The Odd 2D Bubbles, 4D Triangles, and Einstein and Weyl Anomalies in 2D Gravitational Fermionic amplitudes: The Role of Breaking Integration Linearity for Anomalies

Abstract: We investigated Relations Among Green Functions defined in an alternative strategy for coping with the divergences, also called the Implicit Regularization Method (IREG): the mathematical content (divergent and finite) will remain intact until the calculations end. The divergent part will be organized through standardized objects free of physical quantities. In contrast, the finite part is projected in a class of well-behaved functions that carry all the amplitudes' physical content. That relations arise in fermionic amplitudes in even space-time dimensions, where anomalous tensors connect to finite amplitudes as in the bubbles and triangles in two and four dimensions. Those tensors depend on surface terms, whose non-zero values arise from finite amplitudes as requirements of consistency with the linearity of integration and uniqueness. Maintaining these terms implies breaking momentum-space homogeneity and, in a later step, the Ward identities. Meanwhile, eliminating them allows more than one mathematical expression for the same amplitude. That is a consequence of choices related to the involved Dirac traces. Independently of divergences, it is impossible to satisfy all symmetry implications by simultaneously requiring vanishing surface terms and linearity. Then we approach the 1-loop level fermionic correction for the propagation of the graviton in a space-time D=1+1 through the action of a Weyl fermion in curved space-time. In this context, gravitational anomalies arise, and the amplitudes investigated have the highest degree of divergence quadratic. That imposes a substantial algebraic effort; however, the conclusions are in agreement with the non-gravitational amplitudes. At the end of the calculations, we show how it is possible to fix the value of the divergent part through the relations imposed for amplitudes.