PKU HEP Seminar and Workshop (北京大学高能物理组)
Four-loop Non-planar Cusp Anomalous Dimension in N=4 SYM
by
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Asia/Shanghai
B105 (CHEP)
B105
CHEP
School of Physics, PKU
Description
The light-like cusp anomalous dimension (CAD) is an important physical quantity with applications ranging from string theory to flavour physics. In particular, it determines the leading infrared divergences in scattering amplitudes. While in N=4 SYM the CAD has been known to all order based on the AdS/CFT correspondence and integrability since 2006, the non-planar correction starts at four loops and its computation was a long-standing challenging problem. There has been a conjecture of quadratic Casimir scaling, which states that the non-planar correction may be zero in general gauge theories (see e.g. 0903.1126). In this talk, I will describe the first computation of the four-loop non-planar form factor in N=4 SYM. This allows to extract the leading non-planar cusp (and collinear) anomalous dimension, which disproves the Casimir scaling conjecture.