Preface
The new particle physics of the past 30 years, including electroweak theory,
quantum chromodynamics, grand unified theory, supersymmetry, supergravity
and superstring theory, has greatly changed our view of what may have happened
in the universe at temperatures greater than about 10 15 K (100 GeV). Various
phase transitions may be expected to have occurred as gauge symmetries which
were present at higher temperatures were spontaneously broken as the universe
cooled. At these phase transitions topological defects, such as domain walls,
cosmic strings and magnetic monopoles, may have been produced. Various
types of relic particles are also expected. These may include neutrinos with
small mass and axions associated with the solution of the strong CP problem
in quantum chromodynamics. If supersymmetry exists, there should also be
relic supersymmetric partners of particles, some of which could be dark matter
candidates. If the supersymmetry is local (supergravity) these will include the
gravitino, the spin-~ partner of the graviton. Insight may also be gained into
the observed baryon number of the universe from mechanisms for baryogenesis
which arise in the context of grand unified theory and electroweak theory.
Supersymmetry and supergravity theories may have scope to provide the particle
physics underlying the inflationary universe scenario that resolves such puzzles
as the extreme homogeneity and flatness of the observed universe. Superstring
theory also gives insight into the statistical thennodynamics of black holes. In
the context of superstring theory, bold speculations have been made as to a period
of evolution of the universe prior to the big bang ('pre-big-bang' and 'ekpyrotic
universe' cosmology).
These matters, amongst others, are the subject of this book. The book gives
a flavour of the new cosmology that has developed from these recent advances
in particle physics. The aim has been to discuss those aspects of cosmology that
are most relevant to particle physics. From some of these it may be possible to
uncover new particle physics that is not readily discernible elsewhere. This is a
particularly timely enterprise, since, as has been noted by many authors, the recent
data from WMAP and future data expected from Planck mean that cosmology
may at last be regarded as precision science just as particle physics has been for
many years.
xi
The new particle physics of the past 30 years, including electroweak theory,
quantum chromodynamics, grand unified theory, supersymmetry, supergravity
and superstring theory, has greatly changed our view of what may have happened
in the universe at temperatures greater than about 10 15 K (100 GeV). Various
phase transitions may be expected to have occurred as gauge symmetries which
were present at higher temperatures were spontaneously broken as the universe
cooled. At these phase transitions topological defects, such as domain walls,
cosmic strings and magnetic monopoles, may have been produced. Various
types of relic particles are also expected. These may include neutrinos with
small mass and axions associated with the solution of the strong CP problem
in quantum chromodynamics. If supersymmetry exists, there should also be
relic supersymmetric partners of particles, some of which could be dark matter
candidates. If the supersymmetry is local (supergravity) these will include the
gravitino, the spin-~ partner of the graviton. Insight may also be gained into
the observed baryon number of the universe from mechanisms for baryogenesis
which arise in the context of grand unified theory and electroweak theory.
Supersymmetry and supergravity theories may have scope to provide the particle
physics underlying the inflationary universe scenario that resolves such puzzles
as the extreme homogeneity and flatness of the observed universe. Superstring
theory also gives insight into the statistical thennodynamics of black holes. In
the context of superstring theory, bold speculations have been made as to a period
of evolution of the universe prior to the big bang ('pre-big-bang' and 'ekpyrotic
universe' cosmology).
These matters, amongst others, are the subject of this book. The book gives
a flavour of the new cosmology that has developed from these recent advances
in particle physics. The aim has been to discuss those aspects of cosmology that
are most relevant to particle physics. From some of these it may be possible to
uncover new particle physics that is not readily discernible elsewhere. This is a
particularly timely enterprise, since, as has been noted by many authors, the recent
data from WMAP and future data expected from Planck mean that cosmology
may at last be regarded as precision science just as particle physics has been for
many years.
xi