|Speaker:||Takeuchi Michihisa (King's College London)|
|Title:||New physics searches with boosted tops|
|Date (JST):||Wed, Feb 19, 2014, 13:30 - 14:30|
|Place:||Seminar Room A|
The Standard Model describes interactions between elementary particles very well and the origin of masses for all particles are explained by introducing one scalar Higgs boson. 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. Thus top quark is a good probe both for Higgs sector and new physics search. Considering several anomalies has been reported in the top sector, we are likely to find a new physics signature first in the top sector and efficient top quark identification is important at the LHC.
In the recent years understanding of jet substructure based on QCD has been developing, which had been thrown information before. We developed the HEPTopTagger as an efficient top tagging algorithm with a help of the boost and achieved one of the best performances of all top taggers available on the market. Recently, we also developed buckets algorithm aiming for tagging even less boosted tops.
I will show the performances of our top tagger and buckets algorithm and their applications for the several physics cases including stop searches and ttH coupling measurements at the LHC. Some of the results have been tested or are testable by the current LHC data.