Nuclear Theory·nucl-th

Monday·May 13, 2024

10 papers—1 primary·9 cross-listed

02
Fermi-Dirac Integrals in Degenerate Regimes: A Novel Asymptotic Expansion
Jeremiah Birrell🇺🇸 · Martin Formanek🇺🇸 · Andrew Steinmetz🇺🇸 · Cheng Tao Yang🇺🇸 · Johann Rafelski🇺🇸
We characterize in a novel manner the physical properties of the low temperature Fermi gas in the degenerate domain as a function of temperature and chemical potential. For the first time we obtain low temperature $T$ results in the domain where several fermions are found within a de Broglie spatial cell. In this regime, the usual high degeneracy Sommerfeld expansion fails. The other known semi-classical Boltzmann domain applies when fewer than one particle is found in the de Broglie cell. We also improve on the understanding of the Sommerfeld expansion in the regime where the chemical potential is close to the mass and also in the high temperature regime. In these calculcations we use a novel characterization of the Fermi distribution allowing the separation of the finite and zero temperature phenomena. The relative errors of the three approximate methods (Boltzmann limit, Sommerfeld expansion, and the new domain of several particles in the de Broglie cell) are quantified.
↳ cond-mat.quant-gasastro-ph.COhep-phnucl-thInt.J.Theor.Phys.(2024)·3 citations
03
Benchmarking Geant4 photonuclear process model for the photo-induced reaction of deformed nuclei in the GDR region
P. D. Khue · P. V. Cuong · D.L. Balabanski · L. X. Chung · D.V. Thanh · D. T. K. Linh · L. T. Anh
The Geant4 photonuclear process is benchmarked by comparing it with experimental data to verify the ability of the Geant4 toolkit to simulate the photo-induced reaction on deformed nuclei in the Giant Dipole Resonance (GDR) region. The simulation results are compared with experimental data of the deformed nuclei (153Eu, 160Gd, 165Ho, and 186W) targets in terms of both the average neutron energies and the photonuclear cross-sections. The agreement between the calculated results of the Geant4 photonuclear process model and the experimental measurements is analyzed.
↳ physics.comp-phnucl-thNucl.Instrum.Meth.A(2024)·0 citations
04
BBN catalysis by doubly charged particles
Evgeny Akhmedov🇩🇪 · Maxim Pospelov🇺🇸
We consider primordial nucleosynthesis in the presence of hypothetical quasi-stable doubly charged particles. Existence of $X^{--}$ with macroscopic lifetimes will lead to the formation of its bound states with $^{4}$ He and other light elements, significantly facilitating the subsequent formation of lithium nuclei. From observational constraints on maximum allowable amount of lithium, that we update in this work, we derive strong constraints on the abundance and lifetime of $X^{--}$ . In a likely cosmological freeze-out scenario with temperatures initially exceeding the mass of $X^{--}$ , the BBN constrains the lifetime of these particles to be less than about 100 seconds. For parametrically long lifetimes, lithium abundance data constrain $X^{--}$ abundance to be less than $1 0^{- 9}$ relative to protons, regardless of whether these particles decay or remain stable. Stable particles could saturate the dark matter density only if their mass is comparable to or in excess of $1 0^{10}$ GeV, and most of $X^{--}$ will be found in bound states with beryllium nuclei, so that chemically they would appear as abnormally heavy helium isotopes.
↳ hep-phastro-ph.COhep-exnucl-thJCAP(2024)·5 citations
05
First Radial Excitations of Mesons and Diquarks in a Contact Interaction
G. Paredes-Torres🇲🇽 · L.X. Gutiérrez-Guerrero🇲🇽 · A. Bashir🇲🇽 · Ángel S. Miramontes🇲🇽
We present a calculation for the masses of the first radially excited states of forty mesons and diquarks made up of $u, d, s, c$ and $b$ quarks, including states that contain one or both heavy quarks. To this end, we employ a combined analysis of the Bethe-Salpeter and Schwinger-Dyson equations within a self-consistent and symmetry preserving vector-vector contact interaction. The same set of parameters describe ground and excited states of mesons and their diquark partners. The wave-function of the first radial excitation contains a zero whose location is correlated with an additional parameter $d_{F}$ which is a function of dressed quark masses. Our results satisfy the equal spacing rules given by the Gell-Mann Okubo mass relations. Wherever possible, we make comparisons of our findings with known experimental observations as well as theoretical predictions of several other models and approaches including lattice quantum chromodynamics, finding a very good agreement. We report predictions for a multitude of radial excitations not yet observed in experiments.
↳ hep-phnucl-thPRD(2024)·14 citations
06
Reconstructing generalised parton distributions from the lattice off-forward Compton amplitude
A. Hannaford-Gunn🇦🇺 · K. U. Can🇦🇺 · J. A. Crawford🇦🇺 · R. Horsley🇬🇧 · P. E. L. Rakow🇬🇧 · G. Schierholz🇩🇪 · H. Stüben🇩🇪 · R. D. Young🇦🇺 · J. M. Zanotti🇦🇺
We present a determination of the structure functions of the off-forward Compton amplitude $H_{1}$ and $E_{1}$ from the Feynman-Hellmann method in lattice QCD. At leading twist, these structure functions give access to the generalised parton distributions (GPDs) $H$ and $E$ , respectively. This calculation is performed for an unphysical pion mass of $m_{π} = 412 MeV$ and four values of the soft momentum transfer, $t \approx 0, - 0.3, - 0.6, - 1.1 GeV^{2}$ , all at a hard momentum scale of $Q ˉ^{2} \approx 5 GeV^{2}$ . Using these results, we test various methods to determine properties of the real-time scattering amplitudes and GPDs: (1) we fit their Mellin moments, and (2) we use a simple GPD ansatz to reconstruct the entire distribution. Our final results show promising agreement with phenomenology and other lattice results, and highlight specific systematics in need of control.
↳ hep-lathep-phnucl-thPRD(2024)·22 citations
07
Anatomy of critical fluctuations in hadronic matter
Michał Marczenko🇵🇱
Critical phenomena in phase transitions of strongly interacting matter, governed by quantum chromodynamics, are inherently encoded in the fluctuations of conserved charges. In this work, we study the net-baryon number density fluctuations, including the lowest-lying nucleon and the baryonic resonance $Δ (1232)$ , based on the parity doublet model in the mean-field approximation. We focus on the qualitative features of the second-order susceptibility of the net-baryon number density in dense hadronic matter and how the inclusion of $Δ (1232)$ affects it. We demonstrate that the fluctuations of the individual baryons do not necessarily reflect the total net-baryon number fluctuations at finite density, due to the non-trivial correlations between different particle species. Our results highlight the role of baryonic correlations in the interpretation of data from heavy ion collision experiments.
↳ hep-phnucl-thPRD(2024)·8 citations
08
Solar fusion III: New data and theory for hydrogen-burning stars
B. Acharya🇺🇸 · M. Aliotta🇬🇧 · A. B. Balantekin🇺🇸 · D. Bemmerer🇩🇪 · C. A. Bertulani🇺🇸 · A. Best🇮🇹 · C. R. Brune🇲🇽 · R. Buompane🇮🇹 · F. Cavanna🇮🇹 · J. W. Chen🇮🇹 · J. Colgan🇹🇼 · A. Czarnecki🇺🇸 and 38 other authors
In stars that lie on the main sequence in the Hertzsprung-Russel diagram, like our sun, hydrogen is fused to helium in a number of nuclear reaction chains and series, such as the proton-proton chain and the carbon-nitrogen-oxygen cycles. Precisely determined thermonuclear rates of these reactions lie at the foundation of the standard solar model. This review, the third decadal evaluation of the nuclear physics of hydrogen-burning stars, is motivated by the great advances made in recent years by solar neutrino observatories, putting experimental knowledge of the proton-proton chain neutrino fluxes in the few-percent precision range. The basis of the review is a one-week community meeting held in July 2022 in Berkeley, California, and many subsequent digital meetings and exchanges. The relevant reactions of solar and stellar hydrogen burning are reviewed here, from both theoretical and experimental perspectives. Recommendations for the state of the art of the astrophysical S-factor and its uncertainty are formulated for each of them. Several other topics of paramount importance for the solar model are reviewed, as well: recent and future neutrino experiments, electron screening, radiative opacities, and current and upcoming experimental facilities. In addition to reaction-specific recommendations, also general recommendations are formed.
↳ astro-ph.SRastro-ph.HEnucl-exnucl-thRMP(2025)·46 citations
09
Steady electric currents in magnetized QCD and their use for the equation of state
B. B. Brandt🇩🇪 · G. Endrődi🇩🇪 · G. Markó🇩🇪 · A. D. M. Valois🇩🇪
In this paper we study the emergence of steady electric currents in QCD as a response to a non-uniform magnetic background using lattice simulations with 2 + 1 quark flavors at the physical point, as well as leading-order chiral perturbation theory. Using these currents, we develop a novel method to determine the leading-order coefficient of the equation of state in a magnetic field expansion: the magnetic susceptibility of the QCD medium. We decompose the current expectation value into valence- and sea-quark contributions and demonstrate that the dominant contribution to the electric current is captured by the valence term alone, allowing for a comparably cheap determination of the susceptibility. Our continuum extrapolated lattice results for the equation of state confirm the findings of some of the existing studies in the literature, namely that the QCD medium behaves diamagnetically at low and paramagnetically at high temperatures.
↳ hep-lathep-exhep-phhep-th+1JHEP(2024)·8 citations
10
Steps Toward Quantum Simulations of Hadronization and Energy-Loss in Dense Matter
Roland C. Farrell🇺🇸 · Marc Illa🇺🇸 · Martin J. Savage🇺🇸
A framework for simulating the real-time dynamics of composite particles in a simple model of dense matter that is amenable to quantum computers is developed. As a demonstration, we perform classical simulations of heavy-hadrons propagating through a dense medium in the Schwinger model. Measurements of the time-dependent energy and charge density are used to identify mechanisms responsible for energy loss and hadron production (hadronization). A study of entanglement dynamics highlights the importance of quantum coherence between the particles that make up the dense medium. Throughout this work, care is taken to isolate, and remove, phenomena that arise solely from a finite lattice spacing. It is found that signatures of entanglement are more sensitive to lattice artifacts than other observables. Toward quantum simulations, we present an efficient method and the corresponding quantum circuits for preparing ground states in the presence of heavy mesons. These circuits are used to estimate the resources required to simulate in-medium energy loss and hadronization in the Schwinger model using quantum computers.
↳ quant-phhep-lathep-phnucl-thPRC(2025)·37 citations

Affiliations

first authorsco-authorsvia INSPIRE