Standard Model parity violation

The prediction of a heavy boson has received preliminary empirical support [92,96] from an anomaly in Z decay widths that points toward the existence of Z bosons with a mass of 812 GeV 1 33j [92,96] within the SO(l) grand unified field model, and a Higgs mechanism of 145 GeV4gj3. This suggests that a new massive neutral boson has been detected. Analysis of the hadronic peak cross sections obtained at LEP [96] implies a small amount of missing invisible width in Z decays. The effective number of massless neutrinos is 2.985 0.008, which is below the prediction of 3 by the standard model of electroweak interactions. The weak charge Qw in atomic parity violation can be interpreted as a measurement of the S parameter. This indicates a new Qw = 72.06 0.44, which is found to be above the standard model pre-... 

In particular, the consideration of relativistic and QED effects of electronic systems (i.e. free electrons, electronic ions, atoms or molecules) in strong external electromagnetic fields provides various appropriate scenarios for sensitive tests of our understanding of the underlying interactions. Theories of fundamental interactions, such as quantum electrodynamics (QED) or the standard model of electroweak interactions can be tested conclusively by studying QED radiative corrections and parity-violating effects (PNC) in the presence of strong fields. 

Quite generally, however, all these experimental attempts to measure molecular parity violating effects depend on guidance from theory. In the initial stage, theory is needed to identify suitable molecular candidates with favourable properties for an experiment, while at a later stage, theory is needed to analyse and interpret the results of an experiment. In the fom th section, I will describe the methods currently available for the computation of molecular parity violating effects, but first I will outline briefly the way one has to go from the standard model of physics in order to arrive at the final working equations employed in these calculations. 

FROM THE STANDARD MODEL OF PHYSICS TO MOLECULAR PARITY VIOLATION... 

The standard model of the electroweak interaction introduces an effective interaction between nucleons and electrons which violates parity-reversal symmetry. This P-odd interaction, Hp, is given by... 

The use of positive muons in solid-state physics and chemistry is based on the fact that due to the parity violation of the weak interaction (see Chap. 10 in Vol. 1 on Standard Model of... 

For some years it was surmised that all interactions possess these symmetries, but an experiment in 1956 showed that weak interactions violate parity, as seen by the fact that radioactive decay particles are emitted with a large left-right asymmetry [16], Within a decade, an experiment on the decay of kaon particles showed that strong interactions are also not symmetrical, having a small asymmetry under the combined operation CP [17], There is a theorem for the type of theories used to describe particle interactions (local, Lorenz-invariant field theories) that they must be invariant under the triple reflection CPT. Since CP symmetry is broken, this theorem seems to indicate that T symmetry is also broken at the same level. These symmetry (and asymmetry) properties have played an important role in developing the standard model of particle interactions, which describes electromagnetic, weak, and strong interactions. 

An experimental set-up similar to the one used in polarization spectroscopy is employed in experiments testing atomic manifestations of parity violation in the electro-wealc interaction. [9.359-9.361]. The experiments are important for testing the Standard Model hi elementary particle physics. Right-left asymmetries in atomic physics are of the order of 1 10 . A small optical rotation detectable using crossed polarizers is induced by interference between neutral weak and electromagnetic interactions in atoms. The most accurate experiments deal with heavy elements such as mercury, thalhum, lead and bismuth [9.362, 9.363]. Another way of probing the parity violation is to observe the strength of certain forbidden transitions, notably the 7 —... 

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