Discovery at LHC-CERN: Is it the Higgs?

July 4, 2012

Today a new boson has been discovered at the Large Hadron Collider experiment at CERN!

Congratulations to our experimental colleagues for this outstanding achievement. The discovery marks a new era for particle physics! This is the first new particle to be discovered in decades.

What next? 

Is it the standard model Higgs? This is the burning question which the future experimental efforts will try to answer. In fact, given the current experimental status it is not yet possible to establish with certainty that the newly established state is the missing Higgs boson of the Standard Model of particle interactions, although it does smell like it. To determine the nature of the new state the experiments will study how it is produced and how it decays into Standard Model particles. The wait might be over by the end of this year.

Implications on our understanding of Nature

Albeit the nature of the new particle is not fully determined its presence is related to the puzzle of the origin of mass of every elementary particle in the Standard Model. However a better understanding of its nature is needed to fully resolve this puzzle. We envision two major logical possibilities:
  1. The new state is a fundamental  boson as predicted within the Higgs sector of the Standard Model or its supersymmetric extensions. By fundamental here we mean that it is not made out of something else. If this were confirmed it would be a fantastic discovery given that no other elementary spin zero boson has ever been discovered in Nature.
  2. The other possibility is that the new state is not elementary but composed of more fundamental objects. As the proton and neutron are composed by quarks likewise this state may be composed by new type of quarks. In this scenario experiments at CERN have the chance to discover many more new composite particles built from rearranging the new type of quarks in different combinations.

More exotic possibilities have been envisioned by theorists and are not yet excluded by the current experimental results.

What it does not solve!

This extraordinary feat for our understanding of Nature leaves many unsolved puzzles.
  • What is the nature of Dark Matter? The Standard Model accounts for only 4% of the known Universe while Dark Matter for more than 20%!
  • What has killed primordial antimatter in the Universe? The Standard Model Higgs cannot explain the absence of antimatter.
  • Where do the neutrino masses come from?
  • What generates the huge hierarchy among the masses of quarks and leptons?
These and many more questions need to be answered in the near future.  The present discovery constitutes an important piece of the puzzle of the Universe awaiting to fall in the right place.