Tetraquark operators in lattice QCD and exotic flavour states in the charm sector

Cheung, Gavin; Thomas, C.; Dudek, Jozef J.; Edwards, Robert G.

doi:10.1007/jhep11(2017)033

Cited by 91 publications

(89 citation statements)

References 123 publications

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“…However, they are quite close to their thresholds which was also observed in Ref. [80]. Though they could be stable under strong interactions one needs to carry out finite volume analysis to establish their bound state properties, if there is any.…”

Section: Discussionsupporting

confidence: 79%

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Study of doubly heavy tetraquarks in lattice QCD

2019

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We present the results of a lattice calculation of tetraquark states with quark contents q1q2QQ, q1, q2 ⊂ u, d, s, c and Q ≡ b, c in both spin zero (J = 0) and spin one (J = 1) sectors. This calculation is performed on three dynamical N f = 2 + 1 + 1 highly improved staggered quark ensembles at lattice spacings of about 0.12, 0.09 and 0.06 fm. We use the overlap action for light to charm quarks while a non-relativistic action with non-perturbatively improved coefficients with terms up to O(αsv 4 ) is employed for the bottom quark. While considering charm or bottom quarks as heavy, we calculate the energy levels of various four-quark configurations with light quark masses ranging from the physical strange quark mass to that of the corresponding physical pion mass. This enables us to explore the quark mass dependence of the extracted four-quark energy levels over a wide range of quark masses. The results of the spin one states show the presence of ground state energy levels which are below their respective thresholds for all the light flavor combinations. Further, we identify a trend that the energy splittings, defined as the energy difference between the ground state energy levels and their respective thresholds, increase with decreasing the light quark masses and are maximum at the physical point for all the spin one states. The rate of increase is however dependent on the light quark configuration of the particular spin one state. We also present a study of hadron mass relations involving tetraquarks, baryons and mesons arising in the limit of infinitely heavy quark and find that these relations are more compatible with the heavy quark limit in the bottom sector but deviate substantially in the charm sector. The ground state spectra of the spin zero tetraquark states with various flavor combinations are seen to lie above their respective thresholds.1 A diquark can be interpreted as a compact colored object inside a hadron and is made out of two quarks (or antiquarks) in the 3(3) or 6(6) irrep of SU(3) and can have spin zero (scalar) or spin one (vector). With this model one can build rich phenomenology for mesons, baryons, as well as multiquark states.

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Section: Discussionsupporting

confidence: 79%

“…However, they are very close to their respective strong decay thresholds as was also observed in Ref. [80]. Because of their close proximity to thresholds, a careful finite volume analysis [41] is needed to make conclusive statements about the nature of these states.…”

Section: A Analysis Methodssupporting

confidence: 73%

Study of doubly heavy tetraquarks in lattice QCD

2019

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“…As one might anticipate, failing to include all the occurrences of meson-meson operators in a given energy region can lead to an incomplete spectrum. 12 This is demonstrated clearly in figure 8 of [51].…”

Section: Jhep07(2018)043mentioning

confidence: 85%

“…Further applications of the approach presented here include the isospin-1 ωπ system -in the J P = 1 + partial-wave this features a low-lying resonance, the b 1 , which has been measured to have significant coupling 25 to both 3 S 1 and 3 D 1 channels [68]. Furthermore, contemporary experiments in the charmonium sector appear to show resonant behaviour in the exotic-flavour J/ψ π channel; first attempts to determine lattice QCD spectra here have appeared [51,57], but as yet there has been no determination of the scattering amplitudes.…”

Section: Jhep07(2018)043mentioning

confidence: 96%

Dynamically-coupled partial-waves in ρπ isospin-2 scattering from lattice QCD

Woss

Thomas

Dudek

et al. 2018

J. High Energ. Phys.

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We present the first determination of ρπ scattering, incorporating dynamicallycoupled partial-waves, using lattice QCD, a first-principles numerical approach to QCD. Considering the case of isospin-2 ρπ, we calculate partial-wave amplitudes with J ≤ 3 and determine the degree of dynamical mixing between the coupled S and D-wave channels with J P = 1 + . The analysis makes use of the relationship between scattering amplitudes and the discrete spectrum of states in the finite volume lattice. Constraints on the scattering amplitudes are provided by over one hundred energy levels computed on two lattice volumes at various overall momenta and in several irreducible representations of the relevant symmetry groups. The spectra follow from variational analyses of matrices of correlations functions computed with large bases of meson-meson operators. Calculations are performed with degenerate light and strange quarks tuned to the physical strange quark mass so that m π ∼ 700 MeV, ensuring that the ρ is stable against strong decay. This work demonstrates the successful application of techniques, opening the door to calculations of scattering processes that incorporate the effects of dynamically-coupled partial-waves, including those involving resonances or bound states.

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“…More details can be found in the original references. We also refer the reader to the lattice QCD literature providing alternate conclusions on these states [22]. Results in parentheses are obtained with a string tension k = 1/4 × 0.15 GeV 2 in Eq.…”

Section: Arxiv:190310253v2 [Hep-ph] 17 May 2019mentioning

confidence: 99%

Hydrogen bond of QCD

2019

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Using the Born-Oppenheimer approximation, we show that exotic resonances, X and Z, may emerge as QCD molecular objects made of colored two-quark lumps, states with heavy-light diquarks spatially separated from antidiquarks. With the same method we confirm that doubly heavy tetraquarks are stable against strong decays. Tetraquarks described here provide a new picture of exotic hadrons, as formed by the QCD analog of the hydrogen bond of molecular physics.

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Tetraquark operators in lattice QCD and exotic flavour states in the charm sector

Cited by 91 publications

References 123 publications

Study of doubly heavy tetraquarks in lattice QCD

Study of doubly heavy tetraquarks in lattice QCD

Dynamically-coupled partial-waves in ρπ isospin-2 scattering from lattice QCD

Hydrogen bond of QCD

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