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Nuclear Theory·nucl-th

Thursday·July 13, 2023

19 papers—7 primary·12 cross-listed

All19Primary7Cross-lists12
  1. 01

    Comment on "Nuclear Excitation by Free Muon Capture"

    Natalia S. Oreshkina · Julian C. Berengut

    In the paper [1] the process of free muon capture with simultaneous excitation of a nuclear isomer has been suggested, claiming that ``the effect can be detectable for selected isotopes". Here, we argue that this claim can not be confirmed. Briefly, the process is far from the dominant mechanism for nuclear excitation; it excites high energy nuclear levels that will not generally decay to the isomer; the proposal assumes all incident muons will fulfil energy criteria, ignoring dominant capture paths; and nuclei excited by muons will have a shortened lifetime due to muonic capture.

    nucl-thphysics.atom-phPRL(2024)·1 citation
  2. 02

    Thermal phonon fluctuations and stability of the magnetic dual chiral density wave phase in dense QCD

    E. J Ferrer🇺🇸 · W. Gyory🇺🇸 · V. de la Incera🇺🇸

    We study the stability against thermal phonon fluctuations of the magnetic dual chiral density wave (MDCDW) phase, an inhomogeneous phase arising in cold dense QCD in a magnetic field. Following a recent study that demonstrated the absence of the Landau-Peierls (LP) instability from this phase, we calculate the (threshold) temperature at which the phonon fluctuations wash out the long-range order over a range of magnetic fields and densities relevant to astrophysical applications. Using a high-order Ginzburg-Landau expansion, we find that the threshold temperature is very near the critical temperature for fields of order G, and still a sizable fraction of the critical temperature for fields of order G. Therefore, at sufficiently large magnetic fields, the long-range order of the MDCDW phase is preserved over most of the parameter space where it is energetically favored; at smaller magnetic fields, the long-range order is still preserved over a considerable region of parameter space relevant to compact stars. We provide general symmetry arguments to explain why a magnetic field alone is not enough to eliminate the LP instability that characterizes single-modulated phases in 3+1 dimensions.

    nucl-thastro-ph.HEhep-phPRD(2024)·8 citations
  3. 03

    Impact of the Li asymptotic normalization constant onto -induced reactions of astrophysical interest

    Chloë Hebborn · Melina L. Avila · Konstantinos Kravvaris · Gregory Potel · Sofia Quaglioni

    Indirect methods have become the predominant approach in experimental nuclear astrophysics for studying several low-energy nuclear reactions occurring in stars, as direct measurements of many of these relevant reactions are rendered infeasible due to their low reaction probability. Such indirect methods, however, require theoretical input that in turn can have significant poorly-quantified uncertainties, which can then be propagated to the reaction rates and have a large effect on our quantitative understanding of stellar evolution and nucleosynthesis processes. We present two such examples involving -induced reactions, C(O and CO, for which the low-energy cross sections have been constrained with Li transfer data. In this Letter, we discuss how a first-principle calculation of Li leads to a 21% reduction of the CO cross sections with respect to a previous estimation. This calculation further resolves the discrepancy between recent measurements of the CO reaction and points to the need for improved theoretical formulations of nuclear reactions.

    nucl-thastro-ph.SRnucl-exPRC(2024)·12 citations
  4. 04

    Simultaneous study of scattering and fusion hindrance near Coulomb barrier in systems

    Kamala Kanta Jena · Bidhubhusan Sahu · Jajati K. Nayak · Raj Preethi P · B. K. Sharma · Santosh Kumar Agarwalla

    A phenomenological optical potential is used to study the elastic angular distributions for the system close to the Coulomb barrier. This potential is constructed by taking into account the flexible potential developed by Ginocchio. The fluctuations in the real and imaginary parts of the optical model potential follow the trends of the threshold anomaly. The set of optical potential parameters needed to analyze the fusion cross sections of the same system are obtained through analysis of the scattering cross sections. Theoretical fusion cross-sections and results from four different experimental groups well agree for a range of energies. Several Fluorine (F) isotopes are used as projectiles in this study of fusion cross-sections by slightly altering the radial parameter. It was found that the fusion process occurs unfettered in the system below the Coulomb barrier but is seriously hindered in the case of its isotopic projectiles.

    nucl-thnucl-exActa Phys.Polon.B(2023)·5 citations
  5. 05

    Empirical radius formulas for canonical neutron stars from bidirectionally selecting EOS features in extended Bayesian analyses of observational data

    Jake Richter · Bao-An Li

    Given the significant advancement in Bayesian inference of nuclear Equation of State (EOS) from gravitational wave and X-ray observations of neutron stars (NSs), especially since GW170817, is there a data-driven and robust empirical formula for the radius of canonical NSs in terms of the characteristic EOS parameters (features)? What is the single most important but currently poorly known EOS parameter for determining the ? We study these questions by extending the traditional Bayesian analysis which normally ends at presenting the marginalized posterior probability distribution functions (PDFs) of individual EOS parameters and their correlations (or sometimes only the Pearson correlation coefficients which are only reliably useful when the variables are linearly correlated while they are actually often not). Using three regression model-building methodologies: bidirectional step-wise feature selection, Least Absolute Shrinkage Selection Operator (LASSO) regression, and neural network regression on a large set of posterior EOSs and the corresponding values inferred from earlier comprehensive Bayesian analyses of NS observational data, we systematically and rigorously develop the most probable formulas with varying statistical accuracy and technical complexity. The most important EOS parameters for determining are found consistently in each of the feature/model selection processes to be (in order of decreasing importance): curvature , slope , skewness of nuclear symmetry energy, skewness , incompressibility of symmetric nuclear matter, and the magnitude of symmetry energy at the saturation density of nuclear matter.

    nucl-thastro-ph.HEnucl-exPRC(2023)·20 citations
  6. 06

    Short-range expansion for the quantum many-body problem

    Ronen Weiss · Diego Lonardoni · Stefano Gandolfi

    In this work we derive a systematic short-range expansion of the many-body wave function. At leading order, the wave function is factorized to a zero-energy -wave correlated pair and spectator particles, while terms that include energy derivatives and larger orbital angular momentum two-body functions appear at subleading orders. The validity of the expansion is tested for the two-body case, as well as the many-body case, where infinite neutron matter is considered. An accurate and consistent description of both coordinate-space two-body densities and the one-body momentum distribution is obtained. These results show the possibility to utilize such an expansion for describing different observables in strongly-interacting many-body systems, including nuclear, atomic and condensed-matter systems. This work also enables a systematic description of large momentum transfer reactions in nuclear systems sensitive to short-range correlations, provides a link between such experiments and low-energy nuclear physics, and motivates measurement of new observables in these experiments.

    nucl-thPLB(2024)·1 citation
  7. 07

    Relativistic second-order viscous hydrodynamics from kinetic theory with extended relaxation-time approximation

    Dipika Dash🇮🇳 · Sunil Jaiswal🇮🇳 · Samapan Bhadury🇵🇱 · Amaresh Jaiswal🇮🇳

    We use the extended relaxation time approximation for the collision kernel, which incorporates a particle-energy dependent relaxation time, to derive second-order viscous hydrodynamics from the Boltzmann equation for a system of massless particles. The resulting transport coefficients are found to be sensitive to the energy dependence of the relaxation time and have significant influence on the fluid's evolution. Using the derived hydrodynamic equations, we study the evolution of a fluid undergoing (0+1)-dimensional expansion with Bjorken symmetry and investigate the fixed point structure inherent in the equations. Further, by employing a power law parametrization to describe the energy dependence of the relaxation time, we successfully reproduce the stable free-streaming fixed point for a specific power of the energy dependence. The impact of the energy-dependent relaxation time on the processes of isotropization and thermalization of an expanding plasma is discussed.

    nucl-thhep-phhep-thPRC(2023)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE