HE)
Enhanced symmetry energy bears universality of the r-process
José Nicolás Orce · Balaram Dey · Cebo Ngwetsheni · Srijit Bhattacharya · Deepak Pandit · Brenden Lesch · Andile Zulu
The abundance of about half of the stable nuclei heavier than iron via the rapid neutron capture process or $r$ -process is intimately related to the competition between neutron capture and $β$ -decay rates, which ultimately depends on the binding energy of neutron-rich nuclei. The well-known Bethe-Weizsäcker semi-empirical mass formula\cite{weiz,bethe} describes the binding energy of ground states -- i.e. nuclei with temperatures of $T \approx 0$ MeV -- with the symmetry energy parameter converging between $23 - 27$ MeV for heavy nuclei. Here we find an unexpected enhancement of the symmetry energy at higher temperatures, $T \approx 0.7 - 1.0$ MeV, from the available data of giant dipole resonances built on excited states. Although these are likely the temperatures where seed elements are created -- during the cooling down of the ejecta following neutron-star mergers\cite{mergersnucleo} or collapsars\cite{collapsar} -- the fact that the symmetry energy remains constant between $T \approx 0.7 - 1.0$ MeV, suggests a similar trend down to $T \approx 0.5$ MeV, where neutron-capture may start occurring. Calculations using this relatively larger symmetry energy yield a reduction of the binding energy per nucleon for heavy neutron-rich nuclei and inhibits radiative neutron-capture rates. This results in a substantial close in of the neutron dripline -- where nuclei become unbound -- which elucidates the long sought universality of heavy-element abundances through the $r$ -process; as inferred from the similar abundances found in extremely metal-poor stars and the Sun.
Comments:
7 pages, 10 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.00713 [pdf]
MNRAS(2023)·5 citations
12
[Submitted on 3 Oct 2021] (cross-list from nucl-ex)
Search for $α$ condensed states in $^{13}$ C using $α$ inelastic scattering
K. Inaba · Y. Sasamoto · T. Kawabata · M. Fujiwara · Y. Funaki · K. Hatanaka · K. Itoh · M. Itoh · K. Kawase · H. Matsubara · Y. Maeda · K. Suda and 8 other authors
We searched for the $α$ condensed state in $^{13}$ C by measuring the $α$ inelastic scattering at $E_{α} = 388$ MeV at forward angles including 0 degrees. We performed the distorted-wave Born-approximation calculation with the single-folding potential and the multipole decomposition analysis to determine the isoscalar transition strengths in $^{13}$ C. We found a bump structure around $E_{x} = 12.5$ MeV due to the isoscalar monopole ( $I S 0$ ) transition. A peak-fit analysis suggested that this bump consisted of several $1/ 2^{-}$ states. We propose that this bump is due to the mirror state of the 13.5 MeV-state in $^{13}$ N, which dominantly decays to the $α$ condensed state in $^{12}$ C. It was speculated that the $1/ 2^{-}$ states around $E_{x} = 12.5$ MeV were candidates for the $α$ condensed state, but the $3 α + n$ orthogonality condition model suggests that the $α$ condensed state is unlikely to emerge as the negative parity states. We also found two $1/ 2^{+}$ or $3/ 2^{+}$ states at $E_{x} = 14.5$ and 16.1 MeV excited with the isoscalar dipole ( $I S 1$ ) strengths. We suggest that the 16.1-MeV state is a possible candidate for the $α$ condensed state predicted by the cluster-model calculations on the basis of the good correspondence between the experimental and calculated level structures. However, the theoretical $I S 1$ transition strength for this state is significantly smaller than the measured value. Further experimental information is strongly desired to establish the $α$ condensed state in $^{13}$ C.
Comments:
24 pages, 12 figures, published in PTEP
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.00938 [pdf]
PTEP(2021)·5 citations
13
[Submitted on 3 Oct 2021] (cross-list from nucl-ex)
Competition between $(γ, p)$ and $(γ, n)$ photo-disintegration yields
José Nicolás Orce
A comprehensive analysis of the competition between photo-proton and photo-neutron disintegration yields is undertaken by constraining photo-absorption data with physics principles -- namely, dipole sum rules, decay properties to open channels, isospin selection rules and statistical evaporation from compound nucleus formation. The trend and magnitude of disintegration yields for self-conjugate nuclei are in agreement with the evaporation model of Blatt and Weisskopf. A substantial improvement is found between the exponential trend presented in this work and that determined by Morinaga using a similar approach. This work allows for the evaluation of frequently missing or inconsistent photo-proton contributions, which impacts the photo-disintegration of light and neutron-deficient nuclei, where photo-proton contributions are relevant.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.00979 [pdf]
Atom.Data Nucl.Data Tabl.(2022)·7 citations
14
[Submitted on 4 Oct 2021] (cross-list from hep-ph)
Exposing the effect of $p$ -wave in pion triplet under the strong magnetic field
Zanbin Xing🇨🇳 · Jingyi Chao🇨🇳 · Lei Chang🇨🇳 · Yu-xin Liu🇨🇳
The static properties, masses and decay constants, of pseudoscalar meson triplet in a strongly magnetized medium are studied through the Dyson-Schwinger equation approach treatment of a contact interaction. Complementary to the usual vector-vector form, a symmetry-preserving formulation of couplings has been proposed in this work, without modifying the quark propagator, to control the strength of the $p$ -wave component of Bethe-Salpeter amplitude. It is found that, with the help of flexible auxiliary interaction, our simple model is able to reproduce the observation in the lattice QCD simulation, where the spectra of the charged pseudo-scalar meson shows a non-monotonic behavior as the magnetic field grows. The discovery of this work implies the strong magnetic field affects the inner structure of mesons dramatically.
Comments:
17 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2110.01245 [pdf]
PRD(2022)·10 citations
15
[Submitted on 4 Oct 2021] (cross-list from hep-lat)
Investigating the low moments of the nucleon structure functions in lattice QCD
K. U. Can🇦🇺 · A. Hannaford-Gunn🇦🇺 · E. Sankey🇦🇺 · R. Horsley🇬🇧 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · P. E. L. Rakow🇬🇧 · G. Schierholz🇩🇪 · H. Stuben🇩🇪 · R. D. Young🇦🇺 · J. M. Zanotti🇦🇺
We highlight QCDSF/UKQCD Collaboration's recent developments on computing the Compton amplitude directly via an implementation of the second order Feynman-Hellmann theorem. As an application, we compute the nucleon Compton tensor across a range of photon virtuality at an unphysical quark mass. This enables us to study the $Q^{2}$ dependence of the low moments of the nucleon structure functions in a lattice calculation for the first time. We present some selected results for the moments of the $F_{1}$ , $F_{2}$ and $F_{L}$ structure functions and discuss their implications.
Comments:
7 pages, 3 figures. Contribution to the 38th International Symposium on Lattice Field Theory, LATTICE2021 26th-30th July, 2021 Zoom/Gather@Massachusetts Institute of Technology
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2110.01310 [pdf]
PoS(2022)·3 citations
16
[Submitted on 4 Oct 2021] (cross-list from nucl-ex)
Proton inelastic scattering reveals deformation in $^{8}$ He
M. Holl · R. Kanungo · Z. H. Sun · G. Hagen · J. A. Lay · A. M. Moro · P. Navrátil · T. Papenbrock · M. Alcorta · D. Connolly · B. Davids · A. Diaz Varela and 18 other authors
A measurement of proton inelastic scattering of $^{8}$ He at $8.25 A$ ~MeV at TRIUMF shows a resonance at 3.54(6)~MeV with a width of 0.89(11)~MeV. The energy of the state is in good agreement with coupled cluster and no-core shell model with continuum calculations, with the latter successfully describing the measured resonance width as well. Its differential cross section analyzed with phenomenological collective excitation form factor and microscopic coupled reaction channels framework consistently reveals a large deformation parameter $β_{2}$ = 0.40(3), consistent with no-core shell model predictions of a large neutron deformation. This deformed double-closed shell at the neutron drip-line opens a new paradigm.
Comments:
9 pages, 5 figures. Accepted for publication in Physics Letters B
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2110.01592 [pdf]
PLB(2021)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE