Chapter 2
Gauge Theories and the Standard Model
Guido Altarelli and Stefano Forte
2.1 Introduction to Chaps. 2, 3 and 4
Stefano Forte
The presentation of the Standard Model in Chap. 2, Chaps. 3 and 4 was originally
written by Guido Altarelli in 2007. In this introduction we provide a brief update
(with references), and a discussion of the main developments which have taken place
since the time of the writing.
Chapter 2 presents the architecture of the Standard Model, the way symmetries
are realized and the way this can is described at the quantum level. The structure
of the Standard Model is now well-established since half a century or so. The
presentation in this chapter highlights the experimental (and thus, to a certain
extent, historical Chap. 2) origin of the main structural aspects of the theory. The
only aspects of the presentation which require (minimal) updating are the numerical
values given for parameters, such as the Fermi coupling constant G F , see Eq. (2.3).
All of these parameters have been known quite accurately since the early 2000s
(with the exception of neutrino masses, see Sect. 3.7 of Chap. 3), and thus their
values are quite stable. The numbers given below are taken from the then-current
edition of the Particle Data Book (PDG) [7]. At any given time, in order to have the
The original version of this chapter was revised. A correction to this chapter can be found at https://
doi.org/10.1007/978-3-030-38207-0_11
The author “G. Altarelli” is deceased at the time of publication.
G. Altarelli
University of Rome 3, Rome, Italy
S. Forte ()
Dipartimento di Fisica, Università di Milano, Milano, Italy
© The Author(s) 2020, corrected publication 2020
H. Schopper (ed.), Particle Physics Reference Library,
https://doi.org/10.1007/978-3-030-38207-0_2
7
Gauge Theories and the Standard Model
Guido Altarelli and Stefano Forte
2.1 Introduction to Chaps. 2, 3 and 4
Stefano Forte
The presentation of the Standard Model in Chap. 2, Chaps. 3 and 4 was originally
written by Guido Altarelli in 2007. In this introduction we provide a brief update
(with references), and a discussion of the main developments which have taken place
since the time of the writing.
Chapter 2 presents the architecture of the Standard Model, the way symmetries
are realized and the way this can is described at the quantum level. The structure
of the Standard Model is now well-established since half a century or so. The
presentation in this chapter highlights the experimental (and thus, to a certain
extent, historical Chap. 2) origin of the main structural aspects of the theory. The
only aspects of the presentation which require (minimal) updating are the numerical
values given for parameters, such as the Fermi coupling constant G F , see Eq. (2.3).
All of these parameters have been known quite accurately since the early 2000s
(with the exception of neutrino masses, see Sect. 3.7 of Chap. 3), and thus their
values are quite stable. The numbers given below are taken from the then-current
edition of the Particle Data Book (PDG) [7]. At any given time, in order to have the
The original version of this chapter was revised. A correction to this chapter can be found at https://
doi.org/10.1007/978-3-030-38207-0_11
The author “G. Altarelli” is deceased at the time of publication.
G. Altarelli
University of Rome 3, Rome, Italy
S. Forte ()
Dipartimento di Fisica, Università di Milano, Milano, Italy
© The Author(s) 2020, corrected publication 2020
H. Schopper (ed.), Particle Physics Reference Library,
https://doi.org/10.1007/978-3-030-38207-0_2
7