# Unit information: Theoretical Particle Physics in 2020/21

Unit name Theoretical Particle Physics PHYSM0800 10 M/7 Teaching Block 2 (weeks 13 - 24) Professor. Goldstein Not open PHYS30021 and PHYS32011 or the equivalent taken as part of a Year in Industry or Year Abroad, and PHYS30008 Analytical Mechanics. None School of Physics Faculty of Science

## Description

The standard model of particle physics was developed in the 1960s and 1970s, and has successfully explained or predicted the results of high energy experiments up to and including the discovery of the Higgs boson in 2012. The variety of phenomena described by the standard model seems bewilderingly diverse, but it is elegantly built on very straightforward foundations.

This unit explains the principle of “gauge symmetries” (i.e. invariance under local transformations) on which the standard model is based, and introduces (or revises) the required mathematical techniques such as Lagrangian mechanics, Noether’s Theorem and group theory. It then proceeds to build a complete mathematical description of standard model particles as solutions to the Dirac and Klein-Gordon equations, with interactions via the electroweak and strong forces arising from invariance under gauge symmetries.

The theory will include the spontaneous breaking of the electroweak symmetries via the Brout-Englert-Higgs mechanism. and proceeds to develop the mathematical theory of the fundamental particles and their interactions.

The procedures of the Feynman calculus will be derived from the theory, allowing the calculation of scattering cross sections and decay rates from first principles.

There will also be a discussion of the limitations of the standard model and possible physics scenarios beyond it.

## Intended learning outcomes

Students should be able to:

• Describe the principle of gauge invariance and its consequences in particle physics
• Identify the different terms in the standard model Lagrangian and describe their purpose
• Qualitatively describe the Brout–Englert–Higgs mechanism
• Draw Feynman diagrams for any allowed standard model process
• Use Feynman diagrams to calculate matrix elements and interaction rates for standard model processes
• Qualitatively describe the limitations of the standard model and possible new physics scenarios.

## Teaching details

The unit will be taught through a combination of

• asynchronous online materials, including narrated presentations and worked examples
• synchronous group problems classes, workshops, tutorials and/or office hours
• asynchronous directed individual formative exercises and other exercises

## Assessment Details

Formative Assessment: Problem sheets provide formative feedback.

Summative Assessment: Written timed, open-book examination (100%)