Hidden amplitude zeros from the double-copy map
Christoph Bartsch, Taro V. Brown, Karol Kampf, Umut Öktem, Shruti Paranjape, Jaroslav Trnka
Abstract
Recently, Arkani-Hamed proposed the existence of zeros in scattering amplitudes in certain quantum field theories including the cubic adjoint scalar theory <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>Tr</a:mi> <a:mo stretchy="false">(</a:mo> <a:msup> <a:mi>ϕ</a:mi> <a:mn>3</a:mn> </a:msup> <a:mo stretchy="false">)</a:mo> </a:math> , the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>S</e:mi> <e:mi>U</e:mi> <e:mo stretchy="false">(</e:mo> <e:mi>N</e:mi> <e:mo stretchy="false">)</e:mo> </e:math> nonlinear sigma model and Yang-Mills theory. These hidden zeros are special kinematic points where the amplitude vanishes and factorizes into a product of lower-point amplitudes, similar to factorization near poles. In this paper, we show a close connection between the existence of such zeros and the double-copy map. In fact, compatibility with the Bern-Carrasco-Johansson relations requires the presence of these zeros. We also show that these zeros extend via the Kawai-Lewellen-Tye relations to special Galileon amplitudes and their corrections, evincing that these hidden zeros are also present in permutation-invariant amplitudes.