Mary K. Gaillard

Strong and weak CP violation

Abstract We study the renormalization of the QCD vacuum parameter θ which arises from CP violation in the weak interactions. In the Kobayashi-Maskawa extension of the Weinberg-Salam model to include six quarks, the first renormalization of θ occurs in O( α 2 ) and is apparently O(10 −16 ). If we assume that θ = 0 at some unknown “relaxation” scale μ 0 , this renormalization makes a contribution to the neutron electric dipole moment which is probably O(10 −31 to 10 −32 )cm and smaller that the purely perturbative contribution. Infinite renormalization of θ may first occur in O( α 7 ), and we isolate a topological class of diagrams of this order which do indeed require infinite renormalization of θ. For any reasonable choice of the relaxation scale μ 0 , the residual finiteθ renormalization is much smaller than the first finite O( α 2 ) contribution. We finish with some remarks about θ renormalization in other weak interaction models of CP violation.

Attempts at Superunification

At present most particle physicists believe that the known interactions are described by a renormalizable gauge theory, namely

New Quarks and Leptons

SU\left( 3 \right){\,_{colour}}\, \otimes \,SU{\left( 2 \right)_{left}}\, \otimes \,U\,\left( 1 \right)

Search for Charm

(1) and many theorists believe in addition that these interactions become unified*) at a mass scale of about 1015 GeV.

An Updated Historical Prole of the Higgs Boson

Do cosmology and grand unified theories (GUTs) of elementary particle interactions have anything useful to say to each other? There is a great deal of theoretical work on GUTs unifying the strong, weak and electromagnetic interactions1, now that many theorists perceive these individual interactions to be understood in principle. GUTs invoke energy scales of O(1015) GeV which seem vertiginous to many physicists. It is not imaginable to reach these energies in laboratory experiments, and experimentalists are therefore forced to look for very indirect and feeble side-effects of grand unification such as proton decay. Even these valiant efforts may be brought to nought by a (logarithmically) modest increase in the grand unification mass-scale2. However, this mass-scale may be achieved directly in cosmological and astrophysical situations. For example, black hole explosions could in principle achieve temperatures up to the Planck temperature of 1032°K corresponding to energies of 1019 GeV, while temperatures corresponding to particle energies of 1015 GeV or more are generally thought to have occurred very early in the Big Bang when the Universe was about 10−37 seconds old.

Nonlinear Electromagnetic Self-Duality and Legendre Transformations y

Nowadays we are accustomed to think of particle interactions in terms of elementary couplings of quarks and leptons. In table 1 we list major steps which have contributed to our present picture. Entries in square brackets refer to theoretical speculations; round bracketed entries are observed phenomena which demonstrate the dynamical reality of quarks, complementing their algebraic reality which emerged from an analysis of the hadron spectrum. In this course we will be mainly concerned with the weak couplings of quarks and leptons.

Soft pion emission in p

The high energy sector of gauge theories with hard CP violation is discussed with emphasis on ’’strong’’ CP violation and baryon number generation.