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KET-BSM meeting Aachen, April 2006 View from the Schauinsland in Freiburg a couple of weeks ago View from the Schauinsland in Freiburg a couple of weeks ago Sascha Caron University of Freiburg How does nature behave at 1TeV ? A search strategy for SUSY et al. (Note that this is a short and simple talk)

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The situation in 2005 We still don’t know the origin of EW symmetry breaking We still don’t know the origin of EW symmetry breaking The Higgs boson is not discovered yet The Higgs boson is not discovered yet Even with the SM Higgs: Even with the SM Higgs: ‘fine tuning’ is required in the model to remain valid to high energies?, ‘fine tuning’ is required in the model to remain valid to high energies?, Gravity is not included?, Fermion masses? What is Dark Matter?,… Gravity is not included?, Fermion masses? What is Dark Matter?,… typical solutions by increasing the number of typical solutions by increasing the number of symmetries, dimensions, forces, … symmetries, dimensions, forces, … Higgs ? Something else? Higgs ? Something else? Sascha Caron page 1

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Investigate if there is other physics beyond the Standard Model Investigate if there is other physics beyond the Standard Model Investigate if EW symmetry breaking is caused by the Higgs. Investigate if EW symmetry breaking is caused by the Higgs. Part 1 Higgs working groups at ATLAS and CMS Part 1 Higgs working groups at ATLAS and CMS Part 2 This approach: Data mining strategies How to find something potentially interesting and previously unexpected in the data? unexpected in the data? Part 2 This approach: Data mining strategies How to find something potentially interesting and previously unexpected in the data? unexpected in the data? The situation in 2005 Sascha Caron page 2

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What do we expect to find at the LHC? The situation in 2005 One physicist's schematic view of particle physics in the 21st century (Courtesy of Hitoshi Murayama) (Courtesy of Hitoshi Murayama) Sascha Caron page 17

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MSSM CMSSM SUSY VERSIONS OF THE SM NMSSM (an additional Higgs singlet) MN2SSM SUSY with extra Dim Or SUSY with extra forces Or …. The situation in 2005 Choose this point, look at the LHC data, exclude or not! Sascha Caron page 18

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We found no deviation We have excluded this point/area which is epsilon of the parameter space We found a deviation Does this mean that the ‘real’ model is this parameter point? Is it efficient to work like this?

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Examples: General Search for new Phenomena at H1 (2004) and D0 Sleuth analysis (2002 but only top final states) Finding the unexpected – explaining the origin New Strategy: START FROM THE DATA 1)Search for deviations in all final states (they are all interesting either as signal or to understand background) 2)Determine ‘deviation(s)’ or ‘inconsistencies’ (e.g. all muon final states have problems) states have problems) 3) Determine their origin (detector effect, etc.) 4)Re-determine expectation and Go to step 1) until publication in refereed journal Go to step 1) until publication in refereed journal Sascha Caron page 19 (btw. it would be nice to speed up steps 1-4)

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Event yields for HERA 1 data (all channels with SM exp. > 0.01 event) Good agreement for (almost) all channels Example: H1 General Search Sascha Caron page 19 Channels which have not been syst. studied before

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We investigated All M all and ΣP T distributions Sascha Caron page 22 We developed a simple algorithm to find and quantify deviations automatically

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General Search Sascha Caron page 19 I spend some time at the New Phenomena web pages at LHC experiments A count of final states planned to be studied leads to However consider permutations of j,b,e,µ,τ,v,γ, + consider e.g. charge? Up to 8 particle final states lead to about Did you have events with 2 photons, a jet and a muon at your LEP exp.?

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General Search Sascha Caron page 19 I spend some time at the New Phenomena web pages at LHC experiments A count of final states planned to be studied leads to However consider permutations of j,b,e,µ,τ,v,γ, + consider e.g. charge? Up to 8 particle final states lead to about Yes I know we do not want to start with final states at ATLAS What is the strategy?

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Is this possible at LHC? Is this the best strategy for ‘early discovery’? ‘early discovery’? What do we need for this search? What can we learn from theory?

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Is this possible at LHC ? Yes ! H1 has made the ‘proof of principle’

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Is this the best strategy for Is this the best strategy for ‘early discovery’? ‘early discovery’? I’m not sure to be honest. We (Freiburg) start from a ‘simpler’ scenario and extend (after we know some of the physics at 1 TeV) Attempt : Start from channels where you expect something new but you don’t know what exactly pT_miss channels (Dark Matter…?) Idea: less model dependent SUSY searches Idea: less model dependent SUSY searches

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What do we need for this search? -Theory (with uncertainty) in all channels (Multi purpose event generators) (Multi purpose event generators) -Uncertainties and fudge factors from data (calibration with candles, use data without pt_miss, use fits to fudge factors, use a global strategy, make ‘fake data’ for each channel, use fast ways to go from 1-4) (calibration with candles, use data without pt_miss, use fits to fudge factors, use a global strategy, make ‘fake data’ for each channel, use fast ways to go from 1-4) -Later: A way to learn what we have (LHC olympics, QUAERO, Bard) (LHC olympics, QUAERO, Bard) People interested to join such an effort in Germany

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An General analysis of LHC data Theory and ‘Going the way into the other direction’… (Yes this is known as the ‘inverse problem’ now, but my transperancy is older )

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What can we learn from theory? What are ‘model independent’ the best variables to measure (Et, mass, something else?) What do you need to determine Is their an interest to work together (background, signal determination)

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A significant danger is finding correlations and signals that do not really exist. that do not really exist. Many examples in particle physics history We are looking for deviations … How surprised should we be to find some? How likely is a 4-5 sigma deviation at LHC even if there is nothing in the data? Sascha Caron page 24 Unsolvable problem if you use 2000 PhD students

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Step 1: Repeat the whole analysis with a pseudo data experiment (dice your own MC data) many times. Quantify the deviations 3% Sascha Caron page 25 Step 2: Count how many times you find deviations bigger than in those in your real data. 3% of the “Pseudo H1 experiments” have found a bigger deviation Number of channels Probability to find deviation in this channel I know that this is not a new idea, but we do not often use it

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What are the numbers for ATLAS?

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Summary I’ve tried to illustrate some ideas for the ‘searches’ at LHC (ATLAS) and what our group is interested to do

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