Physics Opportunities with Future Proton Accelerators

1. Physics Opportunities with Future Proton Accelerators Report to Neutrino IDS John Ellis, March 29th 2007 POFPA study group: Blondel, Camilleri, Ceccucci, JE, Lindroos, Mangano, Rolandi Advisory group to the CERN DG

2. The High-Energy Frontier @ CERN • Context for our approach to high-intensity, lower-energy proton accelerators • Need to maintain, refurbish CERN’s lower-energy accelerators (linac, booster, PS, SPS) • Ambition to upgrade LHC luminosity by factor ~ 10 around 2015 • Requires upgrade of proton injector chain • Look for possible synergies with other physics

3. European Strategy for Particle Physics • Highest priority is to fully exploit the potential of the LHC: nominal performance and possible luminosity upgrade (SLHC) ~ 2015 • R&D on CLIC, high-field magnets, high-intensity neutrino facility • Participation in ILC R&D, decide ~ 2010 (?) • Prepare for neutrino facility decision ~ 2012 • Non-accelerator physics • Flavour and precision low-energy physics • Interface with nuclear physics, fixed-target experiments Topics for today

4. Possible LHC Upgrade Options • Upgrade of Linac • More intense beam @ 160 MeV: Linac4? • Superconducting Proton Linac • Up to few MW @ few GeV: SPL? • Replace PS • New medium-energy injector: PS2? • Replace SPS • By SC machine @ 1 TeV: SPS+? • New LHC insertions: • Luminosity  1035 cm-2s-1

5. One Possible Scenario for Proton Injectors Proton flux / Beam power L1 Linac2 L1, L2 SL, DL bB, nF k, m, NP Linac4 50 MeV 160 MeV SL, DL bB, nF k, m, NP SL, DL bB, nF k, m, NP L1, L2 SL, DL PSB SPL’ RCPSB SPL 1.4 GeV 4 - 5 GeV L1, L2 SL, DL bB, k, m SL, DL bB, nF k, m L1, L2 PS PS2 RCPS 26 GeV 40 – 60 GeV Output energy L1, L2 SL, DL bB k, m SL, DL bB k, m SPS SPS+ SPL’: RCPSB injector (0.16 to 0.4-1 GeV) RCPSB: Rapid Cycling PSB (0.4-1 to 5 GeV) RCPS: Rapid Cycling PS (5 to 50 GeV) PS2: High Energy PS (5 to 50 GeV) SPS+: Superconducting SPS (50 to1000 GeV) 450 GeV 1 TeV SL LHC DL DLHC 7 TeV ~ 14 TeV

6. Layout of the new LHC Injectors SPS PS2 SPL PS Linac4

7. New Physics @ SLHC Measure triple-gauge-boson coupling with accuracy comparable to radiative corrections Measure triple-Higgs-boson coupling with accuracy comparable to 0.5 TeV LC

8. Examples of Searches for New Physics Extended reach for supersymmetry and a Z’ boson

9. SLHC Physics Reach Compared

10. Additional LHC Remarks • Reducing β* and minimizing the downtime are both desirable. • The interaction regions for the SLHC have yet to be defined • Need significant R&D for focusing magnets, etc. • Layout may have significant implications for the experiments • Bunch spacing 25 or 50ns? • 25ns would require machine elements @ 3m from IP • Shorter spacings have problems with heating of beam pipe • Choice would have implications for injector chain • Final choice of upgrade scenario will require global optimization of accelerator and detector expenses

11. Upgrade Scenarios Currently Favoured - Avoid problems with beam heating - Peak luminosity ~ 1035 cm-2s-1

12. Detector Issues for the SLHC High radiation in central tracker Congested layout in forward direction: space for new low-β* machine elements?

13. Final SLHC Remarks • Definition of preferred LHC upgrade scenario in 2010 will require some inputs from initial LHC operations • E.g., neutron fluence, radiation damage and detector performance, as well as the early luminosity experience and physics results. • Discussion of many possible scenarios for upgrading the LHC injector complex: Linac4 → SPS+ • Common element in all LHC luminosity upgrade scenarios is Linac4: on critical path for optimizing the integrated LHC luminosity • Roles for PS2, low-power SPL

14. The High-Intensity Frontier • Exploration and understanding Novel phenomena Rare processes High statistics • Active option in front-line physics: factories for Z, B, τ/Charm, K, antiproton, anti-Hydrogen • Proton driver  new opportunities for ν, muon, kaon, heavy-ion, nuclear physics

15. Neutrino Oscillation Physics • Programme of precision neutrino oscillation physics, leading to discovery of CP violation, is an important, exciting, high-level goal • If sin2θ13 > 10-2, may be possible to measure δ using superbeam/β beam + megaton water Cerenkov detector • Neutrino factory with one or two distant detectors at very long baselines may be needed to measure δ if sin2θ13 < 10-3 • Analysis is one goal of International Scoping Study

16. νOscillationFacilities @ CERN • CNGS: ν beam from SPS: τ production • Superbeam? intense ν beam from SPL • β beam? signed electron (anti) ν beams from heavy ions • ν factory? muon and electron (anti) ν beams from μ decay

17. CERN Neutrino Beam to Gran Sasso Optimized for τ detection Civil works completed Commissioned in 2006 Physics in 2007? Intensity upgrade under study

18. Fluxes from Different ν Facilities NuMI J-PARC Superbeam βbeam ν factory

19. How to measure δ ? Error in δ as function of θ13 Key information from Double-Chooz/T2K SPL + β-beam sufficient if θ13 large, need ν factory if θ13 small How soon will we know size of θ13?

20. Neutrinos as Probes of Standard Model • Enormous interaction rates in nearby detector • Extraction of αs, sin2 ϑW • Quark and antiquark densities Polarized and unpolarized e.g., strange quarks • Charm production • Polarization of Λbaryons also probe of strange polarization

21. Potential Accuracy for sin2θW

22. Measuring Strange Partons Strange + antistrange Strange - antistrange

23. Muon Physics • Proton source produces many muons • Rare μ decays μ e γ, μ eee, μ A  e A Expected in susy seesaw model: probe unknown parameters • Dipole moments: gμ– 2, electric dipole moment, CPT tests • Nuclear, condensed-matter physics: (radioactive) μ-ic atoms, muonium, μ-ic Hydrogen

24. Many models predict μ eγ close to present experimental limit, e.g., model where sneutrino responsible for inflation, baryogenesis μ eγ in Supersymmetric Seesaw

25. 16 measurable in μ, τ decays, … Measuring SUSY Seesaw Parameters 9 measurable in νphysics mi, θij, Majorana phases 18 parameters in total 12 Generate baryon asymmetry?

26. Comparing μ→ eγ and μ→ 3e μ→ eγabove experimental limit for generic parameter values μ→ 3e also suppressed for these parameter choices μ→ eγsuppressed for some parameter choices

27. μ→ 3e: T-violating asymmetry AT Enhanced when μ→ eγsuppressed: interference between γ exchange and other diagrams →CP, T violation observable

28. ‘Natural’ supersymmetric interpretation Anomalous Magnetic Moment ‘Consensus’ on discrepancy with Standard Model, based on e+e- data Deserves a follow-up experiment

29. K → πνν: Searches beyond Standard Model P-326 proposal for K+→π+νν @ CERN aims at 80 events - could reach 1000 events with 4 MW @ 50 GeV Potential impacts of K →πνν measurements @ CERN

30. Isotope Source for Nuclear Physics • The limits of nuclear existence: neutron & proton drip lines, superheavy elements, extreme nucleonic matter • Nuclear astrophysics: rp-process, r-process • Probes of Standard Model: CKM, P, T, CP • Materials science: radioactive spies, curing chemical blindness, positron annihilation studies, applications to biomedicine, etc.

31. Physics with Radioactive Nuclear Beams Particle physics Extreme nuclei Astrophysics

32. Possible EURISOL Site @ CERN

33. POFPA dixit … • We consider experimentation at the high-energy frontier to be the top priority in choosing a strategy for upgrading CERN's proton accelerator complex. This experimentation includes the upgrade to optimize the useful LHC luminosity integrated over the lifetime of the accelerator, through both a consolidation of the LHC injector chain and a possible luminosity upgrade project we term the SLHC • The absolute and relative priorities of these and high-energy linear-collider options will depend, in particular, on the results from initial LHC runs, which should become available around 2010 Blondel et al: hep-ph/0609102

34. POFPA dixit … redux • We consider providing Europe with a forefront neutrino oscillation facility to be the next priority for CERN’s proton accelerator complex, with the principal physics objective of observing CP or T violation in the lepton sector • The most cost-effective way to do this – either a combination of superbeam and -beam or a neutrino factory using stored muons … will depend, in particular, on the advances to be made in neutrino oscillation studies over the next few years. … R&D is needed on a range of different detector technologies suited for different neutrino sources Blondel et al: hep-ph/0609102

35. POFPA dixit … redux2 • Continuing research on topics such as kaon physics, fixed-target physics with heavy ions, muon physics, other fixed-target physics and nuclear physics offers a cost-effective supplementary physics programme that would optimize the exploitation of CERN’s proton accelerators. … • However, we consider that these topics should not define the proton accelerator upgrade scenario, but rather adapt to whichever might be preferred on the basis of the first two priorities. Blondel et al: hep-ph/0609102

36. PAF dixit: Benefits for Physics