HEP Lattice·hep-lat

Fri·Oct 9, 2026Friday·October 9, 2026

8 papers—1 primary·7 cross-listed

01
Hamiltonian framework for Chiral Gauge Theories on a Disk Boundary
Srimoyee Sen
I propose a Hamiltonian framework for chiral gauge theories (CGT) based on a Euclidean formulation which uses 2n dimensional chiral fermions on the boundary of a 2n+1 dimensional disk. In the original Euclidean formulation, boundary gauge fields were extended into the bulk using $2 n + 1$ dimensional gauge field equations of motion (EOM) which creates a bottleneck for constructing a Hamiltonian. I present an alternate proposal for extending the gauge fields into the bulk that is compatible with both a Hamiltonian framework and a Euclidean path integral. Applying this to Abelian gauge fields produces exact expressions of interior fields as a functional of the boundary fields, which can be directly used in a Hamiltonian formulation. Euclidean analysis of the new gauge field extension shows that it can preserve the non-perturbative content of the original construction, including the behavior of topological charge, associated chiral fermion zero modes and an absence of the strong CP problem when applied to the Standard Model. This construction opens up a route to a Hamiltonian treatment and future quantum simulation of CGTs on a disk boundary.
hep-lathep-phhep-thnucl-th
02
Symbolic Density Estimators for Unnormalized Distributions
Vikas Kanaujia · Riyansha Singh · Shashank Sharma · Vipul Arora
Estimating the symbolic or analytical form of probability density functions (PDFs) from observed samples is a fundamental challenge in statistical and computational modelling. This process is critical for deriving interpretable and generalizable relationships characterizing the underlying phenomenon. Traditionally, this estimation depends strongly on domain expertise and prior field-specific knowledge, with experts selecting appropriate functional forms or parametric families based on empirical evidence and theoretical understanding. The coefficients of these forms are then typically determined through parameter estimation. In this paper, we develop a framework for estimating symbolic expressions of unnormalized distributions from observed samples using domain-specific prior knowledge, such as the range of interactions and a predefined set of primitive functions. We integrate deep generative models with symbolic regression (SR), incorporating inductive biases, such as factorizing large distributions, to keep the problem tractable. The deep generative models we examine include likelihood-based models, viz., flow models, and score-based models. Experiments show the effectiveness of the proposed framework for estimating density functions for multivariate toy distributions as well as lattices from computational physics, namely, XY model and $ϕ^{4}$ theory. When applied to the renormalization problem in $ϕ^{4}$ theory, the proposed framework estimates compact symbolic approximations of the hamiltonian function at different scales directly from samples, yielding expressions that may be challenging to derive using traditional perturbative or analytic approaches in nonperturbative settings.
↳ cs.LGhep-latTransactions on Machine Learning Research…
03
Analog quantum simulation of $ϕ^{4}$ field theory with a superconducting transmission line
Ilan T. Rosen · Neill C. Warrington · Max Hays · Christopher McNally · Joshua Lin · Stephen Sorokanich III · Julian Bender
Understanding the dynamics of interacting quantum fields remains a fundamental challenge. We propose a superconducting transmission line for analog quantum simulation of $(1 + 1)$ -dimensional $ϕ^{4}$ field theory. The transmission line comprises fluxonium-like circuit elements whose continuous and unbounded phase variables encode a scalar field without Hilbert-space truncation. Their anharmonic potentials provide strong interactions. Tuning the circuit parameters provides access to two distinct regimes. In the first, the transmission line emulates $ϕ^{4}$ field theory with a single-well potential. We confirm this correspondence through lattice Monte Carlo calculations of the low-energy spectra of both the circuit and lattice $ϕ^{4}$ theory. This regime enables scattering experiments between counter-propagating particle wave packets. The second parameter set yields a double-well potential that emulates $ϕ^{4}$ theory in the symmetry-broken phase and hosts degenerate vacua. Interfaces between the two vacua form topological kinks, and the transmission line can simulate kink-antikink collisions. We present state preparation and measurement protocols for both collision experiments, enabling spatially resolved, real-time studies of particle and soliton scattering in an interacting quantum field theory.
↳ quant-phcond-mat.mes-hallhep-lat
04
Flavour decomposition of the nucleon tensor multipole moments
U. Özdem
We compute the chiral-odd form factors $H_{T}$ , $E_{T}$ and $\hT$ of the nucleon in light-cone QCD sum rules, separately for the $u$ and $d$ quarks, and organise them into the tensor monopole, dipole and quadrupole moments $g_{T}$ , $κ_{T}$ and $Q_{T}$ . The quadrupole moment, with no chiral-even counterpart at leading twist, and the isoscalar channel, whose sum rules were derived but never evaluated, are new in this framework. The form factors are read from a Lorentz basis independent only after canonical ordering of the Dirac strings; three of the eight surviving structures give the three form factors separately, and the one usually used for the tensor charge is not among the eight. Two exact results follow analytically. The $d$ -quark contributions to $E_{T}$ and $\hT$ are equal and opposite in the chiral limit, broken in proportion to the quark mass and the twist-six amplitude $V_{6}$ , so the $d$ -quark sector carries a single independent function; and the isoscalar tensor charge receives no leading-twist contribution, its twist-three terms cancelling between the flavours. Neither is visible without resolving the flavours. At $μ^{2} = 1$ ~GeV $^{2}$ the two distribution-amplitude sets give $g_{T}^{u - d} = 1.27 (7)$ , $1.08 (6)$ , $κ_{T}^{u - d} = 1.35 (62)$ , $1.58 (59)$ , $Q_{T}^{u - d} = - 4.40 (83)$ , $- 4.20 (73)$ and $g_{T}^{u + d} = 0.39 (7)$ , $0.38 (6)$ , $κ_{T}^{u + d} = 4.47 (62)$ , $4.32 (59)$ , $Q_{T}^{u + d} = 2.41 (53)$ , $1.56 (30)$ . The mean-field relation $2 \hT^{u - d} = - E_{T}^{u - d}$ , tested without any large- $N_{c}$ assumption, holds in sign and order of magnitude, with ratio $0.64 (16)$ and $0.67 (15)$ against the predicted unity. In the impact-parameter plane the moments displace the two flavour distributions in opposite transverse directions by nearly equal amounts, $⟨ b_{y} ⟩ = 0.37$ and $- 0.37$ ~fm, and elongate both across the polarisation axis, the $d$ quark some five to six times more strongly
↳ hep-phhep-exhep-latnucl-th
05
Electromagnetic isospin breaking in hadronic vacuum polarization within a VMD model
Volodymyr Biloshytskyi
One of the challenging components of modern lattice-QCD computations of the leading hadronic vacuum polarization contribution to the muon $(g - 2)_{μ}$ is the isospin-breaking correction due to electromagnetism. Dominated by long distances, this correction suffers from severe signal-to-noise issues and finite-volume effects. To provide infinite-volume benchmarks for various quark-level Wick contractions, we estimate their sizes phenomenologically at the physical point, using a previously developed vector-meson-dominance model. The pion contributions in this model sum to around $- 7.1 \times 1 0^{- 10}$ , dominated by the electromagnetic pion mass shift. The ultraviolet-finite (2+2)a ("dumbbell") contraction accounts for approximately two thirds of this model sum; for both, about 30% comes from Euclidean times beyond 2.8 fm.
↳ hep-phhep-lat
06
Reassessing the $X (2370)$ in $J / ψ \to γ K_{S}^{0} K_{S}^{0} π^{0}$ beyond the one-dimensional mass projections
Xiang-Kun Dong · Teng Ji · Meike Küßner · Ulf-G. Meißner
The BESIII Collaboration recently extracted the properties of the $X (2370)$ from a fit to the one-dimensional $K_{S}^{0} K_{S}^{0} π^{0}$ invariant-mass spectrum in $J / ψ \to γ K_{S}^{0} K_{S}^{0} π^{0}$ . The intermediate two-body structures visible in the mass correlations, including the $K_{0}^{*} (1430)$ bands, require a coherent treatment of cross-channel interference when interpreting the enhancement near 2.3 GeV. We reassess the need for an additional $X (2370)$ contribution by fitting the published data using an effective coupled-channel framework. The three-body parent amplitude is parameterized by a $K$ -matrix as the scattering among several quasi-two-body channels. The seven- and eight-bare-state models give similar mass distributions. Adding the eighth bare state lowers the Poisson deviance by 1.26% and produces an additional pole at $E = (2424 - i 149)$ MeV, substantially broader than the $X (2370)$ mass-width reference. This pole is model-dependent, and its identification with the $X (2370)$ is not clear. The present analysis does not establish the need for an additional $X (2370)$ contribution in $J / ψ \to γ K_{S}^{0} K_{S}^{0} π^{0}$ , thereby weakening the flavor-singlet argument based on the suppression of $K^{*} K ˉ$ relative to the total $K K ˉ π$ contribution. A more comprehensive experimental amplitude analysis, incorporating coherent interference, mass and angular correlations, and detector effects across related decay channels, is needed to establish the role and decay properties of the $X (2370)$ .
↳ hep-phhep-exhep-lat
07
Asymptotic Safety in Gauge Theories beyond Four Dimensions: Perturbative Tests and Fixed-Point Mergers
Aldo Deandrea · Jie Liu · Roman Pasechnik · Zhi-Wei Wang · Yu-Bo Zhao
Non-Abelian gauge theories above four dimensions may admit an interacting ultraviolet fixed point through the competition between canonical scaling and gauge-field antiscreening. Using the four-loop $MS$ beta function continued to $D = 4 + 2 ϵ$ , we determine the largest dimension $D_{pt} = 4 + 2 ϵ_{pt}$ below which successive loop corrections to the fixed point remain hierarchically ordered under a specified ratio criterion, and map $D_{pt}$ over color and flavor numbers for fermions in the fundamental representation of $S U (N)$ . At $D = 5$ , we construct rational anomalous dimensions with a fixed, pole-regularized denominator inspired by the functional renormalization group (fRG). Matching to the $MS$ series through one, two, and three loops produces progressively smaller shifts in the critical flavor number and coupling at the ultraviolet--infrared merger (the point where the infrared and ultraviolet fixed points coincide), yielding $N_{f}^{cr} ≃ 2.09 N$ at large $N$ in the three-loop construction. This low-order stabilization, together with qualitative evidence from fRG flows including higher gauge operators, suggests a potential merger scenario that bounds the candidate asymptotically safe region in flavor number. The resulting color--flavor map provides guidance for five-dimensional model building by displaying both the baseline perturbative-control boundary and the candidate three-loop merger boundary. Four-loop matching, however, retains an interacting ultraviolet fixed point beyond the three-loop merger boundary, with no merger found for integer $2 \leq N \leq 15$ and $0 \leq N_{f} / N \leq 11/2$ . The sensitivity of the fixed-point structure to higher-order terms leaves both scenarios open, highlighting fixed-point annihilation as a potential constraint on five-dimensional asymptotic safety.
↳ hep-thgr-qchep-lathep-ph
08
Machine Learning Meets High-Energy Nuclear Physics: From Pattern Recognition to Physics-Integrated Discovery
Xun Chen · Weiyao Ke · Yu-Gang Ma · Long-Gang Pang · Kai Zhou
Machine learning (ML) in high-energy nuclear physics (HENP) is entering a new stage in which physical knowledge is incorporated more directly into data analysis, simulation, and physics inference. This mini-review focuses on developments that have matured in the past several years. Whereas earlier applications emphasized event classification, pattern recognition, and surrogate models for selected observables, recent work has moved toward physics-integrated workflows: calibrated Bayesian extraction of QCD matter properties, dense-matter equation-of-state inference from heavy-ion and neutron-star data, generative event modeling, neural unfolding of weak physical signals, differentiable inverse solvers, gauge-equivariant and diffusion-based lattice-field samplers, and neural reconstruction of model functions in holographic QCD. We survey recent applications of ML in heavy-ion collisions, neutron-star physics, lattice QFT, and holographic or continuum QCD. The emphasis is not on ML architectures alone, but on how they enter concrete physics workflows, how physical constraints such as symmetries, conservation laws, causality, thermodynamic stability, and topology are imposed, and how uncertainty quantification and validation determine whether an AI-assisted result can support a reliable physics conclusion.
↳ hep-phcs.AIhep-lathep-th+1