To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The state of a quantum-mechanical system can be described by a wave function or a state ket. Each wave function is defined in a specific space (e.g. in the position or momentum space). Conversely, the state kets do not require a specific space. The terms ‘bra’ and ‘ket’ are derived from the word ‘bracket’.
In classical physics, a distinction is made between two different concepts: waves and particles. However, various experiments have shown that this strict distinction must be replaced by a new concept.
In mathematical terms, an operator transforms a given function into a new function. To better understand operators, we summarise the analogies with matrices below.
An approximate solution can be derived from the Schrödinger equation, if the amplitude of the wave function changes only slowly relative to the phase. This procedure is called the Wentzel–Kramers–Brillouin approximation.
A good knowledge of special relativity and quantum mechanics is essential for studying particle physics. Even if the reader is assumed to be already familiar with these two theories, a brief review of special relativity is given in this chapter with emphasis on the covariant and contravariant notations, which may be less well mastered but are very useful in particle physics. Important aspects of quantum mechanics for particle physics, such as the angular momentum, are also addressed.
The determination of particle properties relies mostly on experimental measurements based on their collisions and decays. This chapter introduces the concepts of reaction cross section and particle decay rate. For unstable particles, the origin of its lifetime as well as the notion of branching ratios is presented. Many formulas involving the reactions between two particles are derived in detail, and phase spaces involving three-body decays are presented with Dalitz diagrams. The notion of cross reactions is also presented.