1. Analysis using GaudiPython, python configurables and LoKi in DaVinci Using StdLooseMuons Hits in M2 + M3 for 3 GeV < p < 6 GeV Hits in M2 + M3 + (M4 or M5) for 6 GeV < p < 10 GeV Hits in M2 + M3 + M4 + M5 for P > 10 GeV Decay descriptors from ParticleTable.txt

2. Sources of τ in one year at full running conditions In LHCb acceptance ~ 5 x 10 10 per year Assume BR ~ 2 x 10 -8 ~1000 events per year

3. Background Inclusive b (10000000) – 1,010,045 events ~ 2pb -1 Inclusive b Di μ (10012000) – 523, 217events Inclusive c (20000000) – 104,506 events ~ 30nb -1 Inclusive D s (23263001) – 107,431 events ~ 0.2pb -1 Inclusive J/ Ψ (24142000) – 123,545 events ~ 25pb -1 Signal τ→ 3 μ (31113001) – 30,000 events

4. Inital cuts (from Grant) μ PID vs π > -5 Min IP χ 2 wrt PV > 3 Track χ 2 /DoF < 4 p t > 0.2 GeV τ mass difference from PDG < 120 MeV Vertex χ 2 /DoF < 9 Vertex IP χ 2 < 5 Cos of daughter momentum and direction of vertex > 0.999 Muons Tau

5. Cuts from StrippingTriMuons 3 muons with p t > 0.3 GeV and Min IP χ 2 wrt PV > 4 1 muon with p t > 1 GeV τ mass difference from PDG < 150 MeV Vertex χ 2 < 25 Pseudo-lifetime wrt primary vertex > 40µm Muons Tau

6. Current cuts 3 muons with p t > 0.2 GeV τ mass difference from PDG < 200 MeV Muons Tau

7. Background Datasets Inc B DiMuon 258,339/523,217 = 49.4% Inc B 68,170/ 1,010,045 = 6.7% Inc C 4,900/104,506 = 4.7% Inc Ds 6,703/107,431 = 6.2% Inc J/Psi 10,585/123,545 = 8.6% Signal Datasets Tau 2 3 Mu 25,460,/30,000 = 84.9%

8. Two approaches to analysis (from Grant) 1. Standard Cuts E.g. Tau mass, Muon PIDmu, DiMuon masses 2. Geometrical likelihood E.g. Angles, IP, pt, pt asymmetry