arXiv subjects

Dukjae Jang

Publications and source records attributed to Dukjae Jang.

15 recordsLinked to original sources

arXiv2025

The Non-thermal Energy Window for Laser-Driven Nuclear Reactions

Laser-driven nuclear reactions proceed in non-equilibrium plasma conditions, producing ion energy distributions that are not Maxwellian. Nevertheless, fusion yields in such experiments are often interpreted using effective thermal descriptions based on the conventional Gamow window. In this work, we develop an analytical framework for evaluating nuclear reaction rates for non-thermal ions accelerated by the Target Normal Sheath Acceleration (TNSA) mechanism. Using a self-similar plasma expansion model, we derive a closed form expression for an effective reaction energy window and the corresponding fusion reactivity. The resulting effective energies differ systematically from those predicted by thermal models, indicating limitations of interpretations based on the conventional Gamow window in laser-driven environments. This framework provides a quantitative basis for analyzing fusion yields and for designing laser-driven nuclear experiments.

physics.plasm-ph↗

arXiv2025

Upper Limit of Fusion Reactivity in Laser-Driven $p+{^{11}{\rm B}}$ Reaction

We explore the averaged fusion reactivity of the $p+{^{11}{\rm B}}$ reaction in tabletop laser experiments using a plasma expansion model. We investigate the energy distribution of proton beams accelerated by lasers as a function of electron temperature $T_e$ and the dimensionless acceleration time $ω_{pi} t_{\rm acc}$, where $ω_{pi}$ is the ion plasma frequency. By combining these distributions with the fusion cross-section, we identify the optimal conditions that maximize the fusion reactivity, with $\left\langle σv \right\rangle = 8.12 \times 10^{-16}\,{\rm cm^3/s}$ at $k_B T_e = 10.0\,{\rm MeV}$ and $ω_{pi} t_{\rm acc} = 0.503$. These findings suggest that an upper limit exists for the fusion reactivity achievable in laser-driven $p+{^{11}{\rm B}}$ fusion experiments, even under optimized conditions.

physics.plasm-ph↗

arXiv2025

Constraining Anisotropic Universe Through Big Bang Nucleosynthesis: A Case Study of The Bianchi Type-I Universe

The isotropy and homogeneity of our Universe are the cardinal principles of modern cosmology built on the definition of metric through the prescription by Friedmann-Lema$\hat{i}$tre-Robertson-Walker (FLRW). From the aspects of geometry, the presence of anisotropy, inhomogeneity, or both are allowed in the metrics defined as the Bianchi type I and V metrics. In this letter, the Big Bang Nucleosynthesis (BBN) formalism, and the latest observational constraints on nuclear abundances are being used to put bounds on the global anisotropy offered in the Bianchi type I metrics, providing a new path to explore in the background of global anisotropy.

astro-ph.CO↗

arXiv2025

Big Bang Nucleosynthesis constraints on the Energy-Momentum Squared Gravity: The $\mathbb{T}^{2}$ model

Scale-independent energy-momentum squared gravity (EMSG) allows different gravitational couplings for different types of sources and has been proven to have interesting implications in cosmology. In this paper, the Big Bang Nucleosynthesis (BBN) formalism and the latest observational constraints on nuclear abundances are being used to put bounds on this class of modified gravity models. Using the tight constraint from BBN on the correction term in the Friedmann equation in EMSG scenario, we report the allowed deviation from the standard cosmic expansion rate.

astro-ph.CO↗

arXiv2024

Effects of pair freeze-out on photon distributions in BBN epoch

We investigate the evolution of non-extensivity in the photon distribution during the Big Bang Nucleosynthesis (BBN) epoch using Tsallis statistics. Assuming a minimal deviation from the Planck distribution, we construct the perturbed Boltzmann equation for photons, including the collision terms for pair creation and annihilation processes. We analyze the possibility that these collisions could cause a slight increase in the number of high-frequency photons within the BBN era, and consequently, the primordial plasma might be temporarily placed in a state of chemical non-equilibrium. We also discuss the restoration of the photon distribution to an equilibrium state as the Universe enters the matter-dominated era. These findings, which suggest possible changes in the photon distribution during the epoch between the BBN and the recombination, offer insights that support the previously proposed ansatz solution to the primordial lithium problem in arXiv:1812.09472.

astro-ph.CO↗

arXiv2023

Effects of neutron-rich nuclei masses on symmetry energy

We explore the impact of neutron-rich nuclei masses on the symmetry energy properties using the mass table evaluated by the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) model. First, using the semi-empirical mass formula with the DRHBc mass table, we investigate the symmetry energy at saturation density $ρ_0$, denoted as $S_0$, and the ratio of surface to volume contributions to the symmetry energy, $κ$. As a result, we obtain $S_0=27.85\,{\rm MeV}$ ($κ=1.38$) for $a_{\rm sym}(A) =S_0 (1 - κA^{-1/3})$ (Type I) and $S_0=32.66\,{\rm MeV}$ ($κ=3.15$) for $a_{\rm sym}(A) = S_0 (1 + κA^{-1/3} )^{-1}$ (Type II), which are lower than those obtained using the AME2020 mass table, $S_0=28.54\,{\rm MeV}$ ($κ=1.29$) for Type I and $S_0=33.81\,{\rm MeV}$ ($κ=3.04$) for Type II. Second, we further investigate the effect of these changes in $a_{\rm sym}(A)$ on the density-dependent symmetry energy by employing the empirical model of $S(ρ) = C_k(ρ/ρ_0)^{2/3} + C_1(ρ/ρ_0) + C_2(ρ/ρ_0)^γ$ and universal relation of $a_{\rm sym}(A=208) = S(ρ=0.1\,{\rm fm}^{-3})$. Compared to the experimental constraints, we find that $S_0$ and slope parameter $L$, determined by the DRHBc mass table with Type II, are more suitable to explain the constraints by heavy ion collisions and isobaric analog states than AME2020. We also discuss the neutron skin thickness derived from the $L$, comparing it with experimental measurements.

nucl-th↗

arXiv2023

Oscillating cosmic evolution and constraints on big bang nucleosynthesis in the extended Starobinsky model

We investigate the cosmic evolutions in the extended Starobinsky model (eSM) obtained by adding one $R^{ab}R_{ab}$ term to the Starobinsky model. We discuss the possibility of various cosmic evolutions with a special focus on the radiation-dominated era (RDE). Using simple assumptions, a second-order non-linear differential equation describing the various cosmic evolutions in the eSM is introduced. By solving this non-linear equation numerically, we show that the various cosmic evolutions, such as the standard cosmic evolution ($a \propto t^{1/2}$) and a unique oscillating cosmic evolution, are feasible due to the effects of higher-order terms introduced beyond Einstein's gravity. Furthermore, we consider big bang nucleosynthesis (BBN), which is the most important observational result in the RDE, to constrain the free parameters of the eSM. The primordial abundances of the light elements, such as $^{4}$He, D, $^{3}$He, $^{7}$Li, and $^{6}$Li by the cosmic evolutions are compared with the most recent observational data. It turns out that most non-standard cosmic evolutions can not easily satisfy these BBN constraints, but a free parameter of the viable models with the oscillating cosmic evolution is shown to have an upper limit by the constraints. In particular, we find that the free parameter is most sensitive to deuterium and $^4$He abundances, which are being precisely measured among other elements. Therefore, more accurate measurements in the near future may enable us to distinguish the eSM from the standard model as well as other models.

astro-ph.CO↗

arXiv2023

Revisiting the Gamow Factor of Reactions on Light Nuclei

This study provides an improved understanding of the penetration probabilities (PPs) in nuclear reactions of light nuclei by correcting the assumptions used in the conventional Gamow factor. The Gamow factor effectively describes the PP in nuclear reactions based on two assumptions: low particle energy than the Coulomb barrier and neglecting the dependence of nuclear interaction potential. However, we find that the assumptions are not valid for light nuclei. As a result of a calculation that excludes the assumptions, we obtain the PP that depends on the nuclear interaction potential depth for the light nuclei. For the potential depth fitted by the experimental fusion cross-section, we present that PPs of light nuclei (D+D, D+T, D+$^3$He, p+D, p+$^6$Li, and p+$^7$Li) become higher than the conventional one near the Coulomb barrier. We also discuss the implications of the modified PP, such as changes in the Gamow peak energy, which determine the measurement of the energy range of the nuclear cross-section in experiments, and the electron screening effect.

nucl-th↗

arXiv2023

An exact solution of the higher-order gravity in standard radiation-dominated era

We report that the standard evolution of radiation-dominated era (RDE) universe $a \propto t^{1/2}$ is a sufficient condition for solving a sixth order gravitational field equation derived from the Lagrangian containing $B R^{ab}R_{ab} + C R {R^{;c}}_{c}$ as well as a polynomial $f(R)$ for a spatially flat radiation FLRW universe. By virtue of the similarity between $R^{ab}R_{ab}$ and $R^2$ models up to the background order and of the vanishing property of ${R^{;c}}_{c}$ for $ H = 1/(2t)$, the analytical solution can be obtained from a special case to general one. This proves that the standard cosmic evolution is valid even within modified gravitational theory involving higher-order terms. An application of this background solution to the tensor-type perturbation reduces the complicated equation to the standard second order equation of gravitational wave. We discuss the possible ways to discriminate the modified gravity model on the observations such as the gravitational wave from the disturbed universe and primordial abundances.

gr-qc↗

arXiv2022

Effects of electromagnetic fluctuations in plasmas on solar neutrino fluxes

We explore the effects of electromagnetic (EM) fluctuations in plasmas on solar neutrino fluxes exploiting the fluctuation-dissipation theorem. We find that the EM spectrum in the solar core is enhanced by the EM fluctuations due to the high density of the Sun, which increases the radiation energy density and pressure. By the EM fluctuations involving the modified radiation formula, the central temperature decreases when the central pressure of the Sun is fixed. With a help of the empirical relation between central temperature and neutrino fluxes deduced from the numerical solar models, we present the change in each of the solar neutrino fluxes by the EM fluctuations. We also discuss the enhanced radiation pressure and energy density by the EM fluctuations for other astronomical objects.

astro-ph.SR↗

arXiv2022

Comprehensive Analyses of the Neutrino-Process in the Core-collapsing Supernova

We investigate the neutrino flavor change effects due to neutrino self-interaction, shock wave propagation as well as matter effect on the neutrino-process of the core-collapsing supernova (CCSN). For the hydrodynamics, we use two models: a simple thermal bomb model and a specified hydrodynamic model for SN1987A. As a pre-supernova model, we take an updated model adjusted to explain the SN1987A employing recent development of the $(n,γ)$ reaction rates for nuclei near the stability line $(A \sim 100)$. As for the neutrino luminosity, we adopt two different models: equivalent neutrino luminosity and non-equivalent luminosity models. The latter is taken from the synthetic analyses of the CCSN simulation data which involved quantitatively the results obtained by various neutrino transport models. Relevant neutrino-induced reaction rates are calculated by a shell model for light nuclei and a quasi-particle random phase approximation model for heavy nuclei. For each model, we present abundances of the light nuclei ($^7$Li, $^7$Be, $^{11}$B and $^{11}$C) and heavy nuclei ($^{92}$Nb, $^{98}$Tc, $^{138}$La and $^{180}$Ta) produced by the neutrino-process. The light nuclei abundances turn out to be sensitive to the Mikheyev-Smirnov-Wolfenstein (MSW) region around O-Ne-Mg region while the heavy nuclei are mainly produced prior to the MSW region. Through the detailed analyses, we find that neutrino self-interaction becomes a key ingredient in addition to the MSW effect for understanding the neutrino-process and the relevant nuclear abundances. The normal mass hierarchy is shown to be more compatible with the meteorite data. Main nuclear reactions for each nucleus are also investigated in detail.

nucl-th↗

arXiv2021

Dynamical Screening Effects on Big Bang Nucleosynthesis

A moving ion in plasma creates a deformed electric potential depending on the ion velocity, which leads to the distinct screening effect compared to the standard static Salpeter formula. In this paper, adopting the test charge method, we explore the dynamical screening effects on big bang nucleosynthesis (BBN). We find that the high temperature in the early universe causes the ion velocity to be faster than the solar condition so that the electric potential is effectively polarized. However, the low density of background plasma components significantly suppresses the dynamical screening effects on thermonuclear reaction rates during the BBN epoch. We compare our results with several thermonuclear reaction rates for solar fusion considering the dynamical screening effects. Also, we discuss the additional plasma properties in other astrophysical sites for the possible expansion from the present calculation in the future.

nucl-th↗

arXiv2021

Big Bang nucleosynthesis in a weakly non-ideal plasma

We propose a correction of the standard Big Bang nucleosynthesis (BBN) scenario to resolve the primordial lithium problem by considering a possibility that the primordial plasma can deviate from the ideal state. In the standard BBN, the primordial plasma is assumed to be ideal, with particles and photons satisfying the Maxwell-Boltzmann and Planck distribution, respectively. We suggest that this assumption of the primordial plasma being ideal might oversimplify the early Universe and cause the lithium problem. We find that deviation of photon distribution from the Planck distribution, which is parameterised with the help of Tsallis statistics, can resolve the primordial lithium problem when the particle distributions of the primordial plasma still follow the MaxwellBoltzmann distribution. We discuss how the primordial plasma can be weakly non-ideal in this specific fashion and its effects on the cosmic evolution.

astro-ph.CO↗

arXiv2019

The viability of the 3+1 neutrino model in the supernova neutrino process

Adopting the 3+1 neutrino mixing parameters by the IceCube and shortbase line experiments, we investigate the sterile-active neutrino oscillation effects on the supernova neutrino process. For the sterile neutrino ($ν_s$), we study two different luminosity models. First, we presume that the $ν_s$ does not interact with other particles through the standard interactions apart from the oscillation with the active neutrinos. Second, we consider that $ν_s$ can be directly produced by $ν_e$ scattering with matter. In both cases, we find that the pattern of neutrino oscillations can be changed drastically by the $ν_s$ in supernova environments. Especially multiple resonances occur, and consequently affect thermal neutrino-induced reaction rates. As a result, $^7$Li, $^7$Be, $^{11}$B, $^{11}$C, $^{92}$Nb, $^{98}$Tc and $^{138}$La yields in the $ν$-process are changed. Among those nuclei, $^7$Li and $^{11}$B yields can be constrained by the analysis of observed SiC X grains. Based on the meteoritic data, we conclude that the second model can be allowed while first model is excluded. The viability of the second model depends on the sterile neutrino temperature and the neutrino mass hierarchy.

hep-ph↗

arXiv2017

Effects of sterile neutrino and extra-dimension on big bang nucleosynthesis

By assuming the existence of extra-dimensional sterile neutrinos in big bang nucleosynthesis (BBN) epoch, we investigate the sterile neutrino ($ν_{\rm s}$) effects on the BBN and constrain some parameters associated with the $ν_{\rm s}$ properties. First, for cosmic expansion rate, we take into account effects of a five-dimensional bulk and intrinsic tension of the brane embedded in the bulk, and constrain a key parameter of the extra dimension by using the observational element abundances. Second, effects of the $ν_{\rm s}$ traveling on or off the brane are considered. In this model, the effective mixing angle between a $ν_{\rm s}$ and an active neutrino depends on energy, which may give rise to a resonance effect on the mixing angle. Consequently, reaction rate of the $ν_{\rm s}$ can be drastically changed during the cosmic evolution. We estimated abundances and temperature of the $ν_{\rm s}$ by solving the rate equation as a function of temperature until the sterile neutrino decoupling. We then find that the relic abundance of the $ν_{\rm s}$ is drastically enhanced by the extra-dimension and maximized for a characteristic resonance energy $E_{\rm res}\gtrsim 0.01$ GeV. Finally, some constraints related to the $ν_{\rm s}$, mixing angle and mass difference, are discussed in detail with the comparison of our BBN calculations corrected by the extra-dimensional $ν_{\rm s}$ to observational data on light element abundances.

nucl-th↗