The LHC is the largest and most energetic particle physics experiment ever made. By colliding protons accelerated close to the speed of light to very high energies, the LHC experiments probe the smallest components of matter and study how they interact with each-other in controlled conditions that emulate the Universe a fraction of a second after the Big-Bang. The LHC has been in operation for a decade and its two largest experiments, ATLAS and CMS, have plowed the data producing more than 1000 publications each; achieving a milestone discovery, the one of the Higgs boson, in 2012. 

 

The Universe however, remains puzzling at its most fundamental level. The Standard Model of particle physics is clearly incomplete but nature does not seem to like to strand away from it, at least at the energies we are able to reach at the LHC so far. Although many theoretical models are being tested, most of the questions present before the discovery of the Higgs boson still remain, so we must keep searching. Thinking outside the box could pay off short and long-term. 

 

Long-lived particles are new particles with significant enough lifetimes as to, when produced in collisions, leave distinct signatures in the detectors. Driven by increasingly higher energies, trigger and reconstruction algorithms at particle colliders are optimized for increasingly heavier particles, which in turn, tend to be short-lived. This makes searches for long-lived particles difficult, usually requiring dedicated methods and sometimes also hardware to spot them. However, taking upon the challenge brings enormous potential, since new, long-lived particles feature in a variety of promising new physics models that could answer most of the open questions of the standard model, such as: neutrino masses, Dark Matter, or the matter-antimatter imbalance in the Universe.