International Workshop on Simulations of Low and Intermediate Energy Heavy Ion Collisions, January 8-12, 2014, Shanghai, China

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Simulation programs for heavy ion collisions are essential to interpret the experimental results of heavy ion collisions and to extract the information on all aspects of the nuclear equation-of-state and on in-medium properties of hadrons. Transport theories (either derived from Boltzmann-like equations or from Molecular Dynamics) have been used extensively. However, it is known that some simulations gave widely differing results with seemingly similar physical input. E.g., recent extractions of the density dependence of symmetry energy at supra-normal density using the FOPI Au+Au collision data has resulted in very different density dependences of the symmetry energy from super-soft to super-stiff. This is certainly not a satisfactory state of affairs, as heavy ion studies are only credible, if simulations can be done in a reliable way.

From this motivation code comparison workshops were organized at the ECT* in Trento in 2004 (mainly concerned with particle production around 1 AGeV and published as J. Phys. G 31 (2005) 741) and in 2009 (flow and collision rates at 100 and 400 AMeV, not published, but shown in various conferences). At the recent meetings ICNT2013/NuSYM13 at MSU and IWNDT at TAMU, many of us agreed to make a renewed effort to understand the differences in the codes being used to interpret heavy ions collisions. We believe that this is important to maintain the credibility of the field and to make valid interpretations of the next generation of experiments underway to extract symmetry energy at supra-saturation density regions.

The consensus was to have such workshop in China in view of the extensive activities of various groups in China with heavy ion collisions. A proposed date and place for the workshop is January 8-12, 2014 in Shanghai, China.

In order for the workshop to be most productive, it is important to do some calculations before the meeting (as in Trento). It was found to be useful to have the homework assignments in two stages: one rather simple one due at about 6 weeks (mid-November) before the meeting to get an overview of the status, and one more specifically based on these results due at the meeting. The first homework assignment is proposed to be similar to the one in the 2009 workshop in Trento. Details of the homework are still under discussion and will be sent out soon to all who have expressed interest.

The goal of the workshop will be to determine the accuracy of transport model simulations for heavy ion collisions and to have a clear understanding of the remaining differences. We aim to have a publishable report about the comparison results from the workshop. Before such a publication, all code authors will have the opportunity to make modifications in their codes (perhaps triggered by the results of the comparisons during the conference), or to explain the differences with other codes.

The Organizing Committee