New heavy gauge boson searches at ATLAS and their phenomenological interpretation

Lead Research Organisation: University of Liverpool
Department Name: Physics


The Standard Model (SM) of particle physics is the theory that describes the
fundamental interactions between particles and the way in which we classify the
latter. By combining quantum chromodynamics (QCD) with the unified theory of
electroweak interactions it provides a description for most observed features in the
Universe and has been able to provide successful predictions that lead to discoveries
of particles like the top quark or Higgs boson.
However, this theory is known to be incomplete as it cannot provide explanation
for some observed phenomena such as gravitational interactions, the existence
of dark matter or the strong CP problem, among others [1]. This has led to the
development of extensions for the SM, which are usually referred to as Beyond
Standard Model (BSM).
Many extensions involve the addition of a new U(1)0 symmetry that would complement
the SU(3) x SU(2) x U(1) groups that conform the SM. These theories
include superstring theories, grand unified theories (GUTS) and models involving
new TeV-scale physics. Additional symmetries would involve the existence of new
gauge bosons which, in analogy to the ones existing in the SM, are referred to as
W0 and Z0 bosons. As the explicit structure of BSM physics is yet to be discovered,
a way to parametrize new physics can be obtained by interpreting the SM as the
low energy regime of a more general effective field theory (EFT) [2] and expanding
the operators that SM involves with ones of higher dimensionality.
Experimentally, the search for new physics is performed looking for anomalies
in the distribution of observables when compared to SM predictions, being the
+MET [3] and dilepton [4] channels of special interest for the study of new heavy
gauge bosons as they represent their simplest final state.
This project will consist of a search for new heavy gauge bosons using the full
2015-2018 Run 2 dataset collected in the ATLAS experiment at LHC in the electron
decay channels. The large Run 2 statistics of 140 fb-1 allows to develop searches
that go beyond cut-based analysis, investigating in detail differential kinematic distributions.
Alongside particle search analysis, the project will focus as well in the
interpretation of the measurements, trying to set limits for operators in phenomenologically
motivated extensions of the SM.


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