Nuclear Theory·nucl-th

Friday·July 24, 2026

10 papers—5 primary·5 cross-listed

01
[Submitted on 23 Jul 2026]
Gauge Auxiliary-Field Quantum Monte Carlo Method for Many-Fermion Systems
Zhaozhan Zhang
We propose novel Quantum Monte Carlo (QMC) methods for interacting many-fermion systems by leveraging the stochastic gauge freedom, originally developed in Gaussian phase-space QMC, within the phaseless auxiliary-field QMC (AFQMC) framework. In particular, we reinterpret the conventional force bias in phaseless AFQMC as a drift gauge and explore Fermi gauges based on natural orbitals of a reduced one-body density matrix defined via a mixed estimator, yielding stochastic, time-dependent Hartree-Fock-like dynamics. We propose a symmetry-projection sampling scheme to enhance the sampling efficiency. As a proof of concept, we apply these gauge-augmented AFQMC methods to a simple shell-model Hamiltonian: the Lipkin-Meshkov-Glick model. Numerical results illustrate the potential of stochastic gauges to enhance accuracy and reduce fluctuations, underscoring the promise for advancing these new techniques toward more realistic shell-model applications.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Strongly Correlated Electrons (cond-mat.str-el)
arXiv:
2607.20917 [pdf]
1 citation
02
[Submitted on 23 Jul 2026]
Searching for initial state fluctuations in heavy ion collisions at FAIR energy using Principal Component Analysis
Ekata Nandy🇮🇳 · Subhasis Chattopadhyay🇮🇳
In high energy heavy ion collisions, the initial configurations of the colliding nuclei play an important role in determining the reaction type and the products of the reaction. The initial arrangement of nucleons within the overlap region of two colliding nuclei is generally asymmetric and such asymmetries reflect themselves in the measurement final state momentum anisotropy. Also initial distribution of the nucleons are subjected to large quantum fluctuation causing large energy deposition in a small region. The final state observables related momentum anisotropies although sensitive to such localized fluctuations but their true effect gets diluted because these observables are calculated by averaging over a set of events. Also, such fluctuations in the initial states are random and uncontrolled. Thus, identifying their effect from event-averaged final state observable is difficult. However, it would be interesting to know the origin of such fluctuations and how these fluctuation are eventually translated to the final state. In this work, we at first introduce such localized fluctuations in the initial configurations, also called hot spots, by implementing spatial rearrangements of nucleon position in the colliding nuclei in the central Pb+Pb collisions at E $_{l ab}$ =20 AGeV ( $s$ =6.27 GeV) using the UrQMD event generator. Then the final state distributions of one or two dimensional variables e.g., ( $η$ , $ϕ$ , $p_{T}$ ) and ( $η - p_{T}$ , $ϕ - p_{T}$ , $η - ϕ$ ) of the produced pions are analysed using the principal component analysis (PCA) technique. The eigenvalues of the principal components have been studied for various initial configurations, event fractions containing hot spots in the initial condition and for event centralities with an aim to find it's sensitivity to the initial hot spot configurations.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2607.20971 [pdf]
EPJA(2025)·0 citations
03
[Submitted on 23 Jul 2026]
Impact of Baryon anti-Baryon annihilation on hyperon ( $Λ$ , $Λ ˉ$ ) production and apparent strangeness enhancement in $Λ ˉ / p ˉ$ in heavy ion collisions at SPS energy
Ekata Nandy🇮🇳 · Subhasis Chattopadhyay🇮🇳
A deconfined medium of quarks and gluon, called the Quark-Gluon Plasma (QGP) is produced when heavy-nuclei are collided at relativistic energies. The QGP formation is often characterized by a phenomenon called strangeness enhancement where, the relative production of strange-to-non-strange particles are enhanced in central collisions compared to peripheral or proton-proton interactions. Besides the enhancement in K/ $π$ ratios, a non-monotonic energy dependence was also reported for $Λ ˉ$ to $p ˉ$ ratios at CERN SPS, attributed to a signature for the strangeness enhancement as well. As anti-particles are produced directly from the reaction, the $Λ ˉ$ / $p ˉ$ ratios are considered as a cleaner probe for the strangeness enhancement. However, at this energy range hadronic interactions have a dominant role to play and, importantly for $Λ ˉ$ and $p ˉ$ , processes like baryon-anti-baryon ( $B B ˉ$ ) annihilation can have a significant impact. In this work, we use a hadronic transport model UrQMD, to investigate the role of baryon-anti-baryon ( $B B ˉ$ ) annihilation on $Λ$ , $Λ ˉ$ hyperon production and its effect on $Λ ˉ$ / $p ˉ$ ratios. The UrQMD calculations that include $B B ˉ$ annihilation can produce the trend of average transverse mass spectra for $Λ$ and $Λ ˉ$ , as well as, the characteristic enhancement in $Λ ˉ$ / $p ˉ$ ratios in data as a function of centrality and collision energy. Furthermore, $Λ ˉ$ / $p ˉ$ ratios extracted from the feed-down corrected SPS data are seen to be in good agreement with UrQMD model calculations with $B B ˉ$ annihilation. This suggests that $Λ ˉ$ / $p ˉ$ enhancement is not necessarily because of strangeness enhancement and $B B ˉ$ annihilation has a significant role to play.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2607.21146 [pdf]
EPJA(2022)·2 citations
04
[Submitted on 23 Jul 2026]
Intrinsic coupling between transverse spherocity and elliptic flow in heavy-ion collisions
Subikash Choudhury🇮🇳 · Ekata Nandy🇮🇳
Transverse spherocity ( $S_{0}$ ) is an event-shape observable widely used to classify collision events according to their topology, particularly to distinguish jet-like from isotropic events. Low-spherocity events are generally interpreted as being associated with enhanced jet activity. This event classification has also been applied to heavy-ion collisions to investigate the influence of event topology on several observables, including elliptic flow and constituent-quark-number scaling. In this work, we demonstrate that such an interpretation requires careful reconsideration. Using toy Monte Carlo simulations, A Multiphase Transport (AMPT) model calculations, and an analytical formulation of the spherocity observable, we show that transverse spherocity is intrinsically related to the elliptic flow coefficient, $v_{2}$ . This connection arises because the axis that minimizes the spherocity aligns with the event symmetry plane, causing events with larger elliptic anisotropy to naturally exhibit smaller spherocity values even in the absence of genuine jet-like topologies. We further show that this intrinsic relation gives rise to an inherent anti-correlation between transverse spherocity and $v_{2}$ , implying that several characteristics previously attributed to the enhanced jet-like nature of low-spherocity events in heavy-ion collisions can instead be understood as consequences of collective anisotropic flow. Our results indicate that, in heavy-ion collisions, transverse spherocity should be interpreted primarily as a probe of the collective momentum-space anisotropy rather than as a direct measure of jetty event topology. Consequently, physics conclusions drawn from spherocity-selected events should explicitly account for its intrinsic correlation with elliptic flow.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2607.21161 [pdf]
PRD(2026)·0 citations
05
[Submitted on 23 Jul 2026]
Enhanced hydrodynamic predictions for $v_{02} (p_{T})$
Rupam Samanta🇵🇱 · Tribhuban Parida🇵🇱 · Jean-Yves Ollitrault🇫🇷
We present hydrodynamic predictions for the new observable $v_{02} (p_{T})$ , which measures the correlation of particle spectra with elliptic flow. We implement a data-driven correction so as to match hydrodynamic calculations to elliptic flow ( $v_{2} (p_{T})$ ) data. The corrected results are in fair agreement with $v_{0} (p_{T})$ data up to high $p_{T}$ . We make predictions for $v_{02} (p_{T})$ of unidentified charged hadrons up to $p_{T} = 10$ ~GeV $/ c$ , and of pions, kaons and protons up to $p_{T} = 5 - 6$ ~GeV $/ c$ , in several centrality windows, for Pb+Pb collisions at $s_{N N} = 5.02$ ~TeV. For $p_{T} > 4$ ~GeV $/ c$ , we predict a decrease of $v_{02} (p_{T})$ of charged hadrons in mid-central collisions, and meson-baryon splitting. We also predict a non-monotonic variation of $v_{02} (p_{T})$ for protons at low $p_{T}$ above $30%$ centrality. This is a specific feature of this new observable, which is not observed for the usual flow observables $v_{2} (p_{T})$ and $v_{0} (p_{T})$ .
Comments:
8 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2607.21321 [pdf]
0 citations
06
[Submitted on 22 Jul 2026] (cross-list from astro-ph.HE)
Reaction-constrained composition $g$-modes in neutron stars with antikaon condensates, hyperons, and $\Delta(1232)$ resonances
Prashant Thakur🇰🇷 · Ishfaq Ahmad Rather🇩🇪
We study core composition $g_1$ modes of cold, nonrotating neutron stars containing antikaon condensates, hyperons, and $\Delta(1232)$ baryons and present, to our knowledge, the first calculation in full general relativity of the continuous-composition $g_1$-mode frequency and gravitational-wave damping time for stars with a $K^-$ condensate. Using the BigApple relativistic mean-field equation of state, we compute frequencies, damping times, and frozen-composition tidal overlaps, and identify the buoyancy channels with a species-resolved Ledoux decomposition validated by mode-frequency sensitivities. We compare fully frozen matter with a fast-$K$ limit for $n\leftrightarrow p+K^-$ and a strong-equilibrium limit for the $\Delta$ quartet. Fast-$K$ equilibration retains $36\%$--$44\%$ of the peak local kaon buoyancy and $65.7\%$--$73.4\%$ of the frozen terminal-configuration frequencies, while increasing the damping times by factors of $14.4$--$31.8$; the mode remains above the nucleonic band. Strong $\Delta$ equilibration removes most of the direct $\Delta$-induced enhancement, returning the $N\Delta$ mode toward the nucleonic band, whereas the high-frequency $NY\Delta$ branch survives through the frozen $\Lambda$ gradient. Eigenfunction tracking confirms a continuous $g_1$ branch, and representative DD-ME2 calculations reproduce this hierarchy. The direct full-GR frozen-composition phase shifts satisfy $|\Delta\Phi_{g_1}|\leq1.410\times10^{-3}$ rad, a factor of 21 below the $0.03$-rad favorable-event scale for the Einstein Telescope. An exotic species therefore produces a distinct composition mode only if its composition gradient, or a coupled slowly equilibrating gradient, survives over the oscillation period.
Comments:
20 pages, 9 figures, 8 tables
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2607.20693 [pdf]
0 citations
07
[Submitted on 23 Jul 2026] (cross-list from hep-th)
Flavour current correlators and the non-Abelian hydrodynamic approximation: the charged sector
Thomas Apostolidis🇫🇷 · Matti Järvinen🇨🇳 · Elias Kiritsis🇫🇷 · Francesco Nitti🇫🇷 · Andrea Olzi🇫🇷 · Edwan Préau🇳🇱
Flavor-current correlators are studied in strongly-coupled dense (holographic) matter, at finite quark chemical potential $μ_{q}$ and finite isospin asymmetry. The non-Abelian hydrodynamic description of the charged currents is derived in the presence of an isospin chemical potential $μ_{3}$ . The two-point correlators of charged currents are then computed holographically at finite quark and isospin chemical potentials. In the near-extremal hydrodynamic regime, $ω, k, T, μ_{3} ≪ μ \equiv μ_{q}^{2} + μ_{3}^{2}$ , relevant for cold strongly coupled matter, the IR properties of the correlators are studied. It is shown that in this regime, the correlators agree with the non-Abelian hydrodynamic predictions. Therefore, the traditional regime of validity of standard hydrodynamics extends beyond $ω, k ≪ T ≪ μ$ to the so-called extended hydrodynamic regime $T ≪ ω, k ≪ μ$ . The holographic product formula is applied to the present non-Abelian system, and is used to propose an extended hydrodynamic approximation capturing both hydrodynamic-like poles and the leading effect of AdS $_{2}$ poles, by resumming the low- $ω$ logarithms. The results are verified through a detailed numerical analysis of the exact correlators and quasi-normal mode spectrum.
Comments:
70 pages plus appendices
Subjects:
High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2607.20991 [pdf]
0 citations
08
[Submitted on 23 Jul 2026] (cross-list from hep-ph)
Advanced Statistical Analysis of Linear and Nonlinear Regge Trajectories for Light Non-strange Mesons
S.S. Afonin🇷🇺
A rigorous statistical analysis of Regge-type trajectories for light non-strange meson mass spectra is carried out, which explicitly accounts for experimental uncertainties. We test three scenarios: a linear model with distinct radial ( $n$ ) and orbital ( $l$ ) slopes (Model 1), a linear model with a universal slope (Model 2), and a nonlinear model featuring a universal slope and a Dirac-Coulomb-type term $\propto (l + 1)^{- 1}$ (Model 3). Optimization is performed using a nonlinear $χ^{2}$ minimization framework, where the intrinsic theoretical model uncertainty is determined self-consistently by enforcing $χ^{2} / dof = 1$ . To ensure robust model selection, we employ the Akaike and Bayesian information criteria alongside complementary statistical tests. Our analysis demonstrates that moderate deviations from linearity in the Regge spectrum are predominantly localized within the $S$ -wave resonance sector. These distortions are successfully accommodated by the nonlinear correction in Model 3, from which an approximate Coulomb-type degeneracy, $m^{2} (n, l) \propto n + l$ , emerges as a statistically robust feature. Furthermore, we show that the $l$ -dependent correction to the principal quantum number in light non-strange mesons is consistent with the leading-order relativistic correction to the Coulomb problem.
Comments:
23 pages, 2 figures, 7 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2607.21035 [pdf]
0 citations
09
[Submitted on 23 Jul 2026] (cross-list from hep-lat)
Spin and momentum fraction carried by partons in the nucleon
Constantia Alexandrou (University of Cyprus & The Cyprus Institute) · Simone Bacchio (The Cyprus Institute) · Jacob Finkenrath (Wuppertal University) · Christos Iona (University of Cyprus & The Cyprus Institute) · Giannis Koutsou (The Cyprus Institute) · Christian Kummer · (University of Cyprus & Technical University of Berlin) · Yan Li (The Cyprus Institute) · Bhavna Prasad (The Cyprus Institute) · Gregoris Spanoudes (University of Cyprus)
We determine the momentum fraction and angular momentum carried by quarks and gluons in the proton in lattice QCD. We use four ensembles simulated with up, down, strange and charm quarks with their masses tuned to their physical values. These ensembles have similar physical volume and different lattice spacings allowing us to take the continuum limit directly at the physical pion mass point. We extract the quark and gluon momentum fractions and total angular momentum in the continuum limit as well as the intrinsic quark spin and orbital angular momentum contributions to the proton spin. We find the total momentum fraction $⟨ x_{N} ⟩ = 0.995 (60) (29)$ and the total spin $J_{N} = 0.507 (43) (65)$ , showing that both the momentum and spin sum rules are satisfied. We compare our results to those extracted from phenomenological analyses.
Comments:
8 pages and 7 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2607.21230 [pdf]
0 citations
10
[Submitted on 23 Jul 2026] (cross-list from quant-ph)
Fault-tolerant quantum algorithms for simulating atomic nuclei
James Benstead🇬🇧 · Michael Garn🇬🇧 · Neil Gaspar🇬🇧 · Sean Greenaway🇬🇧 · Angus Kan🇬🇧 · Lloyd La Ronde🇬🇧 · Chandan Sarma🇬🇧 · Paul Stevenson🇬🇧
To maximize the value of fault-tolerant quantum computers, it is essential to develop concrete applications beyond well-established domains such as chemistry and condensed-matter physics. Here we construct and compile quantum algorithms to simulate the structure of atomic nuclei -- a topic that has received relatively little attention from the quantum computing community despite its similarities to the electronic structure problem in chemistry -- via effective shell-model Hamiltonians and no-core-shell-model Hamiltonians with three-body interactions derived from chiral effective field theory. Furthermore, we provide quantum resource estimates, in terms of Toffoli gate and qubit counts, for these algorithms, which, to our knowledge, are the first such estimates for fault-tolerant quantum simulation of atomic nuclei. Notably, the estimates for $^{32}$ Mg and $^{219}$ At shell-model Hamiltonians are comparable to recent estimates of Femoco simulations, a standard benchmark in chemistry. For no-core-shell-model Hamiltonians suitable for light nuclei (up to $^{40}$ Ca or so), we find that resource requirements are significantly higher, suggesting that more bespoke strategies are required to make such simulations practicable. Throughout this work, we draw upon the similarities between nuclear and electronic structure problems, while also highlighting challenges that are specific to the former. We hope this work will spur long-term collaborations between the nuclear and quantum computing community with the ultimate goal of realizing useful nuclear simulations on quantum computers.
Comments:
20 pages, 10 figures, 14 tables
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2607.21563 [pdf]
1 citation

Affiliations

first authorsco-authorsvia INSPIRE