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Department of Physics

Higgs!

The Higgs boson discovery this summer drew a lot of press attention world wide.  That was true at UC Davis as well.  You can find UC Davis Dateline coverage of the Higgs discovery, including videos of UC Davis high energy physicists, here.  

Professor Mulhearn has provided us with the following summary of the discovery and an explanation of the role of UC Davis Physics in this decades-long quest.

Higgs T-Shirt

Over the last half of a century, experimental and theoretical physicists have worked together to develop and test the most predictive and successful theory of subatomic particles to date: the Standard Model of particle physics. After an unprecedented effort from thousands of physicists and engineers who built, operated, and analyzed the largest experiment ever built, the CMS and ATLAS collaborations reported the discovery of a new particle on July 4, 2012. The new particle is the quantum fluctuation of the Higgs field, the most exotic component of hte standard model. The Higgs field permeates all of space and leads to spontaneous symmetry breaking, the mathematical explanation for why the weak force is indeed weak compared to the electromagnetic force. The weakness occurs by virtue of the carriers of the weak force acquiring large mass. In the Standard Model, the Higgs field serves a dual purpose, as it also provides the mathematical basis for fundamental fermions, such as quarks and electrons, to have intrinsic mass. Observation of the Higgs boson is (the only possible) direct evidence for the existence of the Higgs field and thus a crucial test of this component of the standard model.

UC Davis has played a major role in the decades-long search for the Higgs boson. To start, Prof. Gunion literally wrote the book: as co-author of "The Higgs Hunter's Guide" in the 1980's he laid out a detailed plan for detecting the unique signature of the Higgs boson using collider experiments. His ideas helped shape the design of the very CMS and ATLAS detectors which ultimately discovered a new boson. Profs. Richard Lander and Winston Ko along with Dr. Richard Breedon recognized the potential in the newly conceived Large Hadron Collider (LHC) and signed the original letter of intent which was the rst step in making the CMS experiment a reality. Profs. Mani Tripathi and Robin Erbacher helped build the largest component of CMS: the muon detector.  Profs. Maxwell Chertok and John Conway helped build the smallest, most precice, component of CMS: the silicon tracking detector. The latest addition to the team, Prof. Michael Mulhearn, has turned his attention to the fastest component of CMS: the trigger electronics.

The Higgs boson is the last fundamental particle predicted by the Standard Model: all of the other particles have already been discovered. So far, every experimental test devised for the Standard Model has validated its predictions. Prof. Conway has long championed the cause of measuring the precise properties of a newly discovered boson, and his efforts at measuring its decay into tau leptons is now adding to the evidence that we have indeed found the Higgs. Prof. Mulhearn searched for decays into bottom quarks, which recently resulted in the Tevatron collider adding additional evidence.

The discovery of what appears to be a Higgs boson completes our picture of the Standard Model, and it might seem that the last chapter is now being written. But for all its success, particle physicists are certain the Standard Model cannot be the end of the story, and now is our best chance to discover the new theory which supersedes it. Profs. Markus Luty and John Terning have helped develop the theory and phenomenology of a leading contender for this new theory: Supersymmetry (SUSY). Prof. Maxwell Chertok is searching for experimental signatures of the Higgs boson that could result from SUSY.  Professor Gunion has recently published several papers dealing with the nature of the Higgs-like state observed at CERN, focusing in particular on the possibility that it is just one of many Higgs bosons or that the observed resonance is actually a superposition of several (unresolved) Higgs bosons.  We don't know what nature has in store for us, but the UC Davis team will continue to push both theory and experiment toward a deeper undertanding of fundamental particles.

 

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