Hadron Spectroscopy and Interactions

Cutoff effects on lattice nuclear forces
Takumi Doi
Mon, 14:00, Seminar Room G -- Parallels 1G (Slides)

In the past years, there have been extensive studies on nuclear interactions in lattice QCD. In each of these studies, however, lattice simulations were performed only at single lattice spacing, and the effect of lattice discretization errors have not been examined. In this talk, we investigate the cutoff effects on nuclear forces on the lattice, where nuclear potentials are extracted from the Nambu-Bethe-Salpeter (NBS) wave functions by the HAL QCD method. Employing Nf=2 clover fermion configurations generated by CP-PACS Collaboration, we perform numerical simulations at three lattice spacings, 1/a = 0.92, 1.27, 1.83 GeV, with a fixed volume of \(L \sim 2.5\) fm and a quark mass corresponding to \(m_\pi \sim 1.1\) GeV. We observe non-negligible cutoff effects on the short-range part of nuclear potentials. The results are discussed comparing with the prediction by the OPE (operator-product-expansion) calculation. Cutoff effects on the scattering phase shifts are also presented.

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Correlation functions of atomic nuclei in Lattice QCD I
Jana Günther, Balint C Toth, Lukas Varnhorst
Mon, 14:20, Seminar Room G -- Parallels 1G (Slides)

To determine the mass of atomic nuclei in lattice QCD one has to calculate the correlation functions of suitable combinations of quark field operators. However the calculation of these correlation functions requires the evalution of a large number of Wick contractions, which scales as the factorial of the number of nucleons in the system. We explore the possibilities to reduce the computational effort for the evaluation of correlation functions of atomic nuclei by exploiting certain symmetries of the systems. We discuss a recursive approach which respects these symmetries for the simplest case of identical quark sources.

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Correlation functions of atomic nuclei in Lattice QCD II
Lukas Varnhorst, Jana Günther, Balint C Toth
Mon, 14:40, Seminar Room G -- Parallels 1G (Slides)

We discuss generalizations of the recursive algorithm presented in the talk of Jana Günther. These generalizations include baryons from different sources and sinks and the projections to specific spin states. The construction of atomic nuclei as a special case is presented in detail.The computational cost for the recursive construction of correlation functions of atomic nuclei is compared with the cost of other techniques.

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Equation of State of Nucleon Matters from Lattice QCD Simulations
Takashi Inoue
Mon, 15:00, Seminar Room G -- Parallels 1G (Slides)

We study nucleon matters at zero temperature starting from QCD. By using nucleon-nucleon interaction extracted from lattice QCD simulations, we derive the equation of state of matters in the Brueckner-Hartree-Fock framework. We find that well known features of the symmetric nuclear matter, such as the self-binding and the saturation, are reproduced from QCD at some value of quark mass. We find also that the pure neutron matter become stiff at large density as quark mass decreases. We apply these equations of state to the TOV equation and obtain mass and radius of neutron stars.

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Multi-nucleon bound states in \(N_f=2+1\) lattice QCD
Akira Ukawa, Takeshi Yamazaki, Ken-ichi Ishikawa, Yoshinobu Kuramashi
Mon, 15:20, Seminar Room G -- Parallels 1G (Slides)

We present our results of bound states in multi-nucleon channels where the nuclear mass numbers are from two to four. The simulations are performed in \(N_f=2+1\) QCD with Iwasaki and non-perturbative improved Wilson fermion actions at the lattice spacing of a = 0.09 fm with quark mass of \(m_\pi = 0.3\) GeV. The strange quark mass is close to the physical one. We will discuss the volume dependence of the energy difference between the ground state and the free nucleons by using the (4.4 fm)\(^3\) and (5.8 fm)\(^3\) lattices to distinguish a bound state from attractive scattering state. Furthermore the quark mass dependence of the energy difference will be discussed using our previous results of \(m\_pi = 0.5\) GeV.

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Lattice effective field theory for nuclei from A = 4 to A = 28
Timo Laehde, Evgeny Epelbaum, Hermann Krebs, Dean Lee, Ulf Meissner, Gautam Rupak
Mon, 15:40, Seminar Room G -- Parallels 1G (Slides)

Lattice effective field theory is a relatively new method which combines the frameworks of effective field theory and lattice Monte Carlo in ab initio nuclear theory. I will present new results obtained within lattice effective field theory for systems ranging from helium-4 to carbon-12, with emphasis on the quark mass dependence of the triple alpha reaction rate, and discuss the implications for an anthropic view of the Universe. I will also present preliminary lattice effective field theory results for systems up to A = 28.

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Fine lattice simulations with chirally symmetric fermions
Junichi Noaki, Sinya Aoki, Guido Cossu, Hidenori Fukaya, Shoji Hashimoto, Takashi Kaneko
Mon, 16:30, Seminar Room G -- Parallels 2G (Slides)

We carry out numerical simulations of 2+1-flavor QCD with nearly chiral lattice fermions. Lattice spacing is taken at 1/a = 2.4 and 3.6 GeV, while keeping the condition \(m_\pi L>4\). Using the so-called Mobius-type 5D implementation of the Ginsparg-Wilson fermion, the residual mass is always kept lower than 0.5 MeV. In this talk, I report the first physics results including the determination of lattice spacing through the Wilson flow as well as the light hadron mass spectrum.

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Preliminary results from maximally twisted mass lattice QCD at the physical point
Bartosz Kostrzewa, Karl Jansen, Roberto Frezzotti, Carsten Urbach, Giancarlo Rossi, David Palao, Petros Dimopoulos, Mariane Mangin-Brinet, Albert Deuzeman, Urs Wenger, Luigi Scorzato, Abdou Abdel-Rehim, Andrea Shindler, Gregorio Herdoiza, Istvan Montvay, Philippe Boucaud
Mon, 16:50, Seminar Room G -- Parallels 2G (Slides)

In this contribution, first results of simulations with \(N_f=2\) dynamical flavours of maximally twisted mass fermions at the physical point are presented using a newly generated ensemble by the European Twisted Mass Collaboration (ETMC) at one lattice spacing. An overview is given of the newly chosen action, algorithmic stability and the tuning to maximal twist. As a first test, preliminary measurements of mesonic quantities are shown to indicate that the physical pion mass region has been reached on a large volume lattice. Finally, the extension of simulations to \(N_f=2+1+1\) is discussed and current progress is outlined.

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Spectrum of excited states using the stochastic LapH method
Colin Morningstar
Mon, 17:10, Seminar Room G -- Parallels 2G (Slides)

Results for the spectrum of excited mesons obtained from the temporal correlations of spatially-extended single-hadron and multi-hadron operators on anisotropic \(24^3 \times 128\) and \(32^3 \times 256\) lattices are presented. A stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing makes such calculations possible. Light-meson scattering phase shifts may also be presented.

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Isospin breaking effect from lattice QCD and QED
Antonin Portelli
Mon, 17:30, Seminar Room G -- Parallels 2G (Slides)

While electromagnetic and up-down quark mass difference effects on octet baryon masses are very small, they have important consequences. The stability of the hydrogen atom against beta decay is a prominent example. Here we include these effects by adding them to valence quarks in a lattice QCD calculation based on Nf =2+1 simulations with 5 lattice spacings down to 0.054 fm, lattice sizes up to 6 fm and average up-down quark masses all the way down to their physical value. This allows us to gain control over all systematic errors, except for the one associated with neglecting electromagnetism in the sea. We determine the up-down quark mass difference and the corrections to Dashen's theorem. We also compute the octet baryon isomultiplet mass splittings, as well as the individual contributions from electromagnetism and the up-down quark mass difference.

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Determination of the non-degenerate light quark masses from electromagnetic mass splittings in 2+1 flavour lattice QCD+QED
Shane Drury
Mon, 17:50, Seminar Room G -- Parallels 2G (Slides)

We report on a calculation of the effects of isospin breaking in Lattice QCD+QED. This involves using Chiral Perturbation Theory with Electromagnetic corrections to find the renormalized, non-degenerate, light quark masses. The calculations are carried out on QCD ensembles generated by the RBC and UKQCD collaborations using Domain Wall Fermions and the Iwasaki+DSDR Gauge Actions with unitary pion masses down to 170 MeV. Non-compact QED is treated in the quenched approximation. We use a \(32^3\) lattice size with \(a^{-1}= 2.28(3)\) GeV (Iwasaki) and \(1.37(1)\) (Iwasaki+DSDR). This builds on previous work from the RBC/UKQCD collaboration with lattice spacing \(a^{-1} = 1.78(4)\) GeV.

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Symanzik flow on HISQ ensembles
Nathan Brown
Mon, 18:10, Seminar Room G -- Parallels 2G (Slides)

We present a determination of the Symanzik flow and the \(w_0\) scale (proposed by the BMW collaboration) on 2+1+1-flavor HISQ ensembles generated by the MILC collaboration. Continuum extrapolated values are compared to the BMW collaboration's results for stout-smeared staggered and HEX-smeared Wilson-clover fermions, and to HPQCD's results with Wilson flow on some of the same HISQ ensembles. Analysis of quark mass dependence of the scale and autocorrelation length versus flow time will also be presented.

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A relativistic, model-independent, three-particle quantization condition: (I) Derivation
Maxwell Hansen, Stephen Sharpe
Tue, 14:00, Seminar Room G -- Parallels 3G (Slides)

We present a generalization of Lüscher's relation between finite-volume spectrum and S-matrix, to energies above inelastic threshold. Specifically, we consider a scalar field theory, which has a G-parity-like symmetry that prevents even/odd coupling but is otherwise arbitrary. Assuming center of mass energies between three and five particle masses, we evaluate a three-to-three finite-volume correlator to all orders in perturbation theory. Here terms which are exponentially suppressed in volume are neglected. From the poles in the finite-volume correlator we then determine the relation between finite-volume spectrum and scattering amplitudes. Both two-to-two and three-to-three amplitudes enter the final result.

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A relativistic, model-independent, three-particle quantization condition: (II) Threshold expansion
Stephen Sharpe, Maxwell Hansen
Tue, 14:20, Seminar Room G -- Parallels 3G (Slides)

We describe how the general result obtained in the talk of Max Hansen can be expanded near to the three-particle threshold and compared to the non-relativistic result of Beane et al. This provides an important cross-check on our general result.

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Extension of the HAL QCD approach to inelastic and multi-particle scatterings in lattice QCD
Sinya Aoki
Tue, 14:40, Seminar Room G -- Parallels 3G (Slides)

We propose an extension of the HAL QCD method, which successfully describes two hadron interactions below inelastic thresholds in terms of corresponding potentials, to inelastic and multi-particle scatterings. We first derive asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave function at large separation for systems with more than 2 particles in quantum field theories. We express asymptotic behaviors of the NBS wave function for \(n\) particles at low energy in terms of parameters of \(T\)-matrix such as phase shifts and mixing angles. We next construct energy-independent but non-local potentials above inelastic thresholds in terms of NBS wave functions in QCD. These properties are two essential ingredients of the HAL QCD method to define potentials, and justify the HAL QCD's method for 3 or more particles in lattice QCD.

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A comparative study of two lattice approaches to two-body systems
Bruno Charron
Tue, 15:00, Seminar Room G -- Parallels 3G (Slides)

Two-body systems are often studied through the temporal dependence of lattice correlators, which allow the extraction of the first few lattice eigenstates' energies. These energies are related, under some assumptions on the interaction, to the infinite volume binding energies or phase shifts by Luescher's finite size formula or one of its extensions. Another approach is to approximate a non-local interaction kernel common to all lattice eigenstates' Nambu-Bethe-Salpeter amplitudes under the inelastic threshold. One can then obtain approximate amplitudes for these lattice eigenstates and compute the corresponding infinite volume binding energies or phase shifts from their spatial dependence outside the interaction. We study, for a few systems, the relations between the two methods, the challenges in their application and the validity of the approximations.

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Phase shifts in \(I=2\) \({\pi}{\pi}\)-scattering from two lattice approaches
Thorsten Kurth, Noriyoshi Ishii, Takumi Doi, Sinya Aoki, Tetsuo Hatsuda
Tue, 15:20, Seminar Room G -- Parallels 3G (Slides)

We present a lattice QCD study of the phase shift of I=2 \(\pi\pi\) scattering on the basis of two different approaches: the standard finite volume approach by Luscher and the recently introduced HAL QCD potential method. Quenched QCD simulations are performed on a \(32^3\times 128\) lattice with lattice spacing \(a=0.115\) fm using a heavy pion mass of \(m_\pi=940\) MeV. Results of the phase shift and the scattering length are shown to agree quite well between these two methods. In case of the potential method, the error is dominated by the systematic uncertainty associated with the violation of rotational symmetry due to finite lattice spacing. In Luscher's approach, such systematic uncertainty is difficult to be evaluated and thus is not included in this work. In case of the potential method, the phase shift can be calculated for arbitrary energies below the inelastic threshold. In that context, the phase shift obtained from the nonrest-frame extension of Luscher's method obtained at a particular center-of-mass momentum lies on top of the curve predicted by the potential method.

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Two-Nucleon Systems in a Finite Volume
Raul Briceno, Zohreh Davoudi, Thomas Luu
Tue, 15:40, Seminar Room G -- Parallels 3G (Slides)

I will briefly motivate the study of two-nucleon systems in a finite volume and review issues regarding partial wave mixing in a finite volume for both two and three-body systems. I will outline the derivation of the the quantization condition for two nucleons in a finite volume with periodic boundary conditions. The result holds for arbitrary isospin, parity, and momenta below the two-pion production threshold. I will pay close attention to the positive parity sector and consider the implication of the quantization condition for the three smallest boosts. Finally, I will discuss the implications for the two-nucleon spectrum at the physical point.

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Interactions of Charmed Mesons with Light Pseudoscalar Mesons from Lattice QCD and Implications on the Nature of the \(D_{s0}^*(2317)\)
Liuming Liu, Kostas Orginos, Feng-Kun Guo, Christoph Hanhart, Ulf Meissner
Wed, 08:30, Seminar Room G -- Parallels 5G (Slides)

We study the scattering of light pseudoscalar mesons (\(\pi\), \(K\)) off charmed mesons (\(D\), \(D_s\)) in full lattice QCD. The \(S\)-wave scattering lengths are calculated using Lüscher's finite volume technique. We use a relativistic formulation for the charm quark. For the light quark, we use domain-wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We calculate the scattering lengths of isospin-3/2 \(D\pi\), \(D_s\pi\), \(D_sK\), isospin-0 \(D\bar{K}\) and isospin-1 \(D\bar{K}\) channels on the lattice. For the chiral extrapolation, we use a chiral unitary approach to next-to-leading order, which at the same time allows us to give predictions for other channels. It turns out that our results support the interpretation of the \(D_{s0}^*(2317)\) as a \(DK\) molecule. At the same time, we also update a prediction for the isospin breaking hadronic decay width \(\Gamma(D_{s0}^*(2317)\to D_s\pi)\) to \((133\pm19)\)~keV.

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\(D\) \(K\) scattering and the \(D_s\) spectrum
Daniel Mohler, Christian Lang, Luka Leskovec, Sasa Prelovsek, Richard Woloshyn
Wed, 08:50, Seminar Room G -- Parallels 5G (Slides)

We present preliminary results from lattice QCD calculations of the low-lying charmed-strange meson spectrum using two types of Clover-Wilson lattices. In addition to quark-antiquark interpolating fields we also consider meson-meson interpolators corresponding to D K scattering states. To calculate the all-to-all propagation necessary for the backtracking loops we use the Distillation technique. For the charm quark we use the Fermilab method. Preliminary results for the \(J^P=0^+\) and \(1^+\) charmed-strange mesons are presented.

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Twisted mass lattice computation of charmed mesons with focus on \(D_{s}^{**}\)
Martin Kalinowski, Marc Wagner
Wed, 09:10, Seminar Room G -- Parallels 5G (Slides)

We present results of a 2+1+1 flavor twisted mass lattice QCD computation of the spectrum of \(D\) mesons and \(D_s\) mesons and of charmonium. Particular focus is put on the positive parity \(D\) and \(D_s\) states (so-called \(D_s^{**}\) mesons) with quantum numbers \(J^P = 0^+\), \(1^+\) and \(2^+\). Besides computing their masses we are also separating and classifying the two \(J^P = 1^+\) states according to the angular momentum/spin of their light degrees of freedom (light quarks and gluons) \(j = 1/2\), \(3/2\).

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Excited spectroscopy of mesons containing charm quarks from lattice QCD
Graham Moir, Michael Peardon, Christopher Thomas, Sinead Ryan, Liuming Liu
Wed, 09:30, Seminar Room G -- Parallels 5G (Slides)

We present highly excited spectra of mesons containing charm quarks computed using the dynamical anisotropic lattices of the Hadron Spectrum Collaboration. The use of novel techniques has allowed us to extract these spectra with a high degree of statistical precision, while also enabling us to observe states as high as spin 4 and candidate gluonic excitations. The phenomenology of these spectra and new calculations of scattering of charmed mesons will be discussed.

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Hadron spectra from overlap fermions on HISQ gauge configurations.
Nilmani Mathur, Subhasish Basak, Saumen Datta, Andrew Lytle, Padmanath Madanagopalan, Pushan Majumdar
Wed, 09:50, Seminar Room G -- Parallels 5G (Slides)

Adopting a mixed action approach, we report here results on hadron spectra containing one or more charm quarks. On a background of 2+1+1 flavours HISQ gauge configurations of MILC collaboration, we use overlap fermions for valence quarks. We also study the ratio of leptonic decay constants, fD/fDs. Results are obtained at two lattice spacings.

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Rho - meson in external magnetic field
Elena Lushchevskaya
Wed, 10:10, Seminar Room G -- Parallels 5G (Slides)

Correlators of vector and pseudoscalar currents have been calculated in external strong magnetic field in SU(2) gluodynamics on the lattice. Different spin components of rho meson mass were explored in dependence on the magnetic field. The mass of vector meson with zero spin projection to the direction of the magnetic field decreases lenearly with increasing of the field for available values of the field on the lattice \(eB < 2 - 2.5\) GeV\(^2\), such behavior is necessary for a condensation of rho mesons in strong magnetic field.

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Structure of the sigma meson from lattice QCD
Masayuki Wakayama, Chiho Nonaka, Atsushi Nakamura, Motoo Sekiguchi, Hiroaki Wada, Shin Muroya, Teiji Kunihiro
Wed, 11:00, Seminar Room G -- Parallels 6G (Slides)

Our purpose is to obtain insights of structure of the sigma meson from the first principle calculation, lattice QCD. At present we do not reach a conclusive understanding of nature of the sigma meson. Currently it is considered as a usual two-quark state, four-quark states such as a tetraquark and mesonic molecules or superposition of them. Besides, the mixing with glueballs is one of important and interesting ingredients for structure of the sigma meson. Furthermore, a disconnected diagram of the sigma meson plays an important role in the structure of the sigma meson. However, to evaluate the disconnected part of the propagator is not an easy task in lattice QCD calculation. To compute the disconnected part of the propagator, we use the Z2 noise method with the truncated eigenmode acceleration and the time dilution for estimating the all-to-all quark ropagators. Here, we focus on four-quark states in the sigma meson. From investigation of two-quark and four-quark states with the inclusion of disconnected diagrams, we will discuss mass of the sigma meson, and the mixing ratio between the two-quark states and four-quark states.

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Study of the scalar \(a_0(980)\) on the lattice
Abdou Abdel-Rehim, Constantia Alexandrou, Marc Wagner, Luigi Scorzato, Carsten Urbach, Mario Gravina, Mattia Dalla Brida, Joshua Berlin, David Palao
Wed, 11:20, Seminar Room G -- Parallels 6G (Slides)

Understanding the quark substructure and spectrum of light scalar mesons on the lattice is both interesting and challenging. It has been argued that these states are mixtures of conventional quark-antiquark and tetraquarks. In this talk we present results for the \(a_0(980)\) state using a variational approach with quark-antiquark, diquark-antidiquark as well as meson-meson molecule interpolating field operators. The spectrum is computed on gauge configurations with 2+1 clover quarks generated by the PACS-CS collaboration at pion mass of about 300 MeV. Both connected as well as disconnected quark loops are included. We also plan to show preliminary results for an ensemble at near physical pion mass.

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K pi scattering from Lattice QCD
David Wilson
Wed, 11:40, Seminar Room G -- Parallels 6G (Slides)

We study the correlation functions obtained on \(16^3\), \(20^3\) and \(24^3\) anisotropic lattices with the quark content and quantum numbers relevant to \(K \pi\) scattering. We work using a large basis of operators including variationally-optimised projected operators that overlap strongly onto single-particle meson states. We use the distillation framework developed by the Hadron Spectrum Collaboration which enables efficient and precise determination of lattice energy levels. As is expected, the energies are shifted from their non-interacting single-particle counterparts. We apply the Luescher method to these results to obtain the phase shifts.

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\(K\pi\) scattering in moving frames
Christian Lang, Sasa Prelovsek, Luka Leskovec, Daniel Mohler
Wed, 12:00, Seminar Room G -- Parallels 6G (Slides)

We extend our study of the \(K\pi\) system to moving frames and present an exploratory extraction of the masses and widths for the \(K^*\) resonances by simulating \(K\pi\) scattering in \(p\)-wave with \(I=1/2\) on the lattice. Using \(K\pi\) systems with non-vanishing total momenta allows the extraction of phase shifts at several values of \(K\pi\) relative momenta. A Breit-Wigner fit of the phase renders a \(K^*(892)\) resonance mass and \(K^*\to K \pi \) coupling compatible with the experimental numbers. We also determine the \(K^*(1410)\) mass and width assuming that the scattering is elastic in our simulation. We contrast the resonant \(I=1/2\) channel with the repulsive non-resonant \(I=3/2\) channel, where the phase is found to be negative and small, in agreement with experiment.

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Search for possible bound Tcc and Tcs on the lattice
Yoichi Ikeda
Wed, 12:20, Seminar Room G -- Parallels 6G (Slides)

One of the interesting subjects in hadron physics is to look for the possible multiquark configurations that are stable against strong decays. One of the example is the bound H-dibaryon (udsuds) and the possibility of the bound H-dibaryon has been recently studied from lattice QCD [1,2]. In the present study, we extend the HAL QCD method to define potential between hadrons [3,4] to the meson-meson systems including charm quarks to investigate the possible bound Tcc (\(ud \bar{c} \bar{c}\)) and Tcs (\(ud \bar{s} \bar{c}\)) on the \(32^3 \times 64\) \(N_f=2+1\) full QCD gauge configuration generated by PACS-CS Collaboration[5]. We also introduce the relativistic heavy quark action [6] as for the charm quarks. We report our results of the s-wave meson-meson potentials that are relevant to the Tcc and Tcs with pion mass \(m_{\pi}=410\), \(570\), \(700\) MeV. The scattering phase shifts and scattering lengths obtained from our lattice potentials are also presented. [1] T. Inoue et al. [HAL QCD Collaboration], Phys. Rev. Lett. 106 (2011) 162002. [2] S.R. Beane et al. [NPLQCD Collaboration], Phys. Rev. Lett. 106 (2011) 162001. [3] N. Ishii, S. Aoki and T. Hatsuda, Phys. Rev. Lett. 99 (2007) 022001. [4] N. Ishii et al. [HAL QCD Collaboration], Phys. Lett. B712 (2012) 437. [5] S. Aoki, Y. Kuramashi and S.-i. Tominaga, Prog. Theor. Phys.109 (2003) 383.

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Exploring the Roper resonance in Lattice QCD
Waseem Kamleh
Thu, 14:00, Seminar Room G -- Parallels 7G (Slides)

Using a correlation matrix analysis consisting of a variety of smearings, the CSSM Lattice collaboration has successfully isolated the Roper resonance and other "exotic" excited states such as the Lambda(1405) on the lattice at near-physical pion masses. We explore the nature of the Roper resonance by examining the eigenvectors that arise from the variational analysis, demonstrating that the Roper is dominated by the \(\chi_1\) nucleon interpolator and only poorly couples to \(\chi_2\). By examining the probability distribution of the Roper on the lattice, we find a structure consistent with a constituent quark model. In particular, the Roper d-quark wave function contains a single node consistent with a 2S state. A detailed comparison with constituent quark model wave functions is carried out, validating the approach of accessing these states by constructing a variational basis composed of different levels of fermion source and sink smearing.

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The Roper Puzzle
Keh-Fei Liu
Thu, 14:20, Seminar Room G -- Parallels 7G (Slides)

The Roper resonance calculated with Wilson and Clover fermions are higher than that calculated with the overlap fermion by ~400-600 MeV for the range of pion mass below ~ 600 MeV in both the quenched and dynamical fermion calculations. Furthermore, the lowest state in the \(S_{11}\) channel with the overlap fermion is the S-wave \(\pi N\) state; whereas, the lowest one in the Wilson and Clover fermion appears to be \(S_{11}(1535)\) for pion mass below 300 MeV. We address these puzzles with the study of Roper in both the variation and sequential Bayesian fitting methods as well as in terms of the role of chiral dynamics.

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Spectroscopy of doubly and triply-charmed baryons from lattice QCD
Padmanath Madanagopalan, Robert Edwards, Nilmani Mathur, Michael Peardon
Thu, 14:40, Seminar Room G -- Parallels 7G (Slides)

We present the ground and excited state spectra of doubly and triply-charmed baryons by using dynamical lattice QCD. A large set of baryonic operators that respect the symmetries of the lattice and are obtained after subduction from their continuum analogues are utilized. Using novel computational techniques correlation functions of these operators are generated and the variational method is exploited to extract excited states. The lattice spectra that we obtain have baryonic states with well-defined total spins up to \(\frac{7}{2}\) and the low lying states remarkably resemble the expectations of quantum numbers from SU(6) \(\times\) O(3) symmetry. Various energy splittings between the extracted states, including splittings due to hyperfine as well as spin-orbit coupling, are considered and those are also compared against similar energy splittings at other quark masses.

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Charmed Bottom Baryon Spectroscopy
Zachary Brown, Kostas Orginos, Stefan Meinel, William Detmold
Thu, 15:00, Seminar Room G -- Parallels 7G (Slides)

The arena of doubly and triply heavy baryons remains experimentally unexplored to a large extent. This has led to a great deal of theoretical effort being put forth in the calculation of mass spectra in this sector. Although the detection of such heavy particle states may lie beyond the reach of experiments for some time, it is interesting to compare results between lattice QCD computations and continuum theoretical models. Several recent lattice QCD calculations exist for both doubly and triply charmed as well as doubly and triply bottom baryons. In this work we present results from the first lattice calculation of the mass spectrum of doubly and triply heavy baryons including both charm and bottom quarks. The wide range of quark masses in these systems require that the various flavors of quarks be treated with different lattice actions. We use domain wall fermions for 2+1 flavors (up down and strange) of sea and valence quarks, a relativistic heavy quark action for the charm quarks, and non-relativistic QCD for the heavier bottom quarks. The calculation of the ground state spectrum is presented and compared to recent models.

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SU(3) flavour symmetry breaking and charmed states
Roger Horsley
Thu, 15:20, Seminar Room G -- Parallels 7G (Slides)

By extending the SU(3) flavour symmetry breaking expansion from up, down and strange sea quark masses to partially quenched valence quark masses we propose a method to determine charmed quark hadron masses. Initial results for some singly and doubly charmed baryon states are encouraging and demonstrate the potential of the procedure.

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Baryon properties in meson mediums from lattice QCD
Amy Nicholson, William Detmold
Thu, 15:40, Seminar Room G -- Parallels 7G (Slides)

We calculate the ground state mass shifts of various baryons due to the presence of a medium of pions or kaons using lattice QCD. We use a canonical approach to produce the medium by calculating correlators with a fixed number of meson propagators. From the ground state energies we calculate two- and three-body scattering parameters. We also extract low energy constants by comparing our results to tree level Chiral Perturbation Theory at non-zero isospin/kaon chemical potential.

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Lattice study on exotic vector charmonium relevant to X(4260)
Ying Chen, Wei-Feng Chiu, Long-Cheng Gui, Jian Liang, Zhaofeng Liu, Yibo Yang
Thu, 16:30, Seminar Room G -- Parallels 8G (Slides)

In the quenched approximation and with very high statistics, a heavy vector charmonium state, with a mass of roughly 4.30(5) GeV, is disentangled from conventional vector charmonia by using spatially extended hybrid-like interpolating field operators. The leptonic decay width of this state is also investigated through a simultaneous fit of correlation functions built from defferent operators.

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\(\eta\) and \(\eta'\) masses from lattice QCD with 2+1+1 quark flavours
Carsten Urbach, Chris Michael, Konstantin Ottnad
Thu, 16:50, Seminar Room G -- Parallels 8G (Slides)

We investigate the masses of eta and eta' mesons using the Wilson twisted mass formulation with 2+1+1 dynamical quark flavours based on gauge configurations of ETMC. We show how to efficiently subtract excited state contributions to the relevant correlation functions and estimate in particular the eta' mass with improved precision. After investigating the strange quark mass dependence and the continuum and chiral extrapolations, we present our results at the physical point.

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Pseudoscalar flavor-singlet mixing angle and decay constants from \(N_f=2+1+1\) WtmLQCD
Konstantin Ottnad, Chris Michael, Carsten Urbach
Thu, 17:10, Seminar Room G -- Parallels 8G (Slides)

Considering matrix elements in the quark-flavor basis, one expects the mixing in the eta,eta'-system to be described reasonably well by a single mixing and two decay constants \(f_l\), \(f_s\). I discuss how these quantities are determined from pseudoscalar matrix elements in \(N_f=2+1+1\) Wilson twisted mass lattice QCD and present results for three values of the lattice spacing and values of \(M_{PS}\) ranging from 230-500 MeV. The required accuracy of the matrix elements is guaranteed by an improved analysis method involving an excited state subtraction in the connected pieces of the correlation function matrix. Besides the mixing angle, the parameters \(f_l\), \(f_s\) are of phenomenological interest, e.g. they are related to the decay widths of \(\eta \to \gamma \gamma\) and \(\eta' \to \gamma \gamma\).

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Charmonium-like states from scattering on the lattice
Sasa Prelovsek, Luka Leskovec, Daniel Mohler
Thu, 17:30, Seminar Room G -- Parallels 8G (Slides)

We extract charmonium and charmonium-like states by simulating the corresponding scattering in a number of channels with different quantum numbers. Among others, we address also experimentally well-established X(3872) and the recently discovered and manifestly exotic \(Z_c^+(3900)\).

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O(\(a^2\))-improved actions for heavy quarks
Yong-Gwi Cho, Shoji Hashimoto, Junichi Noaki
Thu, 17:50, Seminar Room G -- Parallels 8G (Slides)

We investigate a new class of improved relativistic fermion action on the lattice with a criterion to give excellent energy-momentum dispersion relation as well as to be consistent with tree-level O(\(a^2\))-improvement. Main application in mind is that for heavy quark for which ma~O(0.5). We present tree-level results and a scaling study on quenched lattices.

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On the \(B^{*'} \rightarrow B\) transition
Antoine Gerardin, Benoit Blossier, John Bulava, Michael Donnellan
Thu, 18:10, Seminar Room G -- Parallels 8G (Slides)

We present a first lattice determination of the \(B^{*'}B\pi\) coupling which parametrizes the strong decay of a radially excited \(B^{*}\) meson into the ground state B meson. The simulations are performed using CLS gauge configurations with \(N_f=2\) non-pertubatively \(\mathcal{O}(a)\) improved Wilson-Clover fermions and Heavy Quark Effective Theory in the static limit. Four lattice ensembles, with three lattice spacings in the range [0.05-0.08]~fm and pion masses down to 310 MeV, allow us to perform the continuum extrapolation and check the quark mass dependence. Moreover, to handle with exited states, we solved a Generalized Eigenvalue Problem (GEVP).

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Omega-Omega interaction on the Lattice
Masanori Yamada
Fri, 16:30, Seminar Room C -- Parallels 10C (Slides)

We investigate the Omega-Omega baryon interaction in lattice QCD. In the past studies, the hyperon interactions, which become important in hight density matters such as the core of the neutron star, have been investigated mainly for the octet sector, while a very few investigations have been made for the decuplet sector since almost all decuplet baryons are unstable due to decays via the strong interaction. An exception is the Omega decuplte baryon, which is stable against the strong decays, so its interaction is suitable to be investigated. It is, however, still difficult to investigate the Omega-Omega interaction experimentally due to its short-life time via weak decays. Therefore, the lattice QCD study for the Omega-Omega interaction is necessary and important. We calculate the Omega-Omega potential by the HAL QCD method, where the potential is extracted from the Nambu-Bethe-Salpeter (NBS) wave function. Our numerical results are obtained from 2+1 flavor full QCD gauge configurations at \(m_\pi \sim 875\) MeV and \(m_\Omega\sim 2108\) MeV, generated by the CP-PACS/JLQCD Collaboration. We find that the Omega-Omega interaction is strong attractive. Using the potential obtained, we also calculate the phase shift of Omega-Omega scattering and discuss a possibility of an existence for a shallow Omega-Omega bound state.

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Lattice QCD studies of multi-strange baryon-bayon interactions
Kenji Sasaki
Fri, 16:50, Seminar Room C -- Parallels 10C (Slides)

Derivation of baryon-baryon interactions from lattice QCD is highly awaited to investigate hypernuclear and/or neutron star structure and mechanism of supernova explosions since their experimental data are scarce. Owing to developments of computer performances and simulation techniques, lattice QCD calculations allow us to understand nuclear physics in terms of fundamental theory of the strong interaction (QCD). Our approach to baryon-baryon interactions is deriving a potential from inverting Schroedinger equation using NBS wave function simulated by lattice QCD. This approach have been extended to the coupled channel formalism. Using the coupled channel approach, we investigate multi-strange baryon-baryon interactions by lattice QCD simulation. Our numerical results are obtained from 2+1 flavor QCD gauge configuration provided by the PACS-CS Collaboration. The scattering parameters by these potentials are also discussed.

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The anti-symmetric LS potential in flavor SU(3) limit from Lattice QCD
Noriyoshi Ishii, Keiko Murano, Hidekatsu Nemura, Kenji Sasaki
Fri, 17:10, Seminar Room C -- Parallels 10C (Slides)

Parity-odd hyperon potentials including the anti-symmetric LS potential is calculated in the flavor SU(3) limit with HAL QCD method by using 2+1 flavor gauge configuration on the \(16^3\times 32\) lattice generated by CP-PACS/JLQCD coll. Due to the calculational cost, we restrict ourselves to the S=-1 sector, which makes it possible to access the irreducible representations of 27, 10\(^*\), 10, 8S and 8A of the flavor SU(3) group. These potentials are rotated to the particle basis to discuss a possible cancellation between the symmetric and the anti-symmetric LS potentials in the NLambda sector, which is phenomenologically expected from the spectrum of hyper-nuclei.

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Quark mass dependence of Spin-Orbit force in parity-odd NN system from 2+1 flavor QCD
Keiko Murano
Fri, 17:30, Seminar Room C -- Parallels 10C (Slides)

We report our recent study of Spin-Orbit force between two nucleons in the parity-odd sector from Lattice QCD. In the previous talk, where we reported our first result of Spin-Orbit force calculated at \(m_\pi=1133\) MeV, we found that, while the qualitative behavior of resultant potentials are consistent with phenomenological potentials, these potentials are still weak, probably due to the heavy quark mass employed in our simulations. In this talk, we examine the quark mass dependence of Spin-Orbit force. We reconstruct Spin-Orbit force from 3P0, 3P1 and 3P2 Nambu-Bethe-Salpeter wave functions calculated from Lattice QCD in lighter quark mass region at \(m_\pi=701 - 411\) MeV. The calculation is performed on Blue Gene/Q at KEK by using Nf=2+1 PACS-CS gauge configuration generated by O(a) improved wilson quark action with RG improved (iwasaki) gauge action. We find that the potentials tend to become stronger as the quark mass decreases.

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Pion-nucleon scattering in Lattice QCD
Valentina Verduci, Christian Lang
Fri, 17:50, Seminar Room C -- Parallels 10C (Slides)

Almost all the hadrons of the QCD spectrum are unstable under strong interactions and their resonant nature has to be taken into account for a complete study in lattice QCD. Thanks to improved computational resources and developed theoretical tools, in the last years multi-particle states started to be a new frontier in lattice studies. We examine, for the first time on the lattice, the pion-nucleon system in s-wave (negative parity). We compare the energy levels measured in the one-particle setup with the spectrum of the coupled system. Additional information on the N* resonance are achieved through a phase shift analysis. This work is intended to be an exploratory study of the meson-baryon system on the lattice and a boost for further studies in this direction.

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Looking for a Quarkonium-Nucleus Bound State on the Lattice
Saul Cohen
Fri, 18:10, Seminar Room C -- Parallels 10C (Slides)

The interaction between quarkonia and nuclei will reveal new information about the properties of QCD. Since such systems are composed of hadronic states having no common valence quarks, they interact mainly by multi-gluon exchanges, analogous to a color van der Waals force. Although twenty years have passed since the existence of a bound nucleus-quarkonium state was proposed, model calculations give diverse results. Experiments, such as ATHENNA at JLab or CBM at FAIR, will provide experimental data in the near future. In this talk, we present a first lattice-QCD calculation of the interaction of strange quarkonia with light nuclei, using ensembles with pion masses at the SU(3)-symmetric point. We determine the energies of these multiparticle systems and probe the existence of bound states.

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The Hadronic Decays of Decuplet Baryons
Paul Rakow, Raffaele Millo, Roger Horsley, Holger Perlt, Gerrit Schierholz, James Zanotti
Fri, 18:30, Seminar Room C -- Parallels 10C (Slides)

We report on a project to measure the hadronic decays of the decuplet baryons, for example Delta to N pi and its hyperon analogues, based on 2+1 flavour lattice simulations. We are following two paths towards determining the coupling constants. One is to carefully measure the energies of the ground state and first few excited levels, to see how far they are shifted by the interaction. The other approach is to measure transition rates directly from the time dependence of Greens functions linking the parent baryon at the source and its decay products at the sink.

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2+1 flavor lattice QCD simulation on K computer
Yoshinobu Kuramashi, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Noriyoshi Ishii, Ken-Ichi Ishikawa, Naruhito Ishizuka, Yoshifumi Nakamura, Yusuke Namekawa, Hidekatsu Nemura, Kenji Sasaki, Yusuke Taniguchi, Naoya Ukita, Takeshi Yamazaki
Fri, 18:50, Seminar Room C -- Parallels 10C (Slides)

We first explain the HPCI (High Performance Computing Infrastructure) Strategic Program in Japan aiming to conduct innovative research in five research fields that were selected strategically. The fifth field "the origin of matter and the universe" covers the fundamental sciences consisting of elementary particle physics, nuclear physics and astronomy. We have chosen four research subjects among the field to be performed using a part of the K computer. One of them is a large scale simulation of lattice QCD. We present some preliminary results for 2+1 flavor QCD together with algorithmic details. Future physics plan is also discussed.

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Rho and A-mesons in external magnetic field in SU(2) lattice gauge theory
Olga Larina, Elena Lushchevskaya
Poster Session

Correlators of vector, axial and pseudoscalar currents have been calculated in external strong magnetic field in SU(2) gluodynamics on the lattice. The masses of rho and A-meson s with a zero spin projection s = 0 to the z axis parallel to the external magnetic field B were explored in dependence on the magnetic field. The mass of the corresponding spin component of vector meson decreases with increasing of the magnetic field for available values of the field on the lattice \(eB \sim 2 - 2.5\) GeV\(^2\), such behavior is necessary for a condensation of rho mesons in strong magnetic field.

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The Oscillatory Behavior and The Logarithmic Unphysical Pole of the Domain Wall Fermion
Raza Sufian, Michael Glatzmaier, Keh-Fei Liu
Poster Session

Domain wall fermion formulation can suffer from an unwelcome oscillatory behavior in the hadron correlators which appears when the transfer matrix is complex. In this work, we study the origin of this unphysical pole from the free quark propagator using several different DWF actions, e.g. Shamir, Boriçi, and the Mobius domain wall fermion action. We find that the unphysical mode depends on the domain wall height M, as well as on coeffieicents \(b_s\) and \(c_s\) for Mobius action. We determine the specific ranges of these parameters which give rise to oscillatory behavior.

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SU(2) Lattice Gluon Propagator and Potential Models
Willian M. Serenone, Attilio Cucchieri, Tereza Mendes
Poster Session

We use lattice data for the gluon propagator as an input to model the heavy quark-antiquark potential. Since the approach is based on the one-gluon-exchange approximation, a linear term must be included explicitly, to account for non-pertunative effects. The string tension is left as a free parameter to be determined from fits to experimental results. We present an application to the spectrum of the bottomonium and compare to other methods.

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Glueballs in charmonia radiative decays
Chuan Liu, Ying Chen, Yibo Yang, Yu-Bin Liu, Jian-Ping Ma, Jian-Bo Zhang
Poster Session

The radiative decay of \(J/\psi\) into a pure gauge scalar or tensor glueball is studied in the quenched lattice QCD formalism. The corresponding phenomenological implication of these results is also discussed.

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Flavored pion and kaon masses at next-to-leading order in mixed-action staggered chiral perturbation theory
Jon Bailey, Jongjeong Kim, Weonjong Lee, Hyung-Jin Kim, Boram Yoon
Poster Session

Differently improved staggered fermions can be used in mixed-action calculations to reduce discretization effects and simplify analyses. After recalling the generalization of staggered chiral perturbation theory to the mixed-action case, we describe a calculation of the masses of the flavored pseudo-Goldstone bosons to next-to-leading order. The results can be used to improve determinations of quark masses, Gasser-Leutwyler couplings, and other parameters important for phenomenology.

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Testing the stochastic LapH method in the twisted mass formulation
Christian Jost, Bastian Knippschild, Carsten Urbach
Poster Session

We present first results using the stochastic Laplace-Heaviside (LapH) method in the twisted mass formulation. The calculations are performed on gauge configurations provided by the ETM collaboration with 2+1+1 dynamical quark flavours at a single value of the lattice spacing. In particular, we compute disconnected contributions to flavour singlet pseudo-scalar mesons and compare LapH to standard volume noise methods.

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Bottomonium results from lattice QCD
Christine Davies, Brian Colquhoun, Ben Galloway, Rachel Dowdall, Jonna Koponen, Peter Lepage, Craig McNeile
Poster Session

We discuss a number of different results in bottomonium physics using the HISQ or NRQCD actions for the b quark.

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Hadronic light-by-light contribution to the muon \(g-2\) with charged sea quarks
Tom Blum, Masashi Hayakawa, Taku Izubuchi
Poster Session

We update our calculation of the hadronic light-by-light contribution to the muon anomalous magnetic moment, using increased statistics and more values of momentum transfer, for neutral sea quarks. We use domain wall fermions, Iwasaki gluons, and quenched (non-compact) photons on a lattice of size \(24^3\times 64\times 16\), \(m_\pi=330\) MeV, \(m_\mu=170\) MeV, and \(a^{-1}=1.73\) GeV. The AMA technique is employed to efficiently improve statistical precision. In addition, we describe our new calculation method including charged sea quarks and all diagrams entering at \(O(\alpha^3)\).

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Two-Baryon Correlation Functions in 2-flavor QCD
Chuan Miao, Anthony Francis, Thomas Rae, Hartmut Wittig
Poster Session

We present an initial study of two-baryon correlation functions with the aim of explaining potential dibaryon bound states, specifically the H-dibaryon, which is a hypothesized bound state of QCD. In particular, we comment on our first results for two-baryon correlation functions (\(\langle C_{XY}(t)C_{XY}(0) \rangle\), where \(XY=\Lambda\Lambda, \Sigma\Sigma, N\Xi, \cdots\)), which combine to form the H-dibaryon. The results are obtained using a `blocking' algorithm to handle the contractions, which may easily be extended to N-baryon correlation functions. We also comment on its application to the analysis of single baryon masses (\(n\), \(\Lambda\), \(\Xi\), \(\cdots\)). This study is performed on an isotropic lattice with \(m_\pi = 460\) MeV, \(m_\pi L = 4.7\) and \(a = 0.063\) fm. The measurements are calculated using the CLS ensembles with non-perturbative \(\mathcal{O}(a)\) improved Wilson fermions in \(N_f = 2\) QCD.

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Testing mixed action approaches to meson spectroscopy with twisted mass sea quarks
Joshua Berlin, David Palao, Marc Wagner
Poster Session

We explore several mixed action approaches including Wilson and Wilson twisted mass quarks with and without Clover term. Our main goal is to reduce lattice discretization errors in mesonic spectral quantities, particularly reducing twisted mass parity and isospin mixing.

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Investigating a mixed action approach for \(\eta\) and \(\eta'\) mesons in \(N_f=2+1+1\) lattice QCD
Falk Zimmermann, Konstantin Ottnad, Carsten Urbach
Poster Session

We test Osterwalder-Seiler valence quark action to reproduce eta, eta' meson quantities from twisted mass lattice configurations with 2+1+1 dynamical quark flavours. Flavour singlet quantities gain significant contributions from the sea and the valence quark sector and are, therefore, sensible to mixed regularisations. In particular we employ the freedom to tune the the valence strange quark mass to match pure twisted mass with the mixed action approach. Two matching procedures are proposed and shown to agree in the continuum limit of the eta-meson masses and additional mixing quantities.

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Vacuum polarization function in \(N_f=2+1\) domain-wall fermion
Eigo Shintani, Hyung-Jin Kim, Tom Blum, Taku Izubuchi
Poster Session

We will show preliminary results of calculation of vacuum polarization function (VPF) of vector-current in Nf=2+1 domain-wall fermion. In this calculation we use the all-mode-averaging to extremely suppress the statistical noise, and show the precise calculation of strong coupling constant using Adler function after taking account of the lattice artifacts with two different cut-off scales. We also discuss the precise calculation of muon g-2 using VPF and address the possible systematic errors.

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Meson Spectroscopy using Stochastic LapH Method
Chik Him Wong, Colin Morningstar, David Lenkner, Brendan Fahy, You-Cyuan Jhang, Justin Foley, Jimmy Juge, John Bulava
Poster Session

Excited states of mesons on anisotropic \(24^3 \times 128\) and \(32^3 times 256\) lattices are obtained from single-hadron and multi-hadron operators by utilizing a stochastic method that exploits the Laplacian Heaviside quark-field smearing. Preliminary light-meson scattering phase shifts may also be presented.

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Pseudoscalar Decay Constants of D-Mesons in Lattice QCD with Domain-Wall Fermion
Ting-Wai Chiu, Tung-Han Hsieh, Yu-Chih Chen, Han-Yi Chou, Wen-Ping Chen
Poster Session

We study the masses and decay constants of pseudoscalar mesons in 2 flavors lattice QCD with optimal domain-wall fermion. The gauge ensembles are generated on the \(24^3 \times 48 \) lattice with the extent in the fifth dimension \( N_s = 16 \), and the plaquette gauge action at \( \beta = 6.10 \), for three sea-quark masses corresponding to the pion masses in the range 280-450 MeV. We compute point-to-point quark propagators and measure the time-correlation functions of the pseudoscalar and vector mesons. The inverse lattice spacing is determined by the experimental input of the pion decay constant, while the strange quark and the charm quark masses are determined by the masses of vector mesons \( \phi(1020) \) and \( J/\psi(3097) \) respectively. In this talk, we outline the salient features of our simulations and present our preliminary results of the masses and decay constants of the charmed mesons \(D\) and \(D_s\).

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Charmonium, \(D_s\) and \(D_s^*\) from overlap fermion on domain wall fermion configurations
Yibo Yang, Ying Chen, Zhaofeng Liu
Poster Session

With data on ensembles of two lattice spacings and three sea masses each, we use the masses of \(D_s\), \(D_s^*\) and \(J/\psi\) to determine \(m_c^{\bar{MS}}\)(2GeV, \(m_s^{\bar{MS}}\)(2GeV) and \(r_0\). With those input, we predict the hyperfine-spiltting of charmonium, \(f_{D_s}\), and the masses of P-wave charmonium in the chiral and continuum limits. We also discern the quark mass dependence of the hyperfine-spiltting between pseudo scalar and vector mesons, from light to heavy.

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