1 / 18

2+1 Flavor lattice QCD Simulation on K computer

2+1 Flavor lattice QCD Simulation on K computer. Y.Kuramashi U. of Tsukuba/RIKEN AICS August 2, 2013 @ Mainz. Plan of talk. §1. K computer and Strategic Field Program §2. Physics Plan §3. Simulation Parameters §4. Preliminary results §5. Summary.

liliha
Download Presentation

2+1 Flavor lattice QCD Simulation on K computer

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 2+1 Flavor lattice QCD Simulation on K computer Y.Kuramashi U. of Tsukuba/RIKEN AICS August 2, 2013 @ Mainz

  2. Plan of talk §1. K computer and Strategic Field Program §2. Physics Plan §3. Simulation Parameters §4. Preliminary results §5. Summary

  3. §1. K computer and Strategic Field Program RIKEN AICS Tsukuba Kobe Tokyo Advanced Institute for Computational Science (Note: independent of RIKEN-BNL-Columbia Collab.) Kyoto Logo Peak=11.28PFlops Computer room

  4. Strategic Field Program • For strategic use of K computer • Government selected 5 strategic fields in science and technology for importance from national view point • For each field, Government also selected a core institute • Each core institute is responsible for organizing research and supercomputer resources in the respective field and its community, for which they receive • − priority allocation of K computer resources • − funding to achieve the research goals

  5. §2. Physics Plan • Scientific target • 2+1 flavor QCD ⇒ 1+1+1 flavor QCD+QED • Various physical quantities • Investigation of resonances • Direct construction of light nuclei • Determination of baryon-baryon potentials

  6. Light Nuclei in 2+1 Flavor QCD (1) Yamazaki-Ishikawa-YK-Ukawa 12 Ukawa @this conference 2+1 flavor QCD, mπ＝0.5 GeV, mN=1.32 GeV Successful construction of helium nuclei in 2+1 flavor QCD

  7. Light Nuclei in 2+1 Flavor QCD (2) NN(3S1) and NN(1S0) channels Both 3S1 and 1S0 channels are bound at mπ=0.5 GeV |ΔE(3S1)| > |ΔE(1S0)| is observed Important to investigate quark mass dependence Target on K computer: construction of nuclei at the physical point

  8. Baryon-Baryon Potentials (1) Phenomenological model Ishii-Aoki-Hatsuda 07 based on equal-time BS amplitude Quenched QCD, mN=1.34GeV BS wave function with lattice QCD ⇒ NN Potential

  9. Baryon-Baryon Potentials (2) HAL-QCD @FB12 2+1 flavor QCD, lattice size=323×64, mπ＝0.70, 0.57, 0.41 GeV Attractive phase shift, though the magnitude is just 10% of exp. value (no bound state ⇒ inconsistency against the direct method) Phase shift becomes smaller, as quark mass decreases ⇒ need direct comparison with exp. values at the physical point

  10. Collaboration members N.Ishii, N.Ishizuka, Y.Kuramashi, Y.Namekawa, Tsukuba H.Nemura, K.Sasaki, Y.Taniguchi, N.Ukita T.Hatsuda, T.Doi RIKEN-Wako T.Yamazaki Nagoya S.Aoki Kyoto Y.Nakamura RIKEN-AICS K.-I.Ishikawa Hiroshima HAL QCD Collab. joins to determine baryon-baryon potential

  11. §3. Simulation Parameters • 2+1 flavor QCD • Wilson-clover quark action + Iwasaki gauge action • Stout smearing with α=0.1 and Nsmear=6 • NP CSW=1.11 determined by SF • β=1.82 ⇒ a〜0.1 fm • Lattice size=964 ⇒ (〜9 fm)4 • Hopping parameters: (κud,κs)=(0.126117,0.124790) • Simulation algorithm • − (HB)2DDHMC w/ active link for ud quarks, UVPHMC for s quark • − Block size=124 ⇒ (〜1 fm)4 • − HB parameters: (ρ1,ρ2)=(0.99975,0.9940) • − Multi-time scale integrator: (N1,N2,N3,N4,N5)=(15,2,2,2,8) • − trajectory length: τ=1 • − Npoly=310 • − Chronological inverter guess: Nchrono=16 • − Solver: mixed precision nested BiCGStab

  12. Performance on K computer • Kernel (MatVec) performance: >50% • Solver performance: 〜26% (mixed precision nested BiCGStab) • Weak scaling test • − 63×12/node fixed • − 16 nodes (V=123×24) ⇒ 12288 nodes (V=48×72×962) B/F=0.5 on K computer 12288 2048 256 good weak scaling 16

  13. Non-Perturbative Determination of CSW (1) Taniguchi @Lattice2012 Schördinger functional method − L3×T=83×16 (L3×T=123×24 for volume dependence check) − Choose β such that the lattice spacing becomes around 0.1 fm CSW=1.11 at β=1.82 ⇒ 1/a〜2.1 GeV κC is close to 0.125 at β=1.82

  14. Non-Perturbative Determination of CSW (2) Nsmear dependence of CSW and Kc CSW monotonically decreases as Nsmear increases κC shows a similar behavior

  15. §4. Preliminary results Meson and baryon effective masses for smeared-local correlators Smearing function: Aexp(−Br) − (A,B)=(1.2,0.06) for ud quarks − (A,B)=(1.2,0.12) for s quarks

  16. Hadron spectrum Comparison with experiment (normalized by mΩ) Further tuning to the physical point is planned with reweighting method Clear deviation is already observed for unstable particles (ρ,K*)

  17. ρ Meson Effective Mass Decay channel is open: mρ>2√{mπ2+(π/48)2} mρ=776 MeV 2√{mπ2+(π/48)2} It is hard to find a reasonable plateau (same for Δ baryon effective mass) Analysis of 2×2 correlation matrix (ρ,ππ) is necessary

  18. §5. Summary ・ K computer and strategic field program ・ 2+1 flavor QCD simulation at the physical point on (〜9 fm)4 lattice ・ Preliminary results for hadron spectrum

More Related