Nuclear Theory·nucl-th

Wednesday·October 2, 2024

19 papers—7 primary·12 cross-listed

01
Low-energy enhancement of the magnetic dipole radiation in odd-mass lanthanides
D. DeMartini🇺🇸 · Y. Alhassid🇺🇸
We compute the magnetic dipole (M1) $γ$ -ray strength functions ( $γ$ SF) for the odd-mass lanthanides $^{143 - 151}$ Nd and $^{147 - 153}$ Sm using the shell-model Monte Carlo method in combination with the static-path approximation and the maximum-entropy method. In particular, we quantify the statistical uncertainties in the calculated M1 $γ$ SFs and show that they are under control for the excitation energies relevant to the experiments despite a Monte Carlo sign problem that originates in the projection onto an odd number of neutrons. We identify a low-energy enhancement (LEE) in the M1 $γ$ SFs of these odd-mass lanthanides, which was recently observed experimentally in some of them. We also find a scissors mode resonance (SR) in the strongly deformed isotopes. We observe that the decrease in the LEE strength with neutron number along an isotopic chain is compensated for by an increase in the SR strength in the deformed nuclei. We compare our results with recent experiments.
nucl-thPRC(2025)·4 citations
02
Inferring three-nucleon couplings from multi-messenger neutron-star observations
Rahul Somasundaram🇺🇸 · Isak Svensson🇩🇪 · Soumi De🇺🇸 · Andrew E. Deneris🇺🇸 · Yannick Dietz🇩🇪 · Philippe Landry🇨🇦 · Achim Schwenk🇩🇪 · Ingo Tews🇺🇸
Understanding the interactions between nucleons in dense matter is an important challenge in theoretical physics. Effective field theories have emerged as the dominant approach to address this problem at low energies, with many successful applications to the structure of nuclei and the properties of dense nucleonic matter. However, how far into the interior of neutron stars these interactions can describe dense matter is an open question. Here, we develop a framework that enables the inference of three-nucleon couplings in dense matter directly from astrophysical neutron star observations. We apply this formalism to the LIGO/Virgo gravitational-wave event GW170817 and the X-ray measurements from NASA's Neutron Star Interior Composition Explorer and establish direct constraints for the couplings that govern three-nucleon interactions in chiral effective field theory. Furthermore, we demonstrate how next-generation observations of a population of neutron star mergers can offer stringent constraints on three-nucleon couplings, potentially at a level comparable to those from laboratory data. Our work directly connects the microscopic couplings in quantum field theories to macroscopic observations of neutron stars, providing a way to test the consistency between low-energy couplings inferred from terrestrial and astrophysical data.
nucl-thNature Commun.(2025)·24 citations
03
Magnetic Field Effects on Hadron Yields and Fluctuations
Volodymyr Vovchenko🇺🇸
We explore the impact of an external magnetic field on hadron yields and fluctuations in a thermalized system within the hadron resonance gas (HRG) model using an expanded Thermal-FIST package. The magnetic field sizably enhances the final proton-to-pion (p/ $π$ ) ratio due to $Δ (1232)^{++}$ decay feeddown indicating that this ratio may serve as a potential magnetometer for freeze-out conditions. At the same time, magnetic field does not generate additional dynamical fluctuations of hadron numbers. This suggests that fluctuations in heavy-ion collisions provide limited additional information about the magnetic field beyond what is already inferred from mean multiplicities.
nucl-thhep-phEPJ Web Conf.(2025)·0 citations
04
Vector interaction bounds in NJL-like models from LQCD estimated curvature of the chiral crossover line
Mahammad Sabir Ali🇮🇳 · Deeptak Biswas🇮🇳 · Chowdhury Aminul Islam🇩🇪
We obtain improved bounds on both the flavor-independent and -dependent vector interactions in a $2 + 1$ -flavor Nambu\textendash Jona-Lasinio (NJL) model using the latest precise LQCD results of the curvature coefficients of the chiral crossover line. We find that these lattice estimated curvature coefficients allow for both attractive and repulsive types of interactions in both the cases. With this constrained ranges of vector interactions, we further predict the behavior of the second $(κ_{2}^{B})$ and fourth $(κ_{4}^{B})$ order curvature coefficients as a function of the strangeness chemical potential $(μ_{S})$ . We observe that the flavor mixing effects, arising from the flavor-independent vector interaction as well as from the 't Hooft interaction, play an important role in $k_{2}^{B}$ . We propose that the mixing effects due to the vector interaction can be separated from those arising from the 't Hooft interaction by analyzing the behavior of $k_{2}^{B}$ as a function of $μ_{S}$ . Finally, we locate the critical endpoint in the $T - μ_{B}$ plane using the model-estimated ranges of vector interactions and find the model's predictions to be consistent with the latest LQCD bounds.
nucl-thhep-lathep-phEPJA(2025)·6 citations
05
The comparison of the state-of-the-art nucleon-nucleon potentials from phase shift to nuclear matter
Ke Nan🇨🇳 · Jinniu Hu🇨🇳 · Hong Shen🇨🇳 · Ying Zhang🇨🇳
The nucleon-nucleon ( $N N$ ) potential is the residual interaction of the strong interaction in the low-energy region and is also the fundamental input to the study of atomic nuclei. Based on the non-perturbative properties of the quantum chromodynamics (QCD), $N N$ potential is not yet directly accessible from QCD theory. Therefore, various models of $N N$ interactions have been constructed based on Yukawa's meson exchange pictures since the 1930s, including one-boson-exchange models, coordinate operator models and chiral effective field models. Analysis of extensive $N N$ scattering data has shown that the two-body nuclear force exhibits a short-range repulsion and intermediate-range attraction, and decays rapidly with increasing distance. A series of charge-dependent high-precision $N N$ interactions have been further developed in the past thirty years, such as the AV18 potential, CD-Bonn potential, pvCD-Bonn potentials, and the chiral effective nuclear potentials with momentum expansion up to the fifth order. In this work, the phase shifts at different channels, the cross sections, the entanglement entropy in spin space, and the equations of state of symmetric nuclear matter and pure neutron matter from these high-precision $N N$ interactions are calculated and systematically compared. It can be found that they have significant differences in the cases with high angular momentum, high laboratory energy, and high-density regions.
nucl-thIJMPE(2024)·3 citations
06
Mirror and triplet energy differences in $s d$ -shell nuclei using microscopic interactions with isospin-symmetry breaking effects
Chandan Sarma · Praveen C. Srivastava · Toshio Suzuki · Noritaka Shimizu
In this study, we developed and tested two different isospin symmetry-breaking (ISB) versions of the microscopic DJ16A interaction. Starting with the isospin symmetric DJ16A interaction, we introduced two different Coulomb interactions- Coulomb-CD and Coulomb-w/SRC- along with phenomenological charge symmetry breaking (CSB) and charge independence breaking (CIB) effects. Then, we employed these interactions to calculate $b$ - and $c$ -parameters of the isobaric multiplet mass equation for $∣ T_{z} ∣ = 1/2$ and $∣ T_{z} ∣ = 1$ nuclei across the $s d$ -shell. Our results indicate that the DJ16A $^{†}$ interaction provides the most accurate $b$ -parameter predictions between the two DJ16A-based interactions. Additionally, we explored mirror energy differences (MEDs) in low-energy spectra around $A = 20$ and demonstrated that large MEDs are primarily associated with high occupancies of the $1 s_{1/2}$ orbital. Furthermore, $E 2$ transition strengths were calculated using both DJ16A-based ISB interactions agreed with the experimental data, with minimal ISB effects observed on these transitions. Overall, the DJ16A $^{†}$ interaction serves as a complementary set to the newly developed USD-family interactions, USDC, and USDCm and can be further tested for other mirror nuclei across the $s d$ -shell to study nuclear structure properties and ISB effects in nuclear $β$ -decay.
nucl-thnucl-ex3 citations
07
Ab initio computations of atomic nuclei
T. Papenbrock🇺🇸
Ab initio computations of atomic nuclei, based on Hamiltonians from effective field theories of quantum chromodynamics, are now routinely used to predict and describe properties of medium heavy nuclei, and even the heavy nucleus $^{208}$ Pb has been reached. These lecture notes describe what are the central ideas and concepts behind the Hamiltonians and some of the methods that have enabled this progress.
nucl-th11 citations
08
Entanglement entropy of a color flux tube in (2+1)D Yang-Mills theory
Rocco Amorosso🇺🇸 · Sergey Syritsyn🇺🇸 · Raju Venugopalan🇺🇸
We construct a novel flux tube entanglement entropy (FTE $^{2}$ ), defined as the excess entanglement entropy relative to the vacuum of a region of color flux stretching between a heavy quark-anti-quark pair in pure gauge Yang-Mills theory. We show that FTE $^{2}$ can be expressed in terms of correlators of Polyakov loops, is manifestly gauge-invariant, and therefore free of the ambiguities in computations of the entanglement entropy in gauge theories related to the choice of the center algebra. Employing the replica trick, we compute FTE $^{2}$ for $S U (2)$ Yang-Mills theory in (2+1)D and demonstrate that it is finite in the continuum limit. We explore the properties of FTE $^{2}$ for a half-slab geometry, which allows us to vary the width and location of the slab, and the extent to which the slab cross-cuts the color flux tube. Following the intuition provided by computations of FTE $^{2}$ in (1+1)D, and in a thin string model, we examine the extent to which our FTE $^{2}$ results can be interpreted as the sum of an internal color entropy and a vibrational entropy corresponding to the transverse excitations of the string.
↳ hep-lathep-phhep-thnucl-thJHEP(2024)·22 citations
09
Accessing universal relations of binary neutron star waveforms in massive scalar-tensor theory
Alan Tsz-Lok Lam🇩🇪 · Yong Gao🇩🇪 · Hao-Jui Kuan🇩🇪 · Masaru Shibata🇩🇪 · Karim Van Aelst🇩🇪 · Kenta Kiuchi🇩🇪
We investigate how the quasi-universal relations connecting tidal deformability with gravitational waveform characteristics and/or properties of individual neutron stars that were proposed in the literature within general relativity would be influenced in the massive Damour-Esposito-Farese-type scalar-tensor gravity. For this purpose, we systematically perform numerical relativity simulations of ~120 binary neutron star mergers with varying scalar coupling constants. Although only three neutron-star equations of state are adopted, a clear breach of universality can be observed in the data sets. In addition to presenting difficulties in constructing quasi-universal relations in alternative gravity theories, we also briefly compare the impacts of non-general-relativity physics on the waveform features and those due to the first order or cross-over quantum chromodynamical phase transition.
↳ astro-ph.HEgr-qcnucl-thPRL(2025)·14 citations
10
Probing fermionic asymmetric dark matter cores using global neutron star properties
Nathan Rutherford🇺🇸 · Chanda Prescod-Weinstein🇺🇸 · Anna Watts🇳🇱
It is possible for asymmetric dark matter (ADM) to accumulate in neutron star interiors and affect their global properties. Considering the effects of this accumulation, neutron star mass-radius measurements can deliver new insights into the cold dense matter equation of state (EoS). In this paper, we employ Bayesian parameter estimation using real and synthetic neutron star mass-radius data to infer constraints on the combined baryonic matter and fermionic ADM EoS, where the fermionic ADM forms a core in the neutron star interior. Using currently available mass-radius data, we find that the lower bound of the ratio between ADM effective self-repulsion strength ( $g_{χ} / m_{ϕ}$ ) and particle mass ( $m_{χ}$ ) can be constrained at the 68\% (95\%) credible level to $1 0^{- 6.59}$ ( $1 0^{- 7.77}$ ). We also find that, if neutron star mass-radius measurement uncertainties are reduced to the 2\% level, the constraints on the lower bound of the ratio of $g_{χ} / m_{ϕ}$ to $m_{χ}$ can be improved to $1 0^{- 6.49}$ and $1 0^{- 7.68}$ at the 68\% and 95\% credible levels, respectively. However, all other combinations, of $m_{χ}$ , $g_{χ}$ , and the ADM mass-fraction, $F_{χ}$ , (i.e., the ratio of the gravitational ADM mass to the gravitational mass of the neutron star) are unconstrained. Furthermore, in the pressure-energy density and mass-radius planes, the inferences which include the possibility of fermionic ADM cores are nearly identical with the inferences that neglect fermionic ADM for $F_{χ} \leq 1.7%$ and neutron star mass-radius uncertainties $\geq 2%$ . Therefore, we find that neutron star mass-radius measurements can constrain the ratio of $g_{χ} / m_{ϕ}$ to $m_{χ}$ and that neutron stars with ADM are indistinguishable from purely baryonic stars. This implies that neutron stars with ADM are equally as consistent with the available mass-radius data as neutron stars without ADM.
↳ astro-ph.HEastro-ph.SRhep-phnucl-thPRD(2025)·29 citations
11
Unlocking higher-order moments of parton distribution functions from lattice QCD
Andrea Shindler🇩🇪
We present a new method to calculate moments of parton distribution functions of any order with lattice QCD computations. This method leverages the gradient flow for fermion and gauge fields. The flowed matrix elements of twist-2 operators renormalize multiplicatively, and the matching with physical matrix elements is achieved through the use of continuum symmetries. We derive the matching coefficients at one-loop in perturbation theory for moments of any order in the flavor non-singlet case and provide specific examples of operators suitable for lattice QCD computations. The multiplicative renormalization and matching are independent of the choice of Lorentz indices, allowing the use of temporal indices for twist-2 operators of any dimension. This approach should then also significantly enhance the signal-to-noise ratio in the computation of moments.
↳ hep-lathep-phnucl-thPoS(2025)·1 citation
12
Precise Mass Measurement of the Longest Odd-Odd Chain of \boldmath $1^{+}$ Ground States
B. Liu🇺🇸 · M. Brodeur🇺🇸 · J.A. Clark🇺🇸 · I. Dedes🇵🇱 · J. Dudek🇫🇷 · F. G. Kondev🇺🇸 · D. Ray🇺🇸 · G. Savard🇺🇸 · A.A. Valverde🇺🇸 · A. Baran · D.P. Burdette🇺🇸 · A.M. Houff🇺🇸 and 5 other authors
Precise mass measurements of the ground and isomeric states of the odd-odd $^{108, 110, 112, 114, 116}$ Rh were performed using the Canadian Penning Trap at Argonne National Laboratory, showing good agreement with recent JYFLTRAP measurements. A new possible isomeric state of $^{114}$ Rh was also observed. These isotopes are part of the longest odd-odd chain of identical ground-state spin-parity assignment of 1 $^{+}$ , spanning $^{104 - 118}$ Rh, despite being in a region of deformation. Realistic phenomenological mean-field calculations using ``universal'' Wood-Saxon Hamiltonian were performed, which explained this phenomenon for the first time. In addition, multi-quasiparticle blocking calculations were performed to study the configuration of low-lying states in the odd-odd Rh nuclei, elucidating anomalous isomeric yield ratio observed for $^{114}$ Rh.
↳ nucl-exnucl-thPRC(2025)·7 citations
13
Low- $Q^{2}$ nucleon structure from an infrared-safe evolution scheme
Rong Wang🇨🇳
The low- $Q^{2}$ nucleon structure is given with a simple nonperturbative input of three valence quarks and an all-order infrared-safe evolution scheme, showing some consistences with the experimental data. The resonance peaks in the experimental data of $F_{2}$ structure function are found to be modulated by the valence quark distributions. With little sea quark distribution at low $Q^{2}$ the valence-quark bump is clearly shown in the structure function. The three valence quark distributions at the hadronic scale is found to be the dominant origin of the PDFs at the hard scales. The high-twist corrections are needed to explain the sizeable discrepancy between the theory and the experimental measurements at low $Q^{2}$ . The infrared-safe evolution scheme is a powerful tool for connecting the nucleon structures in the nonperturbative and perturbative regions.
↳ hep-phnucl-th1 citation
14
Molecular states with charm: insights from vacuum and finite-temperature analyses
Juan M. Torres-Rincon🇪🇸
This contribution to the SQM2024 conference covers the molecular hypothesis for the internal structure of some open and hidden charm states. The use of effective theories that incorporate heavy-quark spin symmetry, combined with unitarization techniques, has provided strong evidences supporting this interpretation. In the heavy-light sector, we discuss the double pole structure of the $D_{0}^{*} (2300)$ and the generation of the $D_{s 0}^{*} (2317)$ . In the hidden charm sector, we focus on the exotic $X (3872)$ and its heavy-quark partner, the $X (4014)$ . Furthermore, we emphasize the benefits of femtoscopic measurements in $p + p$ collisions to establish the nature of these states, as well as the potential role of temperature to discern their internal structure.
↳ hep-phnucl-thEPJ Web Conf.(2025)·1 citation
15
Two-dimensional bosonic droplets in a harmonic trap
Fabian Brauneis · Artem G. Volosniev · Hans-Werner Hammer
We investigate a system of bosons in a two-dimensional harmonic trap. In the limit of strong attractive interactions, the bosons make a droplet insensitive to external confinement. For weak interactions, in contrast, the ground state is given by the harmonic trap. In this work, we conduct a variational study of the transition between these two limits. We find that this transition occurs abruptly at the critical interaction strength whose value is universal if scaled appropriately with the number of particles. To connect the abrupt change in the properties of the system to the classical description of phase transitions, we analyze the static response of the Bose gas related to the isothermal compressibility. Finally, we perform numerically exact calculations for a few particles to demonstrate the effects of finite range interactions on this transition. We conclude that finite range effects wash out the point of transition.
↳ cond-mat.quant-gasnucl-thPRA(2025)·3 citations
16
Electric dipole polarizability of $^{58}$ Ni
I. Brandherm · F. Bonaiti · P. von Neumann-Cosel · S. Bacca · G. Colò · G.R. Jansen · Z.Z. Li · H. Matsubara · Y.F. Niu · P.-G. Reinhard · A. Richter · X. Roca-Maza · A. Tamii
The electric dipole strength distribution in $^{58}$ Ni between 6 and 20 MeV has been determined from proton inelastic scattering experiments at very forward angles at RCNP, Osaka. The experimental data are rather well reproduced by quasiparticle random-phase approximation calculations including vibration coupling, despite a mild dependence on the adopted Skyrme interaction. They allow an estimate of the experimentally inaccessible high-energy contribution above 20 MeV, leading to an electric dipole polarizability $α_{D} (^{58} Ni) = 3.48 (31)$ fm $^{3}$ . This serves as a test case for recent extensions of coupled-cluster calculations with chiral effective field theory interactions to nuclei with two nucleons on top of a closed-shell system.
↳ nucl-exnucl-thPRC(2025)·10 citations
17
Quantum Closures for Neutrino Moment Transport
James P. Kneller🇺🇸 · Julien Froustey🇺🇸 · Evan B. Grohs🇺🇸 · Francois Foucart🇬🇧 · Gail C. McLaughlin🇺🇸 · Sherwood Richers🇺🇸
A computationally efficient method for calculating the transport of neutrino flavor in simulations is to use angular moments of the neutrino one-body reduced density matrix, i.e., `quantum moments'. As with any moment-based radiation transport method, a closure is needed if the infinite tower of moment evolution equations is truncated. We derive a general parameterization of a quantum closure and the limits the parameters must satisfy in order for the closure to be physical. We then derive from multi-angle calculations the evolution of the closure parameters in two test cases which we then progressively insert into a moment evolution code and show how the parameters affect the moment results until the full multi-angle results are reproduced. This parameterization paves the way to setting prescriptions for genuine quantum closures adapted to neutrino transport in a range of situations.
↳ hep-phastro-ph.HEnucl-thPRD(2025)·13 citations
18
Recent $J / ψ$ measurements at the PHENIX experiment
Xuan Li (on behalf of the PHENIX collaboration)🇺🇸
Quarkonium is an ideal probe to explore the properties of quantum chromodynamics (QCD). Unlike Large Hadron Collider (LHC) measurements, quarkonium production at the Relativistic Heavy Ion Collider (RHIC) has different production mechanisms, can access different kinematic phase space and may experience different medium densities/temperatures. The PHENIX experiment has collected a large $J / ψ \to μ^{+} μ^{-}$ data set within its unique pseudorapidity region of $1.2 < ∣ η ∣ < 2.2$ in $p + p$ , $p + A$ and $A + A$ collisions at $s$ = 200 GeV from 2014 to 2016. Latest results of normalized charged particle multiplicity dependent normalized forward $J / ψ$ yields and normalized forward $ψ (2 S)$ to $J / ψ$ ratio in 200 GeV $p + p$ collisions as well as forward $J / ψ$ azimuthal anisotropy in 200 GeV Au+Au collisions will be shown. Comparison with other RHIC and LHC measurements and latest theoretical calculations will be discussed. These PHENIX results provide their unique contributions in improving the understanding of the multi-parton interaction contribution to charmonium production and the recombination/coalescence contribution to charmonium formation within Quark Gluon Plasma (QGP) at RHIC energies.
↳ nucl-exhep-exnucl-thPoS(2025)·0 citations
19
Precision Thermodynamics of the Fermi polaron at strong coupling
S. Ramachandran · S. Jensen · Y. Alhassid
The Fermi polaron problem, which describes a mobile impurity that interacts with a spin-polarized Fermi sea, is a paradigmatic system in quantum many-body physics and has been challenging to address quantitatively in its strong coupling regime. We present the first controlled thermodynamic calculations for the Fermi polaron at strong coupling using finite-temperature auxiliary-field quantum Monte Carlo (AFMC) methods in the framework of the canonical ensemble. Modeled as a spin-imbalanced system, the Fermi polaron has a Monte Carlo sign problem, but we show that it is moderate over a wide range of temperatures and coupling strengths beyond the unitary limit of the BCS-BEC crossover. We calculate the contact, a quantity which measures the strength of the short-range correlations, as a function of temperature at unitarity and as a function of the coupling strength at fixed temperature and find good agreement with a variational approach based on one particle-hole excitation of the Fermi sea. We compare our results for the contact with recent experiments and find good agreement at unitarity (within error bars) but discrepancies away from unitarity on the BEC side of the crossover. We also calculate the thermal energy gap at unitarity as a function of temperature.
↳ cond-mat.quant-gasnucl-thPRA(2025)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE