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1. Including tetraquark operators in the low-lying scalar meson sectors in lattice QCD

   https://doi.org/10.1063/5.0008966  

   Darvish, Daniel; Brett, Ruairí; Bulava, John; Fallica, Jacob; Hanlon, Andrew; Hörz, Ben; Morningstar, Colin (January 2020, AIP Conference Proceedings)

   Lattice QCD allows us to probe the low-lying hadron spectrum in finite-volume using a basis of single- and multihadron interpolating operators. Here we examine the effect of including tetraquark operators on the spectrum in the scalar meson sectors containing the K0*(700) (κ) and the a0(980) in Nf = 2+1 QCD, with mπ ≈ 230 MeV. Preliminary results of additional finite-volume states found using tetraquark operators are shown, and possible implications of these states are discussed. 

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2. Low-lying baryon resonances from lattice QCD

   Bulava, John; Cid-Mora Barbara; Hanlon, Andrew; Hoerz, Ben; Mohler, Daniel; Morningstar, Colin; Moscoso, Joseph; Nicholson, Amy; Romero-Lopez, Fernando; Skinner, Sarah; et al (October 2023, Nuovo cimento B, to appear)

   Recent results studying the masses and widths of low-lying baryon resonances in lattice QCD are presented. The S-wave Nπ scattering lengths for both total isospins I=1/2 and I=3/2 are inferred from the finite-volume spectrum below the inelastic threshold together with the I=3/2 P-wave containing the Δ(1232) resonance. A lattice QCD computation employing a combined basis of three-quark and meson-baryon interpolating operators with definite momentum to determine the coupled channel Σπ-NKbar scattering amplitude in the Λ(1405) region is also presented. Our results support the picture of a two-pole structure suggested by theoretical approaches based on SU(3) chiral symmetry and unitarity. 

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3. Low-lying baryon resonances from lattice QCD

   Bulava, J; Cid-Mora, B; Hanlon, A; Hoerz, B; Mohler, D; Morningstar, C; Moscoso, J; Nicholson, A; Romero-Lopez, F; Skinner, S; et al (June 2024, IL NUOVO CIMENTO C)

   Recent results studying the masses and widths of low-lying baryon resonances in lattice QCD are presented. The S-wave Nπ scattering lengths for both total isospins I = 1/2 and I = 3/2 are inferred from the finite-volume spectrum below the inelastic threshold together with the I = 3/2 P-wave containing the ∆(1232) resonance. A lattice QCD computation employing a combined basis of three-quark and meson-baryon interpolating operators with definite momentum to determine the coupled channel Σπ-NK scattering amplitude in the Λ(1405) region is also presented. Our results support the picture of a two-pole structure suggested by theoretical approaches based on SU(3) chiral symmetry and unitarity. 

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4. The quark-mass dependence of the potential energy between static colour sources in the QCD vacuum with light and strange quarks

   https://doi.org/10.1016/j.physletb.2024.138754  

   Bulava, John; Knechtli, Francesco; Koch, Vanessa; Morningstar, Colin; Peardon, Michael (July 2024, Physics Letters B)

   The low-lying energy spectrum of the static-colour-source-anti-source system in a vacuum containing light and strange quarks is computed using lattice QCD for a range of different light quark masses. The resulting levels are described using a simple model Hamiltonian and the parameters in this model are extrapolated to the physical light-quark masses. In this framework, the QCD string tension is found to be sqrt(sigma) = 445(3)_stat (6)_sys MeV. 

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5. $\omega$ Meson from Lattice QCD

   https://doi.org/10.1103/PhysRevLett.133.211906  

   Yan, Haobo; Mai, Maxim; Garofalo, Marco; Meißner, Ulf-G; Liu, Chuan; Liu, Liuming; Urbach, Carsten (November 2024, Physical Review Letters)

   Many excited states in the hadron spectrum have large branching ratios to three-hadron final states. Understanding such particles from first principles QCD requires input from lattice QCD with one-, two-, and three-meson interpolators as well as a reliable three-body formalism relating finite-volume spectra at unphysical pion mass values to the scattering amplitudes at the physical point. In this work, we provide the first-ever calculation of the resonance parameters of the $\omega$meson from lattice QCD, including an update of the formalism through matching to effective field theories. The main result of this pioneering study, the pole position of the $\omega$meson at $\sqrt{s_{\omega }}=\left(778.0\right(11.2)-i3.0(5\left)\right)\mathrm{MeV}$, agrees reasonably well with experiment. In addition we provide an estimate of the $\omega -\rho$mass difference as 29(15) MeV. Published by the American Physical Society2024 

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