1. Welcome/Introduction to RAL (STFC) Norman McCubbin Director of Particle Physics

2. Graduate Lecture. NMcC Oct 2010 2 ~80 people in Particle Physics Department (PPD), ~60 have PhDs, plus engineering, instrumentation, accelerator, and computing in other parts of the laboratories. In many respects we are just like a large university PP department (eg Oxford), but no requirement for undergraduate teaching (though a few do some), and a relatively small number of PhD students for a department of this size. We provide an ‘interface’ for the whole PP UK community to specialist skills in other RAL/STFC departments: –Technology: electronics, mechanical engineering; –Computing: the UK Tier-1 is here, and we are part of the South Grid Tier-2 consortium; –Accelerator R&D: ASTEC, which works closely with the Cockcroft and Adams Institutes; –Project management and administration: e.g financial tendering RAL site has been, and is, undergoing massive change: much more building over last 5 years than in previous 25…. : Diamond, ISIS Target Station 2, new hostel, new main gate, new computer building, new research building,…. All this is part of transformation to Harwell Science and Innovation Campus (HSIC). Particle Physics Department Particle Physics Department

3. Graduate Lecture. NMcC Oct 2010 3 Current projects in PPD ProjectApprox. FTE FundingLocated atProgramme 2010-2012 ATLAS18STFCCERNM&O, analysis, tracker upgrade CMS11STFCCERNM&O, analysis, upgrade LHCb5STFCCERNM&O, analysis, upgrade Computing8STFC, EURALGrid software, Tier (1,2,3) support Neutron EDM4STFCILLDeploy cryo-detector, M&O, analysus Dark Matter4STFCBoulby Laboratory Zeplin III M&O, analysis; plus management of Boulby facility. Detector R&D5STFCRAL, university collaborators Developments for future PP experiments, and non-PP applications Neutrino experiments 6STFCFermilab J-PARC MINOS; T2K Neutrino accelerator R&D 2 + …STFC(+ EU)RALMICE ; Neutrino Factory design studies; FFAG/EMMA NExT3 (joint) STFC/HEFCE RAL + So’ton + RHUL+Sussex (Virtual) Institute for Phenomenology. Support8STFCRAL, UKLOProgramme support for UK community

4. Graduate Lecture. NMcC Oct 2010 4 Programme Support STFC/PPD is an essential pillar of UK particle physics –An amplifier for the national programme –PPD co-located at an institution with powerful engineering and technology capabilities enables Particle Physics UK to carry out projects that it could not otherwise do. For example clean-room for ATLAS, FE and thermal calculations for CMS, …. Especially critical for smaller university groups –PPD is held in high esteem throughout the worldwide PP community, and we are sought-after collaborators. –We are involved in almost all UK PP projects. Provides a significant support role for UK Particle Physics –Annual HEP summer school for all UK students –Management and reporting of budgets –Travel processing, booking and reimbursement –Manage UK Liaison Office (UKLO) at CERN. (Previously also smaller offices at DESY, SLAC, FNAL)

5. Graduate Lecture. NMcC Oct 2010 5 Some big questions The Standard Model, which works so well at lower energies, falls apart above a few TeV –Is there a Higgs boson? Other new particles or forces?

6. Graduate Lecture. NMcC Oct 2010 6 The Large Hadron Collider..getting ready.. ATLAS tracker at RAL ATLAS tracker installed June 2007 CMS calorimeter crystal LHC computing and the Grid NExT Phenomenology initiative with Southampton, RHUL and Sussex CMS Half ECAL installed June 2007

7. Graduate Lecture. NMcC Oct 2010 7 The Large Hadron Collider..data at last!

8. Graduate Lecture. NMcC Oct 2010 8 Some big questions The Standard Model, which works so well at lower energies, falls apart above a few TeV –Is there a Higgs boson? Other new particles or forces? What is the cosmic dark matter? –Can we detect it? Is it particles we can make at colliders?

9. Graduate Lecture. NMcC Oct 2010 9 Direct detection of Dark Matter  low rate, small energy deposits –Very sensitive detectors –Well shielded –Underground to avoid cosmic rays 1100 m STFC operates the Boulby underground facility, Palmer Lab. PPD led ZEPLIN-I and ZEPLIN-II liquid xenon projects. ZEPLIN-II published world class result. ZEPLIN-III running well; beyond Nov 2010? Palmer Lab also hosts DRIFT, SKY,… Long-term future of Boulby? Being addressed now… LAGUNA in long-term?

10. Graduate Lecture. NMcC Oct 2010 10 Some big questions The Standard Model, which works so well at lower energies, falls apart above a few TeV –Is there a Higgs boson? Other new particles or forces? What is the cosmic dark matter? –Can we detect it? Is it particles we can make at colliders? What is the origin of the matter-antimatter asymmetry in the universe? –See effects in quark decays?

11. Graduate Lecture. NMcC Oct 2010 11 Flavour physics Using decays of particles containing b-quarks to explore the small matter- antimatter asymmetry in quark decays –BaBar experiment at SLAC (ended 2008) –LHCb experiment at CERN LHCb cavern LHCb RICH2 detector BaBar Simulation 10 9 events/year at RAL

12. Graduate Lecture. NMcC Oct 2010 12 Neutron Electric Dipole Moment Cryogenic apparatus at ILL in Grenoble –Sussex, RAL, Oxford, Kure, ILL Builds on previous successful experiment –world’s best limit 3  10 -26 e cm Installation complete and device now cooled to 2K Goal is sensitivity of few  10 -28 e cm goal A permanent neutron EDM would imply Parity and Time Reversal Violation Indirect test of matter-antimatter asymmetry Complementary to accelerator searches

13. Graduate Lecture. NMcC Oct 2010 13 Some big questions The Standard Model, which works so well at lower energies, falls apart above a few TeV –Is there a Higgs boson? Other new particles or forces? What is the cosmic dark matter? –Can we detect it? Is it particles we can make at colliders? What is the origin of the matter-antimatter asymmetry in the universe? –See effects in quark decays? –Neutrinos?

14. Graduate Lecture. NMcC Oct 2010 14 Explore CP violation Neutrino Factory Build community, international scoping study, EUROnu  design study RAL is a credible site First events seen. Beam power increasing. T2K A strong role in detector and accelerator development and in physics analysis Build up UK neutrino community MINOS Operations and analysis The Neutrino Programme MICE Demonstrate muon cooling Technology demonstration

15. Graduate Lecture. NMcC Oct 2010 15 Room to dream! ISIS ISIS 1MW upgrade ESS-class 5MW spallation source Neutrino factory Ultimate multi-TeV muon collider Harwell Science and Innovation Campus

16. Graduate Lecture. NMcC Oct 2010 16 Knowledge Exchange Two examples –The LCFI project spent over £500k in industry (e2v) on collaborative development of novel silicon detectors for the International Linear Collider. Patent application in progress. –FFAG accelerators, being developed for future neutrino facilities, also have significant promise in hadron/ion therapy applications. EMMA is an FFAG “proof of principle”, and has just circulated (e-)beam. We are part of a joint project (BASROC) to develop this within the UK. Future accelerator and detector projects are likely to make significantly greater use of industry to develop equipment – “KE through procurement” Our biggest KE impact is probably through our ability to attract and train students and postdocs who go on to careers in other areas

17. Graduate Lecture. NMcC Oct 2010 17 A little bit of physics… 17 UK-HEP_Forum'10-tsv Bound states of u,d,s (anti-)quarks Charm (anti-)quarks Bottom (anti-)quarks.. and the Z

18. Graduate Lecture. NMcC Oct 2010 18 The di-muon mass spectrum.. A significant fraction of the (history of the) Standard Model is directly visible in, or implied by, this mass spectrum: –it’s a quark “directory”, seen through the quark-antiquark bound states; –We see the Z; –Even the non-resonant continuum is “real physics” – though this is a ‘publicity’ plot, and I don’t know how much off-line selection has been done: eg it would be possible, in principle to subtract out the contribution from two semi-leptonic decays, but I would be surprised if this has been done yet. And the rich range of physics topics include: –ρ/ω interference; –“Quarkonium” structure of excited states for c and b systems; –Narrow width of J/ψ and Υ (and large width of ρ/ω); –Drell-Yan continuum; –And the Z width bears directly on number of (light, non-sterile) neutrinos. –

19. Graduate Lecture. NMcC Oct 2010 19 J/ψ width (1) J/ψ is by now probably one of the best studied particles in physics. The Beijing e+e- collider (BEPC) has collected ~58 million of them, and studied many rare decays. The mass has been measured by the VEPP-4M ring with astonishing precision, using the technique of resonance depolarisation: M J/ψ = 3096.917 ± 0.010 ± 0.007 MeV The widths are much tougher to measure: Γ total = 93+- 2 keV; Γ ee = Γ µµ = 5.6 +- 0.1 keV The decay into lepton pairs is (of course) through a virtual photon. Creation (in fermion-antifermion collision) and decay:

20. Graduate Lecture. NMcC Oct 2010 20 J/ψ width (2) This same process can also give decay into quark-antiquark pairs, observed (of course) as hadronic jets: For uubar (via virtual photon) we expect: 3.(2/3) 2 Γ ee = 1.3 Γ ee = 7.4 keV. Do you understand the factors? So, width into u, d and s pairs via virtual photon: ~7.4+1.9+1.9 = ~11keV. Total width is 93 keV, so decay is not ALL ELECTROMAGNETIC. Why not decay involving gluons? Which would presumably give us a ‘strong interaction’ width ~ 100 MeV. First note that the J/psi cannot just ‘fall apart’ into charmed mesons (Why not?) But why not decay via a gluon (analogous to photon diagram)? Can’t decay via one gluon, because of…. Can’t decay via two gluons because of …. CAN decay via three gluons, but this implies (α strong ) 6..and THAT’s why the J/ψ is so narrow!

21. Graduate Lecture. NMcC Oct 2010 21..other vector mesons and SU(2) To finish off, let’s look at leptonic widths of the light vector mesons: –ρ(770): Γ ee = Γ µµ = 7.0 keV –ω(780): Γ ee = Γ µµ = 0.60 keV (actually dimuon mode is not that well measured.) –Φ(1020): Γ ee = Γ µµ = 1.2 keV Can we understand the relative magnitudes? Just as for J/ψ, decay involves coupling to virtual photon. The φ is ssbar: electric charge factor (-1/3) 2 Both ρ and ω are mixtures of u.ubar and d.dbar, but there’s a factor of ~10 difference in leptonic width… The u and d quarks play a special role in the strong interactions because their masses and more importantly the mass difference between them are very small compared to Λ QCD. In other words, seen by the strong interaction the u and d are pretty much identical (coloured) objects. This gives rise to the valuable (for particle physics) and fundamental (for nuclear physics) concept of strong isospin. Mathematically SU(2) symmetry.

22. Graduate Lecture. NMcC Oct 2010 22.. SU(2) The u and d quarks form strong isospin doublet: And combinations of u and d quarks get isospin quantum numbers in a manner that is completely analogous to the usual QM angular momentum rules. And the strong interactions conserve strong isospin. Angular momentum coupling gives us things like: The ω is an isospin singlet (I=0) and the ρ is I=1 – there are three: ρ +,ρ 0,ρ -. Assuming (correctly) that ubar has I 3 =-1/2 and dbar has I 3 =+1/2 would suggest: ω=1/√2(u.ubar – d.dbar) and ρ=1/√2(u.ubar + d.dbar) Giving electric charge factors of (2/3-(-1/3)) 2 /2 for ω and (2/3+(-1/3)) 2 /2 for ρ

23. Graduate Lecture. NMcC Oct 2010 23.. SU(2) (contd) Which is indeed a factor ~10…. BUT THE WRONG WAY ROUND! (predicts Γ ee for ω > Γ ee for ρ ) As is often the case, you have to be just a leeetle careful handling antiparticles! It is correct that ubar has I 3 =-1/2 and dbar has I 3 =+1/2. But it is not correct that the SU(2) rotations on ubar and dbar are IDENTICAL to those on u and d. And that messes up the coupling rules for isospin if you have both quarks and antiquarks. Fortunately, there is a neat way out: it turns out that the doublet transforms exactly like To see this I’ll mimic the discussion given in Halzen and Martin so you can check it later.

24. Graduate Lecture. NMcC Oct 2010 24.. SU(2) (contd) A rotation of π/2 about the ‘2’ axis is where τ 2 is the appropriate Pauli spin matrix. Applying this to a doublet gives: Now apply the charge conjugation operator, C. So Which is equivalent to:

25. Graduate Lecture. NMcC Oct 2010 25.. SU(2) (contd) So the doublet transforms exactly like So, we CAN use standard angular momentum coupling, provided we write –dbar, whenever we want a dbar quark. So ω=1/√2(u.ubar – d.(-dbar)) and ρ=1/√2(u.ubar + d.(-dbar)) And all is well!