%new physics at the lhc
%introduce toptagging on this slide
Classify events into those that origin from a top quark, and those by other qcd particles
to do this, use either calorimeter like images or 4-vectors
classical approach:
first build a theory (for example super symmetry)
make predictions
test them
not very effective in the last time
so try using unsupervised algorithms to find 'weird' stuff
these algorithm are tested quite well using top tagging since
the top quark was only discovered 1995, so before this, tops actually were 'weird'
the top quark has a quite low cross section (about #1# top event for each #10# million collisions)
%slide to show the history of toptagging
classically you use smart physics to differentiate them (arXiv:1806.01263)
but then there were deep learning approaches (arXiv:1704.02124) which do this a bit better
today even better using a fancy graph neuronal network (ParticleNet,arXiv:1902.08570)
Supervised
Training given both the anomaly and the background events
Much easier to do
only able to find one specific anomaly
Unsupervised
Training only given background events
Able to find any anomaly
Used by QCDorWhat (arxiv 1808.08979) for unsupervised toptagging