PH-703   Quantum Field Theory II

  1. Non-abelian gauge theories: Yang-Mills Lagrangian, local and global gauge transformation. Multiple vacua.
  2. Brief review of group theory, quantization of non-abelian gauge theories, ghost field (BRS transformations).
  3. Unitarity: ghost field and unitarity, optical theorem and Cutkosky rules, examples: e + e → hadrons (evidence of color).
  4. Radiative corrections in QCD: one loop divergences (gauge boson self-energy, fermion self-energy), fermion gluon vertices, beta function and asymptotic freedom.
  5. Callan-Symanzik equation: renormalization scale, methods of characteristics, examples in φ4 theory and QCD.
  6. Weak interactions and Fermi theory: spontaneous symmetry breaking, massive gauge bosons (Higgs mechanism), Goldstone theorem with application to pi-sigma lagrangian, Goldstone bosons.
  7. Electroweak unification: Gauge theory with spontaneous symmetry breaking, neutral and charged currents, radiative corrections from fermionic loops, Higgs couplings, Higgs contribution to vector boson self energy, calculation: top quark decay into (i) W + b (ii) φ+ b, Higgs decay into: (i) W+W (ii) φ + W (iii) φ + φ, Yang Mills character of W-bosons (triple tri-linear coupling), triangle anomaly.
  8. Multiple vacua in QCD and the strong CP problem.


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