1 / 34

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

Journees CMS France, 29 - 31 Mars 2006 Mont Sainte Odile, Alsace. Physics potential of a luminosity upgraded LHC (SLHC at ~10 35 cm -2 s -1 ) D. Denegri , CE Saclay/DAPNIA/SPP. aspects discussed: - machine - detectors

makala
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Journees CMS France, 29 - 31 Mars 2006 Mont Sainte Odile, Alsace Physics potential of a luminosity upgraded LHC (SLHC at ~1035 cm-2 s-1) D. Denegri, CE Saclay/DAPNIA/SPP aspects discussed: - machine - detectors - physics

  2. LHC - first years

  3. 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 - longer term L = 1033 L = 1034 SLHC: L = 1035

  4. 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 + experiments (< 0.5 GSF) for ~ 2013-15 a more ambitious upgrade (but ~ 2-3 GSF!) would be to go for a √s ≈ 30 TeV machine changing LHC dipoles (~16T, Nb3Sn?) - not discussed here - 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

  5. Nominal LHC and possible upgrades Nominal LHC: 7 TeV beams, - injection energy: 450 GeV, ~ 2800 bunches, spacing 7.5 m (25ns) - 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 (12.5 nsec), with new 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 ≈ 16 Tesla for beam energy ≈ 14TeV i.e.√s ≈ 28 TeV

  6. Nominal LHC and possible upgrades (II) • increase operating field from 8.3T to 9T • (ultimate field) •  √s ≈ 15 TeV major hardware changes in arcs or injectors: - SPS equipped with superconducting magnets to inject at ≈ 1 TeV  Luminosity increase by factor ≈ 2 - new superconducting dipoles at B ≈ 16 Tesla (Nb3Sn?) for beam energy ≈ 14TeV i.e. √s ≈ 28 TeV Last step would be very expensive…2 - 3 GSF.

  7. CMS areas affected by luminosity upgrade

  8. 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 . Rotating system is near the limits of mechanical strength,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)

  9. CMS longitudinal view/ modifications considered for SLHC - yoke and forward End cap yoke for SLHC, muon 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?

  10. 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

  11. Inner CMStracking 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

  12. Foreseeable changes (overview)to detectors for 1035cm-2s-1 • 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(<10cm) 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), largely to be replaced, L1(trig.elec. and processor) for 80 MHz data sampling VF calorimeter for “jet tagging”

  13. Compact NbTi quadrupoles, 70 mm aperture To be inserted in CMS and ATLAS to reduce L* With iron 160 T/m – Φ 250 mm Φ 340 mm including cryostat No stray field outside cold mass Saturated iron 145 T/m – Φ 160 mm Φ 250 mm including cryostat Stray field outside cold mass 80 mm cold mass 125 mm cold mass For higher gradients (200 T/m with NbTi – 275 T/m with Nb3Sn) cryostat dimensions will increase beyond 400 mm

  14. 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/relevant in ~ 2015! 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

  15. Cost Summary/CMS/SLHC from J.Nash These costs do not include CERN staff required for upgrade work

  16. 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)

  17. 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)

  18. 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mn •   • in channels like: • A/H m A/H m A/H   • A/H  4  to check couplings; HSM, H  etc masses well known by this time! 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

  19. H±mn a MSSM   under study not observable at LHC with 300 fb-1 givesm(H±) Comparison of these two rates should give gHtn/gHmn = mt/mm  f  mfermion • Preliminary results (R. Kinnunen): • for m(H±) = 400 GeV, tgb = 40, 1000 fb-1 • s(H±) = 219 fb (T. Plehn), BR = 0.00049, s*BR = 0.073fb • for ptm > 100 GeV, Etmiss > 150 GeV, muon isolation, • W mass, • one b-jet tag, veto on 4th central jet: • 5 events left, no bkgd from tt and W+jets - hopeful! (more studies of bkgd needed)

  20. 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!

  21. 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

  22. WZ vector resonance in VB scattering If no Higgs found, possibly a new strong interaction regime in VLVL scattering, resonant or not;this could become the central issue at the SLHCexample with a resonant model: 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! at LHC: S = 6.6 events, B = 2.2 events at SLHC: S/B ~ 10

  23. SUSY at SLHC/VLHC - mass reach • Higher integrated luminosity brings an obvious 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 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….

  24. 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

  25. 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

  26. 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 angular distributions 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

  27. Extra-dimensions, Randall-Sundrum model, LHC regime pp GRS eefull simulation and reconstruction chain in CMS, 2 electron clusters, pt > 100 GeV, |h| < 2.5, el. isolation, H/E < 0.1, corrected for saturation from ECAL electronics (big effect on high mass resonances!) signal DY bkgd C. Collard Single experiment fluctuations! c = 0.01 c = 0.01 LHC 100 fb-1 1.8 TeV LHC stat limited! A factor ~ 10 increase in luminosity obviously beneficial (SLHC!) for mass reach - increased by 30% - and to differentiate a Z’ (spin = 1) from GRS (spin = 2)

  28. Conclusions, physics, SLHC vs LHC (I) -ew physics: - multiple VB production, TGC, QGC, SM Higgs….this becomes “precision physics”, the most sure/assured one of being at the rendez-vous, TGC testable at level of SM radiative corrections, - ratios of SM Higgs BRs to bosons and fermions measurable at a ~ 10% level, - Higgs self-couplings, first observation possible only at SLHC, of fundamental importance as a test of ew theory, these measurements however require full performance detectors - strongly coupled VB regime - central issue if no Higgs found! : getting within reach really only at SLHC butrequires full performance calorimetry, forward one in particular - SUSY: - MSSM Higgs (A/H,H±) parameter space coverage significantly improved (A/H  tt, mm), - new modes become accessible (H±  - SUSY discovery and sparticle mass reach augmented by ~ 20-25%, spectrum coverage and parameter determination improved some ofthese measurements (for ex. sparticle spectrum reconstruction ) require full performance detectors,b-tagging,tau-tagging…. in

  29. Conclusions SLHC vs LHC (II) - search for massive objects : -new heavy gauge bosons, manifestations of extra dimensions as KK-recurencies of g, W, Z, gluon, R-S gravitons, LQ’s, q*,…… reach improved by 20-30%, but these are much more speculative/unsure topics, probably only limits to be set….. these measurements are least demanding in terms of detector performances - rare/forbidden decays: - top in t  u/c +g/Z, sensitivity down to BR ~ 10-6; tau in t± 3m, m+m-e, me+e-… possibly to BR ~ 10-8 (to be studied!), B-hadrons etc requires full performance detectors

  30. 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 ifnoHiggs!

  31. spares

  32. Level 1 trigger at SLHC • 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

  33. Within 5 years of LHC start New layers within the volume of the current Pixel tracker which incorporate some tracking information for Level 1 Trigger Room within the current envelope for additional layers Possibly replace existing layers “Pathfinder” for full tracking trigger Proof of principle, prototype for larger system Elements of new Level 1 trigger Utilize the new tracking information Correlation between systems Upgrade to full new tracker system by SLHC (8-10 years from LHC Startup) Includes full upgrade to trigger system Tracker upgrade strategy

  34. Assume new tracker and trigger electronics can cope with the choice of bunch timing Electronics for other detectors ECAL - not easily accessible HCAL - can be changed MUONS - can be changed Situation for 12.5ns or 25ns very different from 10ns or 15 ns Electronics clocked at 40 MHz QPLL which synchronizes links to this clock has a very narrow frequency lock Can clock system at 40 MHz and cope with 12.5ns Issues with bunch crossing timing

More Related