Journal of High Energy Physics (Jul 2024)

Wormholes in the axiverse, and the species scale

  • Luca Martucci,
  • Nicolò Risso,
  • Alessandro Valenti,
  • Luca Vecchi

DOI
https://doi.org/10.1007/JHEP07(2024)240
Journal volume & issue
Vol. 2024, no. 7
pp. 1 – 110

Abstract

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Abstract We analyze a large class of four-dimensional N $$ \mathcal{N} $$ = 1 low-energy realizations of the axiverse satisfying various quantum gravity constraints. We propose a novel upper bound on the ultimate UV cutoff of the effective theory, namely the species scale, which only depends on data available at the two-derivative level. Its dependence on the moduli fields and the number N of axions matches expectations from other independent considerations. After an assessment of the regime of validity of the effective field theory, we investigate the non-perturbative gravitational effects therein. We identify a set of axionic charges supported by extremal and non-extremal wormhole configurations. We present a universal class of analytic wormhole solutions, explore their deformations, and analyze the relation between wormhole energy scales and the species scale. The connection between these wormholes and a special subclass of BPS fundamental instantons is discussed, and an argument in favor of the genericity of certain axion-dependent effective superpotentials is provided. We find a lower bound increasing with N ≫ 1 on the Gauss-Bonnet coefficient, resulting in an exponential suppression of non-extremal wormhole effects. Our claims are illustrated and tested in concrete string theory models.

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