New articles on High Energy Physics - Lattice


[1] 2602.02880

Contact interaction treatment of the nucleon Faddeev equation

Working with a symmetry-preserving treatment of a vector $\otimes$ vector contact interaction (SCI), a largely algebraic three-body Faddeev equation treatment of the nucleon bound state problem is introduced and used to deliver results for all nucleon charge and magnetisation distributions and their flavour separation. A strength of the SCI treatment is that it provides for a transparent understanding of this three-body approach to developing predictions for baryon observables. Comparisons of SCI results with predictions obtained in realistic-interaction Faddeev equation studies reveal the sensitivities of given observable to phenomena associated with the emergence of hadron mass.


[2] 2602.03656

Resolving Quantum Criticality in the Honeycomb Hubbard Model

The interplay between Dirac fermions and electronic correlations on the honeycomb lattice hosts a fundamental quantum phase transition from a semimetal to a Mott insulator, governed by the Gross-Neveu-Heisenberg (GNH) universality class. Despite its importance, consensus on the precise critical exponents remains elusive due to severe finite-size effects in numerical simulations and the lack of conformal bootstrap benchmarks. Here we try to resolve this long-standing controversy by performing projector determinant quantum Monte Carlo (QMC) simulations on lattices of unprecedented size, reaching 10,368 sites. By developing a novel projected submatrix update algorithm, we achieve a significant algorithmic speedup that enables us to access the thermodynamic limit with high precision. We observe that the fermion anomalous dimension and the correlation length exponent converge rapidly, while the boson anomalous dimension exhibits a systematic size dependence that we resolve via linear extrapolation. To validate our analysis, we perform parallel large-scale simulations of the spinless $t$-$V$ model on the honeycomb lattice, which belongs to the Gross-Neveu-Ising class. Our results for the $t$-$V$ model, including the first QMC determination of the fermion anomalous dimension, show agreement with conformal bootstrap predictions, thereby corroborating the robustness of our methodology. Our work provides state-of-the-art critical exponents for the honeycomb Hubbard model and establishes a systematic finite-size scaling workflow applicable to a broad class of strongly correlated quantum systems, paving the way for resolving other challenging fermionic quantum critical phenomena.


[3] 2503.01991

Momentum Flow Mechanisms and Color-Lorentz Forces on Quarks in the Nucleon

Momentum conservation in the nucleon is examined in terms of continuous flow of the momentum current density (or in short, momentum flow), which receives contributions from both kinetic motion and interacting forces involving quarks and gluons. While quarks conduct momentum flow through their kinetic motion and the gluon scalar (anomaly) contributes via pure interactions, the gluon stress tensor has both effects. The quarks momentum flow encodes the information of the color-Lorentz force density on them, and the momentum conservation allows to trace its origin to the gluon tensor and anomaly (a ``negative pressure'' potential). From the state-of-the-art lattice calculations and experimental fits on the form factors of the QCD energy-momentum tensor, we exhibit pictures of the momentum flow and the color-Lorentz forces on the quarks in the nucleon. In particular, the anomaly contributes a critical attractive force with a strength similar to that of a heavy-quark confinement potential.


[4] 2508.12276

Probing $NNΩ_{ccc}$ three-body systems with the modern QCD $NΩ_{ccc}$ interaction

Newly, first-principles lattice QCD results at the physical pion mass, $ m_\pi \backsimeq 137.1 $ MeV, have been reported by the HAL QCD Collaboration for the S-wave interaction between the nucleon ($N$) and the triply charmed Omega baryon ($\Omega_{ccc}$). The $N\Omega_{ccc}$ potentials in the spin-1 $ \left(^{3}S_{1}\right) $ and spin-2 $ \left(^{5}S_{2}\right) $ channels were derived and found to be attractive, though no two-body bound state was supported in these channels. The present work investigates the $NN\Omega_{ccc}$ three-body system using the Malfliet-Tjon $NN$ potential. Analyses of spin-1, spin-averaged, and spin-2 $N\Omega_{ccc}$ channels (at Euclidean times 16, 17, 18) reveal a three-body bound state only for the d-$\Omega_{ccc}$ configuration with spin $(0)1/2^{+}$ and $t/a=16$. Its binding energy ($B_3 = -2.255$ MeV) lies slightly below the deuteron's ($B_d = -2.23$ MeV). Other parameter sets do not yield a bound state, and complex scaling analysis indicates these configurations correspond to virtual states rather than resonances. The Coulomb potential's role was also examined to differentiate charged states.


[5] 2508.16727

A Journey of Seeking Pressure and Forces in the Nucleon

Momentum current density (MCD) $T^{ij}$ is a general physics concept describing the momentum conservation through momentum flow generated from both the kinetic motion of particles and the interacting forces among them. It has been suggested by M. Polyakov et al. that the MCD in the nucleon, characterized by the form factor $C/D$ of the QCD energy-momentum tensor, can be interpreted as the pressure and shear forces between adjacent parts of the system because the nucleon interior approximates a continuous medium. While intuitively appealing, we find that the interpretation is hard to justify from a detailed examination of the physical mechanisms for the momentum flow in QCD. After reviewing through a broad range of classical and quantum systems, we find that while thermal and/or quantum average of isotropic motion contributes to kinetic MCD a pressure term proportional to $\delta^{ij}$, when there is an anisotropic motion, the pressure cannot simply be identified from the MCD tensor. Furthermore, kinetic pressure cannot be considered as the surface force between adjacent parts of a system. More importantly, at the scale of the nucleon dimension, the color forces among quarks and gluons is by no means short-ranged as in a continuous medium, and the resulting interaction MCD cannot be interpreted as normal or shear ``stress'' force, although an isotropic term from the QCD trace anomaly may be interpreted as a ``vacuum pressure.'' Following our previous study of force densities through divergences of kinetic MCDs, we affirm that the vacuum pressure term provides a confining potential on the quarks through color Lorentz forces.


[6] 2509.17510

The odd-parity strange baryons $Σ\,(\frac{1}{2}^-)$ below 1.8 GeV with Hamiltonian effective field theory

We examine the spectrum of the $\Sigma\,(\frac{1}{2}^-)$ family based on the experimental $K^-p$ scattering data and lattice QCD simulations within the Hamiltonian Effective Field Theory. Especially, two different scenarios are constructed in order to clarify whether there is one or two $\Sigma\,(\frac{1}{2}^-)$ resonances with masses around 1.5$\sim$1.7 GeV. The relevant lattice QCD data support our scenario with two resonance poles at $1687-110\,i$ and $1714-14\,i$ MeV in which the bare strange triquark core plays an important role. We also show an extra clear cusp structure around 1.4 GeV in our scattering T matrices associated with the odd-parity strange baryons.


[7] 2510.08682

Two-loop anomalous dimensions for baryon-number-violating operators in SMEFT

We compute the two-loop renormalization-group equations for the baryon-number-violating dimension-six operators in the SMEFT. This includes all three gauge interactions, the Yukawa, and Higgs self-interaction contributions. In addition, we present the one-loop matching of the $S_1$ scalar leptoquark on the SMEFT, which can generate the Wilson coefficients of all four gauge-invariant baryon-number-violating SMEFT operators. Using this example, we demonstrate the cancellation of scheme and matching-scale dependences. Together with the known two-loop renormalization-group evolution below the electroweak scale in the LEFT, as well as the one-loop matching of SMEFT onto LEFT, our results enable consistent next-to-leading-log analyses of nucleon decays, provided that the relevant matrix elements are known at next-to-leading-order accuracy.