核理论学术速递[1.10]
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nucl-th核理论，共计8篇
【1】 Characterization of the inner edge of the neutron star crust
标题：中子星地壳内边缘的表征
链接：https://arxiv.org/abs/2201.02429
备注：11 pages, 6 figures
摘要：The poorly known crustal equation of state plays a critical role in many
observational phenomena associated with a neutron star. Using semi-classical
Monte Carlo simulations, we explore the possible configurations of the inner
edge of the neutron-star crust for a variety of baryon densities and proton
fractions. Applying the Kirkwood--Buff theory to these two-component systems,
we observe how the isothermal compressibility reaches a maximum when isolated
non-symmetric clusters are formed in an extremely dilute neutron gas. To
determine the neutron fraction, we suggest a geometrical model based on the
behavior of the proton-neutron pair correlation function. Accordingly, the
equation of state of the inner crust is calculated, illustrating that the
nuclear energy in beta-equilibrium follows a power-law behavior with baryon
density. As a possible astrophysical outcome of this study, our results could
help refine the mass-radius relation. Finally, our results pave the way towards
further investigations of the impact of the proton-neutron pair correlation
function on transport properties within the neutron-star crust.
【2】 Practical considerations for the effect of finite coverage on the azimuthal dependence of global spin alignment
标题：有限覆盖对全球自旋排列方位依赖性影响的实际考虑
链接：https://arxiv.org/abs/2201.02316
摘要：The global spin alignment of vector mesons is a powerful probe to study the
vorticity field of the system produced in non-central relativistic heavy-ion
collisions. Since the experimental observables of global spin alignment are
sensitive to many factors, proper corrections are need to be taken care of when
measuring the global spin alignment of vector mesons. In this paper, we propose
a method to correct the effect of finite pseudo-rapidity coverage when extract
the azimuthal dependence of spin alignment parameter $\rho_{00}$. The effects
of the finite pseudo-rapidity coverage on the azimuthal dependence of $\phi$
meson spin alignment and the potentially exist intrinsic spin alignment effects
are taken into consideration. The method presented in this paper is verified in
a Monte-Carlo simulation, it allows the measurements of azimuthal dependence of
global spin alignment to be conducted properly and accurately.
【3】 Information content of the differences in the charge radii of mirror nuclei
标题：镜像核电荷半径差异的信息量
链接：https://arxiv.org/abs/2201.02238
备注：6 pages, 4 figures
摘要：Differences in the charge radii of mirror nuclei have been recently suggested
to contain information on the slope of the symmetry energy L. To test this
hypothesis, we perform statistical correlation analysis using quantified energy
density functionals that are consistent with our previous knowledge on global
nuclear observables such as binding energies and charge radii. We conclude that
the difference in charge radii between a mirror pair, R_mir, is an inferior
isovector indicator compared to other observables, such at the neutron skin or
electric dipole polarizability. In particular, this quantity correlates poorly
with both the neutron skin and L. We demonstrate that R_mir is influenced by
pairing correlations in the presence of low-lying proton continuum in the
proton-rich mirror-partner nucleus. Considering the large theoretical
uncertainties on R_mir, we conclude that the precise data on mirror charge
radii cannot provide a stringent constraint on L.
【4】 Coherence dynamics in low-energy nuclear fusion
标题：低能核聚变中的相干动力学
链接：https://arxiv.org/abs/2201.02232
备注：Submitted to Physics Letters B on 5th January 2022
摘要：Low-energy nuclear fusion reactions have been described using a dynamical
coupled-channels density matrix method, based on the theory of open quantum
systems. For the first time, this has been combined with an energy projection
method, permitting the calculation of energy resolved fusion probabilities. The
results are benchmarked against calculations using stationary Schr\"odinger
dynamics and show excellent agreement. Calculations of entropy, energy
dissipation and coherence were conducted, demonstrating the capability of this
method. It is evident that the presence of quantum decoherence does not affect
fusion probability. This framework provides a basis for quantum thermodynamic
studies using thermal environments.
【5】 On the definition of local spatial densities in hadrons
标题：关于强子局域空间密度的定义
链接：https://arxiv.org/abs/2201.02565
备注：5 pages, 1 figure
摘要：We show that the matrix element of a local operator between hadronic states
gives rise to an unambiguous definition of the associated spatial density. As
an explicit example, we consider the charge density of a spinless particle in
the rest and moving frames and clarify its relationship to the electric form
factor. Our results suggest that the interpretation of the spatial densities of
local operators and their moments such as the mean square charge radius needs
to be revised.
【6】 Rethinking the ill-posedness of the spectral function reconstruction -- why is it fundamentally hard and how Artificial Neural Networks can help
标题：关于谱函数重构不适定性的再思考--为什么从根本上说是困难的以及人工神经网络是如何提供帮助的
链接：https://arxiv.org/abs/2201.02564
备注：29 pages, 6 figures
摘要：Reconstructing hadron spectral functions through Euclidean correlation
functions are of the important missions in lattice QCD calculations. However,
in a K\"allen--Lehmann(KL) spectral representation, the reconstruction is
observed to be ill-posed in practice. It is usually ascribed to the fewer
observation points compared to the number of points in the spectral function.
In this paper, by solving the eigenvalue problem of continuous KL convolution,
we show analytically that the ill-posedness of the inversion is fundamental and
it exists even for continuous correlation functions. We discussed how to
introduce regulators to alleviate the predicament, in which include the
Artificial Neural Networks(ANNs) representations recently proposed by the
Authors in [arXiv:2111.14760]. The uniqueness of solutions using ANNs
representations is manifested analytically and validated numerically.
Reconstructed spectral functions using different regularization schemes are
also demonstrated, together with their eigen-mode decomposition. We observe
that components with large eigenvalues can be reliably reconstructed by all
methods, whereas those with low eigenvalues need to be constrained by
regulators.
【7】 Chiral condensates and screening masses of neutral pseudoscalar mesons in thermomagnetic QCD medium
标题：热磁QCD介质中中性赝标介子的手征凝聚和屏蔽质量
链接：https://arxiv.org/abs/2201.02349
备注：11 pages, 9 figures
摘要：We point out that chiral condensates at nonzero temperature and magnetic
fields are in strict connection to the space-time integral of corresponding
two-point neutral meson correlation functions in the pseudoscalar channel via
the Ward-Takahashi identity. Screening masses of neutral pseudoscalar mesons,
which are defined as the exponential decay of the corresponding spatial
correlation functions in the long distance, thus are intrinsically connected to
(inverse) magnetic catalysis of chiral condensates. To study this we performed
lattice simulations of $(2+1)$-flavor QCD on $32^3\times N_t$ lattices with
pion mass $M_\pi\simeq 220$ MeV in a fixed scale approach having temperature
$T\in[17, 281]$ MeV and magnetic field strength $eB\in[0, 2.5]$ GeV$^2$. We
find that screening lengths, i.e. inverses of screening masses of $\pi^0$,
$K^0$ and $\eta^0_{s\bar{s}}$, turn out to have the similar complex $eB$ and
$T$ dependences of the corresponding chiral condensates. Although the
transition temperature is found to always decrease as $eB$ grows, we show that
the suppression due to magnetic fields becomes less significant for hadron
screening length and chiral condensates with heavier quarks involved, and
ceases to occur for $\eta^0_{s\bar{s}}$ and strange quark chiral condensate.
The complex $eB$ and $T$ dependences of both screening masses and chiral
condensates, reflecting the crossover nature of the QCD transition, are
attributed to the competition between sea and valence quark effects. These
findings could be useful to guide low-energy models and effective theories of
QCD.
【8】 Topological confinement in Skyrme holography
标题：Skyrme全息术中的拓扑约束
链接：https://arxiv.org/abs/2201.00105
备注：21 pages, 8 figures, new title, additional author
摘要：We study phase transitions in five-dimensional Einstein Gravity with a
negative cosmological constant, coupled to a Skyrme matter field. These
transitions are topological generalizations of the Hawking-Page transition
between thermal Anti de Sitter (AdS) spacetime and an AdS black hole. Phases
are characterized by a topological number associated with the Skyrme field
configuration. Depending on that topological number and on the Skyrme coupling
strength, there occur transitions between those phases at two, one, or no
value(s) of the temperature. Through the holographic (AdS/CFT) correspondence,
these solutions are dual to topologically non-trivial states in a conformal
field theory (CFT) with an SU(2)-symmetry, which support either confined or
deconfined (quasi-)particles at strong coupling. We compare to similar known
phase transitions, and discuss potential applications to confinement in
topological phases of condensed matter and the quark-gluon plasma.
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