【Large N_c limit QCD and symmetry preserving truncations for DS and BS equations】2017年9月6日（周三）15：30【主讲】王青教授（清华大学）【地点】中国科学院理论物理研究所会议楼322（Conference Hall 322, ITP）【摘要】We develop a framework for deriving Dyson-Schwinger Equations (DSEs) and Bethe-Salpeter Equation (BSE) in QCD at large N_c limit. The starting point is a modified form (with auxiliary fields) of QCD generating functional. This framework provides a natural order by order truncation scheme for DSEs and BSE, and the kernels of the equations up to any order are explicitly given. Chiral symmetry (at chiral limit) is preserved in any order truncation, so it exemplifies the symmetry preserving truncation scheme. It provides a method to study DSEs and BSE beyond the Rainbow-Ladder truncation, and is especially useful to study contributions from non-Abelian dynamics (those arise from gluon self-interactions). We also derive the equation for the quark-ghost scattering kernel, and discuss the Slavnov-Taylor identity connecting the quark-gluon vertex, the quark propagator and the quark-ghost scattering kernel.
9.7（周四）讲座2场
【高不确定性商业环境中的战略选择】2017年9月7日（周四）18:00-20:15【嘉宾】Professor Javier Gimeno（圣戈班亚太区总裁）【地点】清华大学经管伟伦楼404【语言】英文
【The new era of Galactic Archaeology】2017年9月7日（周四）14：00【主讲】Yuan-Sen Ting (Australian National University / Princeton University)【地点】清华大学蒙民伟科技南楼 S-727【报告摘要】Understanding physical processes responsible for the formation and evolution of galaxies like the Milky Way is a fundamental problem in astrophysics. However, a key challenge is that the properties and orbits of the stars can only be observed at present: to understand what happened in the Milky Way at earlier epochs, one must explore “archaeological” techniques. One idea, "chemical tagging,” aims to probe the history of the Milky Way via the unique imprint in chemical abundance space of long-disrupted star forming associations. I will discuss the opportunities and challenges associated with chemical tagging, including a first constraint on the disrupted cluster mass function in the Milky Way, and how Gaia, as well as extragalactic IFU studies, could be informative in the studies of chemical tagging. I will also describe a new set of tools for efficient measuring multi-elemental abundances from large quantities of low-resolution LAMOST spectra, for constraining the binary fraction in the Milky Way, and for inferring asteroseismic parameters from spectra alone.
