Publications 2021

Exploring SU(N) adjoint correlators in 3d
Authors: Andrea Manenti, Alessandro Vichi
Preprint number: UUITP04/21
We use numerical bootstrap techniques to study correlation functions of scalars transforming in the adjoint representation of SU(N). We obtain upper bounds on operator dimensions for all the relevant representations and several values of $N$. We discover several families of kinks, which do not correspond to any known model and we discuss possible candidates. We then specialize to the case N=3,4, which has been conjectured to describe a phase transition respectively in the non compact complex projective space NCCP^2 and the antiferromagnetic complex projective model ACP^3. Lattice simulations provide strong evidence for the existence of a second order phase transition, while an effective field theory approach does not predict any fixed point. We identify a set of assumptions that constrain operator dimensions to a closed region overlapping with the lattice prediction.

Radiation Reaction from Soft Theorems
Authors: Paolo Di Vecchia, Carlo Heissenberg, Rodolfo Russo, Gabriele Veneziano
Preprint number: UUITP03/21
Radiation reaction (RR) terms at the third postMinkowskian (3PM) order have recently been found to be instrumental in restoring smooth continuity between the nonrelativistic, relativistic, and ultrarelativistic (including the massless) regimes. Here we propose a new and intriguing connection between RR and soft (bremsstrahlung) theorems which shortcircuits the more involved conventional loop computations. Although first noticed in the context of the maximally supersymmetric theory, unitarity and analyticity arguments support the general validity of this 3PMorder connection that we apply, in particular, to Einstein's gravity and to its JordanBransDicke extension. In the former case we find full agreement with a recent result by Damour obtained through a very different reasoning.

Cosmic eggs to relax the cosmological constant
Authors: Thomas Hertog, Rob Tielemans, Thomas van Riet
Preprint number: UUITP02/21
In theories with extra dimensions, the cosmological hierarchy problem can be thought of as the unnaturally large radius of the observable universe in KaluzaKlein units. We sketch a dynamical mechanism that relaxes this. In the early universe scenario we propose, three large spatial dimensions arise through tunneling from a 'cosmic egg', an effectively onedimensional configuration with all spatial dimensions compact and of comparable, small size. If the string landscape is dominated by lowdimensional compactifications, cosmic eggs would be natural initial conditions for cosmology. A quantum cosmological treatment of a toy model egg predicts that, in a variant of the HartleHawking state, cosmic eggs break to form higher dimensional universes with a small, but positive cosmological constant or quintessence energy. Hence cosmic egg cosmology yields a scenario in which the seemingly unnaturally small observed value of the vacuum energy can arise from natural initial conditions.

Inozemtsev system as SeibergWitten integrable system
Authors: Philip Argyres, Oleg Chalykh, Yongchao Lu
Preprint number: UUITP01/21
In this work we establish that the Inozemtsev system is the SeibergWitten integrable system encoding the Coulomb branch physics of 4d \cN=2 USp(2N) gauge theory with four fundamental and (for N≥2) one antisymmetric tensor hypermultiplets. We describe the transformation from the spectral curves and canonical oneform of the Inozemtsev system in the N=1 and N=2 cases to the SeibergWitten curves and differentials explicitly, along with the explicit matching of the modulus of the elliptic curve of spectral parameters to the gauge coupling of the field theory, and of the couplings of the Inozemtsev system to the field theory mass parameters. This result is a particular instance of a more general correspondence between crystallographic elliptic CalogeroMoser systems with SeibergWitten integrable systems, which will be explored in future work.