Experimental probes of electroweak baryogenesis at LHC

The mechanism behind the dominance of baryons over anti-baryons in the universe reamins a mystery in modern physics.

This project with four members will search for resonant and non-resonant production of multiple scalar bosons in the ATLAS detector at the CERN Large Hadron Collider (LHC), and by using novel analysis techniques and new theories with reduced prior assumptions it will probe for the origin of the cosmic asymmetry between matter and anti-matter.

One well-motivated solution for the observed asymmetry is electroweak baryogenesis (EWBG).

The key properties of EWBG is that the relevant processes take place in an energy regime around the electroweak scale of the order 100 GeV.

This is a region where ATLAS with LHC Run-3 is starting to have significant sensitivity for the production of multiple scalars. Run-3 will run until the end of 2025 and is expected to accumulate more than twice of previously collected data. The relevant properties for EWBG are at this point in time practically unconstrained.

The EWBG depends on a strong first order phase transition that is determined by the properties of the Higgs potential. Our current best theory at the smallest scales is the Standard Model (SM). The SM has all the ingredients for EWBG, but the actual parameters of the model does not allow for a SFOPT.

So, if nature has chosen EWBG, the SM Higgs scalar potential has to be modified by new physics. All this makes EWBG testable at LHC in events with multiple scalar particles.