Nuclear Theory·nucl-th

Tuesday·April 25, 2023

13 papers—8 primary·5 cross-listed

01
Initial Vorticities of Quark-Gluon Matter in Heavy-ion Collisions
An-Ke Lei🇨🇳 · Du-Juan Wang🇨🇳 · Dai-Mei Zhou🇨🇳 · Ben-Hao Sa🇨🇳 · Laszlo Pal Csernai🇳🇴 · Larissa V. Bravina🇳🇴
We calculate four types of initial vorticities in Au+Au collisions at energies $S_{N N}$ = 5--200 GeV using a microscopic transport model PACIAE. Our simulation shows the non-monotonic dependence of the initial vorticities on the collision energies. The energy turning point is around 10-15 GeV for different vorticities but not sensitive to impact parameter.
nucl-thhep-phhep-thIJMPE(2023)·0 citations
02
Neutrino-induced neutral- and charged-current reactions on $^{40}$ Ar
Toshio Suzuki🇯🇵 · Noritaka Shimizu🇯🇵
Neutrino-induced reactions on $^{40}$ Ar are investigated by shell model for Gamow-Teller transitions and random-phase-approximation (RPA) for forbidden transitions. For the 1 $^{+}$ multipole, an effective interaction in $s d$ - $p f$ shell obtained by the extended Kuo-Krenciglowa (EKK) method from chiral interactions is used to study $B (GT)$ , charged-current reaction $^{40}$ Ar ( $ν_{e}$ , $e^{-}$ ) $^{40}$ K, $B (M 1)$ in $^{40}$ Ar and neutral-current reaction $^{40}$ Ar ( $ν$ , $ν$ ') $^{40}$ Ar. A considerable quenching for spin modes is found in the analysis of $B (M 1)$ , and this quenching is taken into account for the evaluation of the cross sections of the neutral-current reaction. The sensitive dependence of the reaction cross sections on the quenching of the axial-vector coupling constant, $g_{A}$ , is pointed out.
nucl-thPRC(2023)·1 citation
03
Relativistic effects in Green's function Monte Carlo calculations of neutrino-nucleus scattering
Alexis Nikolakopoulos🇺🇸 · Alessandro Lovato🇺🇸 · Noemi Rocco🇺🇸
Microscopic calculations of neutrino-nucleus scattering cross sections are critical for the success of the neutrino-oscillation program. In addition to retaining nuclear correlations in the initial and final state of the reaction, they are based on consistent nuclear interactions and transition current operators, thereby enabling robust uncertainty quantification. In this work, we address a significant limitation of these microscopic methods, which arises from their nonrelativistic nature. By performing the calculations in a reference frame that minimizes nucleon momenta and utilizing the so-called ``two-fragment'' model, we extend the applicability of Green's function Monte Carlo calculations of neutrino-nucleus scattering to higher momenta than currently possible. To validate this approach, we compare our theoretical predictions against inclusive data measured by the MiniBooNE, T2K, and MINER $ν$ A experiments.
nucl-thhep-thPRC(2024)·14 citations
04
Shape transition of Nd and Sm isotopes and neutrinoless double-beta decay nuclear matrix element of $^{150}$ Nd
Yusuke Tsunoda🇯🇵 · Noritaka Shimizu🇯🇵 · Takaharu Otsuka🇯🇵
Neutron-rich Nd and Sm isotopes are known to exhibit shape phase transition as a function of neutron number. Among them, $^{150}$ Nd and $^{150}$ Sm are important not only because they are transitional nuclei, but also the parent and daughter nuclei of double-beta decay. We performed large-scale shell-model calculations of even-even Nd and Sm isotopes including the spherical-deformed shape transition. The quasi-particle vacua shell model enables us to perform shell-model calculations with sufficiently large model space with the $^{110}$ Zr inert core. The shell-model result well reproduces the experimental excitation energies and quadrupole properties of the yrast and non-yrast states. The nuclear matrix element of neutrinoless double-beta decay of $^{150}$ Nd is evaluated showing its modest enhancement by shape mixing.
nucl-thPRC(2023)·18 citations
05
Triaxial-shape dynamics in the low-lying excited $0^{+}$ state: Role of the collective mass
Kouhei Washiyama · Kenichi Yoshida
Background: Non-yrast states in neutron-rich nuclei are being investigated experimentally. These states reveal various aspects and details of the nuclear structure, such as the fluctuation around the axially symmetric shape. Purpose: The beyond-mean-field effects in neutron-rich nuclei with $N ≃ 28$ are investigated. We focus on the role of collective mass in triaxial-shape dynamics. Method: We employ the five-dimensional quadrupole collective Hamiltonian method with the potential obtained in a constrained Hartree--Fock--Bogoliubov approach with a Skyrme energy-density functional and the collective-mass functions obtained by the cranking approximation. The method includes triaxial deformations. Results: We find that $^{42}$ Mg, $^{40}$ Si, $^{44}$ S, and $^{46}$ S show $γ$ -soft: A flat behavior in the potential energy surface along the triaxial deformation. Their low-lying spectra show a strong nucleus dependence, while those obtained with a collective mass assumed as constant are similar to each other. The energy ratio $E (0_{2}^{+}) / E (2_{1}^{+})$ and the $B (E 2)$ ratio $B (E 2; 0_{2}^{+} \to 2_{1}^{+}) / B (E 2; 2_{1}^{+} \to 0_{1}^{+})$ show a unique property of the $0_{2}^{+}$ state, while the energy and $B (E 2)$ ratios in neutron-deficient $γ$ -soft nuclei with $N = 78$ do not depend on nucleus so much. Conclusions: Low-lying spectra are determined by not only the potential energy but also the collective mass. We clarify the important role of the collective mass in low-energy dynamics in the neutron-rich $N \sim 28$ nuclei.
nucl-thPRC(2023)·5 citations
06
Relativistic configuration-interaction density functional theory: Nonaxial effects on nuclear $β β$ decay
Y. K. Wang🇨🇳 · P. W. Zhao🇨🇳 · J. Meng🇨🇳
The relativistic configuration-interaction density functional theory is developed for even-even and odd-odd nuclei and is used to predict the nuclear matrix element of the neutrinoless $β β$ ( $0 ν β β$ ) decay in nucleus $^{76}$ Ge, amongst the most promising $β β$ -decay candidates. The nonaxial deformation, i.e., triaxiality, which poses severe challenges in evaluating the nuclear matrix element of $^{76}$ Ge, is incorporated within a full model space for the first time. The spectroscopic properties of the $β β$ -decay partners $^{76}$ Ge and $^{76}$ Se, and the nuclear matrix element governing the two-neutrino $β β$ ( $2 ν β β$ ) decay in $^{76}$ Ge are well reproduced, providing solid examinations for the validity of theoretical calculations. The inclusion of the triaxial degree of freedom enhances the nuclear matrix element of the $0 ν β β$ decay significantly by a factor around two. The present results indicate that the goals of next-generation experiments searching for the $0 ν β β$ decay in $^{76}$ Ge can be achieved using only a quarter amount of the experimental materials.
nucl-thSci.Bull.(2024)·26 citations
07
Cluster formation near midrapidity -- can the mechanism be identified experimentally?
V. Kireyeu🇩🇪 · G. Coci🇩🇪 · S. Glaessel🇩🇪 · J. Aichelin🇫🇷 · C. Blume🇩🇪 · E. Bratkovskaya🇩🇪
The formation of weakly bound clusters in the hot and dense environment at midrapidity is one of the surprising phenomena observed experimentally in heavy-ion collisions from a low center of mass energy of a few GeV up to a ultra-relativistic energy of several TeV. Three approaches have been advanced to describe the cluster formation: coalescence at kinetic freeze-out, cluster formation during the entire heavy-ion collision by potential interaction between nucleons and deuteron production by hadronic reactions. We identify experimental observables, which can discriminate these production mechanisms for deuterons.
nucl-thhep-exhep-phPRC(2024)·19 citations
08
Probing the neutron-skin of unstable nuclei with heavy ion collisions
Junping Yang · Xiang Chen · Ying Cui · Zhuxia Li · Yingxun Zhang
To improve the constraints of symmetry energy at subsaturation density, measuring and accumulating more neutron skin data for neutron rich unstable nuclei is naturally required. Aiming to probe the neutron skin of unstable nuclei by using low-intermediate energy heavy ion collisions, we develop a new version of improved quantum molecular dynamics model, in which the neutron skin of the initial nucleus and the mean field potential in nucleon propagation are consistently treated. Our calculations show that the three observables, such as the cross sections of the primary projectile-like residues with $A > 100$ ( $σ_{A > 100}$ ), the difference of $σ_{A > 100}$ between $^{132}$ Sn+ $^{124}$ Sn and $^{124}$ Sn+ $^{124}$ Sn systems ( $δ σ_{A > 100}$ ), and the neutron to proton yield ratio ( $R (n / p)$ ) in the transverse direction, could be used to measure the neutron skin of the unstable nuclei and to constrain the slope of the symmetry energy in the future.
nucl-thnucl-exUniverse(2023)·3 citations
09
QCD bound states in motion
Paul Hoyer🇫🇮
I consider the frame dependence of QCD bound states in the presence of a confining, spatially constant gluon field energy density. The states are quantized at equal time in $A^{0} = 0$ (temporal) gauge. I derive the frame dependence of the wave functions, and demonstrate the Lorentz covariance of the electromagnetic (transition) form factors for states of any spin. The wave functions of $J^{P C} = 0^{-+}$ states with CM momentum $P \neq = 0$ are considered in some detail, verifying their local normalizability and the expected frame dependence of the bound state energy.
↳ hep-phnucl-thPRD(2023)·2 citations
10
Investigating the impact of extra resonance states in the van der Waals Hadron Resonance Gas Model
Nachiketa Sarkar🇮🇳
We investigate, in addition to the experimentally established hadrons, how the inclusion of extra resonance states, through the Hagedorn mass spectrum (HS) or Quark Model (QM) predicated states, affects the thermodynamic and transport quantities of the hadronic system in the van der Waals hadron resonance gas (VDWHRG) model. We found that the VDWHRG model with the HS provides the most accurate description of the lattice QCD results, both at zero and finite chemical potential. Moreover, the inclusion of these extra states has a significant impact on the van der Waals (VDW) parameters, which, in turn, affect the thermodynamic and transport quantities as well as the likely position of the liquid-gas phase transition critical point in the QCD phase diagram. Additionally, we infer that there is a strong correlation between the van der Waals parameters and the chemical potential. Overall, our study sheds light on the importance of considering extra resonance states and proper tuning of the VDW parameters in the VDWHRG model to enhance the accuracy and reliability of the model in the context of Ultra-relativistic heavy-ion physics.
↳ hep-phnucl-th3 citations
11
Diquark and chiral condensate in a self-consistent NJL-type model
Wen-Li Yuan🇨🇳 · Jingyi Chao🇨🇳 · Ang Li🇨🇳
In this work, a modified two-flavor NJL-type model is utilized, in which the contact current-current interaction is Fierz-transformed into quark-antiquark interactions and quark-quark interactions, which are directly related to the chiral condensate and diquark condensate, respectively. Under mean-field approximation, the chiral condensate and the diquark condensate are studied on the same footing. We discuss in detail the competition between the chiral condensate and the diquark condensate, which are exclusively paired with u and d quarks, while also investigating the order of the chiral phase transition through an analysis of the resulting chiral susceptibility.
↳ hep-phnucl-thPRD(2023)·14 citations
12
Coexisting single-particle excitations and octupole correlations in transitional nucleus $^{217} Ra$
Madhu · A. Y. Deo · Khamosh Yadav · Dhananjaya Sahoo · Y. Y. Wang · Y. K. Wang · J. Meng · Saket Suman · S. K. Tandel · A. Sharma · I. Ahmed · K. Katre and 6 other authors
The level structure of the transitional nucleus $^{217} Ra$ has been extended with the addition of around 20 new transitions. The discrepancies between the placements of several transitions reported in the earlier studies are resolved. The newly-established negative-parity sequence at low excitation energies hints at the expected parity-doublet structures in this nucleus. The properties of the observed simplex bands are compared with that of similar bands in neighboring nuclei. Since the presence of parity-doublet structures reflect octupole correlations, theoretical calculations using reflection-asymmetric triaxial particle rotor model (RAT-PRM) have been performed. A comparison of the observed features of the simplex bands with the predictions of the RAT-PRM calculations suggests that $^{217} Ra$ exhibits an intermediate the behavior between the extremes of spherical and octupole-deformed nuclei. The termination of the simplex bands at intermediate energies and the structures lying above reflect the dominance of the single-particle excitations at higher excitation energies.
↳ nucl-exnucl-thPRC(2023)·6 citations
13
Colour-Flavour Locked Quark Stars in Light of the Compact Object in HESS J1731-347 and the GW190814 Event
P.T. Oikonomou🇬🇷 · Ch.C. Moustakidis🇬🇷
The central compact object within HESS J1731- 347 possesses unique mass and radius properties that renders it a compelling candidate for a self-bound star. In this research, we examine the capability of quark stars composed of colour superconducting quark matter to explain the latter object by using its marginalised posterior distribution and imposing it as a constraint on the relevant parameter space. Namely, we investigate quark matter for $N_{f} = 2, 3$ in the colour superconducting phase, incorporating perturbative QCD corrections, and we derive their properties accordingly. The utilised thermodynamic potential of this work possesses an MIT bag model formalism with the parameters being established as flavour-independent. In this instance, we conclude the favour of 3-flavour over 2-flavour colour superconducting quark matter, isolating our interest on the former. The parameter space is further confined due to the additional requirement for a high maximum mass ( $M_{TOV} \geq 2.6 M_{⊙}$ ), accounting for GW $190814$ 's secondary companion. We pay a significant attention on the speed of sound and the trace anomaly (proposed as a measure of conformality [\href{https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.252702}{10.1103/PhysRevLett.129.252702}]). We conclude that it is possible for colour-flavour locked quark stars to reach high masses without violating the conformal bound or the $⟨ Θ ⟩_{μ_{B}} \geq 0$ if the quartic coefficient value $α_{4}$ does not exceed an upper limit which is solely dependent on the established $M_{TOV}$ . For $M_{TOV} = 2.6 M_{⊙}$ , we find that the limit reads $α_{4} \leq 0.594$ . Lastly, a further study takes place on the agreement of colour-flavour locked quark stars with additional astrophysical objects including the GW $170817$ and GW $190425$ events, followed by a relevant discussion.
↳ astro-ph.HEhep-phnucl-thPRD(2023)·53 citations

Affiliations

first authorsco-authorsvia INSPIRE