The CMS silicon strip tracker is the largest device of its type ever built. There are 24244 single-sided micro-strip sensors covering an active area of 198m2.
Physics performance of the detector are being constantly assessed and optimized as new data comes.
Members of UCL are playing a major role in the understanding of the silicon strip tracker and in the maintenance and development of the local reconstruction code.
External collaborators: CMS tracker collaboration.
Search for Higgs boson(s) within the Standard Model and beyond and also withing a minimal extension of the scalar sector (2HDM).
The final state under study is a Z decaying into a lepton pair associated with two b-jets. This topology is sensitive to a light SM Higgs via the associate ZH production, as well as a middle mass range SM Higgs boson via the inclusive Higgs production followed by its decay into ZZ with one Z decaying into a lepton pair and the other into bbar.
It is also very sensitive to the production of a non standard heavy Higgs boson decaying into Z plus A (pseudo scalar Higgs boson).
Similar selection (but outside of the Z window) is also sensitive to H->aa->llbb, with "a" a generic light scalar.
External collaborators: CMS collaboration.
The so called Magnet Test Cosmic Challenge (MTCC) was the first comprehensive operational and functional test of the CMS experiment. the MTCC took place in the first months of 2006 and was a slice test in which a small fraction of all the CMS detection equipment was operated in the 4 T solenoid of the experiment. Cosmic rays detected in the muon chambers were used to trigger the readout of all detectors in the global CMS data acquisition system. Prior to data taking, the detectors and their readout electronics were tuned and synchronized with dedicated software procedures. Local reconstruction was carried out online and offline in all sub-detectors for event selection and monitoring purposes. Global reconstruction, linking different sub-detectors, was performed mainly offline. A number of monitoring and visualization tools were also used for validation purposes and monitoring. One of the main goals of the MTCC was the validation of the hardware alignment system functionality.
At the MTCC, UCL had a leading role in the preparation, operation and offline data analysis related to the silicon strip tracker detector.
QCD radiation in heavy colored particle production at the LHC is studied.
In collaboration with Johan Alwall (SLAC)
The goal of this work is to explore the phenomenology of a two Higgs doublet model with a custodial symmetry. It provides topologies that are unusual in the models usually considered in the literature. Notably, it opens the possibility of having an inverted mass spectrum with respect to MSSM with the lightest Higges being a pseudo-scalar and an heavier triplet of charged and neutral higgses.
External collaborators: Simon de Visscher (Zurich university).
The aim of this project is to quantify the impact of using jet matching techniques in the context of the production of multi-jets processes, in the Standard Model and beyond. Such methods mix the PS simulation and the matrix-element calculation, leading notably to a strong reduction of the sensitivity to parton shower parameterization.