The course presents the current theory of the strong, weak and electromagnetic interactions, the so called "Standard Model". The basic concepts and the quantum field theory techniques necessary to build this model are introduced, starting from the analysis of classical and current problems relevant in the phenomenology of particle physics. Main goal of the course is to provide an understanding of the theoretical bases and a knowledge of the techniques necessary to obtain quantitative prediction for physical processes.
Expected learning outcomes
At the end of the course the student: 1) will be able to derive the masses of the gauge, Higgs and matter fields, from the electroweak symmetry breaking parameters; 2) will be able to compute electroweak processes involving W, Z and Higgs bosons; 3) will be able to compute the quark masses and relate them to the CKM matrix; 4) will be able to express the CP violation in terms of the CKM matrix parameters; 5) will be able to compute QCD high-energy processes in the parton model; 6) will be able to compute quantum corrections in QCD to the parton model; 7) will be able to use the Altarelli-Parisi equations to describe scaling violations; 8) will be able to discuss the problem of infrared safety.
Lesson period: First semester
(In case of multiple editions, please check the period, as it may vary)
- Parity violation. Fermi theory of neutron beta decay as an effective theory. Muon decay. - Charged and neutral currents. Electroweak unification. - Electroweak interactions and the gauge group SU(2)xU(1): the boson W and Z and the problem of the gauge boson masses - Spontaneous symmetry breaking. The Goldstone bosons and the Higgs mechanism. - Masses and mixing among the gauge bosons. - The Higgs particle: production and decay. - Quark masses, quark mixing and CP violation.
- Basics elements of QCD. - Running coupling and asymptotic freedom. - Hadron production in electron-positron annihilation. - Infrared divergences and infrared safety. - Deep inelastic lepton-hadron scattering. - The parton model. - Factorization theorem and perturbative calculations. - Parton densities and evolution equations. - Hadronic collisions and the LHC. - Parton branching, shower Monte Carlo and jets. - All order Sudakov resummation.
Prerequisites for admission
Knowledge of the basic elements of quantum field theory: free fields quantisation (scalar, fermionic, vectorial); interacting theory and derivation of the Feynman rules. Ability to compute tree-level amplitudes for QED elementary processes. Ability to compute cross sections.
The course consists of a series of lectures at the blackboard. Theoretical topics with the needed demonstration are presented in detail. Several observables relevant in elementary particle physics are computed explicitly.
C.M.Becchi, G.Ridolfi, "An introduction to relativistic processes and the standard model of the electroweak interactions", Springer
M.E.Peskin, D.V.Schroeder, "An introduction to Quantum Field Theory", Perseus Books
Assessment methods and Criteria
The final exam is an oral discussion. The student solves at home a series of problems indicated at the end of the course, based on the content of the lectures. During the exam, the student must discuss two problems, one in the EW sector and one in the QCD sector. The use of the notes prepared at home by the student is allowed and encouraged. The final grade depends on several factors: the correctness of the final results; the ability to describe every element that appears in the calculation, to clarify its role and meaning; the ability to perform dimensional analyses and to extrapolate the results in interesting limits.