Nuclear Theory·nucl-th

Tuesday·August 27, 2024

11 papers—6 primary·5 cross-listed

01
Bound states of $_{ϕ}^{9}$ Be and $_{ϕϕ}^{6}$ He nuclei with $ϕ$ + $α$ + $α$ and $ϕ$ + $ϕ$ + $α$ cluster models
Igor Filikhin🇺🇸 · Roman Ya. Kezerashvili🇺🇸 · Branislav Vlahovic🇺🇸
We investigate the $_{ϕ}^{9}$ Be and $_{ϕϕ}^{6}$ He $ϕ$ mesic nuclei within the framework of the three-body cluster model as the $ϕ$ + $α$ + $α$ and $ϕ$ + $ϕ$ + $α$ systems, using the Faddeev formalism in configuration space. The $ϕ$ - $α$ potential is determined through a folding procedure of the HAL QCD $ϕ$ - $N$ interaction in the $^{4} S_{3/2}$ channel with the matter distribution of $^{4}$ He. The phenomenological $α$ - $α$ and $ϕ$ - $ϕ$ potentials are taken from the literature. Additionally, we construct a Wood-Saxon (WS) type interaction to simulate the $ϕ$ - $α$ potential, also taken from the literature, based on an effective Lagrangian approach that includes $K K ˉ$ meson loops in the $ϕ$ -meson self-energy. A comparison of binding energies obtained for both types of the $ϕ$ - $α$ interactions reveals qualitative agreement. %between the obtained approaches. We predict the binding energy for the $_{ϕ}^{9}$ Be and $_{ϕϕ}^{6}$ He $ϕ$ mesic nuclei as the mirror $ϕ$ + $α$ + $α$ and $ϕ$ + $ϕ$ + $α$ systems in the range of 1-11 MeV and 3-10 MeV, respectively. The range of values of the binding energies relies on the choice of the WS $ϕ$ - $α$ interaction parameters.
nucl-thPRC(2024)·12 citations
02
Evaluation of fission fragment moments of inertia for spontaneous fission of Cf-252
D.E. Lyubashevsky · P.V. Kostryukov · A.A. Pisklyukov · J.D. Shcherbina
Current work discusses methods for estimating the moments of inertia of fission fragments for spontaneous fission of the isotope Cf-252, in particular, two main approaches are mentioned: statistical and microscopic. In addition, the methods of the classical and superfluid approaches to the calculation of the moments of inertia are discussed, as well as their application to different models of nuclei. Within this framework, the influence of different oscillation modes and nucleon exchange on the moments of inertia and spin distributions of fission fragments is evaluated. The authors emphasizes the need for a comparative analysis of theoretical predictions with experimental data for a deeper understanding of the internal structure of nuclei and fission mechanisms.
nucl-thCPC(2025)·2 citations
03
Bubble $^{36}$ Ar and Its New Breathing Modes
Ge Ren · Chun-Wang Ma · Xi-Guang Cao · Yu-Gang Ma
The bubble nuclei are important components of exotic nuclear structures characterized by special depletions of central densities. Focusing on bubble structures of $^{36}$ Ar, the characterizations of bubble nuclei were explored with the framework of the extended quantum molecular dynamics model. Three density distribution modes were uncovered for the first time, i.e. micro-bubble, bubble, and cluster resonances, which show unique spectral signature compared to the monopole resonance spectrum as the excitation intensity was increased in bubbles. Of pivotal importance is the revelation that the bubble mode's oscillation frequency closely resembles macroscopic bubble dynamics, building a connection between classical macroscopic phenomena and the quantum complexity of the nuclear structure. The discovery marks a crucial step forward in deciphering the relationship between classical and quantum domains within the enigmatic world of atomic nuclei.
nucl-thPLB(2024)·6 citations
04
Convergence of the hydrodynamic gradient expansion in relativistic kinetic theory
Lorenzo Gavassino
We rigorously prove that, in any relativistic kinetic theory whose non-hydrodynamic sector has a finite gap, the Taylor series of all hydrodynamic dispersion relations has a finite radius of convergence. Furthermore, we prove that, for shear waves, such radius of convergence cannot be smaller than $1/2$ times the gap size. Finally, we prove that the non-hydrodynamic sector is gapped whenever the total scattering cross-section (expressed as a function of the energy) is bounded below by a positive non-zero constant. These results, combined with well-established covariant stability criteria, allow us to derive a rigorous upper bound on the shear viscosity of relativistic dilute gases.
nucl-thastro-ph.HEhep-thPRD(2024)·11 citations
05
Analysis of flow factorization and event-plane correlations based on a maximum likelihood estimator
Chong Ye🇨🇳 · Cesar A. Bernardes🇧🇷 · Wei-Liang Qian🇨🇳 · Sandra S. Padula🇧🇷 · Rui-Hong Yue🇨🇳 · Yogiro Hama🇧🇷 · Takeshi Kodama🇧🇷
In this study, we use the maximum likelihood estimator (MLE) to explore factorization and event-plane correlations in relativistic heavy-ion collisions. Our analyses incorporate both numerical simulations and publicly available data from the CMS Collaboration. We focus on Au+Au collisions at 200 GeV and Pb+Pb collisions at 2.76 TeV. The differential flows obtained for various centrality windows and momentum cuts are consistent with conventional methodologies such as multi-particle cumulants and event-plane methods. Leveraging these findings, we proceed to undertake further analysis of flow factorization and event-plane correlations. These quantities are relevant because of their sensitivity to initial-state fluctuations. While higher-order correlators might provide different implementations of factorization ratio, the MLE estimator is readily applied to these scenarios. Moreover, MLE's unique capabilities allow us to compute specific correlators that are typically inaccessible by other means. As an asymptotically normal and unbiased estimator, MLE provides a valuable alternative tool for flow and correlation analysis.
nucl-th3 citations
06
Collisional and radiative energy loss in small systems
Coleridge Faraday🇿🇦 · W. A. Horowitz🇿🇦
We present an energy loss model which includes small system size corrections to both the radiative and elastic energy loss. Our model is used to compute the nuclear modification factor $R_{A B}$ of light and heavy flavor hadrons, averaged over realistic collision geometries for central and peripheral $A + A$ and central $p / d /^{3} He + A$ collisions at LHC and RHIC. We find that the predicted suppression in small systems is almost entirely due to elastic energy loss. Our results are keenly sensitive to the crossover between elastic energy loss calculated with hard thermal loop propagators and vacuum propagators, respectively, which leads to a large theoretical uncertainty. We find that the $R_{A B}$ is largely insensitive to the form of the elastic energy loss distribution - Gaussian or Poisson - surprisingly so in small systems where the central limit theorem is inapplicable. We present an expansion of the $R_{A B}$ in terms of the moments of the energy loss probability distribution, which allows for a rigorous understanding of the dependence of the $R_{A B}$ on the underlying energy loss distribution.
nucl-thhep-phPRC(2025)·11 citations
07
Neutral pion polarizabilities from four-point functions in lattice QCD
Frank X. Lee🇺🇸 · Walter Wilcox🇺🇸 · Andrei Alexandru🇺🇸 · Chris Culver🇬🇧 · Shayan Nadeem🇺🇸
We report a proof-of-principle lattice QCD simulation of the electric and magnetic polarizabilities for a neutral pion in the four-point function method. The results are based on the same quenched Wilson ensembles on a $2 4^{3} \times 48$ lattice at $β = 6.0$ with pion mass from 1100 to 370 MeV previously used for a charged pion. For electric polarizability, the results are largely consistent with those from the background field method and ChPT. In contrast, there are significant differences for magnetic polarizability among the four-point function method, the background field method, and ChPT. The situation points to the potentially important role of disconnected diagrams for a neutral pion. We elucidate a transparent quark decomposition in the four-point function method that can be used to shed light on the issue.
↳ hep-lathep-phnucl-thNPB(2024)·5 citations
08
The effect of vorticity on the dynamical magnetic fields in heavy-ion collisions
Anping Huang🇨🇳 · Xiang-Yu Wu🇨🇦 · Mei Huang🇨🇳
Magnetic fields in heavy-ion collisions are pivotal and subject to diverse factors. In this study, we quantitatively investigate the impact of fluid vorticity on the evolution of magnetic fields in the 20-50\% centrality class in Au+Au collisions, with collision energies of $s_{N N} = (7.7, 14.5, 19.6, 27, 39, 62.4, 200)$ GeV. Our results indicate that fluid vorticity leads to a delay in the evolution of the magnetic field, in which this effect becomes more pronounced as the collision energy decreases. Additionally, we have calculated the mean magnetic field values on the freeze-out hypersurface for various collision energies. Our simulation results align with the values inferred from experimental data of $Λ ˉ - Λ$ , within the error margins.
↳ hep-phhep-thnucl-thPRD(2024)·6 citations
09
Cosmology and nuclear-physics implications of a subsolar gravitational-wave event
Francesco Crescimbeni🇮🇹 · Gabriele Franciolini🇨🇭 · Paolo Pani🇮🇹 · Massimo Vaglio🇮🇹
Detecting a compact subsolar object would have profound implications in physics, the reach of which depends on the nature of the object. Here we explore such consequences for a putative subsolar-mass gravitational wave event detected by the LIGO-Virgo-KAGRA Collaboration. We forecast that the nature of a subsolar binary (made of light neutron stars, primordial black holes, or more exotic compact objects) can be inferred with a great statistical confidence level already during the ongoing fourth observing run, based on the large tidal deformability effects on the signal. The detection of a primordial black hole would have implications for cosmology and dark matter scenarios, while the measurement of the tidal deformability of a subsolar neutron star could rule out or confirm the existence of strange stars made of quarks.
↳ astro-ph.HEgr-qchep-phnucl-thPRD(2025)·19 citations
10
Relativistic spin hydrodynamics with momentum and spin-dependent relaxation time
Samapan Bhadury🇵🇱
Using the extended relaxation time approximation (ERTA) along with the theory of semi-classical spin, we develop a framework of relativistic dissipative spin hydrodynamics such that the relaxation time can depend on the momenta and spin of the constituent spin-1/2 particles. We also consider a general definition of the fluid four-velocity allowing the theory to be valid in a general frame and matching conditions. Consequently, we construct the frame-invariant bulk, shear, particle diffusion, and spin transport coefficients, showing that the evolution of fluid remains unaffected by spin in the limit of small polarization as was the case where the relaxation time was independent of spin or momentum.
↳ hep-phhep-thnucl-thPRC(2025)·18 citations
11
Unitary Designs from Random Symmetric Quantum Circuits
Hanqing Liu🇺🇸 · Austin Hulse🇺🇸 · Iman Marvian🇺🇸
In this work, we study distributions of unitaries generated by random quantum circuits containing only symmetry-respecting gates. We develop a unified approach applicable to all symmetry groups and obtain an equation that determines the exact design properties of such distributions. It has been recently shown that the locality of gates imposes various constraints on realizable unitaries, which in general, significantly depend on the symmetry under consideration. These constraints typically include restrictions on the relative phases between sectors with inequivalent irreducible representations of the symmetry. We call a set of symmetric gates semi-universal if they realize all unitaries that respect the symmetry, up to such restrictions. For instance, while 2-qubit gates are semi-universal for $Z_{2}$ , U(1), and SU(2) symmetries in qubit systems, SU(d) symmetry with $d \geq 3$ requires 3-qudit gates for semi-universality. Failure of semi-universality precludes the distribution generated by the random circuits from being even a 2-design for the Haar distribution over symmetry-respecting unitaries. On the other hand, when semi-universality holds, under mild conditions, satisfied by U(1) and SU(2) for example, the distribution becomes a $t$ -design for $t$ growing polynomially with the number of qudits, where the degree is determined by the locality of gates. More generally, we present a simple linear equation that determines the maximum integer $t_{m a x}$ for which the uniform distribution of unitaries generated by the circuits is a $t$ -design for all $t \leq t_{m a x}$ . Notably, for U(1), SU(2) and cyclic groups, we determine the exact value of $t_{m a x}$ as a function of the number of qubits and locality of the gates, and for SU(d), we determine the exact value of $t_{m a x}$ for up to $4$ -qudit gates.
↳ quant-phcond-mat.stat-mechhep-thmath-ph+218 citations

Affiliations

first authorsco-authorsvia INSPIRE