Leading order multi-soft behaviors of tree amplitudes in NLSM

“…(6.6) starts with O(τ ), which also confirms the result in Ref. [35]. At the subleading order, there are several contributions to be considered.…”

Section: The Subleading Triple Soft Limitsupporting

confidence: 88%

Section: The Subleading Triple Soft Limitmentioning

confidence: 99%

See 1 more Smart Citation

The infrared structure of Nambu-Goldstone bosons

Low

Yin

2018

“…This, as well as independent advances in the notion of a soft bootstrap, has motivated renewed interest in understanding the effect of such non-linear symmetries on the S-matrix, with special attention to its soft limits, 4 see e.g. [41][42][43][44] and references therein. It should be interesting to discover what symmetries survive, and indeed emerge from, the higher-order string-theory type completion encoded in the Ztheory amplitudes presented in [1] and here.…”

Section: Jhep08(2017)135mentioning

confidence: 99%

Semi-abelian Z-theory: NLSM+ϕ 3 from the open string

Carrasco

Mafra

Schlotterer

2017

104

We continue our investigation of Z-theory, the second double-copy component of open-string tree-level interactions besides super-Yang-Mills (sYM). We show that the amplitudes of the extended non-linear sigma model (NLSM) recently considered by Cachazo, Cha, and Mizera are reproduced by the leading α ′ -order of Z-theory amplitudes in the semi-abelian case. The extension refers to a coupling of NLSM pions to bi-adjoint scalars, and the semi-abelian case involves to a partial symmetrization over one of the color orderings that characterize the Z-theory amplitudes. Alternatively, the partial symmetrization corresponds to a mixed interaction among abelian and non-abelian states in the underlying open-superstring amplitude. We simplify these permutation sums via monodromy relations which greatly increase the efficiency in extracting the α ′ -expansion of these amplitudes. Their α ′ -corrections encode higher-derivative interactions between NLSM pions and bi-colored scalars all of which obey the duality between color and kinematics. Through double-copy, these results can be used to generate the predictions of supersymmetric Dirac-Born-Infeld-Volkov-Akulov theory coupled with sYM as well as a complete tower of higher-order α ′ -corrections.1 It may be tempting to refer to the Z-theory scalars as "bi-adjoint", since in the low-energy (α ′ → 0) limit, non-abelian Z-theory becomes bi-adjoint φ 3 . We make a different choice here to emphasize the following important point: the α ′ -corrections imply that Z-theory scalars are not trivially Lie-algebra valued w.r.t. one of the gauge groups -the one dressed by string Chan-Paton factors. Charges under the gauge groups are referred to as "color" throughout this work which may equivalently be replaced by "flavour".

“…The soft limit of scalar EFTs has also been studied using traditional quantum field theory methods [40][41][42]. In particular, in Refs.…”

Section: Contentsmentioning

confidence: 99%

The infrared structure of exceptional scalar theories

Yin

2019

Exceptional theories are a group of one-parameter scalar field theories with (enhanced) vanishing soft limits in the S-matrix elements. They include the nonlinear sigma model (NLSM), Dirac-Born-Infeld scalars and the special Galileon theory. The soft behavior results from the shift symmetry underlying these theories, which leads to Ward identities generating subleading single soft theorems as well as novel Berends-Giele recursion relations. Such an approach was first applied to NLSM in Refs. [1,2], and here we use it to systematically study other exceptional scalar field theories. In particular, using the subleading single soft theorem for the special Galileon we identify the Feynman vertices of the corresponding extended theory, which was first discovered using the Cachazo-He-Yuan representation of scattering amplitudes. Furthermore, we present a Lagrangian for the extended theory of the special Galileon, which has a rich particle content involving biadjoint scalars, Nambu-Goldstone bosons and Galileons, as well as additional flavor structure.