Nuclear Theory·nucl-th

Tuesday·September 26, 2023

10 papers—6 primary·4 cross-listed

01
Why is $Pb^{208}$ the heaviest stable nuclide?
B. P. Kosyakov🇷🇺 · E. Yu. Popov🇷🇺 · M. A. Vronsky🇷🇺
In an effort to understand nuclei in terms of quarks we develop an effective theory to low-energy quantum chromodynamics in which a single quark contained in a nucleus is driven by a mean field due to other constituents of the nucleus. We analyze the reason why the number of $d$ quarks in light stable nuclei is much the same as that of $u$ quarks, while for heavier nuclei beginning with $Ca^{40}$ , the number of $d$ quarks is greater than the number of $u$ quarks. To account for the finiteness of the periodic table, we invoke a version of gauge/gravity duality between the dynamical affair in stable nuclei and that in extremal black holes. With the assumption that the end of stability for heavy nuclei is dual to the occurrence of a naked singularity, we find that the maximal number of protons in stable nuclei is $Z_{m a x}^{H} \approx 82$ .
nucl-thhep-phEPJC(2024)·3 citations
02
What can we learn from recent $2 ν β β$ experiments?
Dong-Liang Fang🇨🇳
With recent measurements of the two neutrino double beta decay high precision electron spectra, combining with charge exchange or $β$ -decay experimental data, we give severe constraints over the current nuclear many body calculations. Our calculation shows that QRPA approach can well reproduce the measured spectra for the two open shell nuclei, $^{82}$ Se and $^{100}$ Mo. For the closed shell nucleus $^{136}$ Xe, QRPA can also reproduce the spectra with proper treatments. We also find that considering the high-lying state reduction, Nuclear Shell Model can also well reproduce the spectra as well as B(GT) strength under a unique quenched $g_{A}$ . For $^{136}$ Xe, we find that the flip of the sign for the decay strength will lead the spectra to go beyond HSD. These results call for future high precision measurement of charge-exchange reaction.
nucl-thnucl-exCPC(2024)·2 citations
03
Strangelets formation in high energy heavy-ion collisions
Huai-Min Chen🇨🇳 · Cheng-Jun Xia🇨🇳 · Guang-Xiong Peng🇨🇳
The properties of phase diagram of strange quark matter in equilibrium with hadronic matter at finite temperature are studied, where the quark phase and hadron phase are treated by baryon density-dependent quark mass model and hadron resonance gas model with hard core repulsion factor, respectively. The thermodynamic conditions for the formation of metastable strange quark droplets ("strangelets") in relativistic nuclear collisions are discussed. We obtained a rich structure of the phase diagram at finite temperature, and study the dynamical trajectories of an expanding strange fireball. Our results indicate that the strangeness fraction fs, perturbation parameter C, and confinement parameter D have strong influence on the properties of phase diagram and the formation of strangelets. Consider the isentropic expansion process, we found that the initial entropy per baryon is less than or equal to 5, which gives a large probability for the formation of strangelets. Furthermore, a sufficiently large strangeness fraction fs and one-gluon-exchange interaction and sufficiently small confinement interaction create possibilities for the formation of strangelets. On the contrary, the fireball will always complete the hadronization process when fs=0 or C>=0 or D^{1/2}>=170 MeV.
nucl-thhep-phPRD(2024)·8 citations
04
Hybrid Strangeon Stars
Chen Zhang🇨🇳 · Yong Gao🇨🇳 · Cheng-Jun Xia🇨🇳 · Renxin Xu🇨🇳
It was conjectured that the basic units of the ground state of bulk strong matter may be strange-clusters called strangeons, and they can form self-bound strangeon stars that are highly compact. Strangeon stars can develop a strange quark matter (SQM) core at high densities, particularly in the color-flavor-locking phase, yielding a branch of hybrid strangeon stars. We explore the stellar structure and astrophysical implications of hybrid strangeon stars. We find that hybrid strangeon stars can meet various astrophysical constraints on pulsar masses, radii, and tidal deformabilities. Finally, we show that the strangeon-SQM mixed phase is not preferred if the charge-neutrality condition is imposed at the strangeon-SQM transition region.
nucl-thastro-ph.HEgr-qchep-phPRD(2023)·19 citations
05
Emergence of hydrodynamics in expanding relativistic plasmas
Jean-Paul Blaizot🇫🇷
I consider a simple set of equations that govern the expansion of boost-invariant plasmas of massless particles. These equations describe the transition from a collisionless regime at early time to hydrodynamics at late time. Their mathematical structure encompasses all versions of second order hydrodynamics. We emphasize that the apparent success of Israel-Stewart hydrodynamics at early time has little to do with ``hydrodynamics'' proper, but rather with a particular feature of Israel-Stewart equations that allows them to effectively mimic the collisionless regime.
nucl-th1 citation
06
Examining the influence of hadronic interactions on the directed flow of identified particles in RHIC Beam Energy Scan energies using UrQMD model
Aswini Kumar Sahoo🇮🇳 · Prabhupada Dixit🇮🇳 · Md Nasim🇮🇳 · Subhash Singha🇨🇳
The directed flow of identified particles can serve as a sensitive tool for investigating the interactions during initial and final states in heavy ion collisions. This study examines the rapidity-odd directed flow ( $v_{1}$ ) and its slope ( $d v_{1} / d y$ ) for $π^{\pm}$ , $K^{\pm}$ , p, and $p ˉ$ in Au+Au collisions at different collision centralities and beam energies ( $s_{N N}$ = 7.7, 11.5, 14.5, 19.6, 27, and 39 GeV) using the UrQMD model. We investigate the impact of late-stage hadronic interactions on charge dependent $v_{1} (y)$ and its slope by modifying the duration of the hadronic cascade lifetime ( $τ$ ). The energy dependence of $d v_{1} / d y$ for p ( $p ˉ$ ) exhibits distinct pattern compared to $π^{\pm}$ and $K^{\pm}$ . Notably, we observe a change in the sign reversal position of proton $d v_{1} / d y$ at different beam energies with varying $τ$ in central and mid-central collisions. Moreover, the difference in $d v_{1} / d y$ between positively and negatively charged hadrons ( $Δ d v_{1} / d y$ ) demonstrates a stark centrality dependence for different particle species. The deuteron displays a significant increase in $d v_{1} / d y$ with increasing $τ$ compared to p and n. This investigation underscores the importance of considering the temporal evolution and duration of the hadronic phase when interpreting the sign reversal, charge splitting of $v_{1}$ and light nuclei formation at lower RHIC energies.
nucl-thnucl-exMod.Phys.Lett.A(2024)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Why is Pb208 the heaviest stable nuclide?

What can we learn from recent 2νββ experiments?

Strangelets formation in high energy heavy-ion collisions

Hybrid Strangeon Stars

Emergence of hydrodynamics in expanding relativistic plasmas

Examining the influence of hadronic interactions on the directed flow of identified particles in RHIC Beam Energy Scan energies using UrQMD model

Affiliations

Why is $Pb^{208}$ the heaviest stable nuclide?

What can we learn from recent $2 ν β β$ experiments?