Skip to main content
Go to the home page of the European Commission (opens in new window)
English en
CORDIS - EU research results
CORDIS

Bounding EFTs with Spontaneous Lorentz Breaking

Objective

Lorentz-invariant Quantum Field Theories (QFTs) are central in physics. At any energy scale, Effective Field Theories (EFTs) systematically describe the relevant degrees of freedom, merging quantum mechanics with special relativity.

Recent advances have shown that not all EFTs admit a healthy UV completion. By combining unitarity and analyticity—rooted in relativistic causality—strong constraints have been derived, successfully carving out the space of consistent Lorentz-invariant EFTs.

However, in many areas of physics one is interested in excitations around a state that is not the Lorentz invariant vacuum, so that Lorentz invariance is spontaneously broken. Many aspects of QFT in this setup are yet to be understood. In particular, little is known about which EFTs are consistent.

BestLobe aims to achieve transformative advances in understanding QFT with spontaneous Lorentz breaking, while establishing rigorous bounds on key physical observables.
In this context, the S-matrix does not enjoy the nice analytic properties of the Lorentz-invariant case. One needs radically novel approaches.

To pursue this overarching goal, BestLobe will investigate 3 different classes of systems:

(1) Condensed-matter-like systems, where there is a preferred frame. In this context what are the constraints on the EFT of Goldstone bosons and hydrodynamics?

(2) Astrophysical compact objects, targets of gravitational wave observations. What are the constraints on the Love numbers that characterize their tidal deformability?

(3) Cosmology. What are the bounds on the EFTs that describe Inflation and Dark Energy? And on the propagation of gravitational waves across the universe?

The resulting bounds will provide theoretical guidance to ongoing and future experiments. If a violation is observed, it would require a true paradigm shift. More broadly, I aim to achieve a level of understanding of QFT in Lorentz-breaking scenarios comparable to that attained in the Lorentz-invariant case.

Fields of science (EuroSciVoc)

Programme(s)

Topic(s)

Funding Scheme

HORIZON-ERC - HORIZON ERC Grants

See all projects funded under this funding scheme

Call for proposal

(opens in new window) ERC-2025-ADG

See all projects funded under this call

Host institution

UNITED NATIONS EDUCATIONAL SCIENTIFIC AND CULTURAL ORGANIZATION
Net EU contribution
€ 2 052 750,00
Address
PLACE DE FONTENOY 7
75007 Paris
France
Region
Ile-de-France Ile-de-France Paris
Activity type
Research Organisations
Links
Total cost
No data

Beneficiaries (1)