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From Theory To History:

The Discovery of the Higgs Boson. Christian Smith Charles Jay Jeremy Umphress Robert Farrar. From Theory To History:. Physics 3313-001 Dr. Jaehoon Yu University of Texas at Arlington December 4, 2013.

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From Theory To History:

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  1. The Discovery of the Higgs Boson Christian Smith Charles Jay Jeremy Umphress Robert Farrar From Theory To History: Physics 3313-001 Dr. Jaehoon Yu University of Texas at Arlington December 4, 2013 http://www.symmetrymagazine.org/article/october-2013/nobel-prize-in-physics-honors-prediction-of-higgs-boson

  2. Today’s Presentation: • The History of the Higgs Particle • The need for broken symmetry • The Higgs mechanism as the solution • Complications with theory • Experimental Process • How to look for the Higgs • Zoning in on the mass of the Higgs • Criterion for the Higgs • Discovery of the Higgs boson • The Discovery and Future • What this discovery means for Physics • What is next?

  3. Why Do We Need Broken Symmetry? • If everything were symmetric, all the particles would be canceled out by their anti-particles. • The imbalance allows the existence of the particles that constitute our existence. • What breaks this symmetry of particle – anti-particle creation?

  4. The Higgs Mechanism • The original theory of broken symmetry was proposed by Sheldon Glashow in 1960. Though he was unsure of what caused this breakage. • “The mass of the charged intermediaries must be greater than the K-meson mass, but the photon mass is zero-surely this is the principle stumbling block in any pursuit of the analogy between hypothetical vector mesons and photons. It is a stumbling block we must overlook.” (Glashow) • Roughly four years later Higgs, Englert and Brout propose a mechanism that would account for this breaking of symmetry.

  5. The Higgs Mechanism (cont.) • In the standard model of Physics all our elementary particles are massless. • We know from experimentation that they have mass, where does this mass come from? • Higgs-Englert-Brout Mechanism would give these particles their mass, thus allowing for the breaking of symmetry. • How do the objects interact with the Higgs field? • How do they obtain their mass from this field?

  6. The Higgs Mechanism (cont.) • At the Big Bang, all the fundamental particles were pure energy. • Within the first second, the universe cooled and the Higgs field was formed. • Each of the fundamental particles interact with this field differently, slowing them down. • The greater the interaction with the Higgs field, the greater the mass. • Particles like photons and gluons do not interact with the Higgs field, while W and Z bosons and top quarks interact heavily with the Higgs Field.

  7. Complications With The Theory • Though the mechanism had been proposed, the Higgs field must have an associated particle in order to observe its existence. • The mass of this particle was not determined in the theory, which means that the mass of the Higgs boson could vary widely.

  8. How To Generate A Higgs • Particles must be massive enough to have enough energy to form Higgs Bosons. • Top Quarks are the preferred particles, but are not commonly found in nature. • Top quarks can be formed through the collision of gluons. • Gluons and up and down quarks are found in protons, so by the collision of protons we can collide gluons. • How do we see the Higgs? http://news.softpedia.com/newsImage/World-039-s-Largest-Physics-Experiment-Hopes-to-Catch-a-Glimpse-of-the-Big-Bang-2.jpg/

  9. Higgs Production • Two gluons are collided to form top quarks which are then used to generate a Higgs. • Higgs decays into W-boson pair. Which then decays to photons. • Higgs decays in bottom quark pair. Which then decays to photons. http://www.nature.com/nphys/journal/v9/n5/fig_tab/nphys2619_F1.html

  10. How To Look For The Higgs (cont.) • Accounting for events and what could generate them. • Formation of γγ, photon pairs. (UC Berkley) • Formation of 4 electrons or muons. (UC Berkley) • Formation of W-Boson Pairs. (Dreiner) • Determining the mass of the particle that would generate the different events. • Ruling out known particles that would generate other events. • Looking for the “anomaly.” (BBC) http://cds.cern.ch/record/1406057

  11. The Possible Mass Of The Higgs LEP (2003) FermiLab (2010) LHC (2011)

  12. The Anomaly • 2012 data run was focused in the mass range between 114 GeV and 145 GeV. • Data collected from both CMS (Bottom Left) and ATLAS (Bottom Right) show anomalies between 120-130 GeV. http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev http://www.atlas.ch/HiggsResources/

  13. Matching The Higgs To Results • Higgs must have enough mass to create a bottom quark pair, photon pair or W-Boson pair. • Higgs must have an integer spin of zero. So angular distribution of products is equally probable in all directions. (CERN) • Must have positive parity. Does not distinguish between left and right. (CERN) • Must be electrically neutral (unaffected by electric or magnetic fields).

  14. Discovery Of The Higgs Particle • On July 04, 2012 CERN announced the results of the data that had been collected between 2010-11 and analyzed. • The ATLAS and CMS experiments independently observed statistical anomalies at 126 GeV (ATLAS) and 124 GeV (CMS). • The results showed a 5-sigma standard deviation (1 in 350 million), this means that there was a 1 in 350 million possibility that the event was caused by background noise. (CMS-CERN)

  15. Future Of The Higgs • Increase in our understanding of the fundamental particles and their creation. • Other theories propose the existence of multiple Higgs, leading into further exploration of nature. • Coupling between matter and the Higgs and the Higgs and dark matter could allow for the observation of dark matter.

  16. What We Have Covered Today • The History of the Higgs Particle • The need for broken symmetry for the existence of particles. • The Higgs mechanism as the solution to break the symmetry • Complications with theory with the lack of mass of the Higgs • Experimental Process • How to look for the Higgs by finding the results of its decompositions • Zoning in on the mass of the Higgs by various experiments • Criterion for the Higgs particle: spin, parity and mass • Discovery of a Higgs boson • The Discovery and Future • Furthered understanding of nature • Study of dark matter and existence of other Higgs Bosons.

  17. Q & A

  18. Sources • Abbiendi, G, et al. “Search for the Standard Model Higgs Boson at LEP.” ALEPH, DELPHI, L3, OPAL Collaborations. (2003) • BBC. Jan 09, 2012. “The Hunt For The Higgs.” http://www.youtube.com/watch?v=r4-wVzjnQRI • CERN Press Office. March 14, 2013. “New Results Indicate that particle discovered at CERN is a Higgs boson.” http://press.web.cern.ch/press-releases/2013/03/new-results-indicate-particle-discovered-cern-higgs-boson • CMS Experiment, CERN. July 04, 2012. http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev • Dreiner, H. “Particle Physics: A Higgs is a Higgs.” Nature Physics. NS-9. 268-9. (2013) • FermiLab Press Release. July 26, 2010. “FermiLab experiments narrow allowed mass range for Higgs Boson.” http://www.fnal.gov/pub/presspass/press_releases/Higgs-mass-constraints-20100726.html • FermiLab Press Release. August 22, 2011. “LHC experiments eliminate more Higgs hiding spots.” http://www.fnal.gov/pub/presspass/press_releases/2011/higgs-hiding-spots-20110822.html • Glashow, S. “Partial Symmetries of Weak Interactions.” Nuclear Physics. NP-22. 579-588. (1961) • UC Berkley. July 13, 2012. “The Higgs Boson Explained.” http://www.youtube.com/watch?v=jchDY6xuiZ0

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