The Standard Model assumed its current form in the mid 1970s and has since achieved remarkable success through discoveries of the weak gauge bosons, the top quark, tau neutrino and the Higgs boson.
The CoEPP research tests the predictions for rates of SM processes or properties of known particles. Currently the measurements of SM processes at the LHC include the analysis framework, AIDA (“An Inclusive Dilepton Analysis”) and a dedicated differential measurement of the top-quark pair production cross-section.
The AIDA project spans CoEPP’s Melbourne and Sydney nodes, and involves partner institute, Duke University. The analysis formally involves the simultaneous measurement of fundamental Standard Model phenomena.
Typically, measurements for these processes are made individually and so simultaneous measurements provide a unique global test of the Standard Model and are a sensitive probe of low-energy quantum chromodynamics models. The latter is owing to their rates being mutually sensitive to proton sub-structure.
Breaking new ground, a project measuring the differential cross section for a so-called “pseudo-top” in the semi-leptonic channel of top pair production separately in top transverse momentum and top rapidity. The measurements are very useful for tuning model descriptions of LHC collision events, and in constraining the gluon content of the proton.
The weak charge of the proton represents the strength of the weak force's pull on the proton, a measure of how strongly a proton interacts via the weak force. Since the Standard Model precisely predicts the weak charge of the proton it is an ideal parameter to measure experimentally. The measurement, in agreement with the Standard Model prediction, uses only four per cent of the available data. Hence an updated measurement using the full data set will provide a rigorous test of the Standard Model and minimally will provide constraints on new physics at the scale of energies being explored at the LHC.