In QFT, a metastable vacuum state can decay through quantum tunnelling. The calculation of the decay rate relies on instantons — non-trivial classical solutions in the Euclideanized theory, saddle points of the Euclidean action. However, sometimes theories with metastable vacua do not have any instanton solutions, thus rendering the usual method of calculating decay rates unusable. An...
The advent of gravitational wave astronomy has brought with it the potential for novel approaches to study physics beyond the Standard Model. In particular, the null searches for signatures of dark matter at direct and indirect detection experiments has left the so-called “nightmare scenario”, where the dark matter interacts with the Standard Model only through gravity, a distinct possibility....
I present an EFT framework for strong, indeed the strongest, cosmological phase transitions this is precisely where standard high-temperature dimensional reduction fails. After reviewing high-temperature dimensional reduction for weak and intermediate transitions and pinpointing where its standard assumptions fail we construct EFTs that remain valid for very strong transitions. The approach...
