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Dilatons Improve (Non)-Goldstones

High Energy Physics - Theory 2026-01-13 v3 General Relativity and Quantum Cosmology High Energy Physics - Lattice High Energy Physics - Phenomenology

Abstract

Shift symmetry forbids conformal coupling of Goldstone bosons from internal symmetries, but not for spontaneously broken conformal symmetry. Its Goldstone boson, the dilaton DD, admits and indeed requires, an improvement term LRRe2D/FD {\cal L}_R \propto R e^{-2D/F_D} as it realises the Goldstone matrix element in the effective theory. The improvement, combined with Weyl-gauging, enables conformal coupling to Goldstone bosons and other particles of arbitrary Weyl-weight. While improvement does not affect scattering amplitudes in flat space, it impacts gravitational form factors decisively, giving rise to the dilaton pole in the spin-zero channel. We compute leading-order scalar, fermion, pion, and dilaton form factors, confirming low-energy constraints. The dilaton decoupling limit further implies that the operator driving spontaneous chiral symmetry breaking has scaling dimension Δ=d2\Delta= d-2.

Keywords

Cite

@article{arxiv.2306.12914,
  title  = {Dilatons Improve (Non)-Goldstones},
  author = {Roman Zwicky},
  journal= {arXiv preprint arXiv:2306.12914},
  year   = {2026}
}

Comments

20 pages + refs, 1 figure, major revision. Includes discussion on Weyl-gauging and the effect of the improvement on gravitational form factors

R2 v1 2026-06-28T11:11:57.725Z