Abstract
Just as the periodic table of the elements forms the basis of chemistry, the standard model of particle physics was formed in the 1970s. According to it, all our known matter consists of only three quasi point-like elementary particles, the up and down quarks as components of the protons and neutrons in the atomic nuclei and the electrons that form the atomic shell. Various force carriers mediate forces between the elementary particles, whose mass is generated by the Higgs mechanism.
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Notes
- 1.
The de Broglie wavelength \(\lambda\) depends on the rest mass m and velocity v of a particle and is the smallest, the smaller the rest mass and the larger the (relativistic) momentum of a particle: \(\lambda = \tfrac{m}{p}\) with m = rest mass and p = \(\gamma\) mv = relativistic momentum with \(\gamma\) = Lorentz factor. Electron microscopes are, among other effects, limited in resolution by the matter wavelength of the electrons. Objects smaller than the matter wavelength can no longer be resolved. Therefore, for a higher resolution, the momentum or the energy of the electrons must be as large as possible.
- 2.
Protons contain two up quarks and one down quark (uud), neutrons one up quark and two down quarks (udd).
- 3.
In addition to the three elementary particles that make up ordinary matter in our universe, there is a small proportion of neutrinos and about five times as much so-called “dark matter”, which does not emit light and cannot be directly observed. This may consist of unknown different elementary particles that could be produced at the LHC. More about this in the essential “Exploring the Large Hadron Collider—the Discovery of the Higgs Boson”.
- 4.
The intrinsic angular momentum (spin) of particles is given in units of \(\hbar = \tfrac{h}{2\pi }\), where h = Planck’s quantum of action. All particles of matter have a half-integer spin \(\tfrac{1}{2}\hbar\) with a so-called antisymmetric quantum mechanical wave function and are called fermions after the Italian physicist Enrico Fermi (1901–1954). All known force carriers, however, have an integer spin of \(1{\mkern 1mu} \,\hbar\), a symmetric wave function and are called bosons after the Indian physicist Satyendra Nath Bose (1894–1974). The asymmetry of the wave function in fermions results in a simplified way in the fact that two matter particles in the same quantum mechanical state cannot be at the same location at the same time (Pauli principle according to Wolfgang Pauli (1900–1958)). Bosons like light particles, on the other hand, can permeate and superimpose each other unhindered and undisturbed.
- 5.
Leptons are named after the Greek leptós, which means “slim,” “thin,” or “light” and, unlike quarks, do not have a strong interaction. The electron is the lightest of three charged leptons, three other leptons are neutral and are called neutrinos.
- 6.
More on the mechanism of mass generation and the discovery of the Higgs particle in the essential “Exploring the Large Hadron Collider—the Discovery of the Higgs Boson” and “Exploring the Large Hadron Collider: The Higgs particle and the Standard Model” (ISBN 978–3-658–11,626-2).
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Hauschild, M. (2021). A Bit of Physics—The Standard Model. In: Exploring the Large Hadron Collider - CERN and the Accelerators. essentials(). Springer, Wiesbaden. https://doi.org/10.1007/978-3-658-32726-2_3
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DOI: https://doi.org/10.1007/978-3-658-32726-2_3
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