ACP Seminar (Astronomy - Cosmology - Particle Physics)

Speaker: Michihisa Takeuchi (King's College London)
Title: Top Quarks and Jet Substructure at the LHC
Date (JST): Thu, Mar 14, 2013, 13:30 - 15:00
Place: Seminar Room A
Related File: 889.pdf
Abstract: The Standard Model describes interactions between elementary particles very well and the origin of masses for all particles are explained by introducing one scalar boson called Higgs. The new particle with its mass of about 125 GeV has been discovered at the LHC and is consistent with the SM predictions so far. However, so called fine tuning problem and existence of dark matter cannot be explained within the SM. We expect new physics beyond the SM plausibly emerges at a TeV scale and it can be probed by an optimal use of the LHC data.
Top quark plays an important role for the fine tuning problem due to its largest yukawa coupling. Many models beyond the SM predict the existence of top partner particles, which are typically coupled to dark matter. Besides that, several anomalies has been reported in the top sector. Thus, we are likely to find a new physics signature first in the top sector and efficient top quark identification is important at the LHC. Moreover, we should note that top quark productions are often the main source of the background for new physics searches.
In the recent years understanding of jet substructure based on QCD has been developing, which had been thrown information before. Using the knowledge several identification algorithms for boosted heavy particles have been proposed. Hadronically decaying tops are among the targets and we developed the HEPTopTagger as an efficient top tagging algorithm. We have achieved one of the best performances of all top taggers available on the market.
I will show the performances of our top tagger and applications for the several physics cases at the LHC. Some of the results have been tested or are testable by the current LHC data.
Seminar Video: [VIDEO]