Nuclear Theory·nucl-th

Friday·February 21, 2025

8 papers—4 primary·4 cross-listed

05
Temperature Dependence of Beam on Plasma Stopping Power in the Resonance Regions of Fusion Reactions
Keh-Fei Liu🇺🇸
A recent proposal of accelerator based fusion reactor considers a scheme where an ion beam from the accelerator hits the target plasma on the resonance of the fusion reaction so that the reactivity ( $σ v$ ) can be an order of magnitude larger than that of a thermonuclear reactor. One of the important inputs is the stopping power which is needed to assess the energy loss of the beam in the plasma. In this work, we shall use the analytic formulation of Brown, Preston and Singleton~\cite{Brown:2005ji} to calculate the temperature dependence of the stopping power due to the target $t,^{3} H_{e}$ , and $^{11} B$ plasmas in the resonance regions of their respective fusion reactions, i.e., $d + t \to n + α, d +^{3} H_{e} \to p + α$ , and $p +^{11} B \to 3 α$ . It is found that the calculated stopping power, especially when the quantum corrections are included, does not go down with temperature as fast at $T^{- 3/2}$ . Instead it decreases slower, more like $T^{- x}$ with $x \leq 1$ in the range of T from $\sim$ 5 to 50 keV for $d$ on $t$ and $^{3} H_{e}$ plasmas around their resonance energies.
↳ physics.plasm-phnucl-exnucl-thphysics.acc-phPlasma Phys.(2024)·0 citations
06
QCD predictions for physical multimeson scattering amplitudes
Sebastian M. Dawid🇺🇸 · Zachary T. Draper🇺🇸 · Andrew D. Hanlon🇺🇸 · Ben Hörz🇩🇪 · Colin Morningstar🇺🇸 · Fernando Romero-López🇨🇭 · Stephen R. Sharpe🇺🇸 · Sarah Skinner🇺🇸
We use lattice QCD calculations of the finite-volume spectra of systems of two and three mesons to determine, for the first time, three-particle scattering amplitudes with physical quark masses. Our results are for combinations of $π^{+}$ and $K^{+}$ , at a lattice spacing $a = 0.063$ fm, and in the isospin-symmetric limit. We also obtain accurate results for maximal-isospin two-meson amplitudes, with those for $π^{+} K^{+}$ and $2 K^{+}$ being the first determinations at the physical point. Dense lattice spectra are obtained using the stochastic Laplacian-Heaviside method, and the analysis leading to scattering amplitudes is done using the relativistic finite-volume formalism. Results are compared to chiral perturbation theory and to phenomenological fits to experimental data, finding good agreement.
↳ hep-lathep-phnucl-thPRL(2025)·22 citations
07
Efficient Monte Carlo Event Generation for Neutrino-Nucleus Exclusive Cross Sections
Mathias El Baz🇨🇭 · Federico Sánchez🇨🇭 · Natalie Jachowicz🇧🇪 · Kajetan Niewczas🇧🇪 · Ashish Kumar Jha🇧🇪 · Alexis Nikolakopoulos🇺🇸
Modern neutrino-nucleus cross section predictions need to incorporate sophisticated nuclear models to achieve greater predictive precision. However, the computational complexity of these advanced models often limits their practicality for experimental analyses. To address this challenge, we introduce a new Monte Carlo method utilizing Normalizing Flows to generate surrogate cross sections that closely approximate those of the original model while significantly reducing computational overhead. As a case study, we built a Monte Carlo event generator for the neutrino-nucleus cross section model developed by the Ghent group. This model employs a Hartree-Fock procedure to establish a quantum mechanical framework in which both the bound and scattering nucleon states are solutions to the mean-field nuclear potential. The surrogate cross sections generated by our method demonstrate excellent accuracy with a relative effective sample size of more than $98.4%$ , providing a computationally efficient alternative to traditional Monte Carlo sampling methods for differential cross sections.
↳ hep-exnucl-thphysics.comp-phPRD(2025)·9 citations
08
Long-Term Multidimensional Models of Core-Collapse Supernovae: Progress and Challenges
H.-Thomas Janka (MPI Astrophysics, Garching)🇩🇪
Self-consistent, multidimensional core-collapse supernova (SN) simulations, especially in 3D, have achieved tremendous progress over the past 10 years. They are now able to follow the entire evolution from core collapse through bounce, neutrino-triggered shock revival, shock breakout at the stellar surface to the electromagnetic SN outburst and the subsequent SN remnant phase. Thus they provide general support for the neutrino-driven explosion mechanism by reproducing observed SN energies, neutron-star (NS) kicks, and diagnostically relevant radioactive isotope yields; they allow to predict neutrino and gravitational-wave signals for many seconds of proto-NS cooling; they confirm correlations between explosion and progenitor or remnant properties already expected from previous spherically symmetric (1D) and 2D models; and they carve out various scenarios for stellar-mass black-hole (BH) formation. Despite these successes it is currently unclear which stars explode or form BHs, because different modeling approaches disagree and suggest the possible importance of the 3D nature of the progenitors and of magnetic fields. The role of neutrino flavor conversion in SN cores still needs to be better understood, the nuclear equation of state including potential phase transitions implies major uncertainties, the SN 1987A neutrino measurements raise new puzzles, and tracing a possible correlation of NS spins and kicks requires still more refined SN simulations.
↳ astro-ph.HEhep-phnucl-thAnn.Rev.Nucl.Part.Sci.(2025)·103 citations

Affiliations

first authorsco-authorsvia INSPIRE

Temperature Dependence of Beam on Plasma Stopping Power in the Resonance Regions of Fusion Reactions

QCD predictions for physical multimeson scattering amplitudes

Efficient Monte Carlo Event Generation for Neutrino-Nucleus Exclusive Cross Sections

Long-Term Multidimensional Models of Core-Collapse Supernovae: Progress and Challenges

Affiliations