Q. Shafi, Higgs boson and new physics at the LHC, AIP Conf. Proc. 1006, 20 (2008). [PDF| I. Gogoladze, N. Okada, and Q. Shafi, Higgs boson mass bounds in a type II seesaw model with triplet scalars, Phys. Rev. D 78, 085005 (2008). [PDF] I. Gogoladze, T. Li, V. N. Senoguz, and Qaisar Shafi, Noncanonical MSSM, unification, and new particles at the CERN LHC, Phys. Rev. D 74, 126006 (2006). [PDF] I. Gogoladze, T. Li, and Q. Shafi, Higgs boson mass from orbifold GUTs, Phys. Rev. D 73, 066008 (2006). [PDF]
The Lardge Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was fired in 2008 for the first time with intention to collide opposing beams of protons accelerated to a whisker below the speed of light in a 27-kilometer ring buried deep below the countryside on the outskirts of Geneva, Switzerland. Billions of protons in the LHC’s two counter-rotating particle beams will smash together at an energy of 14 trillion electron volts. For most of their split-second journey around the ring, the beams travel in two separate vacuum pipes, but at four points they collide in the hearts of the main experiments, known by their acronyms: ALICE, ATLAS, CMS and LHCb.
Why take on such a massive project? Why do particle physicists, cosmologists, and others around the world so eagerly anticipate these data? It is because this machine may point the way to answer some truly fundamental questions that have puzzled scientists for decades. Perhaps foremost among these questions is this: what lies beyond the Standard Model of particle physics? For while the Standard Model is a remarkable theory - it has thus far passed every test made at a particle accelerator - we know it must be incomplete. For example, it cannot account for the Dark Matter that we now know pervades out universe.
The Standard Model’s approach to the breaking of electroweak symmetry is a single new particle, the Higgs boson. The LHC should finally provide definitive evidence for the physics that is responsible for the breaking of the electroweak symmetry, whether it be a single Higgs boson, or something more elegant. The LHC will be the machine that leads us toward the fundamental theories that extend our knowledge beyond the Standard Model, and connects particle physics more strongly to cosmology. No amount of cosmology or astronomy can tell us what the dark matter actually is, or why the universe is made of matter and not equal amounts of matter and antimatter, but the LHC may give us the data needed to answer these questions. It may also help formulate and test string theory.