分类： 物理学 >> 基本粒子与场物理学 提交时间： 2017-08-25
摘要： : We study the form factors of the Konishi operator, the prime example of nonprotected operators in N = 4 SYM theory, via the on-shell unitarity method. Since the Konishi operator is not protected by supersymmetry, its form factors share many features with amplitudes in QCD, such as the occurrence of rational terms and of UV divergences that require renormalization. A subtle point is that this operator depends on the spacetime dimension. This requires a modification when calculating its form factors via the on-shell unitarity method. We derive a rigorous prescription that implements this modification to all loop orders and obtain the two-point form factor up to two-loop order and the three-point form factor to one-loop order. From these form factors, we construct an IR-finite crosssection-type quantity, namely the inclusive decay rate of the (off-shell) Konishi operator to any final (on-shell) state. Via the optical theorem, it is connected to the imaginary part of the two-point correlation function. We extract the Konishi anomalous dimension up to two-loop order from it.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2017-08-25
摘要： We compute the two-loop minimal form factors of all operators in the SU(2) sector of planar N = 4 SYM theory via on-shell unitarity methods. From the UV divergence of this result, we obtain the two-loop dilatation operator in this sector. Furthermore, we calculate the corresponding finite remainder functions. Since the operators break the supersymmetry, the remainder functions do not have the property of uniform transcendentality. However, the leading transcendentality part turns out to be universal and is identical to the corresponding BPS expression. The remainder functions are shown to satisfy linear relations which can be explained by Ward identities of form factors following from R-symmetry
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