Nuclear Theory·nucl-th

Monday·March 28, 2022

13 papers—9 primary·4 cross-listed

01
Hard probe path lengths and event-shape engineering of the quark-gluon plasma
Caitlin Beattie🇺🇸 · Govert Nijs🇺🇸 · Mike Sas🇺🇸 · Wilke van der Schee🇨🇭
As particles traverse the quark-gluon plasma (QGP) formed during a heavy ion collision they undergo energy loss depending on the distance travelled. We study several temperature- and velocity-weighted path length distributions of non-interacting particles as they traverse the plasma using the Trajectum heavy ion code, including those of back-to-back path lengths. We use event-shape engineering (ESE) in combination with in-plane versus out-of-plane selection to accurately control these path lengths. Lastly, we show how soft observables depend on the different ESE classes.
nucl-thhep-phnucl-exPLB(2023)·13 citations
02
On differences between even and odd anisotropic-flow harmonics in non-equilibrated systems
Benedikt Bachmann🇩🇪 · Nicolas Borghini🇩🇪 · Nina Feld🇩🇪 · Hendrik Roch🇩🇪
To assess how anisotropic transverse flow is created in a system out of equilibrium, we compare several kinetic-theoretical models in the few-rescatterings regime. We compare the flow harmonics $v_{n}$ from three types of transport simulations, with either $2 \to 2$ or $2 \to 0$ collision kernels and in the former case allowing the particles to rescatter several times or not, and from analytical calculations neglecting the gain term of the Boltzmann equation. We find that the even flow harmonics are similar in all approaches, while the odd ones differ significantly. This suggests that while even $v_{n}$ harmonics may to a large extent be due to the anisotropic escape probability of particles, this is not the predominant mechanism underlying the odd $v_{n}$ coefficients.
nucl-thhep-phnucl-exEPJC(2023)·10 citations
03
Comprehensive Analyses of the Neutrino-Process in the Core-collapsing Supernova
Heamin Ko🇰🇷 · Dukjae Jang🇰🇷 · Myung-Ki Cheoun🇰🇷 · Motohiko Kusakabe🇨🇳 · Hirokazu Sasaki🇯🇵 · Xingqun Yao🇨🇳 · Toshitaka Kajino🇨🇳 · Takehito Hayakawa🇯🇵 · Masaomi Ono🇯🇵 · Toshihiko Kawano🇺🇸 · Grant J. Mathews🇨🇳
We investigate the neutrino flavor change effects due to neutrino self-interaction, shock wave propagation as well as matter effect on the neutrino-process of the core-collapsing supernova (CCSN). For the hydrodynamics, we use two models: a simple thermal bomb model and a specified hydrodynamic model for SN1987A. As a pre-supernova model, we take an updated model adjusted to explain the SN1987A employing recent development of the $(n, γ)$ reaction rates for nuclei near the stability line $(A \sim 100)$ . As for the neutrino luminosity, we adopt two different models: equivalent neutrino luminosity and non-equivalent luminosity models. The latter is taken from the synthetic analyses of the CCSN simulation data which involved quantitatively the results obtained by various neutrino transport models. Relevant neutrino-induced reaction rates are calculated by a shell model for light nuclei and a quasi-particle random phase approximation model for heavy nuclei. For each model, we present abundances of the light nuclei ( $^{7}$ Li, $^{7}$ Be, $^{11}$ B and $^{11}$ C) and heavy nuclei ( $^{92}$ Nb, $^{98}$ Tc, $^{138}$ La and $^{180}$ Ta) produced by the neutrino-process. The light nuclei abundances turn out to be sensitive to the Mikheyev-Smirnov-Wolfenstein (MSW) region around O-Ne-Mg region while the heavy nuclei are mainly produced prior to the MSW region. Through the detailed analyses, we find that neutrino self-interaction becomes a key ingredient in addition to the MSW effect for understanding the neutrino-process and the relevant nuclear abundances. The normal mass hierarchy is shown to be more compatible with the meteorite data. Main nuclear reactions for each nucleus are also investigated in detail.
nucl-thastro-ph.HEastro-ph.SRhep-phApJ(2022)·20 citations
04
General Chaotic Behaviors of Heavy ion Collisions at Intermediate Energy Based on Dynamical Transport Model
Yong-Zhong Xing🇨🇳 · Wen-Xia Wang🇨🇳 · Hong-Fei Zhang🇨🇳 · Yu-Ming Zheng🇨🇳
Motivated to explore the dynamical mechanism of multi-fragmentation phase transition and expand our knowledge on the deterministic chaos in nonlinear dynamic process, we study systematically the nonlinear dynamical behaviors of heavy ion collisions at intermediate energy. In order to highlight the general characteristics of the collision dynamics, in the present paper, we simulate a simple collision system, $C a + C a$ , and obverse the performances of the typical nonlinear characteristic quantities such as the production of generalized entropy and the fractal structure of the semiclassical phase space during the reaction process. The multifragmentation entropy, information dimension and the dynamical fluctuations of fragment mass distribution in the final state of the reaction are also evaluated. Our results about the intermediate processes and the final products of the reaction are verified mutually so that confirm strongly the existence of nonlinear chaos in the heavy ion collisions at intermediate energy. Meanwhile, we find that the typical characteristics of the critical phase transition obtained in the analysis of the final production of the reaction are relatively more clear in the vicinity of the incident energies $E = 100 M e V$ .
nucl-thNPA(2022)·0 citations
05
Pairing core swelling effect in Pb isotopes at $N > 126$
W. Horiuchi · T. Inakura
We revisit a sudden increase of the isotope shift of the charge radius of Pb isotope at $N > 126$ based on a Skyrme Hartree-Fock-Bogoliubov theory. New parametrizations of the pairing interaction optimized for selected four Skyrme interactions greatly improve a description of this phenomenon. The density-dependent spin-orbit interaction is also investigated and further increases the charge radius. The pairing correlations significantly change the properties of the neutron orbits near the Fermi level and play a vital role in pulling out the well-bound protons in the Pb isotopes at $N > 126$ . Regarding $^{208}$ Pb as a "core" nucleus, a novel pairing core swelling effect is proposed: The pairing interaction reduces the radius of "valence" neutron orbits by the shrinkage of diffused $1 g_{9/2}$ orbit and the mixing of sharp $0 i_{11/2}$ orbit. Simultaneously, the core nucleus swells, leading to the sudden enhancement of the charge radius at $N > 126$ . This characteristic behavior appears in the density profile near the nuclear surface and its measurement is highly desirable.
nucl-thPRC(2022)·17 citations
06
Zero- and finite-temperature electromagnetic strength distributions in closed- and open-shell nuclei from first principles
Y. Beaujeault-Taudière🇫🇷 · M. Frosini🇫🇷 · J.-P. Ebran🇫🇷 · T. Duguet🇫🇷 · R. Roth🇩🇪 · V. Somà🇫🇷
Ab initio approaches to the nuclear many-body problem have seen their reach considerably extended over the past decade. However, collective excitations have been scarcely addressed so far due to the prohibitive cost of solving the corresponding equations of motion. Here, a numerically efficient method to compute electromagnetic response functions at zero- and finite-temperature in superfluid and deformed nuclei from an ab initio standpoint is presented and applied to $^{16}$ O, $^{28}$ Si, $^{46}$ Ti and $^{56}$ Fe. This work opens the path to systematic ab initio calculations of nuclear responses to electroweak probes across a significant portion of the nuclear chart.
nucl-thPRC(2023)·25 citations
07
Shell-model study of octupole collectivity near 208Pb
P. Van Isacker🇫🇷 · M. Rejmund🇫🇷
We show that the collectivity of the particle-hole wave function of low-lying octupole 3^- states in doubly magic nuclei is mainly due to the neutron-proton interaction. Both the enhanced reduced transition probability to the ground state, B(E3;3-_1 -> 0+_1), and the coupling of the octupole excitation to a nucleon result from the coherent action of all the components of the collective state. The results obtained with a realistic shell-model interaction both for 208Pb and 209Pb agree with the geometric collective model of Bohr and Mottelson, where octupole excitations are associated with phonons corresponding to collective shape oscillations of the surface of the nucleus.
nucl-thPRC(2025)·10 citations
08
Collective and dissipative effects in a common microscopic dynamical description
Hung Dinh Viet🇫🇷 · Paolo Napolitani🇫🇷
Depending on the energy regime, the dynamics of heavy-ion collisions reveals a variety of different mechanisms which are attributed to the combination of collective and dissipative effects. Semi-classical approaches have been successful in describing chaotic regimes at Fermi-energies but they gradually lose precision when extending to collective behaviour and in general when low-energy features become more determinant in the dynamics. To improve on this description, we propose a theoretical approach starting from the TDHF scheme. A quantum representation with a moving basis function has been worked out with a double aim. Firstly, achieving a simplified solution to handle the evolution in time. Secondly, introducing beyond-mean-field extensions and stochastic contributions. Applications to nuclear collisions at incident energies around low to Fermi energy are presented.
nucl-thNuovo Cim.C(2022)·2 citations
09
Interplay between surface and volume instabilities in heavy-ion collisions examined within mean-field extensions
P. Napolitani🇫🇷 · H. Dinh Viet🇫🇷 · M. Colonna🇮🇹
In the transition from nuclear matter to finite nuclei, complex finite-size effects which characterise open systems arise, in relation with either the nuclear surface or the bulk. In addition, the non-equilibrium character of the process, typical of violent heavy-ion collisions (from Fermi energy to the intermediate-energy domain) adds up as well. The resulting dynamics is the combination of surface and volume unstable modes which trigger large-amplitude fluctuations. A rich variety of fragmentation patterns may emerge, ranging from collimated streams of nuclear clusters to the split of a stretched nuclear complex into few large fragments. They imply different conditions of density and surface tension, and result in different chronologies. Such phenomenology has been observed in experiments, but it is often difficult to recognise and disentangle the underlying types of instabilities. To draw some example, two extremely deformed nuclear systems, produced below and above Fermi energy, are chosen and followed microscopically all along their evolution within the Boltzmann-Langevin One-Body approach.
nucl-thNuovo Cim.C(2022)·0 citations
10
Investigating saturation effects and the virtual pion in leading neutron events at HERA with the dipole model
Arjun Kumar🇮🇳 · Tobias Toll🇮🇳
We investigate events with very forward neutrons in $e p$ collisions at HERA using impact parameter dependent colour dipole models with and without saturation. This is the first study of the leading neutron process deploying these models. The model predictions are compared with the available HERA measurements for $6 < Q^{2} < 100$ ~GeV $^{2}$ , $70 < W < 245$ ~GeV. Our analysis shows that the models exhibit Feynman scaling, independent of $Q^{2}$ . Our results demonstrate that the $W$ and $Q^{2}$ dependence of the cross section is independent of the presence of a forward neutron as predicted by the limiting fragmentation hypothesis, which is a consequence of Feynman scaling itself. We infer that the HERA leading neutron production inclusive data is insensitive to saturation physics and these cross sections may not be able to distinguish gluon saturation effects in future $e p$ colliders. We provide a good description of the leading neutron structure function $F_{2}^{L N}$ at small $x$ using an assumption that the small- $x$ structure of protons and pions is universal up to a normalisation. We also show that the observables in the exclusive diffractive measurements with a vector meson in the final state are more sensitive to saturation physics at small $x$ than inclusive measurements. At last, we provide a prediction for the $t^$ spectrum in exclusive vector meson production in the dipole model using Yukawa theory to model the virtual pion's spatial wave function.
↳ hep-phnucl-thPRD(2022)·7 citations
11
$cos 2 ϕ_{t}$ azimuthal asymmetry in back-to-back $J / ψ$ -jet production in $e p \to e J / ψ J e t X$ at the EIC
Raj Kishore🇮🇳 · Asmita Mukherjee🇮🇳 · Amol Pawar🇮🇳 · Mariyah Siddiqah🇮🇳
In this article, we investigate the $cos 2 ϕ_{t}$ azimuthal asymmetry in $e p \to e J / ψ J e t X$ , where the $J / ψ$ -jet pair is almost back-to-back in the transverse plane, within the framework of the generalized parton model(GPM). We use non-relativistic QCD(NRQCD) to calculate the $J / ψ$ production amplitude and incorporate both color singlet(CS) and color octet(CO) contributions to the asymmetry. We estimate the asymmetry using different parameterizations of the gluon TMDs in the kinematics that can be accessed at the future electron-ion collider (EIC) and also investigate the impact of transverse momentum dependent (TMD) evolution on the asymmetry. We present the contributions coming from different states to the asymmetry in NRQCD.
↳ hep-phnucl-thPRD(2022)·13 citations
12
NLO JIMWLK evolution with massive quarks
Lin Dai🇮🇱 · Michael Lublinsky🇮🇱
NLO evolution of the Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner (JIMWLK) equation with massless quarks was derived a few years ago. We make a step further to compute the evolution kernels focusing on the effects due to finite quark masses. To this goal, the light-cone wave function of a fast moving dilute hadronic projectile is computed up to $O (g^{3})$ in QCD coupling constant. Compared with the massless case, a new IR divergence emerges, which is eventually canceled by a mass dependent counter term. Our results extend the theoretical tools used in physics of gluon saturation and aim at improving precision in future phenomenological applications.
↳ hep-phhep-thnucl-thJHEP(2022)·11 citations
13
Femtoscopic study on $D D^{*}$ and $D D ˉ^{*}$ interactions for $T_{cc}$ and $X (3872)$
Yuki Kamiya🇩🇪 · Tetsuo Hyodo🇯🇵 · Akira Ohnishi🇯🇵
We investigate $D D^{*}$ and $D D ˉ^{*}$ momentum correlations in high-energy collisions to elucidate the nature of $T_{cc}$ and $X (3872)$ exotic hadrons. Single range Gaussian potentials with the channel couplings to the isospin partners are constructed based on the empirical data. The momentum correlation functions of the $D^{0} D^{*+}$ , $D^{+} D^{* 0}$ , $D^{0} D ˉ^{* 0}$ , and $D^{+} D^{*-}$ pairs are computed with including the coupled-channel effects. We discuss how the nature of the exotic states are reflected in the behaviors of the correlation results.
↳ hep-phnucl-thEPJA(2022)·67 citations

Affiliations

first authorsco-authorsvia INSPIRE