1. Edges and things, and what experimenters do in HEP. Christopher Lester

2. Christopher Lester, November 2004Damtp Pheno What’s this all about?

3. Christopher Lester, November 2004Damtp Pheno Decay chains used Sequential Branched

4. Edge positions

5. Fitted distributions ll lq high llqXq lq low llq Xqllq lq lowlq high llqll

6. What the different invariant mass distributions look like for a selection of plausible supersymmetric models. From Miller et. al. hep-ph/0410303

7. Christopher Lester, November 2004Damtp Pheno ΔM = M T2 (χ) - χ Given: zthe lepton momenta zthe missing transverse momentum zan estimate “Χ” of the neutralino mass Deduce: zlower bound M T2 (Χ) on slepton mass zslepton-neutralino mass difference ΔM

8. Christopher Lester, November 2004Damtp Pheno How does this m T2 work? zFor each event you want a lower bound for m slepton zYou get this by trying ALL POSSIBLE neutralino momenta, k, consistent with xobserved missing momentum, xidentical (unknown) slepton masses, xHypothesised neutralino mass. zFor each of these momenta, k, “that might have been” there is an “m slepton (k) that might have been”. zThere is a least such m slepton (k) (call it m T2 ) which cannot be bigger than the true value of m slepton, because one of the k’s is acutally right! zHence m T2 is a lower bound for m slepton.

9. Christopher Lester, November 2004Damtp Pheno So summarising: zIn each event: ym T2 <=m slepton. zCan show that: ythere exist events for which m T2 = m slepton. zSo: z the endpoint of the m T2 distribution is m slepton !

10. Christopher Lester, November 2004Damtp Pheno Example m T2 distributions (This old plot underestimates SM backgrounds)

11. Christopher Lester, November 2004Damtp Pheno No m qll -thresh, no m lq -low, no m T2

12. Christopher Lester, November 2004Damtp Pheno No m lq -low, no m T2

13. Christopher Lester, November 2004Damtp Pheno No m T2

14. Christopher Lester, November 2004Damtp Pheno Everything!

15. Christopher Lester, November 2004Damtp Pheno A long cascade decay from pp

16. Christopher Lester, November 2004Damtp Pheno Mass Relation Method Results m neutralino (0 to 600 GeV) m others (0 to 1000 GeV) Gluon Squark Neutralino 2 Slepton Neutralino 1