Appendices
281
Here “Gen” is the Generation, J is the angular momentum (spin) of the
quark, B the baryon number, C the charm, S the strangeness, T the topness
and B’ the bottomness. The charge is the electrical charge in units of one
electron charge. It can be seen, as was mentioned earlier, that the charges of
the quarks are 1/3 and 2/3 that of the electronic charge. The charges, and
also the baryon numbers with their values of 1/3, give a clue that baryons are
most likely constructed from three quarks. This is indeed true. The antiquarks
have the opposite quantum numbers to the quarks, and are given the names:
antiup, antidown, etc. Mesons are formed from a quark-antiquark pair, and
are consequently bosons.
A.9.3 Grand Unified Theory (GUT)
and Supersymmetry
Grand Unified Theory (GUT)
In this theory, the three interactions we have discussed thus far (electromagnetic, weak and strong) are merged at high energy into a single force. At
lower energies, the theory should result in the same predictions as the current
Standard Model. However, at high energies, new particles are predicted.
Unfortunately, the energies required to produce these particles are well above
the capabilities of modern accelerators, and as a consequence they have not
been observed.
In the absence of this type of direct evidence, support for the GUT
is sought from indirect observations of physical quantities, such as proton
decay and the electric dipole moments of particles, where the predictions of
the Standard Model are inaccurate. Some versions of the GUT predict the
existence of the magnetic monopole.
All observed magnetic fields arise from pairs of north and south magnetic
poles. These are known as magnetic dipoles. A magnetic monopole would
comprise an isolated north (or south) pole, in the same way that electric charges (positive or negative) can exist in isolation. Due to the lack of
experimental confirmation of its predictions, there is currently no generally
accepted GUT.
Supersymmetry
The distinction between fermions (particles of half odd-integer spin) and
bosons (carrier particles of zero or integer spin) may seem rather arbitrary.
What if each fermion had a supersymmetric partner with identical quantum
281
Here “Gen” is the Generation, J is the angular momentum (spin) of the
quark, B the baryon number, C the charm, S the strangeness, T the topness
and B’ the bottomness. The charge is the electrical charge in units of one
electron charge. It can be seen, as was mentioned earlier, that the charges of
the quarks are 1/3 and 2/3 that of the electronic charge. The charges, and
also the baryon numbers with their values of 1/3, give a clue that baryons are
most likely constructed from three quarks. This is indeed true. The antiquarks
have the opposite quantum numbers to the quarks, and are given the names:
antiup, antidown, etc. Mesons are formed from a quark-antiquark pair, and
are consequently bosons.
A.9.3 Grand Unified Theory (GUT)
and Supersymmetry
Grand Unified Theory (GUT)
In this theory, the three interactions we have discussed thus far (electromagnetic, weak and strong) are merged at high energy into a single force. At
lower energies, the theory should result in the same predictions as the current
Standard Model. However, at high energies, new particles are predicted.
Unfortunately, the energies required to produce these particles are well above
the capabilities of modern accelerators, and as a consequence they have not
been observed.
In the absence of this type of direct evidence, support for the GUT
is sought from indirect observations of physical quantities, such as proton
decay and the electric dipole moments of particles, where the predictions of
the Standard Model are inaccurate. Some versions of the GUT predict the
existence of the magnetic monopole.
All observed magnetic fields arise from pairs of north and south magnetic
poles. These are known as magnetic dipoles. A magnetic monopole would
comprise an isolated north (or south) pole, in the same way that electric charges (positive or negative) can exist in isolation. Due to the lack of
experimental confirmation of its predictions, there is currently no generally
accepted GUT.
Supersymmetry
The distinction between fermions (particles of half odd-integer spin) and
bosons (carrier particles of zero or integer spin) may seem rather arbitrary.
What if each fermion had a supersymmetric partner with identical quantum