Infrared and threshold effects in QCD

• Applicants: Professor Dr. Johannes Henn; Professor Dr. Matthias Steinhauser
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 281686883

In this research proposal we study the infrared structure of QCD, which is both of formal and practical interest. On the one hand, the infrared behavior of gauge theories is determined by fundamental quantities of the theory and on the other hand, it is important in the context of higher order quantum corrections to scattering processes. The research proposal comprises different approaches for obtaining information about the infrared behaviour. In a first step we improve our understanding of infrared divergences by calculating the four-loop massless cusp anomalous dimension. Next, the non-planar three-loop soft anomalous dimension matrix is computed. Finally, in the last part of the project, we consider the heavy quark form factors and related threshold effects in QCD at the three-loop level. We plan to perform the calculations analytically, which guarantees that the results can easily be used by other groups. Furthermore, once the quantities are computed within QCD it is in many cases straightforward to extend them to other gauge theories.

• DFG Programme: Research Grants