Nuclear Theory·nucl-th

Friday·August 14, 2026

8 papers—3 primary·5 cross-listed

01
[Submitted on 13 Aug 2026]
Relativistic dynamical effects in proton emission: the Wentzel-Kramers-Brillouin method for 1+1 dimensional Dirac equation
Guangping Chen · Wenmin Deng · Ganlong Ding · Sibo Wang · Jing Peng · Haozhao Liang
Starting from the $1 + 1$ dimensional (one spatial and one temporal dimension) Dirac equation, we employ the Wentzel-Kramers-Brillouin (WKB) approximation to derive the corresponding relativistic penetration probability. The derivation shows that the semiclassical momentum is determined by the Schrödinger-equivalent potential $U_{eff} (r) = S (r) + \frac{E}{m} V (r) + \frac{S ^{2} ( r ) - V ^{2} ( r )}{2 m}$ , instead of the simple sum of scalar and vector potentials $S (r) + V (r)$ , which has been adopted widely in the studies of relativistic quantum tunneling. We then quantify the relativistic dynamical effects in proton emission by comparing the results obtained with $U_{eff} (r)$ and those obtained with $S (r) + V (r)$ . Incorporating $U_{eff} (r)$ systematically reduces the penetration probability and the assault frequency, and consequently increases the predicted half-life. The relativistic dynamical effect becomes more pronounced with higher orbital angular momentum and can reach about $84%$ in the half-life of $^{144} Tm$ .
Comments:
19 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2608.12767 [pdf]
0 citations
02
[Submitted on 13 Aug 2026]
Parametric Matrix Models for Emulation in Nuclear and Many-Body Physics
Patrick Cook
Progress in nuclear and many-body physics today is predicated on the ability to solve large-scale, strongly correlated quantum many-body problems. As the theoretical models become more sophisticated, they also become more computationally complex. Simultaneously, quantifying uncertainty in model predictions and fitting free parameters to experimental observations requires repeated evaluation of these expensive models. Surrogate models---known as emulators---provide the means of accomplishing these goals. This thesis provides an introduction into the current state of emulation in nuclear and many-body physics. The motivations, goals, and origins of currently popular emulation methods are discussed along with selected examples. We see how many methods are closely mathematically related and how trade-offs are made to optimize specific properties or applications. The central work in this thesis is the method of parametric matrix models (PMMs), an emulation and general machine learning framework which combines aspects of traditional reduced basis method with modern parametric machine learning. PMMs are able to retain as much or as little physical information about the underlying system as desired, yielding not only excellent performance but also nearly unparalleled adaptability, interpretability, and trustworthiness as an emulation method. A formal mathematical framework for PMMs is developed and accompanied by practical step-by-step procedures for the application of the method. As part of this thesis, the open-source pyPMM package was developed. This package enables any researcher to construct, train, share, and deploy PMM-based emulators with modular, extendable, and graphics processing unit (GPU)-optimized code. All PMM examples in this thesis were created using this package.
Comments:
PhD Thesis; https://www.proquest.com/docview/3371453232
Subjects:
Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2608.12837 [pdf]
0 citations
03
[Submitted on 13 Aug 2026]
Effective field theory of quasi-hydrodynamics from kinetic theory
Lorenzo Gavassino🇬🇧
Quasi-hydrodynamics describes systems with quasi-conserved degrees of freedom, namely observables that relax on timescales that are finite but parametrically longer than microscopic relaxation times. Examples include kinetic chemistry and linear viscoelasticity. Here, we develop a rigorous effective-field-theory framework for linear quasi-hydrodynamics from kinetic-type theories. Starting from any linearized, causal kinetic-like theory endowed with slow degrees of freedom, we show that the exact dynamics of conserved and quasi-conserved observables admits a systematic expansion in the fast relaxation timescale. At zeroth order, the resulting equations form a causal, symmetric-hyperbolic theory belonging to the appropriate transient-hydrodynamic universality class, establishing Israel-Stewart-like dynamics as the universal description of slow relaxation modes. Higher-order corrections can be computed systematically and inherit universal symmetry, Onsager, positivity, and causality constraints from the underlying microscopic theory.
Comments:
6 pages and 2 figures (main text) + 8 pages and 0 figures (supplementary material), comments welcome!
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th); Mathematical Physics (math-ph); math.MP (math.MP)
arXiv:
2608.13542 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Relativistic dynamical effects in proton emission: the Wentzel-Kramers-Brillouin method for 1+1 dimensional Dirac equation

Parametric Matrix Models for Emulation in Nuclear and Many-Body Physics

Effective field theory of quasi-hydrodynamics from kinetic theory

Affiliations