Conveners
Session II
- James Michael Keaveney (University of Cape Town (ZA))
Heavy ion collisions at RHIC and at the LHC produce an enormous amount of energy that enables the nuclei and its constituent particles to melt, thus releasing gluons, quarks and anti-quarks, travelling in different directions with different momenta. Studies of these collisions have shown that low transverse momentum observables describe a strongly coupled plasma (quark-gluon plasma), an almost...
Chemical and thermal equilibrium properties of infinite relativistic hadron matter are investigated using a microscopic transport model. This model is used to simulate the ultra-relativistic heavy ion collisions at different energy densities ε, namely the Ultra-relativistic Quantum Molecular Dynamics (UrQMD). The molecular dynamics simulation is performed for a system of zero baryon number...
Gauge-Higgs unification models give interesting solutions to the hierarchy problem in particle physics. The common study of this type of model is done by using a decomposition of 5-dimensional particles in 4-dimensional Kaluza-Klein modes, which is a handy way to compute the infinite sums appearing in the model. In order to take into account the running of coupling constants in these models,...
Composite Higgs models describe a strongly coupled gauge fermion sector which extends the Standard Model, introducing the Higgs boson as a new bound state arising due to the breaking of a global (flavour) symmetry. These models will be accompanied by light states generated by the same dynamics, the detection of which may present the first signs of compositeness. The subject of this work, a...
The production of a single top quark in association with a $W^{\pm}$ and $Z$ boson ($tW^{\pm}Z$) is sensitive to both the neutral and charged electroweak couplings of the top quark as the process involves the simultaneous production of a W boson and a Z boson in association with the top quark. However the process so rare that it has never been observed by any particle physics experiment. The...
The LHC is a top quark factory and the copious amounts of top quarks produced provide valuable insight into the standard model and beyond. Majority of the top quarks produced can be identifed using standard methods such as identifying features such as bottom quarks (b-tagging), W bosons or three jets with an invariant mass that is roughly equal to the top mass. However, some of the top quarks...
We investigate the discovery potential of a Stealth SUSY scenario involving squark decays by reconstructing the lightest neutralino decay products using a large-radius jet containing a high transverse momentum photon. Requirements on the event topology, such as photon and large-radius jet multiplicity result in less background than signal. We also estimated the sensitivity of our analysis and...
Recent studies in particle physics have shown that there are myriad possibilities for strong dark sector studies at the LHC. One signature is the case of semi-visible jets, where parton evolution includes dark sector emissions, resulting in jets overlapping with missing transverse energy. The implementation of semi-visible jets is done using the Pythia Hidden valley module to duplicate the...
The standard electron and jet reconstruction process using information from energy deposits in the electromagnetic (EM) and hadronic calorimeters are carried out independently. This results in an ambiguity in the reconstruction of these objects. to avoid such ambiguity, an overlap removal procedure is applied during electron and jet reconstruction since every reconstructed electron will have a...
Due to a number of features from proton-proton collisions taken during Run 1 data taking period at the LHC, a boson with a mass around the Electro-Weak scale was postulated such that a significant fraction of its decays would entail the Standard Model (SM) Higgs boson and an additional scalar, S. One of the phenomenological implications of a simplified model, where S is treated a SM Higgs...
Anomalies observed in several Standard Model (SM) results, with multiple leptons in the final state from the ATLAS and CMS experiments at the LHC, are interpreted in the context of new physics in Refs. arXiv:1711.07874 and arXiv:1901.05300. This new hypothesis extends the SM considering the presence of additional bosons through the production of a heavy boson, $H$, decaying into a SM Higgs...
With focus on the recent ATLAS search for top associated Higgs production in multi-lepton final states, an anomalous rate for the ttW background is unearthed and quantified in terms of theory uncertainties. This anomalous rate is explored in the context of the previously published multi-lepton anomalies at the LHC (JHEP 1910 (2019) 157), using a simplified new physics model. The impact of the...
