1. LHC FUTURE Sascha Caron (RU and NIKHEF)

2. Outline  Summary of LHC machine plans (7 slides)  The aim of this talk: Discuss Physics questions and prospects in view of LHC options (20 slides)  Have >30 min. time for discussion 2 Disclaimer: Talk represents a personal selection of physics topics and my own judgement ! You might have a different opinion !

3. Physics  Is Electroweak Symmetry breaking caused by the Higgs boson ?  If yes, how do we rescue the Higgs from becoming as heavy as a grain of sand (“hiearchy problem”) ?  What is Dark Matter ? Is it a particle producible at a collider ?  What is the Quark Gluon Plasma ?  CP violation ? How good can we answer these big questions with the future LHC options ? Do we think a big question is missing (e.g. proton pdf at low x?) How good can we answer these big questions with the future LHC options ? Do we think a big question is missing (e.g. proton pdf at low x?) 3

4. LHC and upgrade options 4 ?

5. HL-LHC 5  Current option based on work since 2002 via FP6 and US- LARP grant:  After LHC incident early upgrade plans were transformed to HL-LHC project: - Decreasing beta* and increasing current  Lessons learned from todays LHC operation - Peak lumi near average lumi: Lumi levelling - Note that N_bunches will not be increased Large pile up rate expected Levelling means that the peak lumi is much higher than the levelled (true) Lumi, i.e. levelling value is “de-tuned” Then re-tune again to compensate beam loss  Flat lumi with time (tested already at LHC-B)  Levelling limits pile-up and deposited power Levelling means that the peak lumi is much higher than the levelled (true) Lumi, i.e. levelling value is “de-tuned” Then re-tune again to compensate beam loss  Flat lumi with time (tested already at LHC-B)  Levelling limits pile-up and deposited power Designs for Chamonix 2011

6. HL-LHC 6  Current option based on work since 2002 via FP6 and US- LARP grant:  After LHC incident early upgrade plans were transformed to HL-LHC project: - Decreasing beta* and increasing current  Lessons learned from todays LHC operation - Peak lumi near average lumi: Lumi levelling - Note that N_bunches will not be increased Large pile up rate expected Levelling means that the peak lumi is much higher than the levelled (true) Lumi, i.e. levelling value is “de-tuned” Then re-tune again to compensate beam loss  Flat lumi with time (tested already at LHC-B)  Levelling limits pile-up and deposited power Levelling means that the peak lumi is much higher than the levelled (true) Lumi, i.e. levelling value is “de-tuned” Then re-tune again to compensate beam loss  Flat lumi with time (tested already at LHC-B)  Levelling limits pile-up and deposited power Designs for Chamonix 2011 More radiation and higher detector occupancy require Detector upgrades (mostly trigger, inner and forward detectors)  Not considered in this talk (e.g. ATLAS phase 2 in year 2022) I concentrate on the physics gain of the different accelerator options  Detector comes afterwards (or is already in consideration for HL phase) (see also slides by Nigel)

7. HE-LHC 7  25-33 TeV centre of mass energy  1 TeV injection energy  Critical :15-20 T dipole field  Looks not like a high luminosity machine  Estimated costs 4-6 kMCHF  Difficult seems the quadrupole strenghts and beam injection and extraction 12,5 T reached recently at CERN

8. LHeC 8  Linac Ring (60 GeV) or Ring-Ring option (60-140 GeV electron beam) colliding with LHC beam  Electron Proton, Electron Deuteron and Electron HI options  Allowing simultaneous ep and pp running !

9. Detector Acceptance Requirements - Access to Q 2 =1 GeV 2 in ep mode for all x - 5 x 10 -7 requires scattered electron acceptance to 179 o Similarly, need 1 o acceptance in outgoing proton direction to contain hadrons at high x (essential for good kinematic reconstruction) Slide by Paul Newman 9

10. Design Parameter Summary electron beamRRLR e- energy at IP[GeV]60 140 luminosity [10 32 cm -2 s -1 ]17100.44 polarization [%]4090 bunch population [10 9 ]262.01.6 e- bunch length [mm]100.3 bunch interval [ns]2550 transv. emit.  x,y [mm] 0.58, 0.290.050.1 rms IP beam size  x,y [  m] 30, 1677 e- IP beta funct.  * x,y [m] 0.18, 0.100.120.14 full crossing angle [mrad]0.9300 geometric reduction H hg 0.770.910.94 repetition rate [Hz]N/A 10 beam pulse length [ms]N/A 5 ER efficiencyN/A94%N/A average current [mA]1316.65.4 tot. wall plug power[MW]100 proton beamRRLR bunch pop. [10 11 ]1.7 tr.emit.  x,y [  m] 3.75 spot size  x,y [  m] 30, 167  * x,y [m] 1.8,0.50.1 bunch spacing [ns]25 RR= Ring – Ring LR =Linac –Ring Include deuterons (new) and lead (exists) 10 fb -1 per year looks possible … ~ 100 fb -1 total 10

11. Design Parameter Summary electron beamRRLR e- energy at IP[GeV]60 140 luminosity [10 32 cm -2 s -1 ]17100.44 polarization [%]4090 bunch population [10 9 ]262.01.6 e- bunch length [mm]100.3 bunch interval [ns]2550 transv. emit.  x,y [mm] 0.58, 0.290.050.1 rms IP beam size  x,y [  m] 30, 1677 e- IP beta funct.  * x,y [m] 0.18, 0.100.120.14 full crossing angle [mrad]0.9300 geometric reduction H hg 0.770.910.94 repetition rate [Hz]N/A 10 beam pulse length [ms]N/A 5 ER efficiencyN/A94%N/A average current [mA]1316.65.4 tot. wall plug power[MW]100 proton beamRRLR bunch pop. [10 11 ]1.7 tr.emit.  x,y [  m] 3.75 spot size  x,y [  m] 30, 167  * x,y [m] 1.8,0.50.1 bunch spacing [ns]25 RR= Ring – Ring LR =Linac –Ring Include deuterons (new) and lead (exists) 10 fb -1 per year looks possible … ~ 100 fb -1 total 11

12. Physics at LHeC 12 Search for new phenomena in eP ?  Case very limited, almost all scenarios (LQ, RPV SUSY) studied already with LHC  Depending on new physics (see above) an eP collider is interesting confirmation/study tool Higgs physics ? There are studied that show that eLHC might be better than LHC to study Hbb couplings, smaller background processes. Limited QCD: Aim is very precise alpha_s measurement (important!, needs to be compared with LC) F2 at low x, parton densities (ok) Gluon saturation (not so clear to me if this is guranteed) Physics case for QCD very strong I think  Strong Dutch QCD community ?

13. What is Initial State of LHC AA Collisions? Very limited x, Q 2 and A range for F 2 A so far (fixed target experiments covered x >~ 10 -2 ) LHeC extends kinematic range by 3-4 orders of magnitude with very large A [and eA potentially provides control for AA QGP signatures] Gluons from saturated nuclei  Glasma?  QGP  Reconfinement Slide by Paul Newman 13

14. Status of HL, HE-LHC and LHeC  On the machine side, the HL-LHC project approved  On the experiment side, HL-LHC people work on TDR (funds?)  LHeC status: Draft conceptual design report (>500 pages), under review till may 2011 ?  HE-LHC status: Feasibility study has been launched 14

15. Sqrt(s) upgrade 15 Increase for high mass particles since lower x can produce high mass particle Note the large increase of gluon and sea quark density at low x sqrt(s) upgrade most relevant for high mass searches b-cross section only increased slightly Higgs by factor 3-4 SUSY can be increase by 100! LHC30

16. Prospects LHC-B  My person opinion is that the energy upgrade is irrelevant for LHC-B  Likewise the LeHC option is not interesting for CP violation or rare-decay physics  agreed ?  Most important is the LHC-B luminosity upgrade  LHC-B lumi upgrade and HL-LHC are uncorrelated upgrades !  Increase integrated luminosity from 5 to 50 fb-1in the 2017 ( L > 1033 cm − 2s − 1)  Here the physics case if very strong in my mind! 16

17. LHC-B luminosity upgrade 17  Primary goal of LHCb is to find BSM physics  A limit of 1fb-1 can not be overcome without upgrading the detector  Upgrade would allow 5fb-1 per year and larger trigger rate (40 MHz readout!)  Physics includes besides flavor: Majorana Neutrinos, exotic Higgs decays and precise EW measurements

18. LHC-B luminosity upgrade 18  Physics point very strong (not much needs to be discussed here ?)

19. Prospects ALICE 19  Broadly discussed in talk by Marco van Leeuwen  Is there a physics case for the LHC energy upgrade ?  Not considered, Marco might discuss this…  Physics case for an electron-ion collider strong ?

20. LHC Scenarios considered in the following  What can we do with 300 fb-1 at 14 TeV  What can we do with 3000 fb-1 at 14 TeV  What can we do with 300 fb-1 at 30 TeV 20 Questions of energy and/or lumi upgrade most important for ATLAS Prospects ATLAS

21. WW scattering, BSM searches Higgs BR, BSM searches Higgs BR, BSM measurements No Higgs, no BSM (SUSY) Higgs at 115- 127 GeV, no BSM (SUSY) Higgs at 115- 127 GeV and BSM signal(s) (SUSY) Physics in 2013  Only 3 possible physics scenarios 21 BSM includes LHC-B Signal !

22. Physics in 2013 22  Answer might also depend on Higgs mass: Depending on top mass and alpha_s : New physics scale required if m_higgs < 129 (+- 6) GeV (arxiv 1205.2893)

23. Physics scenarios  No Higgs, no BSM:  Higgs, no BSM:  Higgs, BSM: 23

24. Higgs and BSM signal scenario 24 Squarks likely heavy, maybe in reach of HE-LHC? Consider discovery of a new particle at O(1) TeV (or LHC-B signal for non-BSM decays) Natural question to ask : Is there anything else ? Spectrum ? Pattern ? Is it SUSY? Technicolor? Little Higgs? Even in case of non-observation constraining information…  Very big case for LHC energy upgrade if new BSM particle is discovered directely!  LHC-B signal will be more difficult (which model?) Not much to be discussed…(for me) Consider discovery of a new particle at O(1) TeV (or LHC-B signal for non-BSM decays) Natural question to ask : Is there anything else ? Spectrum ? Pattern ? Is it SUSY? Technicolor? Little Higgs? Even in case of non-observation constraining information…  Very big case for LHC energy upgrade if new BSM particle is discovered directely!  LHC-B signal will be more difficult (which model?) Not much to be discussed…(for me)

25. No Higgs scenario 25  In the SM unitarity is restored in V_L V_L scattering by the scalar Higgs  If no Higgs: Prospects for WW scattering BSM model dependent.  Literature suggests that 300 fb-1 at 14 TeV can probe recent models, some scenarios need 3000 fb-1  Energy range of Linear Collider might be limited…  Let’s consider this scenario only if there is really no signal in the 2012 data…

26. Prospects Higgs physics  Higgs cross section and couplings (BR) consistent with SM predictions ?  More than 1 Higgs ? (2HDM, more) 26 2 important questions after Higgs discovery ? (Again the search for BSM physics)

27. Prospects Higgs physics 27 Higgs cross section : Consistent with SM value? number of Higgs produced and decay to gamma gamma, 0.001) : Statistical uncertainty: 14 TeV (300 fb-1)14 TeV (3000 fb-1)30 TeV (300 fb-1) 15000150 00075000 0.8 %0.25 %0.36 % LO pythia  No big improvement expected from HE-LHC for cross section and couplings!  Note that mass measurement can be done with error limited by EM calorimeter (0.1% precision)  No big improvement expected from HE-LHC for cross section and couplings!  Note that mass measurement can be done with error limited by EM calorimeter (0.1% precision) Higgs BR will still have Large errors With 14TeV 300 fb-1 40-60 % for tau and b’s!?

28. Prospects Higgs physics 28 Higgs cross section : Consistent with SM value? number of Higgs produced and decay to gamma gamma, 0.001) : Statistical uncertainty: 14 TeV (300 fb-1)14 TeV (3000 fb-1)30 TeV (300 fb-1) 15000150 00075000 0.8 %0.25 %0.36 % LO pythia  No big improvement expected from HE-LHC for cross section and couplings!  Note that mass measurement can be done with error limited by EM calorimeter (0.1% precision)  No big improvement expected from HE-LHC for cross section and couplings!  Note that mass measurement can be done with error limited by EM calorimeter (0.1% precision) Higgs BR will still have Large errors With 14TeV 300 fb-1 40-60 % for tau and b’s!? In my mind this will be best done with a Linear Collider ! Quadratic and trilinear Higgs self coupling (Jakobs, Buescher)

29. Prospects : More Higgs particles ? 29  Example 2HDM from MSSM  Shown is reach for 300 fb-1 14 TeV LHC, discovery of heavy higgs not possible everywhere !  Other options need some new dedicated studies I think (also in light of a Higgs discovery)  There might be a case for the HE-LHC

30. Prospects: Standard Model check  LHC will not be the best machine to improve on important SM parameters like top mass, alpha_s (or m_W?).  Strong case for Linear Collider  I see no argument here for HE-LHC …  LHC will not be the best machine to improve on important SM parameters like top mass, alpha_s (or m_W?).  Strong case for Linear Collider  I see no argument here for HE-LHC … 30

31. Prospect : Supersymmetry  SUSY is still Nr.1 BSM theory  In case of no discovery: what is the reach with HL-LHC and HE-LHC  SUSY is alive if m_higgs = 125 GeV  Higgs of 125 GeV points to heavy or degenerated stop quarks  1 st and 2 nd generation squarks might be very heavy >> 1 TeV  SUSY is still Nr.1 BSM theory  In case of no discovery: what is the reach with HL-LHC and HE-LHC  SUSY is alive if m_higgs = 125 GeV  Higgs of 125 GeV points to heavy or degenerated stop quarks  1 st and 2 nd generation squarks might be very heavy >> 1 TeV I think we should use the Hierachy problem solution as guiding principle: -SUSY has min. fine tuning (WHAT FINETUNING DO WE ALLOW?):  Stop should be not too heavy (< 1 – 1.5 TeV)  Gluino should be not too heavy (< 3-5 TeV) 31

32. Prospects: Supersymmetry Number of events Mass of the gluino Number of events needed to place a limit LHC14,300 LHC14,3000 LHC30,300+ Now 32 LO prospino, Gluino production Squarks very heavy Test case: gluino production and decay to stop quarks

33. SUSY via monojet initial state radiation  Initial state radiation monojet signal: Limit for stops now (7 TeV, 1 fb-1): 150 GeV Limit with 14 TeV, 300 fb-1 : 500-700 GeV ? Limit with 14 TeV, 3000 fb-1: 700-900 GeV ? Limit with 30 TeV, 300 fb-1 : >1 TeV ?  Reach difficult to estimate, analysis very sensitive to the systematic uncertainty  It seems that here the 30 TeV is maybe NOT needed to exclude stop till 1 TeV… 33 Consider worst case: Stops decay quasi-invisible (e.g. via charm and neutralino )

34. Case for LC, no strong case for 30 TeV LHC, but for lumi upgrade Case for LC, no strong case for 30 TeV LHC Strong case for LC and 30 TeV LHC No Higgs, no BSM (SUSY) Higgs at 115- 127 GeV, no BSM (SUSY) Higgs at 115- 127 GeV and BSM signal(s) (SUSY) Personal view: Physics in 2020 34 BSM includes LHC-B Signal !

35. Summary: very personal view 35  Must do : LHC luminosity upgrade (incl. LHC-B)  Must do : Linear Collider (which energy?) or muon collider  If resources are available or BSM discovery : LHC energy upgrade  If resources are available: LHeC My judgement prior to the LHC 14 TeV data

36. Extra Slides 36

37. To read  LHC upgrade plans: Options and strategy, L. Rossi  eLHC slides from Paul Newman talks  Letter of intent for the LHC-B upgrade ... Many other sources, no time to list them … 37

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40. Previously considered as `QCD explorer’ (also THERA) Main advantages: low interference with LHC, high E e (  150 GeV?) and lepton polarisation, LC relation Main difficulties: lower luminosity <10 33 cm -2 s -1 ? at reasonable power, no previous experience exists First considered (as LEPxLHC) in 1984 ECFA workshop Main advantage: high peak lumi obtainable (~2.10 33 cm -2 s -1 ) Main difficulties: building round existing LHC, e beam energy (60GeV?) and lifetime limited by synchrotron radiation LINAC-RING RING-RING How Could ep be Done using LHC? … whilst allowing simultaneous ep and pp running … 40

41. Current Knowledge: Nuclear Parton Densities R i = Nuclear PDF i / (A * proton PDF i) Nuclear parton densities don’t scale with A due to Fermi motion, shadowing corrections … All parton types poorly constrained for x < 10 -2 Gluon density essentially unknown Slide by Paul Newman 41

42. LHeC: Schedule and Remarks Aim to start operation by 2023 [high lumi phase of LHC] The major accelerator and detector technologies exist Cost is modest in major HEP project terms Steps: Conceptual Design Report, 2012 Evaluation within CERN / European PP/NP strategy If positive, move towards a TDR 2013/14 42

43. Can Parton Saturation be Established in ep @ LHeC? Conclusion: clearly establishing non-linear effects needs a minimum of 2 observables … (F 2 c may work in place of F L )… Simulated LHeC F 2 and F L data based on a dipole model containing low x saturation (FS04-sat)… … NNPDF (also HERA framework) DGLAP QCD fits cannot accommodate saturation effects if F 2 and F L both fitted 43

44. Prospects: Supersymmetry  I consider therefore as a test case gluino production and decay to stop quarks  Consider stops produced by gluino decays  2 nd possibility: “worst case”, coloured SUSY particles are invisible due to small mass splitting with neutralino  Consider Monojet and monophoton signal 44

45. LHC lumi schedule till upgrade 45 Repair splices Repair splices Some Pre-work for HL phase Some Pre-work for HL phase HL-LHC installation HL-LHC installation

46. LHEC IMPACT ON PARTON DENSITIES Full simulation of inclusive NC and CC DIS data, including systematics  NLO DGLAP fit using HERA technology… … big impact at low x (kinematic range) and high x (luminosity) … precise light quark vector, axial couplings, weak mixing angle … full flavour decomposition possible Gluonu valence

47. ATLAS detector upgrade 47  Phase 0 (2013-2014) : insertable b-layer (4 th pixle layer) and others  Phase 1 (2018) : New muon small wheels (endcap MDT and CSCs) (several techmologies under consideration), new trigger schemes (Fast track trigger, combining triggers at L1)  Phase 2 (2022) : New inner detector, further trigger and new calorimeter readout electronics

48. Summary: very personal view  Seems to be not much we can discuss… since it’s a gradual development: - No HE-LHC without HL-LHC option  Physics case for HE-LHC not clear to me, depends on LHC physics at 14 TeV  Physics case for HL-LHC very clear, needed in order to fully exploit Higgs and BSM parameter space.  LHeC option is very interesting, this is a QCD machine, if no new physics is found at LHC. Needs also support from QGP community.  Personally I can only judge after seeing the 14 TeV LHC data.  In comparison to LHeC and HE-LHC is the Linear Collider a “must-do” experiment 48

49. SUSY summary  HL-LHC: Gluino reach might be increased from 2.2 to 2.9 by luminosity upgrade  HE-LHC: Gluino reach might be increased from 2.9 to 4-4.5 TeV by energy upgrade  Considering also other searches for stops, the case for HE-LHC is not convincingly strong… (if no SUSY discovery before)  Maybe there will be input from next generation Dark Matter direct detection …  LC could directly probe WIMP production ! 49