Nuclear Theory·nucl-th

Wednesday·July 8, 2026

9 papers—7 primary·2 cross-listed

01
Deuterium-Proton Fusion in an Effective Field Theory Constructed from On-Shell Amplitudes
Tim M.P. Tait (University of California, Irvine)
Big Bang nucleosynthesis (BBN) predicts the primordial deuterium abundance to a precision now limited by the nuclear reactions that burn deuterium. For the simplest of them, proton-deuteron radiative capture, d + p -> \gamma + 3He [d(p,\gamma)3He], the precise LUNA data sit below the ab initio benchmark, and BBN reaction networks split on which to adopt. We develop an effective field theory (EFT) expanding in the finite size of the nuclei, building the amplitude with modern on-shell methods that enumerate every tree-level structure consistent with symmetries without the need for an explicit Lagrangian. A global Bayesian fit to the capture data and nuclear-theory priors returns S(0) = 0.209 +/- 0.008 eV b and traces the offset from the ab initio benchmark to a single natural-sized next-to-leading contact term (t_E1 ~ -0.15, the fractional shift of the electric-dipole amplitude) -- equivalently a ~15% lower effective 3He asymptotic normalization. We estimate the leading EFT truncation errors and identify an elastic d-p observable that would separate them. Our results suggest that amplitude methods enable systematic and complete tree-level construction and matching of EFTs for low-energy nuclear reactions.
nucl-thastro-ph.COhep-phhep-th1 citation
02
Full configuration interaction quantum Monte Carlo for accurate $ab initio$ nuclear structure calculations: algorithms and calculation details
Rongzhe Hu · Furong Xu · Baishan Hu · Ali Alavi
Full configuration interaction quantum Monte Carlo (FCIQMC) is a stochastic many-body solver that has been widely applied to electronic, molecular, and condensed-matter systems. In this work we apply FCIQMC to $ab initio$ nuclear structure calculations using interactions derived from chiral effective field theory. We describe the algorithm in detail, including imaginary-time propagation, excitation generation, estimator choices, the initiator approximation with adaptive shift correction, and reduced-density-matrix (RDM) sampling. Benchmark calculations in small model spaces, where deterministic full configuration interaction (FCI) results are available, validate the stochastic calculation of energies, radii, and RDM-based pure estimators. For large model spaces, we analyze the residual finite-walker bias through systematic walker-number convergence and infinite-walker extrapolations. We also demonstrate that FCIQMC can be extended beyond ground-state calculations by computing the low-lying spectrum of $^{6}$ Li.
nucl-thnucl-ex0 citations
03
Can average speed of sound and thermodynamic response functions signal the exotic phases in neutron star cores?
Suman Pal🇮🇳 · Gargi Chaudhuri🇮🇳
The speed of sound in dense nuclear matter is crucial for understanding neutron star structure and constraining the EOS. We have discussed in details the decomposition of speed of sound via the average speed of sound and its logarithmic derivative and have connected it to the other two decomposition schemes via slope and curvature of the energy per particle or through the normalized trace anomaly and its derivative. These thermodynamic variables provide important diagnostic tools for the composition of the inner core of the compact stars. We discuss a new method of understanding phase transition and the microphysics of dense matter through the thermodynamic response functions like isothermal compressibility, baryon number susceptibility and bulk modulus in order to distinguish between local (sharp interface) and global charge (mixed phase) neutrality conditions, thereby revealing the signatures of the phase transition. The corresponding neutron-star mass--radius relations demonstrate that all considered equations of state satisfy current astrophysical constraints, while the most massive stable configurations contain either an extended mixed phase or a quark core depending on the phase-transition construction.
nucl-thEPJC(2026)·0 citations
04
Nonlinear Causality and Strong Hyperbolicity of Einstein-Israel-Stewart Theories of Transient Relativistic Fluid Dynamics
Ian Cordeiro🇺🇸 · Enrico Speranza🇮🇹 · Fábio S. Bemfica🇺🇸 · Marcelo M. Disconzi🇺🇸 · Jorge Noronha🇺🇸
We present the first complete analysis of nonlinear causality and local well-posedness for a very general class of bulk and shear viscous theories of relativistic transient fluid dynamics, which encompasses (i) the original Israel-Stewart theory derived from entropy-current arguments, (ii) approaches derived from kinetic theory, and (iii) resummed gradient-expansion based formulations as particular subcases. Our work establishes, for the first time, simultaneously necessary and sufficient algebraic conditions for causality, alongside sufficient conditions guaranteeing strong hyperbolicity, in the full nonlinear regime. These results are rigorously proven for both systems coupled to Einstein's equations featuring a dynamic metric and on a fixed background, with or without a cosmological constant, and include baryon conservation (in the absence of heat/diffusion currents). The conditions are purely algebraic, require no simplifying spacetime symmetry assumptions or a specific equation of state, and allow all transport coefficients to depend on the dissipative currents. We also demonstrate that the normalization, orthogonality, symmetry, and tracelessness physical constraints on the dynamical variables are properly propagated during the lifetime of the solutions. Our results provide a readily usable toolset with which one can investigate the domain of applicability of relativistic viscous fluid dynamics in numerical and phenomenological studies in heavy-ion collisions and astrophysics.
nucl-thastro-ph.HEgr-qc0 citations
05
Self-consistent description of emission processes in axially-symmetric nuclei
A. Dumitrescu · D. S. Delion
We present a theory of cluster emission processes in terms of proton ( $π$ ) and neutron ( $ν$ ) single--particle (sp) degrees of freedom within a self--consistent mean--field (SCMF) constructed from a two--particle interaction having relative (rel) and center of mass (com) terms centered on the nucler surface, the latter describing the interaction between the com of a pair of particles and the surface of an axially--symmetric nucleus. In this way the $α$ -clustering phenomenon becomes enhanced on the nuclear surface. We present applications for unstable nuclei that decay through the emission of $α$ --particles above $^{100} Sn$ , $^{208} Pb$ and within the actinidies series.
nucl-th0 citations
06
Full Uncertainty Quantification of Sign-Problem-Free Quantum Monte Carlo Methods and Nuclear Lattice Effective Field Theory Benchmarks
Zhong-Wang Niu · Bing-Nan Lu · Shuang Zhang · Yuan-Zhuo Ma · Serdar Elhatisari · Dean Lee · Ulf-G. Meißner
Sign-problem-free quantum Monte Carlo (QMC) methods provide one of the few polynomial-scaling routes to controlled, nonperturbative benchmarks of medium-mass and heavy nuclei. We present a detailed uncertainty analysis of the recently developed sign-problem-free spin-orbit lattice action LAT-OPT1 and use it to benchmark nuclear lattice effective field theory (NLEFT). We quantify various systematic uncertainties, finding that the cumulative many-body computational uncertainty in ground-state energies of doubly magic nuclei up to $^{100}$ Sn is well below the percent level. In response to recent criticism of NLEFT benchmarks, we also revisit the relation between lattice transfer matrices, lattice Hamiltonians, Hartree--Fock variational bounds, finite-box and thermodynamic-limit calculations, and the continuum-limit behavior of regulated lattice interactions. We identify several conceptual and technical errors in the analysis of Ref.~\cite{Rothman2026_NuLattice}. These include (i) the comparison of inequivalent lattice transfer-matrix and lattice-Hamiltonian calculations, (ii) an inconsistent determination of correlation energies from comparisons of Hartree--Fock and full ground-state calculations with different boundary conditions, (iii) the attribution of nuclear saturation to lattice artifacts rather than to nonlocal smearing of interactions, a mechanism that can be demonstrated in continuous space, and (iv) an incorrect renormalization of short-range two-body interactions in the continuum limit. When the same regulated lattice theory, renormalization prescription, and finite-volume boundary conditions are used consistently and analyzed properly, the reported discrepancies and concerns about the corresponding published NLEFT results are resolved.
nucl-th0 citations
07
Bottomonium production in an open quantum system approach with interactions from lattice quantum chromodynamic
Shuhan Zheng🇨🇳 · Shuzhe Shi🇨🇳
Bottomonium production in Pb-Pb collisions at $s_{N N} = 5.02$ TeV is studied using a Lindblad master equation derived from potential non-relativistic quantum chromodynamics (QCD), where quantum regeneration of color-singlet states is matched to the lattice QCD imaginary potential via collapse operators. Two parametrizations of the in-medium heavy-quark potential, both constrained by lattice QCD data, are employed to compute the nuclear modification factors of $Υ (1 S)$ , $Υ (2 S)$ , and $Υ (3 S)$ . The results show sensitivities to both the quantum regeneration effect and the initial condition of the density matrix. The dipole transitions in the collapse operators are found to significantly redistribute populations among different orbital angular momentum channels. It is shown that regeneration is more important when a potential with a larger imaginary part, i.e., stronger transitions between singlet and octet states, is used.
nucl-th0 citations
08
Interplay between Nuclear Shell Structure and Pairing around Doubly Magic $^{132}$ Sn
Rane Simpson · Georgios Palkanoglou · Ellen Brisley · Jaime Cardona · Annabelle Czihaly · Sakshi Kakkar · Makar Simonov · Ethan Taylor · Coulter Walls · Pavithra Weligampola · Chris Chambers · Fernando Maldonado Millan and 11 other authors
Shell structure in finite quantum systems gives rise to sudden changes in observable properties, while pairing correlations often compete against such discontinuities. The region near the doubly magic nucleus $^{132}$ Sn provides a fertile ground for testing the combined effect of shell structure and pairing. Here, we provide a novel phenomenological interpretation of existing mass data in the vicinity of the $Z = 50$ and $N = 82$ shell closures, which we further investigate by performing original Hartree-Fock-Bogolyubov (HFB) mean-field calculations for even- $Z$ nuclei: we find that the proton shell structure enhances an asymmetry of the neutron odd-even staggering in binding energies. We also report mass measurements of $^{137, 138}$ Sb, including the first experimental mass determination of $^{138}$ Sb, performed using TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN). Together with existing experimental data, our results reveal an interplay between shell structure and pairing in odd- $Z$ nuclei which is more challenging to interpret phenomenologically or using HFB, thereby motivating future experimental and theoretical pairing studies in heavy neutron-rich nuclides.
↳ nucl-exnucl-th1 citation
09
Quantum decoherence: a study applied to quarkonium-like bound states in strongly interacting matter
Gabriele Coci🇮🇹 · Salvatore Plumari🇮🇹 · Giuseppe Falci🇮🇹
We study the quantum decoherence of a bound state interacting with a reservoir of strongly interacting matter within the framework of open quantum systems. The bound state is modeled as a quantum harmonic oscillator whose parameters are tuned to reproduce the root-mean-square radius of $J /Ψ$ particle. The surrounding medium, representing the many degrees of freedom of strongly interacting matter, acts as an environment that induces dissipation and decoherence through system-reservoir coupling. By analyzing the time evolution of the reduced density matrix, we quantify the loss of quantum coherence and its dependence on medium properties. Subsequently, we extend the model by introducing a time dependence in the system-thermal bath coupling, thereby simulating a temperature evolution similar to that occurring during the expansion of a fireball in the central region of heavy-ion collisions. We find that a temperature evolution has a relevant impact on the way the system loses coherence through the coupling with the expanding medium. Finally, we estimate the impact of the time-dependent temperature on the decoherence process, also analyzing a scenario that includes viscous effects without finding a significant change with respect to ideal hydrodynamical evolution.
↳ hep-phnucl-thquant-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE