Physics potential of an upgraded LHC (SLHC at ~10 35 cm -2 s -1 ),

1. WAMDO Workshop on Accelerator Magnet Design and Optimization, CERN April. 3 -6 th, 2006 Physics potential of an upgraded LHC (SLHC at ~1035 cm-2 s-1), demands to detectors and machine D. Denegri, CE Saclay/DAPNIA/SPP

2. Z’ ~ 6TeV ADD X-dim@9TeV SUSY@3TeV 3000 Compositeness@40TeV H(120GeV)gg 300 Higgs@200GeV SUSY@1TeV 30 200 fb-1/yr SHUTDOWN 10-20 fb-1/yr 100 fb-1/yr 1000 fb-1/yr First physics run: O(1fb-1) Probable/possible LHC luminosity profile - need for L-upgrade in a longer term L = 1033 L = 1034 SLHC: L = 1035

3. Upgrades considered, physics potential of the LHC at 1035 cm-2 s-1 (SLHC) What improvements in the physics reachoperating theLHC at aluminosity of ~ 1035 cm-2 s-1 with an integrated luminosity ~ 1000 fb-1per year at √s ≈ 14 TeV i.e. retaining present LHC magnets/dipoles - an upgrade at a relatively modest cost for machine (IR) + experiments (< ~ 0.5 GSF) for ~ 2013-15 a more ambitious upgrade (but ~ 2-3 GSF!) would be to go for a √s ≈ 25 - 30 TeV machine (2018-20) changing LHC dipoles (~15T, Nb3Sn?) - just mentioned here For the 1035cm-2 sec-1 case: - expected modifications/adaptations of LHC and experiments/CMS, - improvements in some basic SM measurementsand inSM/MSSM Higgs reach - improvements inreach at high mass scales, main motivations for an upgrade i.e exploit maximally the “existing” machine and detectors

4. Nominal LHC and possible upgrade steps Nominal LHC: 7 TeV beams, - injection energy: 450 GeV, ~ 2800 bunches, spacing 7.5 m (25ns), bunch length 7.5 cm - 1.1 *1011 protons per bunch, b* at IP : 0.5 m  1034 cm-2 s-1 (lumi-lifetime ~10h) Possible upgrades/steps considered: -increase up to 1.7 *1011 protons per bunch (beam-beam limit)  2*1034 cm-2 s-1 - increase operating field from 8.3T to 9T (ultimate field)  √s ≈ 15 TeV minor hardware changes to LHC insertions or injectors: - modify insertion quadrupoles (larger aperture) for b* = 0.5  0.25 m - increase crossing angle 300 mrad  424 mrad - halving bunch spacing (12.5nsec)*, with new machine RF system  L ≈ 5 *1034 cm-2 s-1 major hardware changes in arcs or injectors: - SPS equipped with superconducting magnets to inject at ≈ 1 TeV  L ≈ 1035 cm-2 s-1 - new superconducting dipoles at B ≈ 15 Tesla for beam energy ≈ 13 TeV i.e. √s ≈ 25 TeV *12.5 nsec is more favorable for experiments, 10 or 15 nsec more favorable for the PS/SPS RF systems at 200 MHz, ultimately question of cost of electronics to experiments vs. to accelerators;

5. Main CMS areas affected by luminosity upgrade Tracker Beam pipe Forward shielding Endcap Yoke

6. Shielding between machine and HF Basic functions of the shielding elements between the machine area and HF are: -reduce the neutron flux in the cavern by 3 orders of magnitude -reduce the background rate in the outer muon spectrometer (MB4, ME3,ME4) by 3 orders of magnitude -reduce the radiation level at the HF readout boxes to a tolerable level . A.Ball Rotating system is near the limits of mechanical strength (doubly hinged structure), new concept or supplementary system around existing RS needed for SLHC running, time needed to open and close CMS would increase significantly (~1 week per shutdown) inner quadrupole triplet forward shielding

7. CMS yoke and forward detectors- modifications considered for SLHC End cap yoke for SLHC, acceptance up to |h ~ 2 Reinforced shielding inside forward muons, replacement of inner CSC and RPC’s Supplement YE4 wall with borated polythene Improve shielding of HF PMT’s Possibly increase YE1-YE2 separation to insert another detector layer? Free space in radius in the HF calo is : 14cm beam-pipe radius + 5cm clearance, the issue - if quads were to be located there or in the “TOTEM part”, is the neutron albedo into CMS acceptable

8. Experimental conditions at 1035 cm-2 s-1 (12.5ns) - considerations for tracker and calorimetry ~ 100 pile-up events per bunch crossing - if 12.5 nsec bunch spacing (with adequate/faster electronics, reduced integration time) - compared to ~ 20 for operation at 1034cm-2s-1 and 25 nsec (nominal LHC regime), dnch/dh/crossing ≈ 600 and ≈ 3000 tracks in tracker acceptance H  ZZ  eemm, mH = 300 GeV, in CMS Generated tracks, pt > 1 GeV/c cut, i.e. all soft tracks removed! I. Osborne 1032cm-2s-1 1035cm-2s-1 If same granularity and integration time as now: tracker occupancy and radiation dose in central detectors increases by factor ~10, pile-up noise in calorimeters by ~ 3 relative to 1034

9. Inner CMS tracking for SLHC From R.Horisberger • Pixels to much larger radius • Technology and Pixel size vary with radius • Not too large an extrapolation in sensor technology • Cost/Geometry optimization

10. CMS inner tracking for SLHC From R.Horisberger Pixels to be used to much larger radius, from ~10 cm up to ~ 60 cm Technology and pixel size vary with radius, not too large an extrapolation in sensor technology, cost geometry optimization: 3 pixel systems proposed: - system 1 - for maximal fluence and rate, two layers between ~ 10 -15 cm . ~ 400 CHF/cm2 - system 2 -large pixel system, two layers between ~ 15 - 30 cm . ~ 100 CHF/cm2 - system 3 -large area macro-pixel system,~four layers between ~ 30 - 60 cm . ~ 40 CHF/cm2 This 8 -layer system could eventually deal with up to 1200 tracks per unit of rapidity i.e. 1035 luminosity with 25 nsec bunch spacing.

11. VFCAL (rapidity range 3 - 5), rad. damage In CMS quarz fibers in iron ie Cerenkov calorimetry Tower 1 loses 60% of light during LHC, down to 4% of original after 10 years of SLHC. Tower 2 down to 23% after 10 years of SLHC. SLHC “kills” a few high eta towers. Andre Gribushin

12. Importance of VFCAL/feasability of forward jet tagging at 1035 cm-2 s-1 Fake fwd jet tag (|| > 2) probability from pile-up (preliminary ...) ATLAS full simulation Forward jet tagging needed to improve S/B in VB fusion/scattering processes pp  qqH, qqVV ….if still of interest in ~ 2015 ,but could also be crucial if no Higgs found by then! Cone size 0.2 SLHC regime “tagging jet” LHC regime with present ATLAS granularity cut at > ~ 400 GeV Method should still work at 1035: increase forward calo granularity, reduce jet reconstruction cone from 0.4 to ~ 0.2, optimise jet algorithms to minimize false jets

13. Foreseeable changes to detectors for 1035cm-2s-1overview • changes to CMS and ATLAS : • Trackers, to be replaceddue to increased occupancy to maintain performance, need improved radiation hardness for sensors and electronics - present Si-strip technology is OK at R > 60 cm - present pixel technology is OK for the region ~ 20 < R < 60 cm - at smaller radii(<~10 cm) new techniques required • Calorimeters: ~ OK - endcap HCAL scintillators in CMS to be changed - endcap ECAL VPT’s and electronics may not be enough radiation hard - desirable to improve granularity of very forward calorimeters - for jet tagging • Muon systems: ~ OK - acceptance reduced to |h| <~ 2.0 to reinforce forward shielding • Trigger(L1), to be replaced, L1(trig.elec. and processor) for 80 MHz data sampling VF calorimeter for “jet tagging”

14. Cost expectations for CMS upgrade for SLHC from J.Nash These costs do not include CERN staff required for upgrade work

15. Expectations for detector performances at 1035 cm-2 s-1 - overview • Electron identification and rejections against jets, Et = 40 GeV, ATLAS full simulation • Electron resolution degradation due to pile-up, at 30 GeV:2.5% (LHC)  3.5% (SLHC) • b-jet tagging performance: rejection against u-jets for a 50% b-tagging efficiency Preliminary study, ATLAS • performance degradation at 1035 factor of ~ 8 - 2 depending on Et • increase (pixel) granularity! • Forward jet tagging and central jet vetoing still possible - albeit at reduced efficiencies reducing the cone size to ≈ 0.2probability of fake double forward tag is ~ 1% for Ejet > 300 GeV (|h| > 2) probability of ~ 5% for additional central jet for Et > 50 GeV (|h| < 2)

16. ew physics, triple gauge boson couplings 14 TeV 100 fb-128 TeV 100 fb-1 14 TeV 1000 fb-128 TeV 1000 fb-1  DkZ Z Z Correlations among parameters In the SM TGC uniquely fixed, extensions to SM induce deviations • At LHC the best channels are: Wg Ing • and WZ  lnll Wg WZ 5 parameters describe these TGCs:g1Z (1 in SM), Dkz, Dkg, g, z(all 0 in SM)Wg final state probes Dkg, gand WZ probes g1Z, Dkz, z WZ • TGCs: a case where a luminosity increase by a factor ~10 is better than a center-of-mass energy increase by a factor ~ 2 WZ SLHC can bring sensitivity to g, zand g1Z to the ~ 0.001 level (of SM rad.corrections)

17. Higgs physics - new modes/larger reach Increased statistics would allow: •to look formodes not observable at the LHC for example: HSM Zg (BR ~ 10-3), HSM m+m- (BR ~ 10-4) - the muon collider mode! Hm to check couplings; HSM, H  etc masses well known by this time! • extend significantly coverage of the MSSM parameter space, for example in: A/Hm+m- A/H+-m  A/H+-m H A/H  m  Specific example for a new mode:  HSM m+m- 120 < MH < 140 GeV, LHC (600 fb-1)significance: < 3.5s, SLHC (two exps, 3000 fb-1each) ~ 7s

18. SLHC: improved reach for heavy MSSM Higgs bosons The order of magnitude increase in statistics with the SLHC should allow to extend the discovery domain for massive MSSM Higgs bosons A,H,H± example: A/H  tt  lepton + t-jet, produced in bbA/H Peak at the 5s limit of observability at the LHC greatly improved at SLHC, fast simulation, preliminary: • • • LHC 60 fb-1 S. Lehti SLHC 1000 fb-1  SLHC 1000 fb-1 gain in reach b-tagging performance comparable to present one required!

19. H /VLHC • A/H  mm- channel which most obviously • should benefit from increased statistics at SLHC(and increased cm energy/ VLHC • even more) • easy to trigger - but as main production mechanism is associated bbA/H production, good b-tagging performance highly desirable, i.e. trackers with performances comparable to present ones would be required

20. Higgs pair production and Higgs self coupling Higgs pair production can proceed through two Higgs bosons radiated independently (from VB, top) and from trilinear self-coupling terms proportional to HHHSM HHHSM +…. triple H coupling: HHHSM = 3mH2/v cross sections for Higgs boson pair production in various production mechanisms and sensitivity to lHHH variations very small cross sections, hopeless at LHC (1034), some hope at SLHC channel investigated, 170 < mH < 200 GeV (ATLAS): gg  HH  W+ W– W+ W–  l±njj l±njj with same-sign dileptons - very difficult! total cross section and HHH determined with ~ 25% statistical error for6000 fb-1 provided detector performances are comparable to present LHC detectors  arrows correspond to variations of HHH from 1/2 to 3/2 of its SM value

21. WZ vector resonance in VB scattering If no Higgs found, possibly a new strong interaction regime in VLVL scattering, this could become the central issue at the SLHC! For ex.: Vector resonance (r-like) in WLZL scattering from Chiral Lagrangian model M = 1.5 TeV, leptonic final states, 300 fb-1 (LHC) vs 3000 fb-1 (SLHC) lepton cuts: pt1 > 150 GeV, pt2 > 100 GeV, pt3 > 50 GeV; Etmiss > 75 GeV These studies require both forward jet tagging and central jet vetoing! Expected (degraded) SLHC performance is included Note event numbers! increased cm energy/ VLHC even better!! at LHC: S = 6.6 events, B = 2.2 events at SLHC: S/B ~ 10

22. SUSY at SLHC/VLHC - mass reach • Higher integrated luminosity brings increase in mass reach in squark, gluino searches, i.e. in SUSY discovery potential; • not too demanding on detectorsas very high Et jets, Etmiss are involved, large pile-up not so detrimental with SLHCtheSUSY reachis increased by ~ 500 GeV,up to ~ 3 TeV in squark and gluino masses (and up to ~ 4 TeV for 30 TeV VLHC) SLHC • the advantage of increased statistics • should be in the sparticle spectrum reconstruction • possibilities, larger fraction of spectrum, • requires detectors of comparable performance • to “present ones” Notice advantage of a 28 TeV machine….

23. SUSY at SLHC - importance of statistics After cuts ~ 100 evts at LHC M (gluino) M (sbottom) Reach vs luminosity, jets + Etmiss channel “Reach” means a > 5s excess of events over known (SM) backgrounds; discovering SUSY is one thing, understanding what is seen requires much more statistics! Compare for ex. 100 fb-1 reach and sparticle reconstruction stat limited at 100 fb-1 at “point G” (tgb = 20), as many topologies required, leptons, b-tagging… • This is domain where SLHC statistics may be decisive! but LHC-type detector performance needed

24. New gauge bosons, Z’   reach at SLHC Additional heavy gauge bosons (W, Z-like) are expected in various extensions of the SM symmetry group (LR, ALR, E6, SO(10)…..), LHC discovery potential for Z’ mm Examples of Z’ peaks in some models:  SLHC 1000 fb-1  LHC 100 fb-1 LHC reach ~ 4.0 TeV with 100 fb-1 full CMS simulation, nominal LHC luminosity regime ~ 1.0 TeV gain in reach ~ 1.0 TeV i.e. 25-30% in going from LHC to SLHC

25. Extra dimensions, TeV-1 scale model Theories with extra dimensions - with gravity scale ~ ew scale - lead to expect characteristic new signatures/signals at LHC/SLHC; various models: ADD, ABQ, RS… Example: two-lepton invariant mass TeV-1 scale extra dim model (ABQ-type, one “small” extra dim. Rc = 1/Mc) with Mc = 5 TeV, 3000 fb-1 peak due to first g, Z excitation at ~ Mc ; note interference betweeng, Z and KK excitations g, Z(n), thus sensitivity well beyond direct peak observation from ds/dM (background control!) and from angular distributions/ F-B asymmetry reach ~ 6 TeV for 300 fb-1 (LHC), ~ 7.7 TeV for 3000 fb-1 from direct observation indirect reach (from interference)up to ~ 10 TeV at LHC, 100 fb-1 ~ 14 TeV for SLHC, 3000 fb-1, e + m 10s

26. Possible physics situation after 3-5 years of LHC running/ conceivable scenarios for SLHC

27. General remarks on desirability for detector upgrades, SLHC vs LHC (I) •High mass/ TeV scale searches such as: SUSY reach (squarks, gluinos), W’, Z’, ZKK, R-S gravitons, LQ, extra dim monojets etc not much affected byhigher pile-up, nor by some reduction in acceptance for leptons, |h| < 2.5  |h| < 2.0, as heavy objects are centrally produced; excellent tracker still needed for muon momentum resolution, tracker isolation criteria; b and t-tagging performance somewhat less important •Important topics which would benefit greatly from the ~ 300 fb-1 to 3000 fb-1 increase, but depend on forward jet tagging and/or central jet veto, suffer from increased pile-up: pp  qqH, qqVV (heavy Higgs, MSSM Higgs, resonant or non-resonant WL,ZL scattering - an alternative to Higgs mechanism for EWSB direct slepton pair ( 2 leptons), and chargino-neutralino ( 3 leptons) pair production precision measurements of TGC, QGC ……. These studies require maintaining present calorimetric angular coveragepreferably withimproved granularityespecially in the forward region if “forward jet tagging” turns out to be important (if no Higgs found!), new detector techniques (quartz fibers and clading? or…) to sustain radiation damage

28. General remarks on desirability for detector upgrades, SLHC vs LHC (II) • b-tagging capability - probably most difficult to maintain at 1035 at the present 1034 (expected) level of performance, but would be most desirable, to increase the SUSY spectrum coverage, for stop, sbottom (especially in case of “inverted mass hierarchy” where these could be the only observable sparticles….), for precision measurements on SM Higgs BR’s, to extend MSSM Higgs searches in bbA/H, tbH± etc final states rare top decays (FCNC) t  u/c + g/Z, rare Bos,d decays…… •t-tagging capability, even more demanding on tracker/impact parameter/sec vertex measurements, for A/H  tt , H± t  for SUSY/stau spectroscopy (at large tgb neutralinos largely decay to tau-stau); GMSB with  t G3/2(scenario with NLSP) t± 3m, m+m-e, me+e-……. These topics require highest performance tracker, measurements close to beam pipe for impact parameter/sec. vertices, new tracking technologies needed for r < ~ 10 cm; t-related physics requires understanding hadronic t triggering at high luminosity; these studies also require minimizing pile-up i.e. optimizing the product of b/t-tagging efficiency and integrated luminosity!

29. Conclusions on SLHC In conclusion the SLHC (√s ≈ 14 TeV, L ≈ 1035 cm-2 s-1) would allow to extend significantly the LHC physics reach - whilst keeping the same tunnel, machine dipoles and a large part of “existing” detectors, however to exploit fully its potential inner/forward parts of detectors must be changed/hardened/upgraded, trackers in particular, to maintain performances similar to “present ones”; forward calorimetry of higher granularity would be highly desirable for jet tagging, especially if no Higgs found in the meantime!

30. spares

31. Forward beam pipe CASTOR TOTEM zone LHC thin pipe 13-16 m believed good for 1034 pp CASTOR & TOTEM easily installed/removed for special runs (eg heavy ion), interspersed with high lumi pp SLHC wide pipe (400mm) after HF and in its shadow A.Ball

32. ECAL Replacing EB electronics would be costly 3 MCHF - Off Detector 3 -10 MCHF New Front End electronics Depends on scope of change 4 - 5 MCHF Remove/Dismount/Integrate/Install Total of 10 -18 MCHF for ECAL Other detectors Changing Front End and Off-Detector components will likely be in the range of 1- 3 MCHF for each detector Estimate 10 MCHF for HCAL/Muons total Asynchronous running Still need to evaluate the efficiency losses and cost implications in the off detector electronics Cost issues for 10ns or 15ns

33. Level 1 trigger at SLHC/muon pt resol. at L1? • The trigger/DAQ system of CMS will require an upgrade to cope with the higher occupancies and data rates at SLHC • One of the key issues for CMS is the requirement to include some element of tracking in the Level 1 Trigger • There may not be enough rejection power using the muon and calorimeter triggers to handle the higher luminosity conditions at SLHC • Using the studies for HLT applications gives an idea of what could be gained using elements of the tracker in the Level 1 Muon rates in CMS at 1034 Note limited rejection power (slope) without tracker information!