32nd International Symposium on Lattice Field Theory (Lattice 2014)

Session

Hadron spectroscopy and interaction

2

23 Jun 2014, 14:15

Columbia University

Conveners

Hadron spectroscopy and interaction: Parallel 1B

• Sinya Aoki (Yukawa Institute for Theoretical Physics, Kyoto University)

Hadron spectroscopy and interaction: Parallel 2B

• Marcus Petschlies (Cyprus Institute / CaSToRC)

Hadron spectroscopy and interaction: Parallel 3B

• Shailesh Chandrasekharan (Duke University)

Hadron spectroscopy and interaction: Parallel 4B

• Hiroshi Ohno (Center for Computational Sciences, University of Tsukuba)

Hadron spectroscopy and interaction: Parallel 5B

• Andrew Lytle (TIFR)

Hadron spectroscopy and interaction: Parallel 6B

• Christian B. Lang

Hadron spectroscopy and interaction: Parallel 7B

• Ting-Wai Chiu (National Taiwan University)

Hadron spectroscopy and interaction: Parallel 8B

• Colin Morningstar (Carnegie Mellon University)

70. Pion-pion scattering phase shifts with the stochastic LapH method

Mr Brendan Fahy (Carnegie Mellon University)

23/06/2014, 14:15

Hadron Spectroscopy and Interactions

Talk

Progress in calculating scattering phase shifts on Nf=2+1 anisotropic clover Wilson lattices is described. The stochastic LapH method facilitates computations in large volumes and for light pion masses. Results for pion masses down to 250 MeV, keeping m_pi L > 4, are presented.

190. Pi-Pi Scattering with N_f=2+1+1 Twisted Mass Fermions

Dr Bastian Knippschild (HISKP, University Bonn)

23/06/2014, 14:35

Hadron Spectroscopy and Interactions

Talk

Pi-Pi scattering is investigated for the first time for N_f=2+1+1 dynamical quark flavours using Wilson twisted mass fermions. Lüschers finite size method is used to relate energy shifts in finite volume to scattering quantities like the scattering length in the I=2 channel. The computation is performed at several pion masses and lattice spacings utilysing the stochastic LapH method,...

125. Lattice study of pion-pion scattering using Nf=2+1 Wilson improved quarks with masses down to their physical values.

Mr Thibaut METIVET (CEA Saclay)

23/06/2014, 14:55

Hadron Spectroscopy and Interactions

Talk

for the BMW Collaboration. We use 2HEX smeared gauge configurations generated with the Nf=2+1 clover improved Wilson action to investigate pion-pion scattering in the rho channel. The range of lattice spacings (0.054 fm to 0.12 fm) and space-like extents (32 and 48) allows us to extract the scattering parameters through the volume dependence of the effective mass according to Luscher's...

130. K-pi scattering lengths at physical kinematics

Mr Tadeusz Janowski (University of Southampton)

23/06/2014, 15:15

Hadron Spectroscopy and Interactions

Talk

I will present preliminary results on K-pi scattering lengths obtained by the RBC-UKQCD collaboration. The results are obtained using one of our domain wall fermion ensembles with physical quark masses. I will argue that the large "around-the-world" effects which are present with such light quark masses can be controlled.

181. Resonances in pi-K scattering

Dr David Wilson (Old Dominion University)

23/06/2014, 15:35

Hadron Spectroscopy and Interactions

Talk

We have obtained clear signals of resonances in coupled-channel pi K - eta K scattering. Using distillation and a large basis of operators we are able to extract a precise spectrum of energy levels using the variational method. These energies are analysed using inelastic extensions of the Luescher method to obtain scattering amplitudes that clearly describe S, P and D wave resonances,...

235. Charm in Lattice QCD with Domain-Wall Fermion

Prof. Ting-Wai Chiu (National Taiwan University)

23/06/2014, 16:30

Hadron Spectroscopy and Interactions

Talk

We study the charm physics in two-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 265-465 MeV. We determine the lattice spacing by the Wilson...

236. Hadron spectra and Delta_mix from overlap quarks on a HISQ sea.

Dr Andrew Lytle (TIFR)

23/06/2014, 16:50

Hadron Spectroscopy and Interactions

Talk

We present results of our continuing study on mixed-action hadron spectra and decay constants using overlap valence quarks on MILC's 2+1+1 flavor HISQ gauge configurations. This study is carried out on three lattice spacings, with charm and strange masses tuned to their physical values, and with m_l/m_s = 1/5. I will discuss a determination of the mixed-action parameter Delta_mix, which enters...

110. Spectroscopy of charmed baryons from lattice QCD

Dr Padmanath Madanagopalan (Institute of Physics, University of Graz)

23/06/2014, 17:10

Hadron Spectroscopy and Interactions

Talk

We present the ground and excited state spectra of triply, doubly and singly-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...

197. Low lying charmonium states at the physical point

Dr Daniel Mohler (Fermilab)

23/06/2014, 17:30

Hadron Spectroscopy and Interactions

Talk

We present results for the mass splittings of low-lying charmonium states from a calculation of Wilson clover quarks with the Fermilab interpretation on an asqtad sea. We use five lattice spacings and two values of the light sea quarks to extrapolate our results to the physical point. Sources of systematic uncertainty in our calculation are discussed and we compare our results for the 1S...

72. DK and D* K scattering near threshold

C. B. Lang (Univ. Graz)

23/06/2014, 17:50

Hadron Spectroscopy and Interactions

Talk

We study the three D_s quantum channels J^P = 0^+, 1^+ and 2^+ where experiments have identified the charm-strange states D*_s0 (2317), D_s1(2460), D_s1(2536) near the DK and D*K thresholds, and D*_s2(2573). We consider correlation functions for sets of qbar q operators and, for J^P = 0^+, 1^+, also the DK and D*K meson-meson interpolators and determine for these cases values of the elastic...

437. Conserved currents and results from 2+1f dynamical Mobius DWF simulations at the physical point

Dr Peter Boyle (University of Edinburgh)

23/06/2014, 18:10

Hadron Spectroscopy and Interactions

Talk

We discuss the construction of the almost conserved axial and exactly conserved vector currents in the Mobius generalisation of DWF at finite Ls. I then report on the status of 2+1f DWF simulations at the physical point, with a focus on the determinations of the lattice spacings, and of the pion and kaon decay constants and the Kaon bag parameter in the continuum limit.

132. Relativistic three-particle quantization condition: an update

Prof. Stephen Sharpe (University of Washington)

24/06/2014, 14:15

Hadron Spectroscopy and Interactions

Talk

Last year, we presented a generalization of Luescher's two-particle quantization condition to three identical, degenerate particles. While completing this work, we discovered a technical problem with our derivation which invalidated the result, in the sense that not all finite-volume corrections that fall as powers of the box size were controlled. We have found a fix to this problem,...

185. On the extraction of spectral quantities with open boundary conditions.

Mr Mattia Bruno (DESY, Zeuthen)

24/06/2014, 14:35

Hadron Spectroscopy and Interactions

Talk

We discuss methods to extract decay constants, meson masses and gluonic observables in the presence of open boundary conditions. Our CLS ensembles have 2+1 flavours of O(a)-improved Wilson fermions and are generated with a small twisted mass as proposed by Luescher and Palombi. We analyse the associated reweighting for different observables.

293. Gradient Flow Analysis on MILC HISQ Ensembles

Nathan Brown (Washington University in St. Louis)

24/06/2014, 14:55

Hadron Spectroscopy and Interactions

Talk

We present a final analysis of gradient flow and the associated scale $w_0$ measured on the $N_f=2+1+1$ HISQ ensembles. Compared to previously reported results, we have improved the interpolation to physical quark masses using chiral perturbation theory, adjusted for variations in charm quark mass between ensembles, and derived a `prediction' function for estimating the scale using $w_0/a$ on...

342. Simulating two dimensional two-color QCD using purely bosonic variables

Mr Daniel August (friedrich schiller universität jena)

24/06/2014, 15:15

Hadron Spectroscopy and Interactions

Talk

The numerical calculation of the fermion determinant is one of the most costly computational tasks in lattice QCD. For massless two-color QCD in two dimensions we are able to calculate the fermion determinant analytically, allowing us to obtain high precision results for the mass spectrum of the theory. In the talk we review our lattice formulation in terms of purely bosonic variables...

304. Radial and orbital excitation energies of charmonium

Mr Ben Galloway (University of Glasgow)

24/06/2014, 15:35

Hadron Spectroscopy and Interactions

Talk

The system of charmonium has several excited states below the energy threshold for decay into D and Dbar mesons, which can in principle be studied accurately in lattice QCD. Studies that include many states in the spectrum have typically only been done at one value of the lattice spacing and with light quarks in the sea. Here we give results for radial and orbital excitation energies for...

394. Generating 2+1+1 Flavor Mobius Domain Wall Fermion Configurations

Robert Mawhinney (Columbia University)

24/06/2014, 16:30

Hadron Spectroscopy and Interactions

Talk

The RBC and UKQCD Collaborations are generating 2+1+1 flavor Mobius domain wall fermion configurations with $1/a=3$ and 4 GeV. To achieve good topological tunneling at these weaker couplings, the gauge action is the Wilson action plus a Dislocation Enhancing Determinant (DED) term. The DED term enhances the probability of gauge fields where toplogy-changing dislocations are present,...

221. The Lambda 1405 is an anti-kaon--nucleon molecule

Prof. Derek Leinweber (University of Adelaide)

24/06/2014, 16:50

Hadron Spectroscopy and Interactions

Talk

For almost 50 years the structure of the Lambda(1405) resonance has been a mystery for particle physicists. Even though it contains a heavy strange quark and has odd parity its mass is lower than any other excited spin-1/2 baryon. Before the existence of quarks was confirmed, Dalitz and co-workers speculated that it might be a molecular state of an anti-kaon bound to a nucleon. Although the...

405. Multi-channel 1 to 2 matrix elements in finite volume

andre walker-loud (W&M)

24/06/2014, 17:10

Hadron Spectroscopy and Interactions

Talk

We derive a model-independent expression for finite-volume matrix elements. Specifically, we present a relativistic, non-perturbative analysis of the matrix element of an external current between a one-scalar in-state and a two-scalar out-state. Our result, which is valid for energies below higher-particle inelastic thresholds, generalizes the Lellouch-Luscher formula in two ways: we allow the...

69. Scalar Mesons on the Lattice Using Stochastic Sources on GPU Architecture.

Mr Dean Howarth (Rensselaer Polytechnic Institute)

24/06/2014, 17:30

Hadron Spectroscopy and Interactions

Talk

We describe our studies of multi-pion correlation functions computed using stochastic propagators in quenched lattice QCD, harnessing GPUs for acceleration. We find that projecting onto momentum states for the pions becomes enormously expensive and has a poor scaling with the linear extent of the lattice. It is also found that correlations between stochastic propagators appearing in the same...

258. Heavy Meson Spectrum Tests of the Oktay-Kronfeld Action

Mr Yong-Chull Jang (Seoul National University)

24/06/2014, 17:50

Hadron Spectroscopy and Interactions

Talk

To achieve smaller heavy-quark discretization errors, the OK action was proposed as an improvement of the Fermilab action. The OK action includes the dimension 6 and 7 operators necessary for tree-level matching to QCD through order 1/m_Q^3 for heavy-light mesons and v^6 for quarkonium. To assess the improvement, we extend previous numerical tests with heavy meson masses by analyzing data...

116. Nucleon spectroscopy using multi-particle operators

Dr Waseem Kamleh (University of Adelaide)

25/06/2014, 09:00

Hadron Spectroscopy and Interactions

Talk

The role of 5-quark operators in extracting the nucleon excited state spectrum via correlation matrix techniques is explored. In particular, the coupling of meson-baryon operators to nucleon resonance states and scattering states is studied. Results are presented for 2+1 flavour dynamical ensembles in both the positive and negative parity channels.

322. Lattice QCD with 2+1 Flavors and Open Boundaries: First Results of the Baryon Spectrum

Wolfgang Soeldner (Regensburg University)

25/06/2014, 09:20

Hadron Spectroscopy and Interactions

Talk

Based on CLS simulations with 2+1 flavors and open boundaries we present first results of the baryon spectrum. We report on the status of our effort related to these simulations and the chiral extrapolation to the physical point.

327. Baryon spectrum with Nf=2+1+1 twisted mass fermions

Mr Christos Kallidonis (The Cyprus Institute)

25/06/2014, 09:40

Hadron Spectroscopy and Interactions

Talk

We present results on the masses of the low lying baryons using gauge configurations with $N_f=2+1+1$ flavors of maximally twisted mass fermions. The strange and charm quark masses are tuned to their physical values. We use three values of the lattice spacing, determined from the nucleon mass. Both cut-off effects and volume effects are investigated. We demonstrate that isospin symmetry...

53. Excited isovector mesons using the stochastic LapH method

Prof. Colin Morningstar (Carnegie Mellon University)

25/06/2014, 10:00

Hadron Spectroscopy and Interactions

Talk

The spectrum of excited isovector mesons is studied using a 32^3 x 256 anisotropic lattice with u,d quark masses set to give a pion mass near 240 MeV. Results in the bosonic isovector nonstrange symmetry channels of zero total momentum are presented using correlation matrices of unprecedented size. In addition to spatially-extended single meson operators, large numbers of two-meson operators...

356. An investigation of meson spectroscopy on isotropic clover lattices at the SU(3) flavor-symmetric point

David Richards (Jefferson Laboratory)

25/06/2014, 10:20

Hadron Spectroscopy and Interactions

Talk

We present an investigation of the excited meson spectrum at the N_f= 3 point obtained on isotropic clover lattices with a plaquette Wilson gauge action, and a NP-improved clover fermion action, at a lattice spacing of a \simeq 0.08 fm, and compare with corresponding calculations on an anisotropic lattice at fine temporal lattice spacing but a spatial lattice spacing of a_s \simeq 0.125 fm. ...

256. Comparison between two-quark, tetra-quark and molecular states of the sigma meson from lattice QCD

Mr Masayuki Wakayama (Nagoya University)

25/06/2014, 11:10

Hadron Spectroscopy and Interactions

Talk

Our purpose is to obtain insights of structure of the sigma meson from 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 tetra-quark and mesonic molecules or superposition of them. At present we do not reach a conclusive understanding of nature of the sigma meson....

282. Investigation of the tetraquark candidate a_0(980): technical aspects.

Joshua Berlin (University of Frankfurt)

25/06/2014, 11:30

Hadron Spectroscopy and Interactions

Talk

The structure of the light-scalar meson a_0(980) is under debate. It might be of quark-antiquark, diquark-antidiquark or mesonic molecule type. We have implemented corresponding interpolating field operators composed of two and of four quarks, as well as operators of two-meson type, to study the structure of a_0(980). The computation of the correlation matrix is rather challenging, because of...

371. Investigation of the tetraquark candidate a_0(980): preliminary results

Dr Abdou Abdel-Rehim (The Cyprus Institute)

25/06/2014, 11:50

Hadron Spectroscopy and Interactions

Talk

We carry out a study of the light scalar meson a_0(980) employing interpolating field operators of quark-antiquark, diquark-antidiquark, mesonic molecules and two-particle meson operators. Both connected and disconnected quark loops are investigated. We present preliminary results for two ensembles of 2+1 clover fermion gauge configurations generated by the PACS-CS collaboration...

315. Flavored tetraquark spectroscopy

Dr Andrea Guerrieri (Dipartimento di fisica e INFN Roma "Tor Vergata")

25/06/2014, 12:10

Hadron Spectroscopy and Interactions

Talk

The very recent confirmation of the Z(4430) charged resonance by the LHCb experiment strongly suggests the existence of QCD bound states with four quarks. We report some preliminary results about hypothetical flavored tetraquark hadrons. Such states are particularly amenable to Lattice QCD studies as their interpolating operators do not overlap with those of ordinary hidden-charm mesons.

305. Search for a bound H-dibaryon using local six-quark interpolating operators

Dr Jeremy Green (Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)

25/06/2014, 12:30

Hadron Spectroscopy and Interactions

Talk

Early results will be presented from a Lattice QCD study seeking a bound H-dibaryon using Nf=2 flavors of O(a) improved Wilson fermions and a quenched strange quark. We solve the generalized eigenvalue problem constructed using a variational basis of interpolators consisting of the two independent local products of six positive-parity-projected quarks with the appropriate quantum numbers,...

417. Two-Baryon Systems with Twisted Boundary Conditions

Dr Zohreh Davoudi (Institute for Nuclear Theory-University of Washington)

25/06/2014, 12:50

Theoretical Developments

Talk

We explore the use of twisted boundary conditions in extracting the nucleon mass and the binding energy of two-baryon systems, such as the deuteron, from Lattice QCD calculations. Using the experimentally determined phase shifts and mixing angles, and utilizing the Luescher method extended to baryonic systems with twisted boundary conditions, we determine the expected energies of the deuteron...

261. An improved study of the excited radiative decay $\mathrm{{\rm Y}}(2S)\to {\eta }_b(1S)\gamma$ using lattice NRQCD

Mr Ciaran Hughes (DAMTP, University of Cambridge)

26/06/2014, 14:15

Hadron Spectroscopy and Interactions

Talk

Recently Lewis and Woloshyn's exploratory study using lattice NRQCD to study the radiative decay $\mathrm{{\rm Y}}(2S)\to {\eta }_b(1S)\gamma$ found that next-to-leading order ($v^6$) contributions were large compared to the leading order ($v^4)result.Weexplainthissuppressionofthe$v^4$ term using a simple potential model. We then present our lattice QCD results obtained with three lattice...

174. Determining Sigma - Lambda mixing

Dr Roger Horsley (University of Edinburgh)

26/06/2014, 14:55

Hadron Spectroscopy and Interactions

Talk

SU2 isospin breaking effects in hadron octet and decuplets are due to a combination of up and down quark mass differences and electromagnetic effects. Usually these masses difference are small. Between the Sigma and Lambda the splitting is much larger due to mixing between these states. We determine the QCD mixing matrix and hence find the mixing angle and mass splitting. Provided the...

354. Free-form Smeared Bottomonium Correlation Functions

Mr Mark Wurtz (York University)

26/06/2014, 15:15

Hadron Spectroscopy and Interactions

Talk

Gauge-invariant sources with a hydrogen wave function shape are constructed for bottomonium two-point correlation functions using the free-form smearing technique. The bottomonium spectrum is extracted from free-form smeared correlation functions. Results are compared with conventional smearing techniques.

136. Omega-Omega interaction from 2+1 flavor QCD

Mr Masanori for HAL QCD Coll Yamada (University of Tsukuba)

26/06/2014, 15:35

Hadron Spectroscopy and Interactions

Talk

We report our results of central potential between two Omega baryons from 2+1 flavor full Lattice QCD simulation.In the past studies, there is a possibility that some decuplet baryons have a bound state. However, 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...

244. Quark mass dependence of three-nucleon forces in lattice QCD

Dr Takumi Doi (RIKEN)

26/06/2014, 15:55

Hadron Spectroscopy and Interactions

Talk

Recently, the determination of three-nucleon forces attracts a great deal of interest in light of their role in nuclear and astrophysical phenomena such as EoS of nuclear matter and the structure of the neutron star core. In this talk, we present the lattice QCD calculation of three-nucleon forces utilizing the time-dependent HAL QCD method. In particular, we study the quark mass dependence...

291. A study of scattering in open charm channels

Prof. Sinead Ryan (Trinity College Dublin)

26/06/2014, 16:15

Hadron Spectroscopy and Interactions

Talk

Preliminary results from a study of $DK$ and $D\pi$ scattering are presented using a set of anisotropic $N_f=2+1$ dynamical gauge field configurations generated by the Hadron Spectrum Collaboration. The variational method with a large operator basis is used in two lattice volumes to determine the excitation spectra of open charm mesons with the relevant scattering states containing one...

150. Electromagnetic mass splittings from dynamical lattice QCD+QED

Prof. Gerrit Schierholz (DESY)

27/06/2014, 14:15

Hadron Spectroscopy and Interactions

Talk

First results on electromagnetic mass splittings of octet mesons and baryons from a fully dynamical simulation of QCD+QED are presented.

129. Finite volume effects and the electromagnetic contributions to kaon and pion masses

Prof. Claude Bernard (Washington University St. Louis)

27/06/2014, 14:35

Hadron Spectroscopy and Interactions

Talk

We report on the MILC Collaboration calculation of electromagnetic effects on light pseudoscalar mesons. The simulations employ asqtad staggered dynamical quarks in QCD plus quenched photons, with lattice spacings varying from 0.12 to 0.06 fm. Finite volume corrections for the MILC realization of lattice electrodynamics have been calculated in chiral perturbation theory theory and applied to...

266. Search for Z_c(3900) on the lattice with twisted mass fermions

Liuming Liu (University of Bonn)

27/06/2014, 14:55

Hadron Spectroscopy and Interactions

Talk

Recently a charged resonance-like structure $Z_c(3900)$ has been observed in several experiments. The invariant mass of this structure is close to the DD* threshold, and one possible interpretation is a molecular bound state formed by the D and $\overline{D}\ast$ mesons. We study the low-energy scattering of $D{\overline{D}}^{\ast }$ using lattice QCD with N_f = 2 twisted mass fermion configurations with three...

114. Evidence for the charged charmonium-like state Zc+ from lattice QCD

Mr Luka Leskovec (Institute Jozef Stefan)

27/06/2014, 15:15

Hadron Spectroscopy and Interactions

Talk

We perform a lattice QCD simulation of the charmonium-like channel, where experiments recently found several manifestly exotic states named Zc+ with flavor content bar c c bar d u. In addition to identifying all the scattering states we also observe an additional level in the simulation, which we attribute to Zc+.

167. Updated results from maximally twisted mass QCD at the physical point

Mr Bartosz Kostrzewa (Humboldt Universität zu Berlin, Institut für Physik, Newstonstr. 15, 12489 Berlin, Germany / NIC, DESY, Zeuthen, Platanenallee 6, D-15738 Zeuthen, Germany)

27/06/2014, 15:35

Hadron Spectroscopy and Interactions

Talk

In this contribution, updated results from simulations by the European Twisted Mass Collaboration at the physical point using Wilson twisted mass fermions with a clover term are presented. We discuss results for the pseudoscalar decay constants $f_K$, $f_D$ and $f_{D_s}$ and the corresponding masses. In addition, we provide evidence for a largely reduced flavour symmetry breaking in...