Nuclear Theory·nucl-th

Tuesday·April 1, 2025

21 papers—11 primary·10 cross-listed

01
Separating non-collective effects in d-Au collisions
Satya Ranjan Nayak🇮🇳 · Akash Das🇮🇳 · B.K. Singh🇮🇳
In this work, we present the multiplicity and yield of charged hadrons and particle ratios in d-Au collisions at $s_{N N} = 200$ GeV using the PYTHIA8/Angantyr. The model reproduces the multiplicity ( $N_{c h}$ ) and pseudo-rapidity distribution reasonably well in minimum-biased d-Au collisions without assuming the formation of a thermalized medium. The invariant yield from Angantyr underpredicts the data in central collisions. We discussed the similarity between the nuclear modification factor $R_{AA}$ and data/MC from Angantyr and the possibility of using it as a model-dependent observable to check in-medium effects. The data/MC suggests that the central d-Au collisions exhibit signals like baryon enhancement, but no high $p_{T}$ suppression was found. The d-Au collisions have a much smaller invariant yield than the thermal model calculation for similar $N_{p a r t}$ .
nucl-thhep-phEPJC(2026)·2 citations
02
Relativistic mean-field predictions for dense matter equation of state and application to neutron stars
Luca Passarella🇮🇹 · Jerome Margueron🇺🇸 · Giuseppe Pagliara🇮🇹
Relativistic mean-field models (RMF) based on the exchange of $σ$ , $ω$ , and $ρ$ mesons including non-linear nucleon- $σ$ couplings and density-dependent $ρ$ coupling, are considered. A large set of models is generated using the Markov chain Monte Carlo approach and Bayesian statistics to reproduce nuclear physics knowledge encoded in terms of the nuclear empirical parameters and $χ$ EFT predictions for low-density neutron matter. These models are filtered, in a second step, using astrophysical constraints: the tidal deformability obtained from GW170817 parameter estimation and the observational masses deduced from radio-astronomy. We then obtain a set of selected RMF models that are compatible with present nuclear and astrophysical constraints and that can be employed to make predictions and to quantity their uncertainties. Predictions for masses and radii are compared to NICER masses-radii analyses for PSR J0030+0451 and PSR J0740+6620. We find that RMF models can be made soft enough to predict low values for neutron star radii compatible with GW170817 and, at larger densities, stiff enough to be compatible with NICER analyses for massive neutron stars. Our models can also reach large values for the maximum mass, up to 2.6 $M_{⊙}$ . In addition, for the core composition, we obtain a large distribution of the proton fraction for canonical mass neutron stars, some of them allowing the direct URCA fast cooling process. For massive neutron stars, however, most of our models suggest a large proton fraction in the core allowing direct URCA fast cooling process.
nucl-thPRC(2025)·12 citations
03
Guiding center hydrodynamics with spin
Rajeev Singh🇷🇴
We build upon the recently formulated guiding-center kinetic theory for guiding-center plasma by incorporating spin degrees of freedom in the presence of electromagnetic fields. This approach yields a streamlined set of equations for guiding-center ideal hydrodynamics with spin--fewer than those in traditional spin hydrodynamics--owing to a restriction on motion perpendicular to the magnetic field. We propose that this framework offers a promising tool to comprehending how matter behaves under the influence of intense magnetic fields, such as spin polarization effects observed in experimental measurements.
nucl-thJ.Subatomic Part.Cosmol.(2025)·6 citations
04
Many-channel microscopic cluster model of $^{8}$ Be. I. Formation of high-energy resonance states
V. I. Zhaba · Yu. A. Lashko · V. S. Vasilevsky
The nature and structure of high-energy resonance states in $^{8}$ Be, located just below and above the $p +^{7}$ Li threshold, are investigated in detail. A microscopic many-cluster and many-channel model is employed to study the formation of these resonances. This model includes three distinct three-cluster configurations: $^{4}$ He+ $^{3}$ H+ $p$ , $^{4}$ He+ $^{3}$ He+ $n$ , and $^{4}$ He+ $d$ + $d$ , enabling a comprehensive treatment of all major binary decay channels of $^{8}$ Be, namely $^{4}$ He+ $^{4}$ He, $p +^{7}$ Li, $n +^{7}$ Be, and $d +^{6}$ Li. The primary focus of our analysis is the structure and dominant decay channels of the twin $1^{+}$ , $2^{+}$ , $3^{+}$ , and $4^{+}$ resonance states. Additionally, we propose and implement a model to clarify how the $2^{+}$ resonance states lying below the $p +^{7}$ Li threshold are formed. We demonstrate that these resonances are Feshbach-type states arising due to coupling of the open $^{4}$ He+ $^{4}$ He channel with the closed channels $p +^{7}$ Li, $n +^{7}$ Be, and $d +^{6}$ Li at these energies. Overall, the present approach provides a realistic description of the experimentally observed resonance spectrum near the $^{7}$ Li+ $p$ decay threshold, including negative-parity states $1^{-}$ and $2^{-}$ . Our results are consistent with other microscopic calculations but offer more detailed insight into the internal structure and decay pathways of these resonances.
nucl-thPRC(2025)·1 citation
05
Quantum Simulations of Fundamental Physics
Martin J. Savage🇺🇸
Simulating the dynamics of non-equilibrium matter under extreme conditions lies beyond the capabilities of classical computation alone. Remarkable advances in quantum information science and technology are profoundly changing how we understand and explore fundamental quantum many-body systems, and have brought us to the point of simulating essential aspects of these systems using quantum computers. I discuss highlights, opportunities and the challenges that lie ahead.
nucl-thhep-lathep-phquant-phPoS(2026)·3 citations
06
Neutron stars and Constraints for the Equation of State of Dense Matter
Rajesh Kumar · Veronica Dexheimer · Johannes Jahan
Neutron stars provide a natural laboratory for studying the properties of dense nuclear matter under extreme conditions. In this proceeding, we review our current understanding of dense isospin symmetric and asymmetric matter and neutron star physics. We focus on modern theoretical, experimental, and observational constraints, including first-principle calculations from lattice and perturbative Quantum Chromodynamics (QCD), as well as chiral effective field theory approaches at nuclear densities. From the experimental perspective, constraints on the equation of state arise from heavy-ion collisions, low-energy nuclear physics, and astrophysical observations, including neutron star masses, radii, and gravitational wave signatures from mergers. These multidisciplinary comparisons are crucial for bridging the gap between nuclear physics and astrophysical observations, in order to expand our knowledge of matter at supra-nuclear densities.
nucl-thhep-exhep-latPoS(2025)·2 citations
07
Bayesian method for quantifying the non-Gaussian fluctuations in low-intermediate energy heavy ion collisions
Xinyu Wang🇨🇳 · Xiang Chen🇨🇳 · Junping Yang🇨🇳 · Ying Cui🇨🇳 · Zhuxia Li🇨🇳 · Kai Zhao🇨🇳 · Yingxun Zhang🇨🇳
In this work, we present a model-independent method to quantify the non-Gaussian fluctuations in the observable distributions, which are assessed by the difference between the measured observable distributions and reconstructed observable distributions via the Bayesian method. Our results indicate that the strength of non-Gaussian fluctuation increases with the beam energy, and is primarily driven by non-central collision mechanisms. The experimental measurement of the strength of non-Gaussian fluctuation of the observable distributions will provide valuable insights into understanding the nonequilibrium effects in heavy ion collisions and the liquid-gas phase transition in finite nuclei.
nucl-thhep-exhep-phnucl-exPLB(2025)·0 citations
08
Pfaffian formulas for non equivalent bases
L.M. Robledo
Pfaffian formulas used to compute overlaps necessary to carry out generator coordinate method calculations using a set of Hartree- Fock- Bogoliubov wave functions, is generalized to the case where each of the HFB states are expanded in different arbitrary bases spanning different sub-space of the Hilbert space. The formula obtained is compared with previous results proving to be completely equivalent to them. A discussion of equivalent formulas obtained in the literature is carried out.
nucl-thcond-mat.str-elPLB(2025)·2 citations
09
Nuclear clustering process in heavy-ion collisions : experimental constraints on the low-temperature region of the QCD phase diagram
E. Bonnet🇫🇷 · B. Borderie🇫🇷 · R. Bougault🇫🇷 · A. Chbihi🇫🇷 · Q. Fable🇫🇷 · J.D. Frankland🇫🇷 · D. Gruyer🇫🇷 · M. La Commara🇮🇹 · A. Le Fèvre🇩🇪 · N. Le Neindre🇫🇷 · I. Lombardo🇮🇹 · J. Łukasik🇵🇱 and 3 other authors
In this article, we study the production of Hydrogen and Helium isotopes in heavy-ion collisions in the incident energy range between 80 and 150 MeV/nucleon. We compare their inclusive multiplicities emitted in the transverse plane of the reaction with the predictions given by the thermal model. As a first step, we validate the choice of this approach to describe the experimental measurements. We also show that the transient states have to be explicitly taken into account for a good statistical description of the experimental multiplicities. From the thermodynamical parameter values obtained we complete the existing database built with the use of thermal-statistical models to reproduce particle production in the (ultra-)relativistic-energy measurements. We then proposed a new constraint on the so-called freeze-out region in the temperature (T) versus baryonic chemical potential (muB) phase diagram of the quantum chromodynamics. These new results indicate that there is a common framework to describe the hadron production and nuclear clustering processes in heavy-ion collisions.
nucl-thhep-phnucl-exPRC(2025)·4 citations
10
Investigating nuclear beta decay using lattice quantum Monte Carlo approach
Teng Wang🇨🇳 · Xu Feng🇨🇳 · Bing-Nan Lu🇨🇳
We present an \textit{ab initio} calculation of nuclear $β$ decay within the framework of nuclear lattice effective field theory (NLEFT), employing auxiliary-field quantum Monte Carlo methods to solve the nuclear many-body problem. Our approach combines next-to-next-to-leading order two- and three-body chiral interactions with one- and two-body axial current operators, all consistently derived in chiral effective field theory. Low-energy constants are determined exclusively from nucleon-nucleon scattering phase shifts and few-body observables for systems with $A \leq 3$ . Using these interactions and transition operators, we perform two-channel Monte Carlo simulations to compute the $β$ -decay matrix element for $^{6}$ He, obtaining results in reasonable agreement with experimental measurements. To address the Monte Carlo sign problem, we implement a perturbative expansion around a leading-order Hamiltonian with approximate Wigner-SU(4) symmetry. This systematic approach provides a foundation for extending NLEFT simulations to precision studies of weak processes in medium-mass nuclei.
nucl-thhep-latPRC(2025)·8 citations
11
Time-Dependent Density Functional Theory Description of $^{238}$ U(n,f), $^{240, 242}$ Pu(n,f) and $^{237}$ Np(n,f) Reactions
Aurel Bulgac · Ibrahim Abdurrahman · Matthew Kafker · Ionel Stetcu
In nuclei with an odd nucleon number the non-vanishing spin number density is the source of a pseudo-magnetic field, which favors the splitting of the nucleon Cooper pairs. Such an pseudo-magnetic field is generated always in the dynamics of any nucleus, but its effects on Cooper pairs is significantly enhanced in the dynamic evolution of nuclei with an odd number of nucleons. We present for the first time a microscopic study of the induced fission of the odd neutron compound nuclei $^{239}$ U, $^{241, 243}$ Pu, and the odd proton, odd neutron compound nucleus $^{238}$ Np, performed within the time-dependent density functional theory extended to superfluid fermion systems, without any simplifying assumptions and with controlled numerical approximations, and for a very large number of initial conditions. Due to the presence of the unpaired odd nucleon(s), the time-reversal symmetry of the fission compound nucleus is spontaneously broken, an aspect routinely neglected in the most advanced microscopic approaches of the past. The emerging fission fragment properties are quite similar to the properties of fission fragments of neighboring even-even nuclei. The time from saddle-to-scission is often significantly longer in odd-N-odd-Z or odd-A nuclei than for even-even nuclei since systems with unpaired nucleons are easier to excite and the potential energy surfaces of these nuclei have more structure, often resembling a very complicated obstacle course, rather than a more direct evolution of the nuclear shape from the top of the outer fission barrier to the scission configuration. The Pauli blocking approximation, often invoked in the literature, expected to inhibit the fission of nuclei with unpaired nucleons, is surprisingly strongly violated during the fission dynamics.
nucl-thPRL(2025)·7 citations
12
Crossover between the zeptosecond and attosecond physics
T. Nandi · Yash Kumar · Adya P. Mishra · Nishchal R. Dwivedi · Chandra Kumar · Gajendra Singh · N.Sowmya · H.C.Manjunatha · Sudhir R. Jain · A.S. Kheifets
Nuclear orbiting resonances have been revealed at the sub-barrier energies as an atomic phenomenon by means of x-ray spectroscopy experiments. This interpretation is supported by several phenomenological models and theoretical estimates of the nuclear orbiting timescale and cross-section, inelastic scattering cross section including both nuclear and Coulomb excitation, and the Wigner-Smith time delay. We demonstrate that a multi-photon exchange during nuclear orbiting is responsible for an atomic excitation. Furthermore, proximity of the projectile and target nucleus during the nuclear orbiting modifies the effective charge of the projectile. Even though this orbiting induced excitation is triggered in zeptoseconds, it can still be observed in the attosecond time scale because of the Wigner-Smith time delay inherent to autoionization. Thus, we demonstrate the crossover between the zeptosecond and attosecond time scales which are native to nuclear and atomic physics, respectively. Markedly, this crossover may be the reason for x-ray production from ultra short nuclear processes ( $\leq 1 0^{- 21}$ sec). This explanation is likely to resolve the fission time scale anomaly and can stimulate cross-disciplinary research ranging from solid state to high-energy physics.
↳ physics.atom-phnucl-exnucl-th0 citations
13
The Cosmic One-Eyed Smile: Revealing the Hidden Face of Mike Wazowski
Chun Huang
We present a novel and somewhat whimsical approach to pulsar hotspot modeling by drawing inspiration from the iconic one-eyed monster, Mike Wazowski, from \emph{Monsters, Inc.}. Utilizing X-ray high-quality timing data from NICER, we apply a Bayesian inference framework to model the X-ray pulse profile of PSR J0437--4715. Our analysis employs a \emph{Wazowski Configuration} (WC) in which the conventional hotspot parametrization is replaced with a predefined image template, whose redness and size are adjusted to mimic temperature variations. The results reveal a configuration where two hotspots--one brighter and smaller in the north represents the energetic ``University time Wazowski", and one larger yet cooler in the south represents the ``Monster, Inc. time Wazowski"--combine to produce the observed X-ray pulse profile. These findings not only demonstrate the sensitivity of pulse profile modeling to hotspot morphology but also open up the intriguing possibility that the X-ray emission of some pulsars may be interpreted as a cosmic homage to our favorite animated character.
↳ astro-ph.HEastro-ph.SRnucl-th0 citations
14
Neutrino Scattering: Connections Across Theory and Experiment
L. Alvarez-Ruso🇪🇸 · A.M. Ankowski🇵🇱 · A. Ashkenazi🇮🇱 · J. Barrow🇺🇸 · M. Betancourt🇺🇸 · K. Borah🇺🇸 · M. Sajjad Athar🇮🇳 · E. Catano-Mur🇺🇸 · P. Coloma🇪🇸 · P. Dunne🇬🇧 · L. Doria🇩🇪 · A. Fedynitch🇹🇼 and 22 other authors
In this document drafted by the Neutrino Scattering Theory Experiment Collaboration (NuSTEC), we provide input on the synergies between theoretical and experimental efforts that can provide critical input to the prediction accuracy needed for the forthcoming high-precision neutrino measurements. These efforts involve a wide range of energies and interaction processes, as well as target nuclei and interaction probes. The challenges discussed will be overcome only through the active support of integrated collaboration across strong and electroweak physics from both the nuclear and high energy physics communities.
↳ hep-exhep-thnucl-exnucl-th7 citations
15
The effect of recoils on soft-drop-groomed observables in $γ$ -tagged jets in a multistage approach
Y. Tachibana🇯🇵 · C. Sirimanna🇺🇸 · A. Majumder🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. A. Bass🇺🇸 · Y. Chen🇺🇸 · R. Datta🇺🇸 · L. Du🇨🇦 · R. Ehlers🇺🇸 · H. Elfner🇩🇪 · R. J. Fries🇺🇸 and 40 other authors
We investigate medium-induced modifications to jet substructure observables that characterize hard components in central Pb-Pb collisions at $s_{N N} = 5.02$ ~TeV. Using a multistage Monte Carlo simulation of in-medium jet shower evolution, we explore flavor-dependent medium effects through simulations of inclusive and $γ$ -tagged jets. The results show that quark jets undergo a nonmonotonic modification compared with gluon jets in observables such as the Pb-Pb to $p$ - $p$ ratio of the soft drop prong angle $r_{g}$ , the relative prong transverse momentum $k_{T, g}$ , and the groomed mass $m_{g}$ distributions. Due to this nonmonotonic modification, $γ$ -tagged jets, enriched in quark jets, provide surprisingly clear signals of medium-induced structural modifications, distinct from effects dominated by selection bias. Further systematic studies demonstrate that these effects are dominated by recoil medium response. This work highlights the potential of hard substructures in $γ$ -tagged jets as powerful tools for probing the jet-medium interactions in high-energy heavy-ion collisions, in particular by enabling detailed investigations of jet-medium parton scatterings via their associated medium response. All simulations for $γ$ -tagged jet analyses carried out in this paper used triggered events containing at least one hard photon, which highlights the utility of these observables for future Bayesian analysis.
↳ hep-phnucl-exnucl-thPRC(2026)·9 citations
16
Semisuper Efimov effect induced by resonant pair exchange in mixed dimensions
Yusuke Nishida
We introduce a new member to the class of semisuper Efimov effects, where an infinite number of bound states emerge with their binding energies obeying the universal scaling law $E_{n} \sim e^{- 2 (π n / γ)^{2}}$ for sufficiently high excitation $n \in N$ . Our system consists of a pair of two-component fermions in three dimensions at infinite scattering length, which furthermore interact with a boson confined in two dimensions so as to form a three-body bound state at zero energy. When another boson is added, the exchange of the resonant pair of fermions between two bosons leads to the semisuper Efimov effect of four such particles with the scaling exponent $γ$ determined by the mass ratio of bosons to fermions. If bosons exist in three dimensions, an infinite number of bound states do not emerge, but some of them may survive for a large mass ratio, making our findings potentially relevant to two-neutron halo nuclei as well as ultracold atoms.
↳ cond-mat.quant-gasnucl-thPRA(2025)·1 citation
17
Production of $K^{+} K^{-}$ Pairs Through Decay of $ϕ$ Meson
Xin-Nan Zhu🇨🇳 · Xin-Li Sheng🇮🇹 · Defu Hou🇨🇳
We develop a theoretical framework for the production of $K^{+} K^{-}$ pairs through the decay of $ϕ$ mesons produced from a thermal background, based on the Nambu-Jona-Lasinio (NJL) model. The differential production rate of $K^{+} K^{-}$ is related to the self-energy of the $ϕ$ meson, incorporating the contributions of the quark loop at leading order and the kaon loop at next-to-leading order in the $1/ N_{c}$ expansion. We numerically evaluate the invariant mass spectrum of the $K^{+} K^{-}$ pair both in vacuum and at finite temperature. The inclusion of the kaon loop results in a finite width of the spectrum, improving agreement with experimental data. We also investigate the spin alignment of the $ϕ$ meson induced by its motion relative to the thermal background. In the NJL model with only chiral condensates, we find that deviations from the unpolarized limit of 1/3 are negligible.
↳ hep-phhep-thnucl-thPRD(2025)·2 citations
18
Worldvolume fermion as baryon with homogeneous instantons in holographic $QCD_{3}$
Si-wen Li🇨🇳 · Xiao-tong Zhang🇨🇳
(ArXiv version) We investigate holographically the effective theory of the worldvolume fermion on the flavor branes in the D3/D7 model with homogeneously smeared D(-1)-branes. As a top-down approach in gauge-gravity duality, the D(-1)-branes are instantons and violate the CP symmetry in the dual theory. In the confined geometry, we introduce a baryon vertex as a D5-brane wrapped on $S^{5}$ , then identify the fermionic fluxes produced by the $N_{c}$ open strings on the D7-brane as a baryonic operator. Afterwards, we study the spectrum and the holographic correlation function of the baryonic fermion on the D7-branes. Remarkably, the fermionic spectrum is in agreement with the dispersion curves obtained from the confined correlation function, and the mass ratio of the lowest baryon and meson in our model is close to the associated experimental data. Moreover, the effective interaction terms of the holographic baryon and meson are derived and all the coupling constants take order of $N_{c}^{1/2}$ agreeing with the evaluation from the large $N_{c}$ field theory. In the deconfined geometry, the holographic correlation function is also evaluated numerically while the fermion on D7-brane is identified to plasmino instead of baryon. The dispersion curves from the deconfined correlation function basically covers the results from the hard thermal loop approximation and may imply the instanton-induced interaction with spin. Overall, this work constructs a holographic theory about baryonic fermion and mesonic boson with instantons or CP violation.
↳ hep-thhep-phnucl-thPRD(2025)·4 citations
19
KNO scaling in quark and gluon jets at the LHC
Xiang-Pan Duan🇨🇳 · Lin Chen🇪🇸 · Guo-Liang Ma🇨🇳 · Carlos A. Salgado🇪🇸 · Bin Wu🇪🇸
The Koba-Nielsen-Olesen (KNO) scaling of hadron multiplicity distributions, empirically confirmed to hold approximately in $e^{+} e^{-}$ collisions and Deep Inelastic Scattering, has been observed to be violated in hadron-hadron collisions. In this work, we show that the universality of KNO scaling can be extended to hadron-hadron collisions when restricted to QCD jets. We present a comprehensive study of KNO scaling in QCD jets produced in proton-proton collisions at the LHC. Using perturbative QCD calculations in the double logarithmic approximation and PYTHIA simulations, we find that KNO scaling approximately holds for both quark and gluon jets across a broad jet $p_{T}$ range, from $0.1$ TeV to $2.5$ TeV, at both the parton and hadron levels. Especially, we highlight characteristic differences between the KNO scaling functions of quark and gluon jets, with the quark-jet scaling function lying above that of gluon jets at both low and high multiplicities. This distinction is essential for interpreting inclusive jet data at the LHC. Furthermore, we propose direct experimental tests of KNO scaling in QCD jets at the LHC through quark-gluon discrimination using jet substructure techniques, as demonstrated by applying energy correlation functions to PYTHIA-generated data.
↳ hep-phhep-exnucl-thPRD(2025)·11 citations
20
Quark production in the bottom-up thermalization
Sergio Barrera Cabodevila🇪🇸 · Xiaojian Du🇪🇸 · Carlos A. Salgado🇪🇸 · Bin Wu🇪🇸
We investigate the impact of quark production on bottom-up thermalization in heavy-ion collisions. First, we extend the parametric estimates of bottom-up thermalization in pure gluon systems by incorporating quark production in the weak-coupling (high-energy) limit. Our analysis reveals that quark production does not alter the qualitative features of the three-stage thermalization process in this limit. Furthermore, we obtain the scaling behavior of the quark number density over time at each stage. Then, by solving the Boltzmann equation in diffusion approximation (BEDA) for longitudinally boost-invariant systems, we demonstrate how our detailed numerical simulations approach the predicted three-stage thermalization picture as the strong coupling $α_{s}$ decreases. Finally, we carry out a detailed comparison of our BEDA results with those obtained by solving the QCD effective kinetic theory for intermediate values of $α_{s}$ , observing remarkably good quantitative agreement between the two approaches.
↳ hep-phnucl-thPLB(2025)·8 citations
21
Leading qT/Q correction for Drell-Yan in TMD factorization
Arturo Arroyo-Castro🇪🇸 · Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇪🇸
The transverse momentum dependent (TMD) factorization theorem accommodates various types of power corrections. Among them, the least studied are qT/Q corrections, which become significant at large values of transverse momentum. These corrections partially originate from higher-twist TMD distributions, which exhibit singularity at small transverse distances. We propose a decomposition that reveals this singularity explicitly, and makes the qT/Q correction manifest. As a concrete application, we consider the next-to-leading power correction for the angular distributions in Drell-Yan, and determine the leading qT/Q corrections. These corrections are significant for the angular distributions A1 and A3, in complete agreement with the data.
↳ hep-phhep-exhep-latnucl-ex+1JHEP(2025)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE