### Session B5: Invited Session: Applications of Graphical Processing Units in Physics

 Saturday, March 31, 2012 10:45AM - 11:21AM B5.00001: Lattice QCD and Graphical Processing Units Invited Speaker: Balint Joo Graphical Processing Units (GPUs) have brought about a disruptive improvement in the cost effectiveness of certain lattice QCD calculations. These days, GPUs are in mainstream use in a variety of lattice computations worldwide. In this talk I will discuss some relevant architectural features of GPU based systems, some recent software successes and outline some future perspectives in the context of large scale GPU calculations. Saturday, March 31, 2012 11:21AM - 11:57AM B5.00002: Application of Graphics Processing Units to Newtonian stellar dynamics Invited Speaker: Evghenii Gaburov Newtonian stellar dynamics is traditionally on the forefront of high-performance computing: it required a dedicated Newtonian solver to study the stability of the solar system, and a special purpose GRAPE hardware to understand the dynamics of dense stellar system. Emergence of general-purpose computations on Graphics Processing Units (GPGPU) have opened new and exciting opportunities in computational stellar dynamics. A wide range of advanced algorithms which compute Newtonian gravitational force, ranging from the direct summation to sophisticated fast-multipole methods, have been successfully implemented on graphics processing units, and their performance eclipse that of special purpose hardware. In this contribution I will talk about GPGPU and why it has become an excellent computational tool for stellar dynamics. Saturday, March 31, 2012 11:57AM - 12:33PM B5.00003: GPUs in experimental particle physics Invited Speaker: Niklaus Berger Many applications in particle and nuclear physics demand vast computational power with high throughput and low latency. Graphics Processing Units (GPUs) provide such massively parallel floating point computing power at low cost. Indeed many problems are easily parallelized and can be sped up by orders of magnitude by the use of GPUs. The talk will discuss two very different examples, namely the use of GPUs for partial wave analysis and on-line track reconstruction. Partial wave analysis is a key tool in hadron spectroscopy. The unbinned likelihood fits employed are an almost perfect match for the architecture of GPUs. GPU based partial wave analysis was pioneered at the Beijing Spectrometer III experiment in order to deal with world's largest datasets from electron-positron collisions in the charm threshold energy region and is now employed by many groups in the field. The presentation will describe the challenges for implementing a GPU based partial wave analysis and how they were overcome. Usually the most time consuming part of analysing particle physics events is the reconstruction of tracks of charged particles. A new generation of high rate experiments running without a hardware trigger (e.g.~the LHCb upgrade, PANDA, a proposed $\mu \rightarrow eee$ search) will be relying on very fast on-line event reconstruction, including tracking. This in turn requires massive amounts of computing power, which is currently best provided by GPUs. The talk will describe the state of GPU based tracking efforts.