Nuclear Theory·nucl-th

Friday·February 7, 2025

17 papers—4 primary·13 cross-listed

01
Emulators for Scarce and Noisy Data: Application to Auxiliary-Field Diffusion Monte Carlo for Neutron Matter
Cassandra L. Armstrong · Pablo Giuliani · Kyle Godbey · Rahul Somasundaram · Ingo Tews
Understanding the equation of state (EOS) of pure neutron matter is necessary for interpreting multimessenger observations of neutron stars. Reliable data analyses of these observations require well-quantified uncertainties for the EOS input, ideally propagating uncertainties from nuclear interactions directly to the EOS. This, however, requires calculations of the EOS for a prohibitively large number of nuclear Hamiltonians, solving the nuclear many-body problem for each one. Quantum Monte Carlo methods, such as auxiliary-field diffusion Monte Carlo (AFDMC), provide precise and accurate results for the neutron matter EOS, but they are very computationally expensive, making them unsuitable for the fast evaluations necessary for uncertainty propagation. Here, we employ parametric matrix models to develop fast emulators for AFDMC calculations of neutron matter and use them to directly propagate uncertainties of coupling constants in the Hamiltonian to the EOS. As these uncertainties include estimates of the effective field theory truncation uncertainty, this approach provides robust uncertainty estimates for use in astrophysical data analyses. This Letter will enable novel applications such as using astrophysical observations to put constraints on coupling constants for nuclear interactions.
nucl-thPRL(2025)·27 citations
02
Radii of light nuclei from the Jacobi No-Core Shell Model
Xiang-Xiang Sun · Hoai Le · Ulf-G. Meißner · Andreas Nogga
Accurately determining the size of the atomic nucleus with realistic nuclear forces is a long outstanding issue of nuclear physics. The no-core shell model (NCSM), one of the powerful ab initio methods for nuclear structure, can achieve accurate energies of light nuclei. The extraction of converged radii is more difficult. In this work, we present a novel method to effectively extract the radius of light nuclei by restoring the long-range behavior of densities from NCSM calculations. The correct large distance asymptotic of two-body relative densities are deduced based on the NCSM densities in limited basis size. The resulting radii using the corrected densities show a nice convergence. The root-mean-square matter and charge radii of $^{4, 6, 8}$ He and $^{6, 7, 8}$ Li can be accurately obtained based on Jacobi-NCSM calculations with the high-precision chiral two-nucleon and three-nucleon forces combined with this new method. Our method can be straightforwardly extended to other ab initio calculations, potentially providing a better description of nuclear sizes with realistic nuclear forces.
nucl-thPRC(2025)·6 citations
03
Three-body structures of low-lying nuclear states of $^{8}$ Li
E. Garrido · A.S. Jensen
The four nucleons in $^{8}$ Li outside the $α$ -particle ( $α =^{4}$ He) can be divided into pairs of one neutron ( $n$ ) and 3 nucleons in the triton ( $t =^{3}$ H), or 2 in the deuteron ( $d =^{2}$ H) and two neutrons in a dineutron ( $^{2} n$ ). The corresponding three-body structures, $α$ + $t$ + $n$ or $α$ + $d$ + $^{2} n$ , are suggested to describe the bulk part of the low-energy ( $< 10$ ~MeV) states of $^{8}$ Li. Several breakup thresholds influence the structures and possible decays. We calculate the three-body structures of the various $J^{π}$ states, where different clustering appear, e.g. $^{7}$ Li*+ $n$ , $^{6}$ Li* $+^{2} n$ , $^{6}$ He* $+ d$ . The experimental $^{8}$ Li spectrum can be reproduced with fine tuning by a three-body potential parameter. Three unobserved $0^{+}$ and an excited 2 $^{+}$ states are found. All states appear as bound states or resonances. The lowest or highest energies have cluster structures, $α$ + $t$ + $n$ or $α$ + $d$ + $^{2} n$ , respectively. We give calculated energy and width (if possible), geometry, and partial wave decomposition for all states.
nucl-thnucl-exPRC(2025)·1 citation
04
Exploring the limits of nucleonic metamodelling using different relativistic density functionals
Prasanta Char · Chiranjib Mondal
In this work, we explore two classes of density dependent relativistic mean-field models, their predictions of proton fractions at high densities and neutron star structure. We have used a metamodelling approach to these relativistic density functionals. We have generated a large ensemble of models with these classes and then applied constraints from theoretical and experimental nuclear physics and astrophysical observations. We find that both models produce similar equations of state and neutron star mass-radius sequences. But, their underlying compositions, denoted by the proton fraction in this case, are vastly different. This reinstates previous findings that information on composition gets masqueraded in $β$ -equilibrium. Additional observations of non-equilibrium phenomena are necessary to pin it down.
nucl-thastro-ph.HEPRD(2025)·12 citations
05
Developing techniques for Simulation of SU(3) Quantum Field Theories on State-of-the-Art Quantum Devices
Ivan Chernyshev
Quantum computing has long been an experimental technology with the potential to simulate, at scale, phenomena which on classical devices would be too expensive to simulate at any but the smallest scales. Over the last several years, however, it has entered the NISQ era, where the number of qubits are sufficient for quantum advantage but substantial noise on hardware stands in the way of this achievement. This thesis details NISQ device-centered improvements to techniques of quantum simulation of the out-of-equilbrium real-time dynamics of lattice quantum chromodynamics (LQCD) and of dense 3-flavor neutrino systems on digital quantum devices. The first project concerning LQCD is a comparison of methods for implementing the variational quantum eigensolver (VQE) that initializes the ground state of an SU(3) plaquette-chain. The thesis then pivots to a 1+1D lattice of quarks interacting with an SU(3) gauge-field. A VQE-based state-preparation for the vacua and a Trotterized time-evolution circuit is designed and applied to the problems of simulating beta and neutrinoless double beta decay. Finally, these circuits are adapted to a version useable on quantum devices with nearest-neighbor connectivity with minimal overhead, with an eye towards utilizing the higher qubit count of such devices for hadron dynamics and scattering. This thesis covers two projects that concern dense 3-flavor neutrino systems. The first details design and testing of Trotterized time-evolution circuits on state-of-the-art quantum devices. The second, motivated by the Gottesman-Knill theorem's result that deviation from stabilizer states ("magic") is necessary for a problem to exhibit quantum advantage, details results with implications for the Standard Model in general that the 3 flavor ultradense neutrino systems with the highest, most-persistent magic are those that start with neutrinos in all 3 flavors.
↳ quant-phhep-latnucl-th2 citations
06
Small- $x$ factorisation in the target fragmentation region
Paul Caucal🇫🇷 · Farid Salazar🇺🇸
We consider the differential cross-section for single-inclusive jet production with transverse momentum $P_{⊥}$ in Deep Inelastic Scattering (DIS) at small Bjorken $x_{Bj}$ , mediated by a virtual photon with virtuality $Q^{2}$ . Unlike most studies at small $x$ , which focus on particle production in the current fragmentation region, we investigate the kinematic regime where the jet is produced in the target fragmentation hemisphere of the Breit frame, and with $P_{⊥} ≪ Q$ . For a longitudinally polarised photon, we demonstrate that this cross-section is not power suppressed in $P_{⊥} / Q$ and we derive a factorised expression in terms of extended quark and gluon jet fracture functions. Our formula, valid at next-to-leading order in $α_{s}$ at small $x$ , is akin to the Altarelli-Martinelli identity for the longitudinal DIS structure function. Numerical estimates show that the extended quark jet fracture function is the most sensitive to saturation effects in large nuclei.
↳ hep-phnucl-thPRL(2026)·13 citations
07
Theory of resonances
Maxim Mai🇨🇭
We give a pedagogical introduction to the theory of resonances, focusing specifically on the spectrum of excited strongly interacting particles. After providing historical context starting from the atomic theory, we summarize the status of theoretical and experimental research. We discuss then the methodology to determine universal resonance parameter through the analytical properties of the transition amplitudes. For this, the main aspects of the $S$ -matrix theory are introduced including some explicit calculations in simplified cases. In the last section, we summarize several frequently used amplitude types also making a connection to Effective Field Theories, as well as provide first glimpse into some more advanced applications to further resonance properties.
↳ hep-phnucl-th13 citations
08
Bremsstrahlung photon contributions to parton energy loss at high virtuality ( $Q^{2}$ ) : a perturbative calculation at $O (α_{s} α_{e m})$
Amit Kumar🇨🇦 · Gojko Vujanovic🇨🇦
In this work, real photon production scattering kernels from jet-medium interactions in the QCD medium are perturbatively calculated using the higher-twist (HT) formalism. Focus is given towards real photon production from a highly virtual (and highly energetic) quark, taking into account heavy-quark mass scales [Phys. Rev. C 94, 054902 (2016)], fermion-boson conversion processes [Nucl. Phys. A 793, 128 (2007)], as well as coherence effects [Phys. Rev. C 105, 024908 (2022)]. A generalized factorization procedure, such as that used in e-A deep-inelastic scattering, is employed to derive an improved single-scattering medium-induced photon emission kernels that go beyond the traditional in-medium gluon exchange approximation. Diagrams with real-photon emission from the hard quark are classified based on the final-state particles, and include two types of scattering kernels at $O (α_{e m} α_{s})$ giving the following final states: (i) real photon and real quark, (ii) real photon and real gluon. The collisional kernels, thus derived, include full phase factors from all non-vanishing diagrams and complete second-order derivative terms in the transverse momentum gradient expansion. Moreover, the calculation includes heavy-quark mass effects, thus exploring heavy-quark energy loss. The in-medium parton distribution functions and the related jet transport coefficients have a hard transverse momentum dependence (of the emitted gluon or photon) present within the phase factor. It is observed that the jet transport coefficients resemble the transverse-momentum-dependent parton distribution functions.
↳ hep-phnucl-exnucl-thPRC(2025)·4 citations
09
Baryon-Electric Charge Correlations and Chemical Potentials as Probes of Magnetized QCD
Heng-Tong Ding🇨🇳 · Jin-Biao Gu🇨🇳 · Arpith Kumar🇨🇳 · Sheng-Tai Li🇨🇳 · Jun-Hong Liu🇨🇳
We present the first lattice QCD results of quadratic fluctuations and correlations of conserved charges in (2+1)-flavor lattice QCD in the presence of a background magnetic field. The simulations were performed using the Highly Improved Staggered Quarks with physical pion mass $m_{π}$ = 135 MeV on $N_{τ} = 8$ and 12 lattices. We find that the correlation between net baryon number and electric charge, denoted as $χ_{11}^{BQ}$ , can serve as a magnetometer of QCD. At pseudocritical temperatures ( $T_{p c}$ ) the $χ_{11}^{BQ}$ starts to increase rapidly with magnetic field strength $e B ≳ 2 M_{π}^{2}$ and by a factor 2 at $e B ≃ 8 M_{π}^{2}$ . By comparing with the hadron resonance gas model, we find that the $e B$ dependence of $χ_{11}^{BQ}$ is mainly due to the doubly charged $Δ$ (1232) baryon. Although the doubly charged $Δ$ (1232) could not be detected experimentally, its decay products, protons and pions, retain the $e B$ dependence of $Δ$ (1232)'s contribution to $χ_{11}^{BQ}$ . Furthermore, the ratio of electric charge chemical potential to baryon chemical potential, $μ_{Q} / μ_{B}$ , shows significant dependence on the magnetic field strength and varies with the ratio of electric charge to baryon number in the colliding nuclei in heavy ion collisions. These results provide baselines for effective theory and model studies, and both $χ_{11}^{BQ}$ and $μ_{Q} / μ_{B}$ could be useful probes for the detection of magnetic fields in relativistic heavy ion collision experiments as compared with corresponding results from the hadron resonance gas model.
↳ hep-lathep-exhep-phnucl-thPoS(2025)·4 citations
10
Extraordinary nature of the nucleon scalar charge and its densities as a signal of nontrivial vacuum structure of QCD
Masashi Wakamatsu🇯🇵
It is widely known that the nucleon scalar charge is proportional to the pion-nucleon sigma term as one of the important low energy observables of QCD. Especially interesting to us is the physics of the nucleon scalar charge densities. This comes from the fact that the corresponding operator has the same quantum number as the physical vacuum. It indicates unusual behavior of the the nucleon scalar density as a function of the distance $r$ from the nucleon center. Namely, it would not be reduced down to zero at the spatial infinity but rather approaches some nonzero constant corresponding to the vacuum quark condensate. Naturally, this unique nature of the nucleon scalar density in the position space also affects the corresponding density in the momentum space, i.e. the corresponding parton distribution function (PDF) as a function of the Bjorken variable $x$ . This PDF is known as the chiral-odd twist-3 PDF $e (x)$ . We argue that $e (x)$ is likely to have a delta-function type singularity at $x = 0$ , and that the appearance of this singularity can be interpreted as a signal of the nontrivial vacuum structure of the QCD.
↳ hep-phhep-exhep-latnucl-thSymmetry(2024)·3 citations
11
Multidisciplinary Science in the Multimessenger Era
Eric Burns · Christopher L. Fryer · Ivan Agullo · Jennifer Andrews · Elias Aydi · Matthew G. Baring · Eddie Baron · Peter G. Boorman · Mohammad Ali Boroumand · Eric Borowski · Floor S. Broekgaarden · Poonam Chandra and 73 other authors
Astrophysical observations of the cosmos allow us to probe extreme physics and answer foundational questions on our universe. Modern astronomy is increasingly operating under a holistic approach, probing the same question with multiple diagnostics including how sources vary over time, how they appear across the electromagnetic spectrum, and through their other signatures, including gravitational waves, neutrinos, cosmic rays, and dust on Earth. Astrophysical observations are now reaching the point where approximate physics models are insufficient. Key sources of interest are explosive transients, whose understanding requires multidisciplinary studies at the intersection of astrophysics, gravity, nuclear science, plasma physics, fluid dynamics and turbulence, computation, particle physics, atomic, molecular, and optical science, condensed matter and materials science, radiation transport, and high energy density physics. This white paper provides an overview of the major scientific advances that lay at the intersection of physics and astronomy and are best probed through time-domain and multimessenger astrophysics, an exploration of how multidisciplinary science can be fostered, and introductory descriptions of the relevant scientific disciplines and key astrophysical sources of interest.
↳ astro-ph.HEgr-qcnucl-exnucl-th+16 citations
12
Higgs Thermal Nonequilibrium in Primordial QGP
Cheng Tao Yang🇺🇸 · Shelbi Foster🇺🇸 · Johann Rafelski🇺🇸
In this work we investigate the chemical and kinetic nonequilibrium dynamics of the Higgs boson during the primordial Universe QGP (quark-gluon plasma) epoch $130 GeV > T > 10 GeV$ . We show that the Higgs bosons is always out of chemical abundance equilibrium with a fugacity $Υ_{h} = 0.69$ due to virtual decay channels. Additionally, Higgs momentum distribution is found to be ``cold'' for $T < 25$ \,GeV, since the scattering rate drops below the production rate.
↳ hep-phastro-ph.COnucl-thEur.Phys.J.ST(2025)·1 citation
13
First-order CP phase transition in two-flavor QCD at $θ = π$ under electromagnetic scale anomaly via a Nambu-Jona-Lasinio description
Yuanyuan Wang🇨🇳 · Shinya Matsuzaki🇨🇳 · Mamiya Kawaguchi🇨🇳 · Akio Tomiya🇯🇵
We discuss the thermal CP phase transition in QCD at $θ = π$ under a weak magnetic field background, where the electromagnetic scale anomaly gets significant. To explicitize, we work on a two-flavor Nambu-Jona-Lasinio model at $θ = π$ in the mean field approximation, including the electromagnetic-scale anomaly term. We find that the thermal CP phase transition becomes first order and the strength of the first order gets more prominent as the magnetic field increases. The associated potential barrier is thermally created by the electromagnetic scale anomaly and gives rise to criticality due to the induced potential of a non-perturbative form $\sim \frac{∣ e B ∣ ^{3}}{f _{π}} \frac{∣ P ∣}{P ^{2} + m _{0}^{2}}$ , where $e B$ denotes the magnetic field strength; $P$ the CP order parameter, and $m_{0}$ the isospin-symmetric current-quark mass.
↳ hep-phhep-lathep-thnucl-thPRD(2025)·1 citation
14
Renormalization group invariant mean-field model for QCD at finite isospin density
Bastian B. Brandt🇩🇪 · Volodymyr Chelnokov🇩🇪 · Gergely Endrodi🇩🇪 · Gergely Marko🇩🇪 · Daniel Scheid🇩🇪 · Lorenz von Smekal🇩🇪
QCD at nonzero isospin chemical potentials has phenomenological relevance for a series of physical systems and provides an ideal testground for the modeling of dense strongly interacting matter. The two-flavor quark-meson model is known to effectively describe the condensation of charged pions in QCD that occurs in this setting. In this paper, we derive a renormalization-group invariant mean-field formulation of the model and demonstrate that the resulting phase diagram and equation of state are in quantitative agreement with data from lattice QCD simulations at small and intermediate isospin chemical potentials. In particular, the speed of sound from the model shows an excess over the conformal bound as previously seen in lattice computations in agreement with chiral perturbation theory. We then consider the speed of sound in the limit of large isospin chemical potentials and see that it approaches the conformal limit from above, in qualitative agreement with recent lattice results and in quantitative agreement with perturbation theory in the presence of a BCS gap. Finally, we consider the phase diagram in the approach to the chiral limit. We find that within the model the chiral phase transition connects to the pion condensation phase boundary in the chiral limit and we discuss the implications for the properties of the chiral transition point.
↳ hep-phhep-latnucl-thPRD(2025)·24 citations
15
Absence of CP Violation in the Strong Interaction: Vacuum thwarts Axion
Gerrit Schierholz🇩🇪
QCD admits a contribution to the action, the $θ$ term, which potentially gives rise to nontrivial phases and violates CP. This is essentially a question of how the vacuum reacts to the $θ$ term. In this talk I will address the problem using new developments on the lattice. The overall solution is contrasted with the axion `solution'.
↳ hep-lathep-phhep-thnucl-thPoS(2025)·4 citations
16
Landau-Khalatnikov-Fradkin Transformations in Quantum Electrodynamics: For Perturbation Theory and Dynamical Mass Generation
Anam Ashraf🇵🇰 · M. Jamil Aslam🇵🇰 · Faisal Akram🇵🇰 · Adnan Bashir🇪🇸
We carry out a comprehensive analysis of the Landau-Khalatnikov-Fradkin transformations for a charged fermion propagator at the two-loop level in quantum electrodynamics (QED). Starting with an arbitrary covariant gauge $ξ$ and space-time dimension $d$ , we provide its explicit expressions in three and four-dimensional QED. We begin with the tree-level fermion propagator in the Landau gauge and gauge-transform it to obtain an analytical expression for an all order result in an arbitrary covariant gauge. We expand it out to two-loops both for the massless and massive propagators in three and four space-time dimensions. In addition to comparing with all earlier results in the literature wherever possible, we also study constraints of multiplicative renormalizabilty of our results in four-dimensional QED which are logarithmically divergent. Finally, we analyze representative solutions of the fermion propagator which correspond to dynamical chiral symmetry breaking and mass generation in QED. We study the gauge dependence of these emergent solutions, that of the Euclidean pole mass and the chiral fermion condensate.
↳ hep-phhep-thnucl-thPRD(2025)·0 citations
17
Fundamental Oscillation Modes in Neutron Stars with Hyperons and Delta Baryons
O. P. Jyothilakshmi🇮🇳 · P. E. Sravan Krishnan🇩🇪 · V. Sreekanth🇮🇳 · Harsh Chandrakar🇮🇳 · Tarun Kumar Jha🇮🇳
For a new parameterization of the modified effective chiral model, developed primarily to regulate the density content of the symmetry energy and its higher order terms, equations of state (EoSs) for hyperon-rich matter ( $H$ ) and delta baryon matter ( $Δ$ ) were obtained. The models were used to investigate the emission of gravitational waves (GWs) through $f$ -mode oscillations in the corresponding neutron stars. We obtained the stellar structure, $f$ -mode frequency and tidal deformability $Λ$ for our models. We report that the $Δ$ EoS is stiffer compared to the $H$ EoS. We also analyzed the velocity of sound in these media. The corresponding mass--radius relationships were obtained and compared with various observations. We studied the dependence of $f$ -mode frequencies on the stellar mass, redshift and tidal deformability. We employed the well known Cowling approximation to obtain the $f$ -mode frequencies for $l = 2, 3$ and $4$ modes of oscillation. We found that the $f$ -mode frequencies of the $H$ and $Δ$ EoSs were almost the same in the lower mass region, while we observed a substantial difference between them in the high-mass region. We also obtained an empirical relation for the EoSs considered. The various attributes obtained for our models showed close agreement with various observational constraints from pulsars and GW events.
↳ astro-ph.HEnucl-thSymmetry(2025)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE