Nuclear Theory·nucl-th

Tuesday·August 23, 2022

11 papers—8 primary·3 cross-listed

01
Application of the cranking method to the semimicroscopic algebraic cluster model and nuclear molecules
David Stefan Lohr-Robles · Giovani Erick Morales-Hernández · Enrique Lopez-Moreno · Peter Otto Hess
A particular quantum phase transition (QPT) is studied at excited energies of light nuclei within the Semimicroscopic Algebraic Cluster Model (SACM), using a combination of catastrophe theory and a direct minimization of the potential. A distinct change from a compact nucleus to a nuclear molecule is described as a second order QPT occurring at a certain value of angular momentum. This finding is in accordance with experimental observations when nuclear molecules appear. The method has implication in the fission of heavy nuclei.
nucl-thNPA(2023)·1 citation
02
Determination of asymptotic normalization coefficients for the channel $^{16}$ O $\to α +^{12}$ C. Excited state $^{16}$ O( $0^{+}; 6.05$ MeV)
L. D. Blokhintsev · A. S. Kadyrov · A. M. Mukhamedzhanov · D. A. Savin
Asymptotic normalization coefficients (ANC) determine the overall normalization of cross sections of peripheral radiative capture reactions. In the present paper, we treat the ANC $C$ for the virtual decay $^{16}$ O $(0^{+}; 6.05$ MeV) $\to α +^{12}$ C(g.s.), the known values of which are characterized by a large spread $(0.29 - 1.65) \times 1 0^{3}$ fm $^{- 1/2}$ . The ANC $C$ is found by analytic continuation in the energy of the $α^{12}$ C $s$ -wave scattering amplitude, known from the phase-shift analysis of experimental data, to the pole corresponding to the $^{16}$ O bound state and lying in the unphysical region of negative energies. To determine $C$ , two different methods of analytic continuation are used. In the first method, the scattering data are approximated by the sum of polynomials in energy in the physical region and then extrapolated to the pole. The best way of extrapolation is chosen on the basis of the exactly solvable model. Within the second approach, the ANC $C$ is found by solving the Schrödinger equation for the two-body $α^{12}$ C potential, the parameters of which are selected from the requirement of the best description of the phase-shift analysis data at a fixed experimental binding energy of $^{16}$ O $(0^{+}; 6.05$ MeV) in the $α +^{12}$ C channel. The values of the ANC $C$ obtained within these two methods lie in the interval (886--1139) fm $^{- 1/2}$ .
nucl-thastro-ph.SRnucl-exEPJA(2022)·9 citations
03
Hadro-chemistry effects on charm decayed leptons in heavy-ion collisions
Kai Lu🇨🇳 · Min He🇨🇳
Charm-hadrons possess versatile hadro-chemistry as characterized by various transverse-momentum-dependent ratios between their different species. In particular, the charm hadro-chemistry may be modified in relativistic heavy-ion collisions with respect to proton-proton collisions at the same energy, as caused by novel diffusion and hadronization mechanisms of charm quarks in the environment of the created quark-gluon plasma (QGP) in the former. Inspired by recent measurements of leptons from charm-hadron decays (separated from bottom decays) in Pb-Pb and Au-Au collisions, we investigate the effects of the charm hadro-chemistry on the leptonic observables. We find that full consideration of charm hadro-chemistry in both proton-proton and heavy-ion collisions causes only mild change of charm-leptons' suppression factor with respect to previous calculations hadronizing charm quarks into $D$ mesons only, whereas the resulting change (increase) in the charm-leptons' elliptic flow turns out to be more pronounced as a consequence of the larger collectivity of $Λ_{c}$ baryons than $D$ mesons.
nucl-thhep-phnucl-exPRC(2022)·0 citations
04
Local equilibrium and Lambda polarization in high energy heavy ion collisions
Andrea Palermo🇮🇹 · Francesco Becattini🇮🇹 · Matteo Buzzegoli🇺🇸 · Gabriele Inghirami🇩🇪 · Iurii Karpenko🇨🇿
The polarization of the $Λ$ hyperon has become an important probe of the Quark-Gluon Plasma produced in relativistic heavy-ion collisions. Recently, it has been found that polarization receives a substantial contribution from a local equilibrium term proportional to the symmetric derivative of the four-temperature vector, the thermal shear tensor. We show that, at very high energies, this term can restore the agreement between the experimental measurements and the predictions of the hydrodynamic model, provided that the hadronization hypersurface is isothermal. We review the theoretical derivation of this new term, discuss numerical computations at RHIC and LHC energies, and compare them with the experimental data. We also present the effect of feed-down corrections.
nucl-thEPJ Web Conf.(2023)·11 citations
05
Bottomonium sequential suppression and strong heavy-quark potential in heavy-ion collisions
Liuyuan Wen🇨🇳 · Baoyi Chen🇨🇳
We employ the time-dependent Schrödinger equation with different complex potentials to study the bottomonium sequential suppression in Pb-Pb collisions at $s_{N N} = 2.76$ TeV and 5.02 TeV and Au-Au collisions at $s_{N N} = 200$ GeV. Both color screening effect and the random scatterings with thermal partons are considered in the real and imaginary parts of the heavy-quark potentials. As the real part of the heavy-quark potential is between the free energy $F (T, r)$ and the internal energy $U (T, r)$ of heavy quarkonium, we parametrize different potentials with a function of $F$ and $U$ to evolve the bottomonium wave packages in the medium. We find that when the real part of the potential is close to $U (T, r)$ , it can explain well the pattern of bottomonium sequential suppression where their nuclear modification factors satisfy the relation $R_{AA} (1 s) > R_{AA} (2 s) > R_{AA} (3 s)$ observed in experiments. In the other limit of $F (T, r)$ , bottomonium wave packages tend to expand due to weak attracted force, which results in evident transitions from $Υ (2 s)$ to $Υ (3 s)$ components and does not satisfy the sequential suppression pattern. We suggest that the bottomonium sequential suppression can be a probe of strong heavy-quark potential in the medium.
nucl-thPLB(2023)·19 citations
06
Models for Pairing Phenomena
Xiang-Xiang Sun · Shan-Gui Zhou
Pairing effects manifests themselves in many aspects in nuclear systems ranging from finite nuclei to nuclear matter and compact stars. Although with some specific features for nuclear systems, the mechanism of pairing between nucleons in these systems resembles that of electrons in superconductors. The Bardeen-Cooper-Schrieffer (BCS) theory, the first successful and microscopic theory for superconductivity, and the Bogoliubov transformation, the generalization of the BCS theory, have been widely used to describe pairing correlations in nuclear systems. To deal with the problem of particle number non-conservation in the BCS method and generalized Bogoliubov transformation, particle number projection techniques as well as several approaches which keep the particle number conserved, have been proposed. In the study of exotic nuclei, which are quantum open systems, the continuum contributions have to be taken into account. In this chapter, a thorough but brief discussion of pairing effects in nuclear systems will be introduced. Then nuclear models dealing with pairing correlations in nuclear structure properties will be presented to different extent of details. Although formulas are given, the emphasis is mainly put on the basic ideas concerning these models.
nucl-thIn: Tanihata, I., Toki, H., Kajino, T. (e…·0 citations
07
Analysis of the interaction between $ϕ$ meson and nucleus
Xiao-Yun Wang🇨🇳 · Chen Dong🇨🇳 · Quanjin Wang🇨🇳
In this work, we systematically study the $ϕ$ meson and nucleus interaction by analyzing and fitting the cross sections of $γ N$ $\to ϕ$ $N$ ( $N$ represent the nucleus) reactions near the threshold. With the help of vector meson dominant model, the distribution of $ϕ$ - $N$ scattering length as a function of energy is presented, and the results show that there is a slight increase in scattering length with increasing energy. Based on this, the average scattering length of $ϕ$ -proton is obtained as $0.10 \pm 0.01$ fm by combining experimental data and theoretical models. Moreover, the average scattering length of $ϕ$ -deuteron interaction is derived to be $0.014 \pm 0.002$ fm for the first time. Further, the effect of the momentum transfer $∣ t_{min} ∣$ on the $ϕ$ - $N$ scattering length at the threshold is discussed. The obtained results not only provide important theoretical information for a more comprehensive and accurate study of the $ϕ$ - $N$ scattering length, but also provide a basis for future experimental measurements of $ϕ$ meson production.
nucl-thhep-phCPC(2023)·9 citations
08
High-order isospin-dependent surface tension contribution to the fourth-order symmetry energy of finite nuclei
Bao-Jun Cai · Rui Wang · Zhen Zhang · Lie-Wen Chen
The relation between the fourth-order symmetry energy $E_{sym, 4} (ρ_{0})$ of nuclear matter at saturation density $ρ_{0}$ and its counterpart $a_{sym, 4} (A)$ of finite nuclei in a semiempirical nuclear mass formula is revisited by considering the high-order isospin-dependent surface tension contribution to the latter. We derive the full expression of $a_{sym, 4} (A)$ , which includes explicitly the high-order isospin-dependent surface tension effects, and find that the value of $E_{sym, 4} (ρ_{0})$ cannot be extracted from the measured $a_{sym, 4} (A)$ before the high-order surface tension is well constrained. Our results imply that a large $a_{sym, 4} (A)$ value of several MeVs obtained from analyzing nuclear masses can nicely agree with the empirical constraint of $E_{sym, 4} (ρ_{0}) ≲ 2$ MeV from mean-field models and does not necessarily lead to a large $E_{sym, 4} (ρ_{0})$ value of $\approx 20$ MeV obtained previously without considering the high-order surface tension. Furthermore, we also give the expression for the sixth-order symmetry energy $a_{sym, 6} (A)$ of finite nuclei, which involves more nuclear matter bulk parameters and the higher-order isospin-dependent surface tension.
nucl-thastro-ph.HEnucl-exPRC(2022)·4 citations
09
Electromagnetic probes of the Quark-Gluon Plasma
Gojko Vujanovic🇺🇸
The penetrating nature of electromagnetic probes makes them an ideal candidate to study properties of the Quark-Gluon Plasma (QGP). A selection of recent developments in the theory and phenomenology of electromagnetic probes is discussed, with an emphasis given towards how these probes can be used to constrain QGP trapnsport coefficients. A Bayesian treatment of electromagnetic radiation, similar to the one of soft hadronic observables and jets, is suggested as a path towards imposing more stringent constraints on various transport coefficients of the QCD medium.
↳ hep-phnucl-exnucl-thActa Phys.Polon.Supp.(2023)·2 citations
10
Medium effects for hadron-tagged jets in proton-proton collisions
B.G. Zakharov
We study the medium modification factor $I_{pp}$ within the light-cone path integral approach to induced gluon emission. We use parametrization of the running coupling $α_{s} (Q, T)$ which has a plateau around $Q \sim κ T$ . We calculate $I_{pp}$ with no free parameters using $κ$ fitted to the LHC data on the nuclear modification factor $R_{AA}$ . We find that the theoretical multiplicity dependence of the ratio $I_{pp} / ⟨ I_{pp} ⟩$ for $5.02$ TeV $pp$ collisions agrees reasonably with the recent preliminary data from ALICE [1].
↳ hep-phnucl-thPisma Zh.Eksp.Teor.Fiz.(2022)·6 citations
11
Recent Progress in Two-proton Radioactivity
L. Zhou · S. M. Wang · D. Q. Fang · Y. G. Ma
During the last few decades, rare isotope beam facilities have provided unique data for studying the properties of nuclides located far from the beta-stability line. Such nuclei are often accompanied by exotic structures and radioactive modes, which represent the forefront of nuclear research. Among them, two-proton (2p) radioactivity is a rare decay mode found in a few highly proton-rich isotopes. The 2p decay lifetimes and properties of emitted protons hold invaluable information regarding the nuclear structures in the presence of a low-lying proton continuum; as such, they have attracted considerable research attention. In this review, we present some of the recent experimental and theoretical progress regarding the 2p decay, including technical innovations for measuring nucleon--nucleon correlations and developments in the models that connect their structural aspects with their decay properties. This impressive progress should play a significant role in elucidating the mechanism of these exotic decays, probing the corresponding components inside nuclei, and providing deep insights into the open quantum nature of dripline systems.
↳ nucl-exnucl-thNucl.Sci.Tech.(2022)·57 citations

Affiliations

first authorsco-authorsvia INSPIRE