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Elastic scattering amplitudes for I = 0 DK and I = 0, 1 DK¯ are computed in S, P and D partial waves using lattice QCD with light-quark masses corresponding to mπ = 239 MeV and mπ = 391 MeV. The S-waves contain interesting features including a near-threshold JP = 0+ bound state in I = 0 DK, corresponding to the Ds0∗(2317), with an effect that is clearly visible above threshold, and suggestions of a 0+ virtual bound state in I = 0 DK¯. The S-wave I = 1 DK¯ amplitude is found to be weakly repulsive. The computed finite-volume spectra also contain a deeply-bound D* vector resonance, but negligibly small P -wave DK interactions are observed in the energy region considered; the P and D-wave DK¯ amplitudes are also small. There is some evidence of 1+ and 2+ resonances in I = 0 DK at higher energies.

Elastic scattering amplitudes for I = 0 DK and I = 0, 1 D K ¯ $$ D\overline{K} $$ are computed in S, P and D partial waves using lattice QCD with light-quark masses corresponding to m π = 239 MeV and m π = 391 MeV. The S-waves contain interesting features including a near-threshold J P = 0+ bound state in I = 0 DK, corresponding to the D s 0 ∗ $$ {D}_{s0}^{\ast } $$ (2317), with an effect that is clearly visible above threshold, and suggestions of a 0+ virtual bound state in I = 0 D K ¯ $$ D\overline{K} $$ . The S-wave I = 1 D K ¯ $$ D\overline{K} $$ amplitude is found to be weakly repulsive. The computed finite-volume spectra also contain a deeply-bound D * vector resonance, but negligibly small P -wave DK interactions are observed in the energy region considered; the P and D-wave D K ¯ $$ D\overline{K} $$ amplitudes are also small. There is some evidence of 1+ and 2+ resonances in I = 0 DK at higher energies.

We present preliminary calculations towards radiative transitions in charmonium using anisotropic $\textit{Nf}$=2+1 dynamical ensembles generated by the Hadron Spectrum Collaboration. With the use of newer technologies we aim to investigate transitions between states, including potential exotic charmonium states, lying higher in the spectrum than in previous studies. A crucial ingredient in this work is the use of variationally optimised interpolating operators which allow for a reliable determination of the three-point correlation functions needed. Using these operators, we perform first calculations of relevant three-point correlation functions before discussing future directions., We thank our colleagues within the Hadron Spectrum Collaboration. COH acknowledges support from the School of Mathematics at Trinity College Dublin. GM acknowledges support from the Herchel Smith Fund at the University of Cambridge. SMR acknowledges support from Science Foundation Ireland [RFP-PHY-3201]. CET acknowledges support from the U.K. Science and Technology Facilities Council (STFC) [grant ST/L000385/1].

We present the first lattice QCD study of coupled-channel $D\pi$, $D\eta$ and $D_{s}\bar{K}$ scattering in isospin-1/2 in three partial waves. Using distillation, we compute matrices of correlation functions with bases of operators capable of resolving both meson and meson-meson contributions to the spectrum. These correlation matrices are analysed using a variational approach to extract the finite-volume energy eigenstates. Utilising L\"uscher's method and its extensions, we constrain scattering amplitudes in $S$, $P$ and $D$-wave as a function of energy. By analytically continuing the scattering amplitudes to complex energies, we investigate the $S$-matrix singularities. Working at $m_\pi \approx 391$ MeV, we find a pole corresponding to a $J^{P} = 0^{+}$ near-threshold bound state with a large coupling to $D\pi$. We also find a deeply bound $J^{P} = 1^{-}$ state, and evidence for a $J^{P} = 2^{+}$ narrow resonance coupled predominantly to $D\pi$. Elastic $D\pi$ scattering in the isospin-$3/2$ channel is studied and we find a weakly repulsive interaction in $S$-wave.

We present highly excited spectra of charm-light and charm-strange mesons from dynamical lattice QCD. Our calculations are performed on anisotropic $N_{f} = 2+1$ dynamical ensembles generated by the Hadron Spectrum Collaboration. The use of novel techniques and a large basis of interpolating operators have allowed us to extract these spectra to a high degree of statistical precision, extract states of high spin and observe candidate hybrid mesons. We interpret and discuss our results in light of the current experimental situation., Comment: 8 pages, 3 figures, to appear in the proceedings of the Confinement X conference (8-12 October 2012, TUM Campus Garching, Munich.)

Decoupling of heavy quarks at low energies can be described by means of an effective theory as shown by S. Weinberg in Ref. [1]. We study the decoupling of the charm quark by lattice simulations. We simulate a model, QCD with two degenerate charm quarks. In this case the leading order term in the effective theory is a pure gauge theory. The higher order terms are proportional to inverse powers of the charm quark mass $M$ starting at $M^{-2}$. Ratios of hadronic scales are equal to their value in the pure gauge theory up to power corrections. We show, by precise measurements of ratios of scales defined from the Wilson flow, that these corrections are very small and that they can be described by a term proportional to $M^{-2}$ down to masses in the region of the charm quark mass., Comment: 20 pages, 3 figures, 3 tables, v2: Introduction and Conclusions expanded, new fits added to Figure 2 and 3, References updated

We study the effective theory of decoupling of a charm quark at low energies. We do this by simulating a model, QCD with two mass-degenerate charm quarks. At leading order the effective theory is a pure gauge theory. By computing ratios of hadronic scales we have direct access to the power corrections in the effective theory. We show that these corrections follow the expected leading behavior, which is quadratic in the inverse charm quark mass., 8 pages, 4 figures. Proceedings from the 35th International Symposium on Lattice Field Theory (Lattice2017), Granada, Spain

We report on the progress in the study of a five-dimensional SU(2) Gauge-Higgs Unification model. In this non-perturbative study, the Higgs mechanism is triggered by the spontaneous breaking of a global symmetry. In the same region of the phase diagram, we observe both dimensional reduction and the ratio of Higgs and Z boson masses to take the value known from experiment. We present the first results on the construction of a line of constant physics in this region, including the prediction for the mass scale of the first excited states of the Higgs and gauge bosons., Comment: Proceedings from the 34th annual International Symposium on Lattice Field Theory, 24-30 July 2016, University of Southampton, UK, Modified acknowledgements

We present highly-excited charmonium, $\textit{D}$$_{s}$ and $\textit{D}$ meson spectra from dynamical lattice QCD calculations with light quarks corresponding to $\textit{M}$$_{π}$ ∼ 240 MeV and compare these to previous results with $\textit{M}$$_{π}$ ∼ 400 MeV. Utilising the distillation framework, large bases of carefully constructed interpolating operators and a variational procedure, we extract and reliably identify the continuum spin of an extensive set of excited mesons. These include states with exotic quantum numbers which, along with a number with non-exotic quantum numbers, we identify as having excited gluonic degrees of freedom and interpret as hybrid mesons. Comparing the spectra at the two different $\textit{M}$$_{π}$ , we find only a mild light-quark mass dependence and no change in the overall pattern of states., GC is supported by the Cambridge European Trust, the U.K. Science and Technology Facilities Council (STFC) and St. John's College, Cambridge. COH acknowledges support from the School of Mathematics at Trinity College Dublin. GM acknowledges support the Herchel Smith Fund at the University of Cambridge. SMR acknowledges support from Science Foundation Ireland [RFP-PHY-3201]. CET acknowledges support from the STFC [grant ST/L000385/1]. DT is supported by the Irish Research Council Government of Ireland Postgraduate Scholarship Scheme [grant GOIPG/2014/65]. For further information please visit the publisher's website.

We compute and compare the continuum limits of several quantities in QCD with and without a dynamical charm quark. We consider both low energy quantities, like the hadronic scales $r_0$ and $t_0$, and high energy quantities, like the charmonium masses., 7 pages, 7 figures, 34th International Symposium on Lattice Field Theory (lattice 2016), 24-30 July 2016, Southampton, UK

The hadro-quarkonium picture [S. Dubinskiy and M.B. Voloshin, Phys. Lett. B 666, 344 (2008)] provides one possible interpretation for the pentaquark candidates with hidden charm, recently reported by the LHCb Collaboration, as well as for some of the charmonium-like "X,Y,Z" states. In this picture, a heavy quarkonium core resides within a light hadron giving rise to four- or five-quark/antiquark bound states. We test this scenario in the heavy quark limit by investigating the modification of the potential between a static quark-antiquark pair induced by the presence of a hadron. Our lattice QCD simulations are performed on a Coordinated Lattice Simulations (CLS) ensemble with $N_f = 2+1$ flavours of non-perturbatively improved Wilson quarks at a pion mass of about 223 MeV and a lattice spacing of about 0.0854 fm. We study the static potential in the presence of a variety of light mesons as well as of octet and decuplet baryons. In all these cases, the resulting configurations are favoured energetically. The associated binding energies between the quarkonium in the heavy quark limit and the light hadron are found to be smaller than a few MeV, similar in strength to deuterium binding. It needs to be seen if the small attraction survives in the infinite volume limit and supports bound states or resonances., 16 pages, 17 figures, V2: 1 figure added, changes to the abstract and various places in the text for enhanced clarity, update of references

We present the first lattice QCD study of coupled-channel $D\pi$, $D\eta$ and $D_{s}\bar{K}$ scattering in isospin-1/2 in three partial waves. Using distillation, we compute matrices of correlation functions with bases of operators capable of resolving both meson and meson-meson contributions to the spectrum. These correlation matrices are analysed using a variational approach to extract the finite-volume energy eigenstates. Utilising L\"uscher's method and its extensions, we constrain scattering amplitudes in $S$, $P$ and $D$-wave as a function of energy. By analytically continuing the scattering amplitudes to complex energies, we investigate the $S$-matrix singularities. Working at $m_\pi \approx 391$ MeV, we find a pole corresponding to a $J^{P} = 0^{+}$ near-threshold bound state with a large coupling to $D\pi$. We also find a deeply bound $J^{P} = 1^{-}$ state, and evidence for a $J^{P} = 2^{+}$ narrow resonance coupled predominantly to $D\pi$. Elastic $D\pi$ scattering in the isospin-$3/2$ channel is studied and we find a weakly repulsive interaction in $S$-wave.