In 1997 Peter Dornan was elected Spokesman of ALEPH

2. In 1997 Peter Dornan was elected Spokesman of ALEPH • After 7 fantastic years spent exploring the Z peak (around 91.1872 GeV/c2) measuring the number of neutrinos (3), the Z width and asymmetries and predicting the top quark mass, not to mention discovering Bs, b and doing wonderful  physics… • We had started exploring higher energies, thanks to the adjunction of superconducting RF cavities in LEP. • LEPII physics had several characteristics: • Event numbers counted in thousands and no longer in millions. Most of it was boson pair production (, Z, WW, ZZ…. and HZ) • We began to perform kinematic fits using “jets” as particles • 3. ALEPH was already built and running and many important and “experienced” physicists started eying on LHC for the continuation of their careers. • It was thus important to retain the best, young and fit! • To this effect PJD reorganized the analysis groups by nominating • TWO ‘less experienced ’ conveners for each group. • This worked very well in *most* cases. • 4. and he asked me to be the “physics coordinator”. • THANKS!

3. Most events were still Zs!

4. WW pair event

5. Unclaimed discovery:observation of events with 2 jets, a tau and a massless missing momentum was clear and very clean direct discovery of the tau neutrino!!!

7. The HIGGS Boson Arguably the strangest and most exciting beast in the Standard Model. 1. While all the known (observed) elementary particles have spin 1 or ½ the famous boson is afflicted with spin 0. No spinning and no dancing. theorists blame on infinite loops that a) it must be heavy b) there should be supersymmetry … otherwise there will be no light Higgs boson to play with. thereby Supersymmetry is very popular model of physics beyond. (did I miss something?) 2. The Higgs boson generates considerable eagerness and lust among particle physicists and there was no exception in ALEPH: 3. Two groups worked very hard and VERY competitively at LEPI which the Higgs boson limit was around 60 GeV (Z-> HZ*). Since the process for Higgs production is e+e-  HZ starting around Ecm> Mz+60 +  =160 we would be hunting for the Higgs again. And hunt we did.

8. On searches New particle searches had always been taken very seriously in ALEPH, and in particular by the Orsay group (and friends) on one hand and the Wisconsin group on the other. We published more than ~200 papers on searches of new particles. In hindsight it is not a surprise that some unexpected searches turned out to give positive signals. Among them most famously the ll Vanalysis at LEP I, and the “four jet events” a.k.a. ‘lapino’ (from Jeanneau (Janot) Lapin, french child’s book character) at LEP 1.5. These ‘false alarms’ were very trying on the collaboration and the spokesman… The proponents (O or W) of a new effect were extremely excited, had worked very hard, and had “scandinavia dreams”. (PJD expression). At the same time they were vigoroulsy criticized by the other (W or O) group. Some talked too much when we wanted them to be quiet, ….and the others would not even talk to us, except in writing.

9. The ONLINE analysis At Xmas 1998 an email storm culminated in a downright abusive message to Peter. (I think the subject had to do with ‘whose analysis would be chosen and on which criterion) this was a looow point. After letting things settle for a couple months Peter and I decided to let both teams have their analysis published (one was ‘CUTS based’ and one ‘NN based’), But in exchange we requested the analyses to be run ONLINE: -- all details (cuts, estimators etc…) were to be fixed and locked before data taking resumed in 1999. -- a well defined set of data quality checks were to be processed and shown to the collaboration. -- the analysis would run automatically online and the result would be published on a web page available to the collaboration on a daily basis This motivating plan settled the internal controversies. The analyses were extremely sophisticated, being based on the calculation for each event of the probability of either ‘only background’ or “background + Higgs signal” as function of MH would give an event more ‘signal like’ than the one observed. Many variables were used for each Higgs channel and the probabilities were estimated using massive amounts of MonteCarlo and toy MonteCarlos.

10. 1999

11. 1999 The rumors had picked on this: But the online code also calculated the significance And it was only 1.15 …

13. 2000 The ALEPH Experience, http://aleph.web.cern.ch/aleph/alpub/draft/AlephHistory.pdf

14. 2000 2000 was to be the last year of LEP. (in 1997 it had been decided in the high spheres of CERN to remove LEP from the LEP/LHC tunnel to install LHC (instead of building LHC on top of LEP as originally foreseen. I have to admit that I did not realize this at the time, and it certainly was not publicized among the LEP community. So the removal would be final). LEP run was entirely focused on the Higgs boson discovery. Patrick Janot was the LEP coordinator. Given that the maximum accessible beam energy was a function of the beam intensity we had devised a ‘miniramp’ system that would keep increasing the beam energy during the two hours of a LEP fill. The ONLINE Higgs-hunt web site was being looked at every day with fever…. This was not a BLIND analysis at all … but rather an unbiased EYES WIDE OPEN analysis… with no human control. We had fixed that no result would be communicated apart from pre-fixed dates: -- LEPC, summer conferences, end of run.

15. Detector performance Detector working very well, data quality is high DAQ efficiency = 95.4% Background conditions are good Results based on 92.7 pb-1 @ 203-208 GeV 61.5 pb-1 @ 204.9 GeV 31.2 pb-1 @ 206.7 GeV All results are PRELIMINARY Gary Taylor, LEPC 20 July 2000

16. SM Higgs 84 observed c/w 82.7 expected Cb= 0.02 100 pb-1 Excess SM Deficit

17. SM Higgs bbqq candidate

18. SM Higgs bbqq candidate - vertex region

19. As Gary was speaking a second event showed up and sent the no-signal probability CLb down to a few 10-3If someone had plotted the time development of CLb it would have looked like this: 1 10-1 10-2 10-3 10-4 10-5 10-6 CLb End of LEP LEPC LEPC Integrated luminosity Heavily dominated by the appearance of very significant qqbb events. On my return from vacation August 18 2000 I found CLb at 7 10-6 or so… i.e. more than 4 sigmas. …emotions!

20. LEPC Sept 5, 2000 D. Schlatter

21. Online Higgs Analyses Two independent streams: NN(19 variables) and Cuts Entries/(4 GeV/c2) mrecon=m12+m34-91.2

22. CL for Background Hypothesis, Cb NN analyses CUT analyses Min.: ~ 6 10-5 @ 115.5 GeV Four Jets alone: min(1-Cb) = 3 10-5 @114.5 GeV all others: min(1-Cb) = 0.03

23. Significance of Excess NN CUT 3.9 s  @ 115.5 3.8 s  @ 115.5 The peak is dominated by 4 jet candidates!

24. SM Higgs: Likelihood Ratio Significance s+b hypo. bkg only median exp. NN observed s+b hypo. Min.@ 113.5 LEPC Sept 5, 2000 D. Schlatter

25. The rest of the story is well known: The other LEP experiments also had candidates, but of lesser significance. Some were rejected after the fact (reconstruction or visual inspection). The four LEP experiments (NB spokesperson’s meeting was intitiated by PJD in 1999) agreed, requested and obtained two run extensions in 2000, But the significance of the effect kept decreasing slowly (as it should, really) and the combined LEP result is less than 2 sigmas. In Fine the ALEPH excess never really went away; the final publication including all data still describes a positive search with a final significance of more than 3 sigma for a Higgs boson of ~115 GeV/c2. The SPC (of which PJD became member in 2003) had special meetings arranged to discuss the matter but it was felt that with LHC in 2005, the significance was not strong enough to delay the CERN flagship project. CERN decided to close LEP operations definitively. The Higgs flag has been taken up by Tevatron but it will take a long time to know whether our observation was the first harbinger of the Higgs Boson. 115 GeV is still the likeliest place for it to be found....

27. According to these early sensitivity studies, mH< 130 should be nearly Excluded by now No VTX upgrade +very difficult region Will require more analysis time!

28. 115 GeV/c2 Situation will be similar at LHC: low mass Higgs is very difficult. In particular 115 GeV Higgs (LEP ‘hint’/limit) will take a very long time to confirm/exclude

29. From Heavy Flavours to the lightest Flavours PJD was always a man of flavour. Very soon after neutrino flavour changes were established by SuperK in 1998, it became clear that there was a new and rich domain of Physics leading eventuallyto leptonic CP violation and, via leptogenesis, a possible solution to the matter-antimatter asymmetry in the universe. Peter as director of Imperial and influent member of the UK particle physics community gave great support to the development of -- neutrino factory studies in UK and in particular the approval and funding of MICE -- was the first MICE collaboration board chair and wrote the MICE collaboration charter -- Supported the International Scoping study, which he chaired He is now member of the CERN SPC Neutrino panel who should give recommendations on CERN role in the European strategy for (accelerator based) neutrino physics

33. Muon Ionization Cooling Eexperiment (MICE) Collaboration Coupling Coils 1&2 Focus coils Spectrometer solenoid 2 Spectrometer solenoid 1 m RF cavities RF power Beam PID TOF 0, TOF 1 Cherenkovs Downstream particle ID: TOF 2, KL SWCalorimeter VariableDiffuser Liquid Hydrogen absorbers 1,2,3 Incoming muon beam Trackers 1 & 2

34. Overall comparisons from ISS sign Dm213 q13 More range = more precision NuFACT does it all… (+ univ. test etc…) but when can it do it and at what cost? CP phase d

35. Final quote: As everyone who has organized a large […] meeting knows, it is not the quality of the talks, the seating or audiovisuals of the lecture halls that everyone remembers. It is the dinner. PJD in ‘The ALEPH experience’