Speaker
Description
In this talk I review established as well as recently uncovered connections between string-derived scalar amplitudes (Z-theory) and amplitudes of pions in the chiral non-linear sigma model (NLSM). Non-abelian Z-theory [1] amplitudes generalize the open string Veneziano amplitude and represent a stringy completion (including corrections in the string scale $\alpha$') of a cubic bi-adjoint field theory of scalars (BAS). Abelian Z-theory [2] amplitudes on the other hand describe string-completed NLSM amplitudes of pions, and can be obtained from their non-abelian counterparts by a straightforward combinatoric procedure. Therefore pion amplitudes are encoded in the structure of the much simpler BAS theory.
A recent discovery [3] established an even more immediate connection between field theory BAS amplitudes and those of the NLSM using a simple kinematic shift which remarkably extends to loop-level integrands.
In this context I will formulate new Berends-Giele-like recursion relations for NLSM amplitudes and planar integrands that leverage the close tie to the BAS theory. The recursive procedure is highly efficient as its input are large building blocks in the form of mixed amplitudes coupling pions and bi-adjoint scalars. Furthermore the recursion requires only a single cubic vertex to build NLSM amplitudes with any number of legs and loops and naturally generalizes the well-known Adler zero of tree amplitudes to loop integrands [4].
[1] arXiv:1609.07078 [hep-th]
[2] arXiv:1608.02569 [hep-th]
[3] arXiv:2401.05483 [hep-th]
[4] arXiv:2401.04731 [hep-th]
