arXiv subjects

Jozef J. Dudek

Publications and source records attributed to Jozef J. Dudek.

At least 19 recordsLinked to original sources

arXiv2026

Exotics with gluonic excitations

That the gluons of quantum chromodynamics self-interact with a strong coupling suggests the possibility of hadrons in which the gluonic field plays an essential role: Glueballs in which gluons stick together to produce a hadron in which no quarks are required, and hybrids in which an excited gluonic field couples to quarks. This chapter presents our contemporary theoretical understanding of such states, and the challenges associated with definitively identifying their presence within the experimental spectrum of hadrons.

hep-ph↗

arXiv2026

Radiative decays of the $h_c$ meson from lattice QCD

We explore, for the first time in lattice QCD, the radiative decays to $γη$ and $γη'$ of the $J^{PC}=1^{+-}$ charmonium state, $h_c$. This work expands upon a previous calculation of $J/ψ$ decays to the same final states, incorporating novel technology to access the $h_c$ where it is an excited state and to separate the independent electric dipole and longitudinal form--factors. Results for the radiative decay rates, computed on three-flavor lattices with $m_π\sim $ 391 MeV show a suppression relative to experiment that is similar to that observed in the prior calculation of $J/ψ\to γη^{(\prime)}$. The timelike $Q^2$ dependence of both form--factors together influence the Dalitz decays, $h_c \to \ell^+ \ell^- η^{(\prime)}$, which are as yet unmeasured experimentally.

hep-lat↗

arXiv2026

$D\bar{D}$ interactions are weak near threshold in QCD

We study near-threshold $D\bar{D}$ scattering in $S$ and $D$-wave to determine whether or not resonances or bound states are present. Working in the approximation where charm-annihilation is forbidden, with two degenerate light-quark flavors and a heavier strange quark, isospin is a good quantum number, and the only other other channel that is kinematically open is $η_cη$. Using lattice QCD we compute, as a function of varying light-quark mass, the $S$-matrix for coupled-channel $η_cη- D\bar{D}$ scattering and find only weakly interacting meson pairs. In contrast to several other studies, we find no evidence for any bound-state or resonance singularity in the energy region between the deeply-bound $χ_{c0}(1P)$ state and the $D_s\bar{D}_s$ threshold.

hep-lat↗

arXiv2025

$η$ and $η'$ meson production in $J/ψ$ radiative decays from lattice QCD

We report on the computation of amplitudes describing the radiative decay processes $J/ψ\to γ\, η$ and $J/ψ\to γ\, η'$ from first principles via lattice QCD. Using lattices with two degenerate flavors of light quark and a heavier strange quark where $m_π\sim 391$ MeV, we compute three-point correlation functions using optimized meson operators with a range of momenta. The use of optimized operators allows access to the $η'$, even though it appears as an excited state, lying above the ground-state $η$ in the isoscalar pseudoscalar channel. Statistically precise signals are obtained in this disconnected process by averaging over large numbers of kinematically equivalent correlators. We determine transition form-factors as a function of photon virtuality across the timelike region, which describe also the 'Dalitz' processes $J/ψ\to e^+ e^- \, η^{(\prime)}$. Significantly lower magnitudes of transition form-factor for both the $η$ and $η'$ are found than those extracted from experimental data, and possible explanations for this observation are presented.

hep-lat↗

arXiv2025

$η$ and $η'$ production in $J/ψ$ radiative decays from quantum chromodynamics

We present a first principles calculation within quantum chromodynamics (QCD) of the radiative decays of the $J/ψ$ into the light pseudoscalar mesons $η$ and $η'$. Within a lattice computation we obtain the transition form-factors as a function of photon virtuality from the timelike region, accessible experimentally via the 'Dalitz' decay $J/ψ\to e^+ e^-\, η^{(\prime)} $, through to the real photon point corresponding to $J/ψ\to γ\, η^{(\prime)} $. This is the first calculation in lattice QCD with two (heavier than physical) degenerate flavors of light quark and a heavier strange quark, in which the $η'$ appears as the first-excited state with pseudoscalar isoscalar quantum numbers. We access it reliably by using variationally optimized operators, use of which also improves the purity of the $J/ψ$ and $η$ signals, reducing systematic uncertainties. High quality results at a large number of kinematic points are obtained in a typically noisy disconnected process by using a novel correlator averaging procedure. Our results show the expected enhanced production of the $η'$ over the $η$ in this process, and suggest that the demonstrated lattice technology is suitable for future calculations considering processes in which light meson resonances are produced.

hep-lat↗

arXiv2024

Coupled-channel $J^{--}$ meson resonances from lattice QCD

We extend an earlier calculation within lattice QCD of excited light meson resonances with $J^{PC}=1^{--}, 2^{--}, 3^{--}$ at the SU(3) flavor point in the singlet representation, by considering the octet representation. In this case the resonances appear in coupled-channel amplitudes, which we determine, establishing the relative strength of pseudoscalar-pseudoscalar to pseudoscalar-vector decays. Combining the new octet results with the prior results for the singlet, we perform a plausible extrapolation to the physical quark mass, and compare to experimental $ρ^\star_J, K^\star_J, ω^\star_J$ and $ϕ^\star_J$ resonances.

hep-lat↗

arXiv2024

Determination of crossing-symmetric $ππ$ scattering amplitudes and the quark mass evolution of the $σ$ constrained by lattice QCD

Lattice QCD spectra can be used to constrain partial-wave scattering amplitudes that, while satisfying unitarity, do not have to respect crossing symmetry and analyticity. This becomes a particular problem when extrapolated far from real energies, e.g. in the case of broad resonances like the $σ$, leading to large systematic uncertainties in the pole position. In this manuscript, we will show how dispersion relations can implement the additional constraints, using as input lattice--determined $ππ$ partial-wave scattering amplitudes with isospin--0,1,2. We will show that only certain combinations of amplitude parameterizations satisfy all constraints, and that when we restrict to these, the $σ$ pole position is determined with minimal systematic uncertainty. The evolution of the now well-constrained $σ$ pole with varying light quark mass is presented, showing how it transitions from a bound-state to a broad resonance.

hep-lat↗

arXiv2023

Quark mass dependence of $ππ$ scattering in isospin 0, 1, and 2 from lattice QCD

Using lattice QCD we extract $ππ$ scattering amplitudes with isospin--0,1,2 in low partial-waves at two values of the light quark mass corresponding to $m_π\sim 283$ and $330$ MeV. We confirm expectations of weak repulsion in isospin--2, and the presence of a narrow $ρ$ resonance in isospin--1, and study the pion mass dependence of these channels. In isospin--0 we find that the two pion masses considered straddle the point at which the $σ$ transitions from being a stable bound-state to being either a virtual bound-state or a subthreshold resonance. We discuss the ability of lattice calculations like these to precisely determine the $σ$ pole location when it is a resonance, and propose an approach in which the full complement of amplitudes computed in this paper can be used simultaneously to provide more constraint.

hep-lat↗

arXiv2023

Charmonium $χ_{c0}$ and $χ_{c2}$ resonances in coupled-channel scattering from lattice QCD

In order to explore the spectrum of hidden-charm scalar and tensor resonances, we study meson-meson scattering with $J^{PC}=0^{++}, 2^{++}$ in the charmonium energy region using lattice QCD. Employing a light-quark mass corresponding to $m_π\approx 391$ MeV, we determine coupled-channel scattering amplitudes up to around 4100 MeV considering all kinematically relevant channels consisting of a pair of open-charm mesons or a charmonium meson with a light meson. A single isolated scalar resonance near 4000 MeV is found with large couplings to $D\bar{D}$, $D_s \bar{D}_s$ and the kinematically closed $D^* \bar{D}^*$ channel. A single tensor resonance at a similar mass couples strongly to $D\bar{D}$, $D\bar{D}^*$ and $D^* \bar{D}^*$. We compare the extracted resonances to contemporary experimental candidate states, previous lattice results and theoretical modeling. In contrast to several other studies, we do not find any significant feature in the scalar amplitudes between the ground state $χ_{c0}(1P)$ and the resonance found around 4000 MeV.

hep-lat↗

arXiv2023

Scalar and tensor charmonium resonances in coupled-channel scattering from QCD

We determine $J^{PC}=0^{++}$ and $2^{++}$ hadron-hadron scattering amplitudes in the charmonium energy region up to 4100 MeV using lattice QCD, a first-principles approach to QCD. Working at $m_π\approx 391$ MeV, more than 200 finite-volume energy levels are computed and these are used in extensions of the Lüscher formalism to determine infinite-volume coupled-channel scattering amplitudes. We find that this energy region contains a single $χ_{c0}$ and a single $χ_{c2}$ resonance. Both are found as pole singularities on the closest unphysical Riemann sheet, just below 4000 MeV with widths around 70 MeV. The largest couplings are to kinematically-closed $D^* \bar{D}^*$ channels in $S$-wave, and couplings to several decay channels consisting of pairs of open-charm mesons are found to be large and significant in both cases. Above the ground state $χ_{c0}$, no other scalar bound-states or near-$D\bar{D}$ threshold resonances are found, in contrast to several theoretical and experimental studies.

hep-lat↗

arXiv2022

Lattice QCD and Particle Physics

Contribution from the USQCD Collaboration to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021).

hep-lat↗

arXiv2021

Constraining $1+\mathcal{J}\to 2$ coupled-channel amplitudes in finite-volume

Whether one is interested in accessing the excited spectrum of hadrons or testing the standard model of particle physics, electroweak transition processes involving multi-hadron channels in the final state play an important role in a variety of experiments. Presently the primary theoretical tool with which one can study such reactions is lattice QCD, which is defined in a finite spacetime volume. In this work, we investigate the feasibility of implementing existing finite-volume formalism in realistic lattice QCD calculation of reactions in which a stable hadron can transition to one of several two-hadron channels under the action of an external current. We provide a conceptual description of the coupled-channel transition formalism, a practical roadmap for carrying out a calculation, and an illustration of the approach using synthetic data for two non-trivial resonant toy models. The results provide a proof-of-principle that such reactions can indeed be constrained using modern-day lattice QCD calculations, motivating explicit computation in the near future.

hep-lat↗

arXiv2021

Decays of an exotic $1^{-+}$ hybrid meson resonance in QCD

We present the first determination of the hadronic decays of the lightest exotic $J^{PC}=1^{-+}$ resonance in lattice QCD. Working with SU(3) flavor symmetry, where the up, down and strange quark masses approximately match the physical strange-quark mass giving $m_π\sim 700$ MeV, we compute finite-volume spectra on six lattice volumes which constrain a scattering system featuring eight coupled channels. Analytically continuing the scattering amplitudes into the complex energy plane, we find a pole singularity corresponding to a narrow resonance which shows relatively weak coupling to the open pseudoscalar--pseudoscalar, vector--pseudoscalar and vector--vector decay channels, but large couplings to at least one kinematically-closed axial-vector--pseudoscalar channel. Attempting a simple extrapolation of the couplings to physical light-quark mass suggests a broad $π_1$ resonance decaying dominantly through the $b_1 π$ mode with much smaller decays into $f_1 π$, $ρπ$, $η' π$ and $ηπ$. A large total width is potentially in agreement with the experimental $π_1(1564)$ candidate state, observed in $ηπ$, $η' π$, which we suggest may be heavily suppressed decay channels.

hep-lat↗

arXiv2020

Excited $J^{--}$ meson resonances at the SU(3) flavor point from lattice QCD

We present the first calculation within lattice QCD of excited light meson resonances with $J^{PC} = 1^{--}$, $2^{--}$ and $3^{--}$. Working with an exact SU(3) flavor symmetry, for the singlet representation of pseudoscalar-vector scattering, we find two $1^{--}$ resonances, a lighter broad state and a heavier narrow state, a broad $2^{--}$ resonance decaying in both $P$- and $F$-waves, and a narrow $3^{--}$ state. We present connections to experimental $ω^\star_J, ϕ^\star_J$ resonances decaying into $πρ$, $K\bar{K}^*$, $ηω$ and other final states.

hep-lat↗

arXiv2020

Efficient solution of the multi-channel Lüscher determinant condition through eigenvalue decomposition

We present a method for efficiently finding solutions of Lüscher's quantisation condition, the equation which relates two-particle scattering amplitudes to the discrete spectrum of states in a periodic spatial volume of finite extent such as that present in lattice QCD. The approach proposed is based on an eigenvalue decomposition in the space of coupled-channels and partial-waves, which proves to have several desirable and simplifying features that are of great benefit when considering problems beyond simple elastic scattering of spinless particles. We illustrate the method with a toy model of vector-vector scattering featuring a high density of solutions, and with an application to explicit lattice QCD energy level data describing $J^P=1^-$ and $1^+$ scattering in several coupled channels.

hep-lat↗

arXiv2019

Hadrons and Nuclei

This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD calculations related to the structure and spectroscopy of hadrons and nuclei. An overview of recent lattice calculations of the structure of the proton and other hadrons is presented along with prospects for future extensions. Progress and prospects of hadronic spectroscopy and the study of resonances in the light, strange and heavy quark sectors is summarized. Finally, recent advances in the study of light nuclei from lattice QCD are addressed, and the scope of future investigations that are currently envisioned is outlined.

hep-lat↗

arXiv2019

The $b_1$ resonance in coupled $πω$, $πϕ$ scattering from lattice QCD

We present the first lattice QCD calculation of coupled $πω$ and $πϕ$ scattering, incorporating coupled $S$ and $D$-wave $πω$ in $J^P=1^+$. Finite-volume spectra in three volumes are determined via a variational analysis of matrices of two-point correlation functions, computed using large bases of operators resembling single-meson, two-meson and three-meson structures, with the light-quark mass corresponding to a pion mass of $m_π\approx 391$ MeV. Utilizing the relationship between the discrete spectrum of finite-volume energies and infinite-volume scattering amplitudes, we find a narrow axial-vector resonance ($J^{PC}=1^{+-}$), the analogue of the $b_1$ meson, with mass $m_{R}\approx1380$ MeV and width $Γ_{R}\approx 91$ MeV. The resonance is found to couple dominantly to $S$-wave $πω$, with a much-suppressed coupling to $D$-wave $πω$, and a negligible coupling to $πϕ$ consistent with the `OZI rule'. No resonant behavior is observed in $πϕ$, indicating the absence of a putative low-mass $Z_s$ analogue of the $Z_c$ claimed in $πJ/ψ$. In order to minimally present the contents of a unitary three-channel scattering matrix, we introduce an $n$-channel generalization of the traditional two-channel Stapp parameterization.

hep-lat↗

arXiv2019

The quark-mass dependence of elastic $πK$ scattering from QCD

We present a determination of the isospin-1/2 elastic $πK$ scattering amplitudes in S and P partial waves using lattice Quantum Chromodynamics. The amplitudes, constrained for a large number of real-valued energy points, are obtained as a function of light-quark mass, corresponding to four pion masses between 200 and 400 MeV. Below the first inelastic threshold, the P-wave scattering amplitude is dominated by a single pole singularity that evolves from being a stable bound-state at the highest quark mass into a narrow resonance that broadens as the pion and kaon masses are reduced. As in experiment, the S-wave amplitude does not exhibit an obviously resonant behavior, but instead shows a slow rise from threshold, which is not inconsistent with the presence of a $κ$/$K_0^\star(700)$-like resonance at the considered quark masses. As has been found in analyses of experimental scattering data, simple analytic continuations into the complex energy plane of precisely-determined lattice QCD amplitudes on the real energy axis are not sufficient to model-independently determine the existence and properties of this state. The spectra and amplitudes we present will serve as an input for increasingly elaborate amplitude analysis techniques that implement more of the analytic structure expected at complex energies.

hep-lat↗