TRR 55: Hadronenphysik mit Gitter-QCD
Informatik, System- und Elektrotechnik
Mathematik
Zusammenfassung der Projektergebnisse
The overarching goal of SFB/TRR-55 was to combine three different research fields, namely Lattice QCD, advanced mathematical algorithms and novel developments in High Performance Computing in such a way • that an improved level of precision is realized in Lattice QCD and that a much extended spectrum of questions in hadron physics, both at zero and finite temperature, can be answered. • that new algorithms are not only developed but also widely used in practical applications, such that their performance can directly steer further innovation. • that new HPC hard- and software is developed, in close cooperation with major international computer companies, which provides an unprecedented cost-performance ratio for Lattice QCD calculations. To reach this goal one of the main design criteria was to achieve much improved energy efficiency. All of these goals have been achieved, see subsection 1.3. Over the 12 years SFB/TRR-55 existed all three, highly dynamical fields have spawned most interesting new developments which have been taken up by SFB/TRR-55 and which have both extended and modified its scope of research activities compared to the first proposal. Some of these are: • At the time SFB/TRR-55 was created many fundamental issues of QCD thermodynamics were still unclear, e.g. the QCD phase diagram and the QCD equation of state. • At the time of the first proposal in 2007 the community had very high hopes concerning the use of chiral fermions (overlap or domain wall) which, therefore, played an important role in that proposal. It was hoped that chiral fermions would lead to such large systematic improvements (in particular improving control of the continuum limit) that this would more than compensate for their larger computational cost. The results of us and many other groups moderated these expectations. Today, simulations with chiral and e.g. Wilson fermions are performed with comparable computer resources and one has learned which problems can be investigated best with which fermion type. Consequently, overlap fermions played a reduced role in the continuation proposals. • As was finally announced January 2020 the heavy-ion and polarized proton-proton program at the RHIC accelerator of Brookhaven National Laboratory will come to an end in few years, getting replaced by electron-proton/nucleus physics performed at the Electron-Ion-Collider (EIC) which will recycle much of the RHIC infrastructure. This project is realized jointly with JLab, the Thomas Jefferson National Accelerator Facility. In addition the electron-proton/nucleus accelerator JLab@12 GeV has started operating in 2017. At CERN a roughly ten year long upgrade phase of LHC to the High Luminosity LHC (HL-LHC) has started. Somewhat disappointingly the present LHC has not yet identified the signals for Beyond the Standard Model (BSM) physics which one had hoped for. The much increased luminosity will significantly extend its discovery potential along what is called the ’precision frontier’ just as the EIC will do for hadron structure physics. Both developments offer new opportunities and pose increased challenges for highprecision Lattice QCD because in both cases the main source of systematic theoretical uncertainties comes from non-perturbative QCD. Another important development is the impressive increase in experimental precision reached in searches for axions and other astrophysically relevant particles. Our collaboration has positionned itself to optimally profit from all these developments, see subsection 1.5. • To fulfill the increased demands on high precision QCD also requires significant progress along the lowenergy frontier much of which has to come from the lattice. This development is illustrated best by the rapidly increasing importance of the FLAG reports, see e.g. [X1] of which Dr. Sara Collins and Dr. Stephan Dürr were co-authors. page 5 of 135 Part A Research section Research achievements and outcomes • For all phenomenological applications, methods of nonperturbative renormalization were developed further in a systematic drive to reduce the associated systematic and statistical errors to the precision goals aimed at. • The major new German research facility FAIR approaches completion. Therefore, it was a particularly timely and relevant issue to develop techniques to describe the QCD plasma at nonvanishing temperatures and chemical potentials, which will be the main focus point of the CBM (Compressed Baryon Matter) experiment at FAIR. We have made a significant progress towards this important direction. • Adaptive algebraic multigrid methods have evolved into an important solver technology for linear systems where the required operator hierarchy does not arise naturally from the physical model. Adaptive algebraic multigrid methods can be used in a variety of contexts, and their use when solving the Wilson-Dirac equation has algorithmically reduced computational efforts by at least one order of magnitude. This crucially contributed to our today’s capability to simulate at physical quark masses. The adaptive algebraic multigrid approach has a variety of different facets which require a deeper mathematical understanding as well as the careful selection of parameters. Research is still ongoing, but for lattice simulations we have already demonstrated significant progress in aggregation-based coarsening and in the bootstrap principle for the setup. • The problem of an increasingly slow memory speed vs. a high processor speed became even more pronounced on current architectures during the lifetime of the SFB. As an algorithmic reaction to this problem, block methods—like, e.g., treating several linear systems with the same matrix simultaneously—have become increasingly important. The numerical linear algebra community has contributed various novel techniques on how to combine different Krylov subspaces in the linear system context and analyzed their influence on the speed of convergence, and so did we. • SFB/TRR-55 co-designed five large HPC systems (QPACE 1 through QPACE 4 and iDataCool) together with major computer companies (IBM, Intel, Eurotech, Fujitsu, Arm) and supercomputing centers (JSC, LRZ, RIKEN R-CCS). These efforts, which generated substantial international visibility, were accompanied by the development of algorithms and high-performance software. As a result, we obtained close-to-optimal sustained performance for key Lattice QCD (and other) applications at highly competitive cost-performance and power-performance ratios. A major theme was the early adoption of new computing architectures such as IBM’s Cell processor, Intel’s Xeon Phi processors (Knights Corner and Knights Landing) and Fujitsu’s A64FX. Through our close collaboration with the processor manufacturers we had access to chip simulators and early engineering samples so that our codes could be developed and optimized before the new processors came to market. Another major theme was energy efficiency, which has become a major design goal in HPC. Of our five systems, three were large enough to make the TOP 500 list of the largest HPC systems worldwide. On the Green 500 list, which orders these machines by energy efficiency, our systems were No. 1 (QPACE 1 in 2009 and 2010), No. 15 (QPACE 2 in 2015) and No. 5 (QPACE 3 in 2016). The iDataCool system we developed together with IBM went one step further and demonstrated the possibility of hot-water cooling with energy reuse. It is certainly fair to say that SFB/TRR-55 and thus DFG have contributed significantly to crucial trends in HPC developments on par with major players in the field.
Projektbezogene Publikationen (Auswahl)
- “Ab-Initio Determination of Light Hadron Masses”. In: Science 322 (2008), pp. 1224–1227
S. Durr et al.
(Siehe online unter https://doi.org/10.1126/science.1163233) - “Electroproduction of the N*(1535) resonance at large momentum transfer”. In: Phys. Rev. Lett. 103 (2009), p. 072001
V. M. Braun et al.
(Siehe online unter https://doi.org/10.1103/PhysRevLett.103.072001) - “Hadron Spectroscopy with Dynamical Chirally Improved Fermions”. In: Phys. Rev. D 79 (2009), p. 054501
Christof Gattringer et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.79.054501) - “Effective noise reduction techniques for disconnected loops in Lattice QCD”. In: Comput.Phys.Commun. 181 (2010), pp. 1570–1583
Gunnar S. Bali, Sara Collins, and Andreas Schafer
(Siehe online unter https://doi.org/10.1016/j.cpc.2010.05.008) - “Short-recurrence Krylov subspace methods for the overlap Dirac operator at nonzero chemical potential”. In: Comput. Phys. Commun. 181 (2010), pp. 1378–1387
Jacques C. R. Bloch et al.
(Siehe online unter https://doi.org/10.1016/j.cpc.2010.04.004) - “Fluctuations of conserved charges at finite temperature from lattice QCD”. In: JHEP 1201 (2012), p. 138
Szabolcs Borsanyi et al.
(Siehe online unter https://doi.org/10.1007/JHEP01(2012)138) - “High-precision scale setting in lattice QCD”. In: JHEP 1209 (2012), p. 010
Szabolcs Borsanyi et al.
(Siehe online unter https://doi.org/10.1007/JHEP09(2012)010) - “Perturbative and Nonperturbative Renormalization in Lattice QCD”. In: Phys. Rev. D 82 (2010). [Erratum: Phys.Rev.D 86, 099903 (2012)], p. 114511
M. Gockeler et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.82.114511 https://doi.org/10.1103/PhysRevD.86.099903) - “Precision SU(3) lattice thermodynamics for a large temperature range”. In: JHEP 1207 (2012), p. 056
Sz. Borsanyi et al.
(Siehe online unter https://doi.org/10.1007/JHEP07(2012)056) - “QCD equation of state at nonzero chemical potential: continuum results with physical quark masses at order mu2”. In: JHEP 1208 (2012), p. 053
Sz. Borsanyi et al.
(Siehe online unter https://doi.org/10.1007/JHEP08(2012)053) - “QCD quark condensate in external magnetic fields”. In: Phys.Rev. D86 (2012), p. 071502
G.S. Bali et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.86.071502) - “Strangeness Contribution to the Proton Spin from Lattice QCD”. In: Phys. Rev. Lett. 108 (2012), p. 222001
Gunnar S. Bali et al.
(Siehe online unter https://doi.org/10.1103/PhysRevLett.108.222001) - “The QCD phase diagram for external magnetic fields”. In: JHEP 1202 (2012), p. 044
G.S. Bali et al.
(Siehe online unter https://doi.org/10.1007/JHEP02(2012)044) - “Nucleon mass and sigma term from lattice QCD with two light fermion flavors”. In: Nucl. Phys. B 866 (2013), pp. 1–25
G. S. Bali et al.
(Siehe online unter https://doi.org/10.1016/j.nuclphysb.2012.08.009) - “SU(2) chiral perturbation theory low-energy constants from 2+1 flavor staggered lattice simulations”. In: Phys.Rev. D88 (2013), p. 014513
Szabolcs Borsanyi et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.88.014513) - “Adaptive Aggregation Based Domain Decomposition Multigrid for the Lattice Wilson Dirac Operator”. In: SIAM J.Sci.Comput. 36 (2014), A1581–A1608
Andreas Frommer et al.
(Siehe online unter https://doi.org/10.1137/130919507) - “Convergence of restarted Krylov subspace methods for Stieltjes functions of matrices”. In: SIAM J. Matrix Anal. Appl. 35.4 (2014), pp. 1602–1624
Andreas Frommer, Stefan Güttel, and Marcel Schweitzer
(Siehe online unter https://doi.org/10.1137/140973463) - “Freeze-out parameters from electric charge and baryon number fluctuations: is there consistency?” In: Phys.Rev.Lett. 113 (2014), p. 052301
S. Borsanyi et al.
(Siehe online unter https://doi.org/10.1103/PhysRevLett.113.052301) - “Full result for the QCD equation of state with 2+1 flavors”. In: Phys.Lett. B730 (2014), pp. 99–104
Szabolcs Borsanyi et al.
(Siehe online unter https://doi.org/10.1016/j.physletb.2014.01.007) - “Lattice QCD with Domain Decomposition on Intel Xeon Phi Co-Processors”. The International Conference for High Performance Computing, Networking, Storage, and Analysis: SC14: HPC matters (SC) New Orleans, LA, USA, November 16-21, 2014
Simon Heybrock et al.
(Siehe online unter https://doi.org/10.1109/SC.2014.11) - “The QCD equation of state in background magnetic fields”. In: JHEP 08 (2014), p. 177
G. S. Bali et al.
(Siehe online unter https://doi.org/10.1007/JHEP08(2014)177) - “Ab initio calculation of the neutron-proton mass difference”. In: Science 347 (2015), pp. 1452–1455
Sz. Borsanyi et al.
(Siehe online unter https://doi.org/10.1126/science.1257050) - “Dual lattice representations for O(N) and CP(N−1) models with a chemical potential”. In: Phys. Lett. B 749 (2015). [Erratum: Phys.Lett.B 751, 595–595 (2015)], pp. 495–501
Falk Bruckmann et al.
(Siehe online unter https://doi.org/10.1016/j.physletb.2015.08.015 https://doi.org/10.1016/j.physletb.2015.10.033) - “Effects of Heavy Sea Quarks at Low Energies”. In: Phys. Rev. Lett. 114.10 (2015), p. 102001
Mattia Bruno et al.
(Siehe online unter https://doi.org/10.1103/PhysRevLett.114.102001) - “QPACE 2 and Domain Decomposition on the KNC”. In: PoS LATTICE2014 (2015), p. 021
Paul Arts et al.
(Siehe online unter https://doi.org/10.22323/1.214.0021) - “Simulation of QCD with Nf = 2 + 1 flavors of non-perturbatively improved Wilson fermions”. In: JHEP 1502 (2015), p. 043
Mattia Bruno et al.
(Siehe online unter https://doi.org/10.1007/JHEP02(2015)043) - “Approaches to the sign problem in lattice field theory”. In: Int. J. Mod. Phys. A 31.22 (2016), p. 1643007
Christof Gattringer and Kurt Langfeld
(Siehe online unter https://doi.org/10.1142/S0217751X16430077) - “Calculation of the axion mass based on high-temperature lattice quantum chromodynamics”. In: Nature 539.7627 (2016), pp. 69–71
Sz. Borsanyi et al.
(Siehe online unter https://doi.org/10.1038/nature20115) - “Novel quark smearing for hadrons with high momenta in lattice QCD”. In: Phys. Rev. D 93.9 (2016), p. 094515
Gunnar S. Bali et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.93.094515) - “ρ and K∗ resonances on the lattice at nearly physical quark masses and Nf = 2”. In: Phys. Rev. D 93.5 (2016), p. 054509
Gunnar S. Bali et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.93.054509) - Lattice Quantum Chromodynamics: Practical Essentials. SpringerBriefs in Physics. Springer, 2017. isbn: 978-94-024-0997-0
Francesco Knechtli, Michael Günther, and Michael Peardon
(Siehe online unter https://doi.org/10.1007/978-94-024-0999-4) - “Hadroquarkonium from lattice QCD”. In: Phys. Rev. D 95.7 (2017), p. 074501
Maurizio Alberti et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.95.074501) - “Pion distribution amplitude from Euclidean correlation functions: Exploring universality and higher-twist effects”. In: Phys. Rev. D 98 (2018), p. 094507
G.S. Bali et al.
(Siehe online unter https://doi.org/10.1103/PhysRevD.98.094507) - “Light-cone distribution amplitudes of octet baryons from lattice QCD”. In: Eur. Phys. J. A 55.7 (2019), p. 116
Gunnar S. Bali et al.
(Siehe online unter https://doi.org/10.1140/epja/i2019-12803-6) - “Light-cone distribution amplitudes of pseudoscalar mesons from lattice QCD”. In: JHEP 08 (2019), p. 065
Gunnar S. Bali et al.
(Siehe online unter https://doi.org/10.1007/JHEP08(2019)065) - The QCD crossover at finite chemical potential from lattice simulations. In: Phys. Rev. Lett. 125 (2020), p. 052001
Szabolcs Borsanyi et al.
(Siehe online unter https://doi.org/10.1103/PhysRevLett.125.052001) - “Block Krylov Subspace Methods for Functions of Matrices II: Modified Block FOM”. In: SIAM J. Matrix Anal. Appl. 42 (2020), pp. 804–837
Andreas Frommer, Kathryn Lund, and Daniel B. Szyld
(Siehe online unter https://doi.org/10.1137/19M1255847) - “Performance Modeling of Streaming Kernels and Sparse Matrix-Vector Multiplication on A64FX”. 2020 IEEE/ACM Performance Modeling, Benchmarking and Simulation of High Performance Computer Systems, PMBS@SC 2020, Atlanta, GA, USA, November 12, 2020. IEEE, 2020, pp. 1–7
Christie L. Alappat et al.
(Siehe online unter https://doi.org/10.1109/PMBS51919.2020.00006) - Andreas Frommer et al. “A multigrid accelerated eigensolver for the Hermitian Wilson–Dirac operator in lattice QCD”. In: Comput. Phys. Commun. 258 (2021), p. 107615
Andreas Frommer et al.
(Siehe online unter https://doi.org/10.1016/j.cpc.2020.107615) - “Leading-order hadronic vacuum polarization contribution to the muon magnetic moment from lattice QCD”. In: Nature 592.7853 (2021)
Sz. Borsanyi et al.
(Siehe online unter https://doi.org/10.1038/s41586-021-03418-1)
