HEP Lattice·hep-lat

Tue·Jul 28, 2026Tuesday·July 28, 2026

5 papers—2 primary·3 cross-listed

01
First constraints on the nonperturbative gluon Collins-Soper kernel
Artur Avkhadiev🇺🇸 · Yang Fu🇺🇸 · Phiala E. Shanahan🇺🇸 · Michael L. Wagman🇺🇸 · Yong Zhao🇺🇸
The gluon Collins-Soper kernel, which encodes the rapidity evolution of transverse-momentum-dependent gluon distributions, is constrained for the first time in the nonperturbative regime, for transverse momentum scales $q_{T} \in [300 MeV, 1.3 GeV]$ . The constraints are determined in lattice QCD at a close-to-physical pion mass $M_{π} = 172 (3) MeV$ , a single lattice spacing $a = 0.15 fm$ , and next-to-next-to-leading logarithmic matching in Large-Momentum Effective Theory. These results represent the first step toward a controlled determination of the gluon Collins-Soper kernel in QCD, with eventual phenomenological import and relevance to present and future experiments sensitive to the gluon structure of hadronic matter.
hep-lathep-phnucl-th1 citation
02
Analytic decomposition of two-body electroweak processes with left-hand cuts
André Baião-Raposo🇩🇪 · Raúl A. Briceño🇺🇸 · Nicolas Lang🇪🇸 · Felipe G. Ortega-Gama🇺🇸 · Bianca Pol🇺🇸
We derive an on-shell representation for electroweak $2 + J \to 2$ transition amplitudes involving two hadrons in both the initial and final state for systems where there are left-hand singularities generated by light-particle exchange, e.g. one-pion exchange. The derivation treats the insertion of the electroweak current perturbatively, keeping only the leading-order contribution in the external field, while the hadronic interactions are treated to all orders, including one-particle exchange effects. We find that, in such processes, the amplitude can have logarithmic singularities, as well as one-particle pole singularities, due to these exchanges. We isolate those contributions, as well as previously identified triangle singularities. The result is expressed in terms of the purely hadronic amplitude, exchange-current kernels, triangle functions, and a class of short-distance transition functions that are real and smooth below unaccounted-for thresholds. While we consider only transitions with spinless particles, this work is an important step toward constraining form factors of systems involving nucleons or vector mesons in the heavy quark sector, where the one-pion-exchange singularity is quite close to threshold.
hep-lathep-phnucl-th1 citation
03
Effects of flavor-mixings on charged kaon and pion parton distribution functions
Fabio L. Braghin🇧🇷 · Parada T. P. Hutauruk🇯🇵
We investigate the charged kaon and pion parton distribution functions (PDFs) in the U(3) Nambu--Jona-Lasinio (NJL) model, considering a novel flavor-mixing interaction arising from vacuum polarization that differs from the instanton-induced 't~Hooft interaction. In this work, the proper-time regularization scheme is employed, and, effectively, it might take quark confinement into account. The gap equations, the meson masses, and the meson--quark coupling constants are calculated in the presence of flavor mixing interactions. The valence-quark distributions of the charged kaon and pion are calculated and compared with existing experimental data and JAM analysis results at scales $μ^{2} =$ 4 and 27 GeV $^{2}$ . The strength of mixing effects on the PDFs is found to be proportional to the quark effective masses and their differences. We further find that the dominant flavor mixing effects in the pion valence up-quark distribution at scales $μ^{2} =$ 27 and 4 GeV $^{2}$ are around $x ≃ 0.3$ and $x ≃ 0.8$ , while for the kaon, the effects are shown at around $x ≃ 0.2$ and $x ≃ 0.7$ . We also find similar strength of mixing effects on the PDFs at both scales $μ^{2} = 4$ and 27 GeV $^{2}$ ; however, it certainly improves the pion and kaon PDFs.
↳ hep-phhep-exhep-latnucl-th1 citation
04
Electromagnetic form factors of singly charmed baryons $Σ_{c}$ and $Λ_{c}$ in a covariant quark-diquark model
Ye Cao🇨🇳 · Cheng Chen🇨🇳 · Dongyan Fu🇨🇳 · Ju-Jun Xie🇨🇳
We present a systematic study of the spacelike electromagnetic form factors of the ground-state singly charmed baryons, $Σ_{c}$ ( $Σ_{c}^{++}, Σ_{c}^{+}, Σ_{c}^{0}$ ) and $Λ_{c}^{+}$ , within a covariant quark-diquark model. Based on this framework, we obtain their magnetic moments as well as electric charge and magnetic moment radii. Such observables are important to understand the internal structure and the inner dynamics of these heavy baryon states. Our theoretical calculations are in qualitative agreement with available lattice QCD results of $Σ_{c}^{++}$ and $Σ_{c}^{0}$ baryons. We also discuss the mechanism behind the dependence of the numerical results on the charm quark and light diquark. A key finding is that the electric form factors of the singly charmed baryons fall off much more slowly with momentum transfer $Q^{2}$ than that of the proton, indicating a more compact electric charge distribution, which is attributed to the heavy charm quark acting as a localized core. More importantly, we observe a striking difference in the magnetic structure: while the magnetic form factors of $Σ_{c}$ are dominated by the light axial-vector diquark, those of $Λ_{c}^{+}$ are unexpectedly governed by the charm quark due to the vanishing contribution of the scalar diquark. This highlights the decisive role of the light-diquark spin configuration in determining the magnetic properties. Finally, using an empirical asymptotic relation connecting the spacelike and timelike regions, we predict the total cross section for $e^{+} e^{-} \to Σ_{c} Σ ˉ_{c}$ . Our findings can be tested at existing facilities including the BESIII, Belle II and LHCb, as well as the proposed Super Tau-Charm Facility.
↳ hep-phhep-exhep-lat0 citations
05
Dynamical Quarks in the Ensemble of Center Vortices with Monopole Defects: Color Confinement Beyond External Probes
Luis E. Oxman🇧🇷
We consider the interaction of dynamical quarks with the ensemble of oriented and nonoriented center vortices proposed to describe flux-tube formation between quark probes in pure Yang-Mills theory. The quark sector is described in terms of bosonized color currents. Within this fluid-like framework, the infrared vortex--monopole condensate restricts finite-energy configurations to be color neutral. Furthermore, neutral distributions of constituent color densities embedded in the condensate generate frustrated regions, providing a mechanism for their localization into finite-size configurations. The resulting picture is consistent with lattice evidence indicating that center vortices play a central role in shaping the hadron spectrum.
↳ hep-thhep-lathep-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE

First constraints on the nonperturbative gluon Collins-Soper kernel

Analytic decomposition of two-body electroweak processes with left-hand cuts

Effects of flavor-mixings on charged kaon and pion parton distribution functions

Electromagnetic form factors of singly charmed baryons Σc​ and Λc​ in a covariant quark-diquark model

Dynamical Quarks in the Ensemble of Center Vortices with Monopole Defects: Color Confinement Beyond External Probes

Affiliations

Electromagnetic form factors of singly charmed baryons $Σ_{c}$ and $Λ_{c}$ in a covariant quark-diquark model