IV International Symposium on LHC Physics, Fermilab, May 1-3, CMS Physics Reach at High and Super-High Luminosities Jim Rohlf Boston University

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1 IV International Symposium on LHC Physics, Fermilab, May 1-3, 2003 CMS Physics Reach at High and Super-High Luminosities Jim Rohlf Boston University

2 Big Picture: Reaching for what? FIRST look at the TeV mass scale to find a clue to the hierarchy problem... (What lies between the weak scale and the Planck mass?) Medium Picture: EXPLORE the mechanism for electroweak symmetry breaking... (How do W/Z interact at high energies?) Small Picture: NAIL down the elusive Higgs... J. Rohlf, LHC IV p. 2

3 pp collisions s = 14 TeV Compact Muon Solenoid low luminosity (initial) high luminosity (design) super-high luminosity instantaneous integral integral (cm 2 s 1 ) 1 month 4 months (LHC y) fb 1 20 fb fb fb fb fb 1 Needs hardware upgrades! J. Rohlf, LHC IV p. 3

4 σ LHC Rates s = 14 TeV, cm 2 s 1 Jet mass (GeV) high lum. pp W/Z 0 top TeV jets TeV exotica level-1 hardware level-2/3 software Last event: x F = ½ 10 for super-high lum. L1 trigger (high lum.) (GeV) (khz) Trigger Thresh. Rate iso. e/γ e/γ iso. µ µ τ τ jet jet jet miss jet E T 113/ e jet 25/ µ jet 15/ min. bias 1.0 total (10% overlap) 33.5 (designed for 100 khz with 3 safety) J. Rohlf, LHC IV p. 4

5 Calculating Reach Calculating physics reach at the next collider has become a cottage industry in the last 20 years. True reach involves many subtleties: Trigger, detector resolution and efficiency, event pileup, and the ubiquitous QCD backgrounds (which always seem to be underestimated!). For processes near the limit of detection (usually the most interesting) we need a full simulation and event reconstruction (ORCA = Object-oriented Reconstruction for CMS Analysis) CPU time needed on a GHz P-3 is 500 s to simulate a TeV-scale event! J. Rohlf, LHC IV p. 5

6 Standard-Model Higgs Recent Studies + Inclusive Cross Section Events 100 fb 1 σ (pb) M. Spira et al. NLO QCD m H (GeV) J. Rohlf, LHC IV p. 6

7 SM: H 0 Branching Ratio and Width Typical QCD corrections: M. Spira Branching Ratio Total Width "toilet bowl" J. Rohlf, LHC IV p. 7

8 SM: qqh 0 Vector Boson Fusion (depends only on WWH coupling, not top) main background: t t + X H 0 WW* l + ν l ν D. Green et al. signal Rapidity of tagged jets φ ll fb σ T M H =120 GeV Forward jets (p T > 20 GeV, η > 4.20) b-jet veto (impact parameter cuts) lepton iso. (p T > 20 GeV, η < 2.5) signal + background lepton cuts (m l l < 60 GeV, φ l l < 140 ) jet-jet mass (m j j > 600 GeV) extra jet veto (p T > 20 GeV) WW m T ( GeV) H W W* background signal signal m ll background cuts 100 fb 1 : 220 events, 680 background events per 10 GeV J. Rohlf, LHC IV p. 8

9 SM: t t H 0 final state: qqb lνb bb event selection: lepton, 4 b-tag jets, 2 non-b jets, W mass, t mass (2) b E T b Rapidity H main backgrounds: t t bb, t t Z b b V. Drollinger et al. events per 10 GeV efficiency: t t H (115 GeV) 1.3% t t bb 0.4% t t Z 0.2% J. Rohlf, LHC IV p. 9

10 SM: WH 0 Wbb final state: l ± ν bb H b σ = 2.5 pb at M H =100 GeV, huge backgrounds from: tt (570 pb), tb (320 pb), Wjj (30 pb),wz (27 pb) b-tag is important b V. Drollinger et al. WWH coupling J. Rohlf, LHC IV p. 10

11 SM: γ γ,ww, Z Z J. Rohlf, LHC IV p. 11 events per 500 MeV events per 50 GeV γγ 100 fb 1 m (GeV) γγ WW l + νl ν qqh m/m ~ 0.1% CMS Warhorses events per 2 GeV events per 50 GeV ZZ* l + l l + l m (GeV) m 4l (GeV) WW l ± νjj qqh events per 20 GeV events per 10 GeV ZZ l + l l + l Γ/Γ ~ 5-10% m 4l (GeV) M. Dittmar ZZ l + l νν (no mass peak) (m T ) WW (GeV) m WW (GeV) missing E T

12 SM Higgs: Summary signal significance Observable in multiple modes over entire mass range. final state: lν bb σ WH l ± νbb tth qqh jjblνbbb j jl + ν l ν γ γ high luminosity, 100 fb 1 l + νl ν l + l l + l qqh jjl ± νjj ννjj l + l l + l 1000 fb 1 5σ m H (GeV) J. Rohlf, LHC IV p. 12

13 MSSM Higgs Two parameters: Minimal Supersymmetric Standard Model... a 3-ring circus of Higgs bosons LEP limits are substantial! stay alive with maximal top-squark mixing h 0 behaves like SM-Higgs and is light low-mass SM channels are important H + H H 0 h 0 A 0 J P =0 J P = m h max. mixing m A = 1 TeV tan β Review of Higgs Physics: J. Gunion PASCOS 03. m t = 175±5 TeV min. mixing (decoupling limit) J. Rohlf, LHC IV p. 13 h 0 H ± H 0

14 MSSM Higgs Radiation from b s is important couplings: bbh 0, bba 0 ~ tanβ τ + τ H 0, τ + τ A 0 tanβ τ + τ also an important decay BR A 0 tanβ = 30 10% J. Rohlf, LHC IV p. 14

15 MSSM: bbh 0 /A bbτ + τ bb j j b H τ + Background dominated by QCD b b τ τ b H τ + events per 30 GeV R. Kinnunen, A. Nikitenko 60 fb 1 m A = 500 GeV tanβ = 20 fb σ T signal + back ground trigger signal impact parameter φ(j,j)<178 mass reco. b-tag E T >20 GeV 2 nd jet veto mass cut m ττ (GeV) 20% background from W, Z, top after cuts J. Rohlf, LHC IV p. 15

16 MSSM: bbh 0 /A bbτ + τ bbl ± j fb events per 20 GeV mass window ( GeV) The lepton b-tag is isolation important! signal + background signal τ selection b-tag cuts Backgrounds before b-tag events per 20 GeV τ-selection reduces b background b-tag reduces W/Z background After cuts, W τ from top dominates background R. Kinnunen, A. Nikitenko m A = 300 GeV 30 fb 1 tanβ = 40 m ττ (GeV) m ττ (GeV) J. Rohlf, LHC IV p. 16

17 MSSM: bbh 0 /A 0 bbτ + τ bbeµ 2 isolated high-p T leptons: no track p T >2 GeV with R < 0.3 main background from top, Z b-tag suppresses the WW background events per 10 GeV S. Lehti ττ eµ 30 fb 1 m A = 200 GeV tanβ = 20 fb σ T signal + background iso. lepton, p T >20 GeV, η <2.5 impact parameter m ττ (GeV) signal cuts b-tag E T >20 GeV (e + e and µ + µ suffer from high DY background) J. Rohlf, LHC IV p. 17

18 MSSM: H 0 /A 0 χ 0 χ 0 4l Easy target if kinematically possible l l ~ 0 Backgrounds from SM χ ~ H 0 /A 0 2 ~ 0 l χ (t t, ZZ, Zbb, Zcc, Wtb) 1 l and SUSY are suppressed ~ 0 l with jet and Z veto χ 2 ~ l ~ 0 χ fb 1 Events per 15 GeV 20 m A = 350 GeV m (GeV) J. Rohlf, LHC IV p. 18

19 semileptonic t m t (GeV) m tb (GeV)

20 MSSM: th t τ ν Main backgrounds: t t, W + X th + t τ + ν hadronic tau decay events per 40 GeV Radiation from a b-quark b H ν t R. Kinnunen 30 fb 1 m H = 400 GeV τ fb σ T E τ > 100 GeV p τ /E τ > 0.8 signal + background signal missing E T > 100 GeV 3 jets E T >20 GeV m jj m W < 15 GeV cuts m jjj m t < 20 GeV b-tag E T > 30 GeV φ(τ, miss E T ) < 60 m (τ, miss. E T ) (GeV) J. Rohlf, LHC IV p. 20

21 MSSM: bbh 0 /A 0 bbµ + µ b H µ + b µ µ b H µ + events per GeV b 20 fb 1 small BR: (m µ /m τ ) 2 = m A = 150 GeV tanβ = 30 clean signature R. Kinnunen J. Rohlf, LHC IV p. 21 m µµ (GeV) m µµ (GeV) t t background reduced with central jet veto

22 MSSM Higgs: Summary SM-like h 0 H 0, A 0 H ± tanβ th ± ttb ττ l+jet 30 fb 1 χ 0 χ 0 No signal: small BR to τ + τ m A (GeV) J. Rohlf, LHC IV p. 22

23 SUSY: Sparticle Search Supersymmetry Distinctive signature of leptons, jets, missing E T for some events J. Rohlf, LHC IV p. 23

24 Sparticle Reconstruction J. Rohlf, LHC IV p. 24 g ~ pair produced with squark or 2 nd gluino (1 or 2 jets + missing E T ) b b ~ Example: m 1/2 = 375 GeV, m 0 = 120 GeV, tanβ = 20 ~ χ 2 0 b l ~ l ± ± ~ 0 χ 1 l ± Event signature: 2 leptons, p T >15 GeV, η < b-jets, p T >20 GeV, η < 2.0 Large Missing E T SM backgrounds: t t, Z+jet, W+jet, ZZ, WW, ZW 500 fb 1 missing E T > 250 GeV A. Tricomi et al. Z 0 end point: 139±3 GeV ±14 GeV 913±10 GeV Dilepton mass (GeV) 0 ~ b mass (GeV) g ~ mass (GeV)

25 msugra Minimal Supergravity gaugino S. Abdoulline squark scalar gluino J. Rohlf, LHC IV p. 25

26 Kaluza-Klein Graviton Randall-Sundrum Model Exploiting the geometry of spacetime to solve the hierarchy problem. events per 10 GeV events per 20 GeV (or gluons) Electrons m e + e G G σ b = 86 fb Muons m µ + µ G. Wrochna et al. 100 fb 1 events per 2.5 GeV σ b = 1.4 fb c γ m γγ m G J. Rohlf, LHC IV p. 26

27 Z Z l + No. of events e + e + µ + µ l 1000 fb 1 mass reach 100 fb fb 1 Corrected for: acceptance reconstruction efficiency resolution crystal saturation pileup at cm 2 s 1 Backgrounds: Drell-Yan 2% t t < 1% m Z J. Rohlf, LHC IV p. 27

28 CMS Mass Reach: Summary Luminosity upgrade extends the mass reach by about 20%. Graviton Z 1000 fb 1 Mass (TeV) (heavy higgs) m/m ~ 0.1% Γ/Γ ~ 5-10% σ/σ ~ 10% SUSY gaugino/ scalar (tanβ=35) SUSY squark/ gluino 100 fb 1 SM Higgs complete coverage J. Rohlf, LHC IV p. 28

29 Longitudinal W/Z 0 Scattering Possible scenario: events per 20 GeV Z 0 Z 0 4 leptons 3000 fb 1 J. Rohlf, LHC IV p. 29 m ZZ Super-high luminosity is essential! (more energy would be better)

30 Compositeness Cross section gets a term s/(αλ 2 ), where s = m 2 Dominates when s >> αλ 2 σ (pb) DY Contact interaction modifies Drell-Yan Λ = 2 TeV Λ (TeV) 5σ limit e + e A. Gupta et al. 5 TeV 400 GeV Λ = 10 TeV Λ = 20 TeV 1000 fb 1 reach to Λ = 50 TeV 1 GeV 100 MeV J. Rohlf, LHC IV p. 30 m e + e 132 ev, 100 fb 1 nucleus 10 MeV

31 My last invited talk at Fermilab was 20 years ago... W Spin and ParityViolation Jets! Tests of QCD 1/r2 behavior of strong force at m! W Mass (2%) First Z0 events 4 e+e 2 µ+µ J. Rohlf, LHC IV p. 31

32 Where we stood then... M. Veltman (SLAC Accelerator Summer School, 1982) quoted by Leon Lederman: "The outstanding problems in today s theory of particles are such that none of the projections beyond the standard model can be considered with any confidence. What we need is experimental guidance: exposure to the no-mans land of lepton-lepton or quark-quark collisions up to the mass range of 1 TeV and beyond." N o t J. Rohlf, LHC IV p. 32

33 Where we stand now... From: "M.J.G. Veltman" To: James Rohlf Date: Fri, 7 Mar :20: Dear Jim; Well, you know as well as I do that essentially nothing has changed. Supersymmetry and strings have not come closer to reality. The Higgs is more elusive than ever. I am happy to see that I saw that correctly in Best wishes, Tini N o t J. Rohlf, LHC IV p. 33

34 Summary and Outlook In the two years since Sardinia, we have come at least one year closer to the realization of TeV physics! When I get invited back to Fermilab in 2023, I hope to be able to report on some exciting new physics from CMS......that was NOT anticipated at this conference! J. Rohlf, LHC IV p. 34