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Introduction to Particle Physics

Introduction to Particle Physics. How to compute the Universe?. What do we study?. How did we get from here… … to here?. So, how did we get from particles to galaxies?. Brief history of the Universe. Thus, we have to understand what our world is made of….

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Introduction to Particle Physics

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  1. Introduction to Particle Physics How to compute the Universe?

  2. What do we study? How did we get from here… … to here?

  3. So, how did we get from particles to galaxies?

  4. Brief history of the Universe

  5. Thus, we have to understand what our world is made of…

  6. What is the world made of? • Fire • Water • Earth • Air … that is, according to the Greeks!

  7. Modern understanding: the ``onion’’ picture Nucleus Let’s see what’s inside!

  8. Modern understanding: the ``onion’’ picture Let’s see what’s inside!

  9. Modern understanding: the ``onion’’ picture Mesons and baryons Let’s see what’s inside!

  10. Modern understanding: the ``onion’’ picture Quarks and gluons Let’s see what’s inside!

  11. Modern understanding: the ``onion’’ picture ? … so the answer depends on the energy scale!

  12. Aside: units used in particle physics Energy: electron-volt: 1 eV = 1.6x10-19 J (energy that an electron gains going through a potential difference of 1 Volt) E = mc2, so set c=1! natural units Mass: electron-volt proton mass mp = 938.27 MeV Momentum: electron-volt

  13. … same thing about the interactions • The answer depends on the energy scale….

  14. Unification of forces

  15. The Standard Model of Elementary Particle Physics • ``Periodic table’’ of matter • Interactions:electromagnetic, weak, strong, (gravity)… • Contains 26 parameters: needs experimental input + Higgs particle

  16. Open questions • Higgs particle is not (yet) discovered mechanism of electroweak symmetry breaking • Standard Model does not have ``enough’’ asymmetry between particles and antiparticles to create the Universe as we know it CP-violation and baryonogenesis • New Physics beyond the Standard Model? supersymmetry, strings, extra dimensions…

  17. Example: What is CP(T)? Classical mechanics is invariant under C,P, and T!

  18. Classical Field Theory: E&M Maxwell’s equations are invariant under C,P, and T!

  19. Why do we want to study CP-violation? Matter-antimatter imbalance in the Universe • Baryon (and lepton) number - violating processes to generate asymmetry • Universe that evolves out of thermal equilibrium to keep asymmetry from being washed out • Microscopic CP-violation to keep asymmetry from being washed out A.D. Sakharov

  20. How to observe CP-violation? I. Intrinsic particle properties • electric dipole moments: Low energy strong interaction effects might complicate predictions!

  21. II. Transitional particle properties Low energy strong interaction effects complicate predictions!

  22. Why study B-physics? ``B-factories’’ are hunting for signs of CP-violation in the decays of B-mesons • Possibility to control strong interactions • controllable theoretical expansions • New Physics sensitivity • new physics contributions destroy SM relations Example: CKM unitarity: Vud Vub* + Vcd Vcb*+ Vtd Vtb*= 0

  23. Experimental methods

  24. Experimental methods II Theoretical predictions can be tested experimentally! • Threshold (e+ e-) B-factories (CLEO, BaBar, Belle) • Hadronic (pp) machines (CDF, D0, B-Tev, LHCb) • ep-machines (HERA at DESY)

  25. Experimental Facilities Cornell University SLAC

  26. Experimental Facilities II KEK (Japan)

  27. Experimental Facilities III FermiLab (Batavia, IL)

  28. Theory Alexey Petrov William Rolnick Experiment Giovanni Bonvichini David Cinabro Robert Harr Paul Karchin Stephen Takach Research in Particle Physics … as well as postdoctoral research associates and graduate students

  29. Conclusions? • What the particle physics is • Why we study particles • How we study particles • Further questions? Prof. Alexey A Petrov Physics Research, Rm. 260 apetrov@physics.wayne.edu

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