Nuclear Theory·nucl-th

Friday·February 23, 2024

18 papers—7 primary·11 cross-listed

01
Recent advances in chiral EFT based nuclear forces and their applications
Ruprecht Machleidt🇺🇸 · Francesca Sammarruca🇺🇸
During the past two decades, chiral effective field theory has evolved into a powerful tool to derive nuclear forces from first principles. Nearly all two-nucleon interactions have been worked out up to sixth order of chiral perturbation theory, while, with few exceptions, three-nucleon forces, which play a subtle, but crucial role in microscopic nuclear structure calculations, have been derived up to fifth order. We review the current status of these forces as well as their applications in nuclear many-body systems. While the ab initio description of light nuclei is generally very successful, we point out and analyze problems encountered with medium-mass nuclei. We also survey the construction of equations of state for symmetric nuclear matter and neutron-rich matter based on chiral forces. A focal point is the symmetry energy and its impact on neutron skins and systems of astrophysical relevance. The physics of neutron-rich systems, from nuclei to compact stars, is essentially determined by the density dependence of the symmetry energy. We review the status of predictions in comparison with latest empirical constraints, with particular attention to those extracted from parity violating electron scattering.
nucl-thPPNP(2024)·79 citations
02
Upper Bound on the Speed of Sound in Nuclear Matter from Transport
Mauricio Hippert🇺🇸 · Jorge Noronha🇺🇸 · Paul Romatschke🇺🇸
We point out that there is an upper bound on the speed of sound squared given by $c_{s}^{2} \leq 0.781$ valid for all known systems described by relativistic transient hydrodynamics where calculations of certain ratios of hydrodynamic transport coefficients can be performed from first principles. Assuming this bound is valid for ultradense matter implies that the maximum mass of isolated (non-rotating) neutron stars cannot be larger than 2.7 solar masses.
nucl-thastro-ph.HEhep-phPLB(2025)·27 citations
03
Fragmentation of the Giant Pairing Vibration in 14C induced by many-body processes
Francisco Barranco · Gregory Potel · Enrico Vigezzi
We present a theoretical framework for treating the full excitation spectrum of J{\pi} = 0+ pair addition modes, including the well-known low-lying and bound Pairing Vibration on par with the predicted Giant Pairing Vibration lying in the continuum. Our formalism includes the coupling to low-energy collective quadrupole modes of the core, in such a way that both single-particle self-energy effects and the pairing interaction induced by phonon exchange are accounted for. The theory is applied to the case of the excitation spectrum of 14C, recently populated by two-neutron transfer reactions.
nucl-thPRL(2025)·4 citations
04
Properties of H particle-admixed compact star
Xuhao Wu🇨🇳 · Liming Wang · Hong-Tao An · Min Ju🇨🇳 · Hong Shen🇨🇳
We explore the potential manifestation of a hexaquark, the H particle, as a constituent within neutron stars. The H particle, characterized by a quark composition of $uu dd ss$ , is constructed using the framework of Chromomagnetic Interaction (CMI). Specifically, we contemplate the flavor-singlet state H with $J^{P} = 0^{+}$ . Our computations indicate that the three-flavor hexaquark state, the H particle, possesses a lower mass of $2212.7 MeV$ in comparison to the $d^{*} (2380)$ , implying greater stability than the two-flavor $d^{*} (2380)$ . The analysis involving the H particle is carried out using the relativistic mean-field (RMF) model. We investigate the influence of H particle couplings, a key factor in determining the system stability, and focus on the potential existence of H particle within neutron stars. We find that H particle could potentially endure as a stable constituent within neutron stars, and lead to a reduction of the maximum mass.
nucl-thEPJC(2026)·3 citations
05
Bayesian Model Averaging (BMA) for nuclear data evaluation
E. Alhassan · D. Rochman · G. Schnabel · A.J. Koning
To ensure agreement between theoretical calculations and experimental data, parameters to selected nuclear physics models, are perturbed, and fine-tuned in nuclear data evaluations. This approach assumes that the chosen set of models accurately represents the `true' distribution. Furthermore, the models are chosen globally, indicating their applicability across the entire energy range of interest. However, this approach overlooks uncertainties inherent in the models themselves. As a result, achieving satisfactory fits to experimental data within certain energy regions for specific channels becomes challenging, as the evaluation is constrained by the deficiencies of the selected models. In this work, we propose that instead of selecting globally a winning model set and proceeding with it as if it was the `true' model set, we instead, take a weighted average over multiple models within a BMA framework, each weighted by its posterior probability. The method involves executing a set of TALYS calculations by randomly varying multiple nuclear physics models and their parameters to yield a vector of calculated observables. Next, the likelihood function was computed at each considered incident energy point for selected cross sections by comparing the vector of calculated observables with that of the selected differential experimental data. As the cross sections and elastic angular distributions were updated locally on a per-energy-point basis, the approach typically results in discontinuities or "kinks" in the curves, and these were addressed using spline interpolation. The proposed BMA method was applied to the evaluation of proton induced reactions on $^{58}$ Ni within 1 - 100 MeV. The results demonstrate favorable comparisons with experimental data, as well as with the TENDL-2021 evaluation.
nucl-thNucl.Sci.Tech.(2024)·8 citations
06
Estimating angular momenta of fission fragments from isomeric yield ratios
Zhihao Gao · Andreas Solders · Ali Al-Adili · Simone Cannarozzo · Mattias Lantz · Stephan Pomp
Purpose: To deduce the angular momenta of fission fragments based on the observed isomeric yield ratios (IYR) in 25-MeV proton-induced fission of 238U and to compare these using Wilson's model. Method: A surrogate model of GEF has been developed to generate properties of primary fission fragments. Based on the excitation energy and angular momentum of fission fragments from GEF, an energy versus angular momentum matrix is reconstructed using a set of parameters. With such matrices as input, TALYS is used to calculate the de-excitation of the fission fragments, from which the IYRs are obtained. By varying one of the parameters, the root-mean-square angular momentum (Jrms), which determines the angular momentum distribution of the matrix, Jrms-dependent IYRs are obtained. Considering all primary fission fragments contributing to the IYR for a given fission product, the average angular momentum of those fragments is estimated. Results: Data of 31 IYRs in proton-induced fission of 238U were analysed. As a result, the average Jrms, equivalent to average angular momentum Jav, with uncertainties of 24 fission products, are presented. Considering the neutron emissions of the primary fission fragments, the Jav as a function of the primary fission fragment is presented. A mass dependency of Jav is observed in the proton-induced fission of 238U. Moreover, the Jav for A larger than 131 could be described by the parameterisation proposed by J. Wilson. In general, higher Jav are observed in the present work compared to those from Wilson et al. This is likely due to the higher excitation energy of the fissioning nuclei in this work compared to Wilson's. Furthermore, systematic measurements of the Jav of fission products in the symmetric mass region are presented for the first time. A decreasing trend with mass numbers is observed, which can not be explained by the proposal in Wilson's paper.
nucl-thPRC(2024)·4 citations
07
Bayesian inference of thermal effects in dense matter within the covariant density functional theory
Adriana R. Raduta🇷🇴 · Mikhail V. Beznogov🇷🇴 · Micaela Oertel🇫🇷
The high temperatures reached in a proto-neutron star or during the post-merger phase of a binary neutron star coalescence lead to non-negligible thermal effects on the equation of state (EOS) of dense nuclear matter. Here we study these effects within the covariant density functional theory employing the posteriors of a Bayesian inference, which encompasses a large sample of EOS models. Different densities and temperatures are considered. We find that for a number of quantities thermal effects are strongly correlated with the Dirac effective mass ( $m^{*}$ ) of the nucleons and/or its logarithmic derivative as a function of density. These results can be explained within the low temperature approximation though they survive beyond this limit.
nucl-thPLB(2024)·6 citations
08
Isotropic and anisotropic neutron star structure in 4D Einstein Gauss Bonnet Gravity
Gholam Hossein Bordbar🇮🇷 · Mohammad Mazhari🇮🇷 · Ahmad Poostforush🇮🇷
With regard to the coupling constant and the strong magnetic field of neutron stars, we have studied these stars in the 4D Einstein Gauss Bonnet (4D EGB) gravity model in order to grasp a better understanding of these objects. In this paper, we have shown that the neutron star properties are considerably affected by the coupling constant and magnetic field. We have found that as a consequence of the strong magnetic field and the coupling constant, the maximum mass and radius of a neutron star are increasing functions of the coupling constant, while Schwarzschild radius, compactness, surface gravitational redshift, and Kretschmann scalar are decreasing functions. Additionally, our study has shown that the physical properties of a magnetized neutron star are greatly influenced not only by the strong magnetic field, but also by the anisotropy. Moreover, we have shown that to obtain the hydrostatic equilibrium configuration of the magnetized material, both the local anisotropy effect and the anisotropy due to the magnetic field should be considered. Finally, we have found that in the anisotropic magnetized neutron stars, the maximum mass and radius do not always increase with increasing the internal magnetic field.
↳ gr-qcastro-ph.HEhep-thnucl-thEur.Phys.J.Plus(2024)·11 citations
09
An optimized basis for hadronic light-by-light scattering
Martin Hoferichter🇨🇭 · Peter Stoffer🇨🇭 · Maximilian Zillinger🇨🇭
We present a new basis for the hadronic light-by-light (HLbL) tensor that is optimized for the evaluation of narrow-resonance contributions to HLbL scattering in the anomalous magnetic moment of the muon. As main advantage, kinematic singularities are manifestly absent for pseudoscalar, scalar, and axial-vector states, while the remaining singularities for tensor resonances are minimized, even avoided for special cases, and simple crossing relations among the scalar functions maintained. We scrutinize the properties of this new basis for the scalar-QED pion box, demonstrating that the partial-wave convergence even slightly improves compared to our previous work, and discuss the physical sum rules that ensure basis independence of the HLbL contribution. Finally, we provide explicit expressions for narrow (pseudo-)scalar, axial-vector, and tensor intermediate states in terms of their respective transition form factors.
↳ hep-phhep-exhep-latnucl-thJHEP(2024)·57 citations
10
Introductory visual lecture on QCD at large- $N_{c}$ : bound states, chiral models, and phase diagram
Francesco Giacosa🇵🇱
In these lectures, we present the behavior of conventional $q ˉ q$ mesons, glueballs, and hybrids in the large- $N_{c}$ limit of QCD. To this end, we use an approach based on rather simple NJL-like bound-state equations. The obtained large- $N_{c}$ scaling laws are general and coincide with the known results. A series of consequences, such as the narrowness of certain mesons and the smallness of some interaction types, the behavior of chiral and dilaton models at large- $N_{c},$ and the relation to the compositeness condition and the standard derivation of large- $N_{c}$ results, are explained. The bound-state formalism shows also that mesonic molecular and dynamically generated states do not form in the large- $N_{c}$ limit. The same fate seems to apply also for tetraquark states, but here further studies are needed. Next, following the same approach, baryons are studied as bound states of a generalized diquark ( $N_{c} - 1$ antisymmetric object) and a quark. Similarities and differences with regular mesons are discussed. All the standard scaling laws for baryons and their interaction with mesons are correctly reproduced. The behavior of chiral models involving baryons and describing chirally invariant mass generation is investigated. Finally, properties of QCD in the medium at large- $N_{c}$ are studied: the deconfinement phase transition is investigated along the temperature and the chemical potential directions, respectively. Within the QCD phase diagrams, the features of different models at large- $N_{c}$ are reviewed and the location of the critical endpoint is discussed. In the end, the very existence of nuclei and the implications of large- $N_{c}$ arguments for neutron stars are outlined.
↳ hep-phhep-thnucl-thActa Phys.Polon.B(2024)·4 citations
11
Constraints on new physics with (anti)neutrino-nucleon scattering data
Oleksandr Tomalak🇺🇸 · Minerba Betancourt🇺🇸 · Kaushik Borah🇺🇸 · Richard J. Hill🇺🇸 · Thomas Junk🇺🇸
New physics contributions to the (anti)neutrino-nucleon elastic scattering process can be constrained by precision measurements, with controlled Standard Model uncertainties. In a large class of new physics models, interactions involving charged leptons of different flavor can be related, and the large muon flavor component of accelerator neutrino beams can mitigate the lepton mass suppression that occurs in other low-energy measurements. We employ the recent high-statistics measurement of the cross section for $ν ˉ_{μ} p \to μ^{+} n$ scattering on the hydrogen atom by MINERvA to place new confidence intervals on tensor and scalar neutrino-nucleon interactions: $Re C_{T} = - 1_{- 13}^{+ 14} \times 1 0^{- 4}$ , $∣ Im C_{T} ∣ \leq 1.3 \times 1 0^{- 3}$ , and $∣ Im C_{S} ∣ = 4 5_{- 19}^{+ 13} \times 1 0^{- 3}$ . These results represent a reduction in uncertainty by a factor of $2.1$ , $3.1$ , and $1.2$ , respectively, compared to existing constraints from precision beta decay.
↳ hep-phhep-exnucl-exnucl-thPLB(2024)·7 citations
12
Automated Resonance Identification in Nuclear Data Evaluation
Noah A. W. Walton · Oleksii Zivenko · William Fritsch · Jacob Forbes · Amanda Lewis · Jesse Brown · Vlad Sobes
Global and national efforts to deliver high-quality nuclear data to users have a broad impact across applications such as national security, reactor operation, basic science, medical fields, and more. Cross section evaluation is a large part this effort as it combines theory and experiment to produce suggested values and uncertainty for reaction probabilities. In most isotopes, the cross section exhibits resonant behavior in what is called the resonance region of incident neutron energy. Resonance region evaluation is a specialized type of nuclear data evaluation that can require significant, manual effort and months of time from expert scientists. In this article, non-convex, non-linear optimization methods are combined with concepts of inferential statistics to infer a set of optimized resonance models from experimental data in an automated manner that is not dependent on prior evaluation(s). This methodology aims to enhance the workflow of a resonance evaluator by minimizing time, effort, and prior biases while improving reproducibility and document-ability, addressing widely recognized challenges in the field.
↳ physics.comp-phnucl-thNucl.Sci.Eng.(2025)·3 citations
13
Finite-energy sum rules at finite chemical potential and zero temperature
Alfredo Raya🇲🇽 · Cristian Villavicencio🇨🇱
In this article we explore the effect of chemical potential at zero temperature in the implementation of in-medium effects in the perturbative sector in finite energy sum rules. For this purpose, we explore the axial, axial-pseudoscalar and pseudoscalar current correlators involving charged pions. The inclusion of non-normal ordered condensates with chemical potential effects in the operator mixing is considered. As a result, the contribution of the operator mixing with chemical potential dependence cancels all the explicit chemical potential contribution of the perturbative sector, aligned with the so-called "silver blaze problem". We find an abrupt transition when $μ = s_{0} /2$ , with $s_{0}$ representing the hadronic continuum threshold. Exploring beyond this critical chemical potential we found similarities with low-energy effective meson models at high chemical potential.
↳ hep-phnucl-thEPJC(2025)·0 citations
14
Radiative Corrections in Super Rosenbluth Experiments
Quinn Stefan🇺🇸 · Axel Schmidt🇺🇸
Super Rosenbluth experiments, elastic electron-proton scattering experiments that eschew traditional electron detection and opt instead for the detection of the recoiling proton, have several experimental advantages. One claimed advantage is that radiative corrections are more favorable, i.e., smaller and with less kinematic dependence. In this paper, we explore this claim by conducting Monte Carlo simulations of both Super Rosenbluth and traditional Rosenbluth experiments with different models of radiative effects. When using a model that employs the peaking approximation, we indeed confirm the reduced kinematic dependence of the radiative corrections. However, we find that more sophisticated models that avoid the peaking approximation are unable to produce numerically stable results, due to a large enhancement to the cross section for bremsstrahlung radiation from the proton when the momentum transfer, $Q^{2}$ , approaches zero. Since this enhancement is not modelled in the peaking approximation, a more robust approach to radiative corrections in Super Rosenbluth experiments is needed.
↳ hep-phnucl-exnucl-thEPJA(2024)·2 citations
15
Neutron-nucleus dynamics simulations for quantum computers
Soorya Rethinasamy🇺🇸 · Ethan Guo🇺🇸 · Alexander Wei🇺🇸 · Mark M. Wilde🇺🇸 · Kristina D. Launey🇺🇸
With a view toward addressing the explosive growth in the computational demands of nuclear structure and reactions modeling, we develop a novel quantum algorithm for neutron-nucleus simulations with general potentials, which provides acceptable bound-state energies even in the presence of noise, through the noise-resilient training method. In particular, the algorithm can now solve for any band-diagonal to full Hamiltonian matrices, as needed to accommodate a general central potential. While we illustrate the approach for exponential Gaussian-like potentials and ab initio inter-cluster potentials (optical potentials), it can also accommodate the complete form of the chiral effective-field-theory nucleon-nucleon potentials used in ab initio nuclear calculations. In this study, we provide a comprehensive analysis for the efficacy of this approach for three different qubit encodings, including the one-hot, binary, and Gray encodings, in terms of the number of Pauli strings and commuting sets involved. We also discuss the advantages of the algorithm for Hamiltonians of various band-diagonal widths, especially critical for potentials of perturbative nature, leading to a drastically reduced runtime of quantum simulations. We prove that the Gray encoding allows for an efficient scaling of the model-space size $N$ and is more resource efficient for band-diagonal Hamiltonians having bandwidth up to $N$ . We introduce a new commutativity scheme called distance-grouped commutativity (DGC) and compare its performance with the well-known qubit-commutativity (QC) scheme. We lay out the explicit grouping of Pauli strings and the diagonalizing unitary under the DGC scheme, and we prove that it outperforms the QC scheme, at the cost of a more complex diagonalizing unitary. Lastly, we provide first solutions of the neutron-alpha dynamics from quantum simulations suitable for current quantum processors.
↳ quant-phnucl-thQuantum Sci.Technol.(2026)·7 citations
16
Towards the quark mass dependence of $T_{cc}^{+}$ from lattice QCD
Sara Collins🇩🇪 · Alexey Nefediev🇸🇮 · M. Padmanath🇮🇳 · Sasa Prelovsek🇸🇮
The $D D^{*}$ scattering phase shifts in the $T_{cc}^{+} = cc u ˉ d ˉ$ channel are extracted from lattice QCD for five different charm quark masses and a fixed light-quark mass corresponding to $m_{π} ≃ 280$ ~MeV. The phase shifts are analysed employing two approaches: effective range expansion and Lippmann--Schwinger equation derived in the effective field theory. In the latter case, the results imply an attraction at short range parametrised by contact terms and a slight repulsion at long range mediated by one-pion exchange with $m_{π} > m_{D^{*}} - m_{D}$ . The poles in the amplitude across the complex energy plane are extracted and their trajectories are discussed as the charm quark mass is varied. Two complex conjugate poles corresponding to a resonance below threshold are found for $m_{c}$ close to the physical value. They turn into a pair of virtual states at the largest $m_{c}$ studied. With further increasing $m_{c}$ , one virtual pole representing $T_{cc}^{+}$ is expected to move towards the two-body threshold and turn into a bound state. The light-quark mass dependence of the $T_{cc}^{+}$ pole is briefly discussed using the data on $D D^{*}$ scattering from other lattice collaborations.
↳ hep-lathep-phnucl-thPRD(2024)·69 citations
17
TMD factorisation for diffractive jets in photon-nucleus interactions
S. Hauksson🇫🇷 · E. Iancu🇫🇷 · A.H. Mueller🇺🇸 · D.N. Triantafyllopoulos🇮🇹 · S.Y. Wei🇨🇳
Using the colour dipole picture and the colour glass condensate effective theory, we study the diffractive production of two or three jets via coherent photon-nucleus interactions at high energy. We consider the hard regime where the photon virtuality and/or the transverse momenta of the produced jets are much larger than the saturation momentum $Q_{s}$ of the nuclear target. We show that, despite this hardness, the leading-twist contributions are controlled by relatively large parton configurations, with transverse sizes $R \sim 1/ Q_{s}$ , which undergo strong scattering and probe gluon saturation. For exclusive dijets, this implies that both final jets have semi-hard transverse momenta ( $P_{⊥} \sim Q_{s}$ ) and that one of them is aligned with the photon. The dominant contributions to the diffractive production of hard dijets ( $P_{⊥} ≫ Q_{s}$ ) rather come from three-jet final states, which are very asymmetric and will be referred to as 2+1 jets: two of the jets are hard, while the third one is semi-hard. We demonstrate that the leading-twist contributions to both exclusive dijets and the diffractive production of 2+1 jets admit transverse-momentum dependent (TMD) factorisation, in terms of quark and gluon diffractive TMD distribution functions, for which we obtain explicit expressions from first principles. We show that the contribution of 2+1 jets to diffractive SIDIS (semi-inclusive deep inelastic scattering) takes the form of one step in the DGLAP evolution of the quark diffractive PDF.
↳ hep-phnucl-thJHEP(2024)·27 citations
18
Generalized eikonal identities for charged currents
Ryan Plestid🇺🇸
We discuss QED radiative corrections to contact operators coupling two heavy fields and one light field. New eikonal identities are derived in the static limit that demonstrate the equivalence of a class of ladder graphs to an equivalent theory with a single heavy-light vertex and a background Coulomb field which communicates exclusively with the light field. We apply these new identities to nuclear beta decays and demonstrates that the "independent particle model" used by Jaus, Rasche, Sirlin \& Zucchini is closely related, though not identical, to a model independent EFT calculation.
↳ hep-phhep-thnucl-thJHEP(2024)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE