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…
What is the world made of? Fire Water Earth Air … that is, according to the Greeks!
Modern understanding: the ``onion’’ picture Let’s see what’s inside! Nucleus
Modern understanding: the ``onion’’ picture Let’s see what’s inside!
Modern understanding: the ``onion’’ picture Let’s see what’s inside! Mesons and baryons
Modern understanding: the ``onion’’ picture Let’s see what’s inside! Quarks and gluons
Modern understanding: the ``onion’’ picture … so the answer depends on the energy scale!
Aside: units used in particle physics Energy: electron-volt: 1 eV = 1.6 x J (energy that an electron gains going through a potential difference of 1 Volt) E = mc 2, so set c=1! natural units Mass: electron-volt proton mass m p = MeV Momentum: electron-volt
… same thing about the interactions The answer depends on the energy scale….
Unification of forces
The Standard Model of Elementary Particle Physics ``Periodic table’’ of matter Interactions: electromagnetic, weak, strong, (gravity)… needs experimental input Contains 26 parameters: needs experimental input + Higgs particle
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…
Example: What is CP(T)? Classical mechanics is invariant under C,P, and T!
Classical Field Theory: E&M Maxwell’s equations are invariant under C,P, and T!
Why do we want to study CP-violation? Baryon (and lepton) number - violating processes generate to generate asymmetry Universe that evolves out of thermal equilibrium keepbeing washed out to keep asymmetry from being washed out Microscopic CP-violation keepbeing washed out to keep asymmetry from being washed out Matter-antimatter imbalance in the Universe A.D. Sakharov
How to observe CP-violation? I. Intrinsic particle properties electric dipole moments: Low energy strong interaction effects might complicate predictions!
II. Transitional particle properties Low energy strong interaction effects complicate predictions!
Why study B-physics? Possibility to control strong interactions controllable theoretical expansions New Physics sensitivity new physics contributions destroy SM relations ``B-factories’’ are hunting for signs of CP-violation in the decays of B-mesons Example: CKM unitarity: V ud V ub * + V cd V cb * + V td V tb * = 0
Experimental methods
Experimental methods II Threshold (e + e - ) B-factories (CLEO, BaBar, Belle) Hadronic (pp) machines (CDF, D0, B-Tev, LHCb) ep-machines (HERA at DESY) Theoretical predictions can be tested experimentally!
Experimental Facilities Cornell UniversitySLAC
Experimental Facilities II KEK (Japan)
Experimental Facilities III FermiLab (Batavia, IL)
Research in Particle Physics Theory Alexey Petrov William RolnickExperiment Giovanni Bonvichini David Cinabro Robert Harr Paul Karchin Stephen Takach … as well as postdoctoral research associates and graduate students
Conclusions? What the particle physics is Why we study particles How we study particles Further questions? Prof. Alexey A Petrov Physics Research, Rm. 260