Nuclear Theory·nucl-th

Friday·June 23, 2023

9 papers—4 primary·5 cross-listed

01
Nuclear structure and elastic scattering observables obtained consistently with different NN interactions
R.B. Baker · M. Burrows · Ch. Elster · P. Maris · G. Popa · S.P. Weppner
Nucleon-nucleon ( $N N$ ) interactions based on chiral effective theories are commonly used in ab initio calculations of light nuclei. Here we present a study based on three different NN interactions (up to next-to-next-to-leading order) for which structure and elastic proton scattering observables are consistently calculated for $^{4}$ He, $^{12}$ C, and $^{16}$ O. The interactions are compared at the two-body level in terms of Wolfenstein amplitudes, and their predictions for ground state energies, point-proton radii, and charge form factors, as well as proton elastic scattering observables in the leading-order spectator expansion in the energy range between 65 and 160 MeV projectile energy are presented. To gain further insight into differences visible in elastic scattering observables, we investigate the behavior of the calculated effective nucleon-nucleus interactions for the $^{12}$ C nucleus based on the different $N N$ interactions.
nucl-thnucl-exPRC(2023)·5 citations
02
Efficient solver of relativistic hydrodynamics with implicit Runge-Kutta method
Nathan Touroux🇯🇵 · Masakiyo Kitazawa🇯🇵 · Koichi Murase🇯🇵 · Marlene Nahrgang🇫🇷
We propose a new method to solve the relativistic hydrodynamic equations based on implicit Runge-Kutta methods with a locally optimized fixed-point iterative solver. For numerical demonstration, we implement our idea for ideal hydrodynamics using the one-stage Gauss-Legendre method as an implicit method. The accuracy and computational cost of our new method are compared with those of explicit ones for the (1+1)-dimensional Riemann problem, as well as the (2+1)-dimensional Gubser flow and event-by-event initial conditions for heavy-ion collisions generated by TrENTo. We demonstrate that the solver converges with only one iteration in most cases, and as a result, the implicit method requires a smaller computational cost than the explicit one at the same accuracy in these cases, while it may not converge with an unrealistically large $Δ t$ . By showing a relationship between the one-stage Gauss-Legendre method with the iterative solver and the two-step Adams-Bashforth method, we argue that our method benefits from both the stability of the former and the efficiency of the latter.
nucl-thhep-phphysics.comp-phphysics.flu-dynPTEP(2024)·1 citation
03
Detailed study of the astrophysical direct capture reaction $^{6} Li (p, γ)^{7} Be$ in a potential model approach
E.M. Tursunov · S.A. Turakulov · K.I. Tursunmakhatov
The astrophysical $S$ factor and reaction rates of the direct capture process $^{6}$ Li(p, $γ)^{7}$ Be are estimated within a two-body single-channel potential model approach. Central potentials of the Gaussian-form in the $^{2} P_{3/2}$ and $^{2} P_{1/2}$ waves are adjusted to reproduce the binding energies and the empirical values of the asymptotic normalization coefficients (ANC) for the $^{7}$ Be(3/2 $^{-}$ ) ground and $^{7}$ Be(1/2 $^{-}$ ) excited bound states, respectively. The parameters of the potential in the most important $^{2} S_{1/2}$ scattering channel were fitted to reproduce the empirical phase shifts from the literature and the low-energy astrophysical $S$ factor of the LUNA collaboration. The obtained results for the astrophysical $S$ factor and the reaction rates are in a very good agreement with available experimental data sets. The numerical estimates reproduce not only the absolute values, but also the energy and temperature dependence of the $S$ factor and reaction rates of the LUNA collaboration, respectively. The estimated $^{7} Li/H$ primordial abundance ratio $(4.67 \pm 0.04) \times 1 0^{- 10}$ is well consistent with recent BBN result of $(4.72 \pm 0.72) \times 1 0^{- 10}$ after the Planck observation.
nucl-thastro-ph.SRPRC(2023)·7 citations
04
Generative modeling of nucleon-nucleon interactions
Pengsheng Wen · Jeremy W. Holt · Maggie Li
Developing high-precision models of the nuclear force and propagating the associated uncertainties in quantum many-body calculations of nuclei and nuclear matter remain key challenges for ab initio nuclear theory. In the present work we demonstrate that generative machine learning models can construct novel instances of the nucleon-nucleon interaction when trained on existing potentials from the literature. In particular, we train the generative model on nucleon-nucleon potentials derived at second and third order in chiral effective field theory and at three different choices of the resolution scale. We then show that the model can be used to generate samples of the nucleon-nucleon potential drawn from a continuous distribution in the resolution scale parameter space. The generated potentials are shown to produce high-quality nucleon-nucleon scattering phase shifts. This work provides an important step toward a comprehensive estimation of theoretical uncertainties in nuclear many-body calculations that arise from the arbitrary choice of nuclear interaction and resolution scale. Source code for this project can be found at https://github.com/pswen2019/Glow-nuclear-potential.git.
nucl-thPRL(2024)·8 citations
05
Impact of Pycnonuclear Fusion Uncertainties on the Cooling of Accreting Neutron Star Crusts
R. Jain · E. F. Brown · H. Schatz · A. V. Afanasjev · M. Beard · L. R. Gasques · S. S. Gupta · G. W. Hitt · W. R. Hix · R. Lau · P. Moller · W. J. Ong · M. Wiescher · Y. Xu
The observation of X-rays during quiescence from transiently accreting neutron stars provides unique clues about the nature of dense matter. This, however, requires extensive modeling of the crusts and matching the results to observations. The pycnonuclear fusion reaction rates implemented in these models are theoretically calculated by extending phenomenological expressions and have large uncertainties spanning many orders of magnitude. We present the first sensitivity studies of these pycnonuclear fusion reactions in realistic network calculations. We also couple the reaction network with the thermal evolution code dStar to further study their impact on the neutron star cooling curves in quiescence. Varying the pycnonuclear fusion reaction rates alters the depth at which nuclear heat is deposited although the total heating remains constant. The enhancement of the pycnonuclear fusion reaction rates leads to an overall shallower deposition of nuclear heat. The impurity factors are also altered depending on the type of ashes deposited on the crust. These total changes correspond to a variation of up to 9 eV in the modeled cooling curves. While this is not sufficient to explain the shallow heat source, it is comparable to the observational uncertainties and can still be important for modeling the neutron star crust.
↳ astro-ph.HEastro-ph.SRnucl-thApJ(2023)·7 citations
06
Two species $k$ -body embedded Gaussian unitary ensembles: $q$ -normal form of the eigenvalue density
Manan Vyas · V. K. B. Kota
Eigenvalue density generated by embedded Gaussian unitary ensemble with $k$ -body interactions for two species (say $π$ and $ν$ ) fermion systems is investigated by deriving formulas for the lowest six moments. Assumed in constructing this ensemble, called EGUE( $k : π ν$ ), is that the $π$ fermions ( $m_{1}$ in number) occupy $N_{1}$ number of degenerate single particle (sp) states and similarly $ν$ fermions ( $m_{2}$ in number) in $N_{2}$ number of degenerate sp states. The Hamiltonian is assumed to be $k$ -body preserving $(m_{1}, m_{2})$ . Formulas with finite $(N_{1}, N_{2})$ corrections and asymptotic limit formulas both show that the eigenvalue density takes $q$ -normal form with the $q$ parameter defined by the fourth moment. The EGUE( $k : π ν$ ) formalism and results are extended to two species boson systems. Results in this work show that the $q$ -normal form of the eigenvalue density established only recently for identical fermion and boson systems extends to two species fermion and boson systems.
↳ quant-phmath.STnlin.CDnucl-th+1J.Stat.Mech.(2023)·1 citation
07
Exclusive $J /Ψ$ plus jet associated production in ultraperipheral $P b P b$ collisions
Victor P. Goncalves🇩🇪 · Michael Klasen🇩🇪 · Bruno D. Moreira🇧🇷
The study of exclusive processes in ultraperipheral collisions at the Large Hadron Collider (LHC) has allowed us to test several aspects of the Standard Model and to search for New Physics. In this letter, we investigate the possibility of using these processes to improve our understanding of the quarkonium production mechanism through the study of the exclusive $J /Ψ$ plus jet associate production in ultraperipheral $P b P b$ collisions. We estimate the transverse - momentum and rapidity distributions considering that the $γ γ \to J /Ψ + X$ ( $X = γ, g$ ) subprocess is described by the Non - Relativistic QCD (NRQCD) formalism and present predictions for the rapidity ranges covered by central and forward detectors. The experimental separation of these events is discussed and the results indicate that a future experimental analysis is, in principle, feasible in future runs of the LHC and the Future Circular Collider (FCC).
↳ hep-phnucl-thEPJC(2023)·3 citations
08
Production of fully-heavy tetraquark states through the double parton scattering mechanism in $pp$ and $p A$ collisions
L. M. Abreu🇧🇷 · F. Carvalho🇧🇷 · J. V. C. Cerqueira🇧🇷 · V. P. Goncalves🇩🇪
The production of fully-heavy tetraquark states in proton-proton ( $pp$ ) and proton-nucleus ( $p A$ ) collisions at the center-of-mass energies of the Large Hadron Collider (LHC) and at the Future Circular Collider (FCC) is investigated considering that these states are produced through the double parton scattering mechanism. We estimate the cross sections for the $T_{4 c}$ , $T_{4 b}$ and $T_{2 b 2 c}$ states and present predictions for $pp$ , $pC a$ and $pP b$ collisions considering the rapidity ranges covered by central and forward detectors. We demonstrate that the cross sections for $p A$ collisions are enhanced in comparison to the $pp$ predictions scaled by the atomic number. Moreover, our results indicate that a search of these exotic states is, in principle, feasible in the future runs of the LHC and FCC.
↳ hep-phnucl-thEPJC(2024)·17 citations
09
Holographic description of elastic photon-proton and photon-photon scattering
Akira Watanabe🇨🇳 · Zabihullah Ahmadi🇨🇳 · Zhibo Liu🇨🇳 · Wei Xie🇨🇳
We investigate the elastic photon-proton and photon-photon scattering in a holographic QCD model, focusing on the Regge regime. Considering contributions of the Pomeron and Reggeon exchange, the total and differential cross sections are calculated. While our model involves several parameters, by virtue of the universality of the Pomeron and Reggeon, for most of them the values determined in the preceding study on the proton-proton and proton-antiproton scattering can be employed. Once the two adjustable parameters, the Pomeron-photon and Reggeon-photon coupling constant, are determined with the experimental data of the total cross sections, predicting the both cross sections in a wide kinematic region, from the GeV to TeV scale, becomes possible. We show that the total cross section data can be well described within the model, and our predictions for the photon-proton differential cross section are consistent with the data.
↳ hep-phhep-exnucl-exnucl-thPLB(2024)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE