Discovery potential for SUGRA/SUSY at CMS

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1 Discovery potential for SUGRA/SUSY at CMS Stefano Villa, Université de Lausanne, April 14, 2003 (Based on talk given at SUGRA20, Boston, March 17-21, 2003) Many thanks to: Massimiliano Chiorboli, Filip Moortgat, Salavat Abdullin, Daniel Denegri April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 1

2 Contents SUSY in a nutshell LHC and CMS. Getting the right events: SUSY triggers in CMS: - Low luminosity - High luminosity Inclusive SUSY studies (msugra) SUSY Higgs SUSY Spectroscopy: - Point B, 10 fb -1 - Point B, 300 fb -1 - Point G, 300 fb -1 Conclusion April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 2

3 Why SUSY? Try to fix some problems in the Standard Model: - hierarchy (Weak-GUT-Planck) - naturalness (need fine tuning to keep scalar masses small) - no gravity Get some positive side effects: - unification of couplings - SUSY is there basically in all extensions of the SM which include gravity April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 3

4 SUSY in a nutshell A symmetry which relates fermions and bosons would solve the naturalness problem: SUSY Bosons Fermions: same number of deg. of freedom in each supermultiplet Fermions Sfermions (squarks, selectrons ) Bosons -inos (gluinos, higgsinos, gauginos ) CLEARLY, SUSY is broken! sparticles should have the same mass as their partners we do not see them. April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 4

5 SUSY in a nutshell Minimal SUSY extension of the SM is MSSM - 2 Higgs doublets. >100 parameters (too many) - introduce constrained MSSM. Parameters: m 1/2 : common gaugino mass at GUT scale m 0 : common scalar mass at GUT scale m A : pseudoscalar Higgs mass tanβ : ratio of vev of the two Higgs doublets µ : Higgs mixing parameter A t,b,τ : stop, sbottom, stau mixing parameters April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 5

6 SUSY in a nutshell Add more assumptions (SUSY breaking communicated by gravitation) minimal supergravity (msugra). only 5 parameters: m 1/2, m 0, tanβ, sign(µ (µ), A 0 One more variable in the game: R-parity: P R = (-1) 3(B-L)+2s P R = +1 for standard particles P R = -1 for sparticles If R-parity conserved the lightest sparticle is stable (LSP, a good candidate for dark matter) and sparticles are always produced in even numbers. April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 6

7 The LHC machine. pp collisions at 14 TeV center of mass energy scheduled to start in April 2007 luminosity cm -2 s -1 (initially 2x10 33 cm -2 s -1 ) 20 interactions per beam crossing at 40 MHz rate σ(pp) 70 mb H 4µ event plus 20 min. bias: quite crowded April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 7

The CMS detector General purpose detector: main aims: Higgs, SUSY or other New Physics in the TeV range for SUSY, need - good jet and missing E T resolution - hermetic

8 The CMS detector General purpose detector: main aims: Higgs, SUSY or other New Physics in the TeV range for SUSY, need - good jet and missing E T resolution - hermetic calorimeters - efficient b-tagging and τ identification - precise lepton and jet energy scales April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 8

9 Typical SUSY event squark-gluino production Signature: - many high P T jets - missing E T - (leptons) April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 9

10 SUSY triggers April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 10

11 SUSY triggers Problem: select interesting events with the highest efficiency at an affordable rate. Studies performed at Low luminosity = cm -2 s -1 High luminosity = cm -2 s -1 at 3+3 msugra benchmark points. look also at R-parity violation All results obtained with GEANT + full reconstruction software. CMS Data Acquisition & High Level Trigger Technical Design Report just published (CERN/LHCC ) April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 11

12 Low luminosity trigger Just above Tevatron II reach Along M squark 400 GeV curve April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 12

13 Low luminosity trigger Consider jets and missing E T ; combine 2 selections: msugra 1 jet > 180 GeV 4 jets, E T >113 GeV miss point: > 123 GeV E T R-viol. Signal efficiency w.r.t. L1 (%) R 5R 6R (11) (14) (16) (28) (30) 9 26 (20) High Level Trigger efficiency Background (6.8) rate (Hz) Trigger efficiency still very good in R-violating case April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 13

14 High luminosity trigger Explore higher mass scale ( 2 TeV), R-parity viol. as well Low luminosity points April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 14

15 R-parity violating event Expect less missing E T : still some remains (lots of b, W/Z, τ, neutrinos) Additional jets April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 15

16 N jet and missing E T R-parity conserved E jet > 50 GeV T R-parity violated April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 16

17 High luminosity trigger results Very simple cuts do the job... miss msugra E > 239 GeV 4 jets, E T T >185 GeV point: R-viol. Signal efficiency w.r.t. L1 (%) R 8R 9R (18) (28) (28) (75) (78) (52) High Level Trigger efficiency Background (1.5) rate (Hz) Efficiency quite high, also in the R-parity violating case. April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 17

18 Inclusive SUSY searches April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 18

19 Inclusive SUSY searches Need to reduce the number of parameters msugra Final states investigated: E T E T E T E T E T E T miss miss miss miss miss miss + jets + jets + no leptons + jets + 1 lepton + jets + 2 OS leptons + jets + 2 SS leptons + jets + 3 leptons Strategy: look for signal (ISAJET) excess over SM (PYTHIA) background in the chosen final states detector response: fast simulation (CMSJET) explore reach in the (m 0, m 1/2 ) msugra plane Try a few tanβ values DISCOVERY defined as N signal (N signal + N bgd ) 1/2 5 April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 19

20 CMS reach on msugra mass plane 100 fb -1 ; A 0 = 0 tanβ = 2, µ > fb -1 ; A 0 = 0 tanβ = 35, µ < 0 April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 20

CMS reach on msugra mass plane A 0 =0, tanβ=35, µ>0 Final integ. luminosity One year at high lumi One year at low lumi One month at low lumi Final reach for squark and gluino mass: 2.6-3.

21 CMS reach on msugra mass plane A 0 =0, tanβ=35, µ>0 Final integ. luminosity One year at high lumi One year at low lumi One month at low lumi Final reach for squark and gluino mass: TeV valid in the bulk of the parameters space; possible exceptions depend on mass hierarchy little dependence on sign(µ) missing E T signature gives the best reach April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 21

22 , reach in the MSSM: q% %g Similar study on other (non msugra) sets of parameters: April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 22

23 SUSY Higgs April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 23

MSSM Higgs Discovery reach for MSSM Higgs bosons: Look for the heavy Higgs in low/intermediate tanβ region, where only h can be discovered through SM decays.

24 MSSM Higgs Discovery reach for MSSM Higgs bosons: Look for the heavy Higgs in low/intermediate tanβ region, where only h can be discovered through SM decays. Two strategies: 1. Chargino and neutralino decays of A, H, H m 2. h,a,h bb in SUSY cascades April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 24

mainly produced via gb th m try to reconstruct associated top Main backgrounds:

25 Neutralino and chargino decays A, H χ~ 0 2 χ~ 0 2 4l m If neutralinos are light enough: H m χ~ 0 ~ m 2,3 χ 1,2 3l m + X Main backgrounds: ttx and SUSY cascades mainly produced via gb th m try to reconstruct associated top Main backgrounds: SUSY+ZZ April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 25

GeV miss E T > 150 GeV miss M eff = Σ E T + E T > 1200 GeV 2 b-tagged

26 Higgs in SUSY cascades Several scenarios analysed; choose (a good) one... Look for bb decays of neutral Higgs: N jets > 5 E T hardest jet > 300 GeV miss E T > 150 GeV miss M eff = Σ E T + E T > 1200 GeV 2 b-tagged jets April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 26

27 Mass reach of h bb in cascades 2 msugra scenarios: - April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 27

28 SUSY spectroscopy April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 28

Cosmologically interesting region CMS Studied B and G in

29 Post-LEP benchmark points More points in msugra space, chosen to perform full sparticle reconstruction Cosmologically interesting region CMS Studied B and G in detail April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 29

30 Sparticles spectrum (GeV) Point B with 10 fb -1 Start with gluino-sbottom decay chain; expect: 2 SFOS isolated leptons 2 b-jets missing E T April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 30

31 Step 1: dilepton mass 2-body decay: edge in M ll B 10 fb -1 April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 31

32 Step 2: fit the edge B Subtract OFOS lepton pairs: reduce background Generated value: M max ll = GeV April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 32

33 Step 3: sbottom reconstruction B 0 Assume M( χ~ 1) known For evts in the edge: 65 GeV < M < 81 GeV ll combine with most energetic b-jet Fit result: ~ ~ Generated: M(b L )=496 GeV; M(b R )=524 GeV April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 33

34 Step 4: gluino reconstruction B ~ Combine b to the closest b-jet b-tag parameter Generated value: M( g~ ) = GeV April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 34

35 Non-b squark reconstruction ~ Now look at : u~, d, ~ c, s~ Look for non-b jets; expect more combinatorial background B April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 35

36 Non-b squark reconstruction Repeat same procedure as for sbottom: 1,2. dilepton inv. mass: SM B 3. Using evts. in the edge, form squark invariant mass. Apply b-veto: no jets in event with σ>3 Fit result: Generated: April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 36

combinatorics due to jets coming from squarks.

37 Gluino reconstruction 4. Combine reconst. squark to nearest jet. B Fit result: Apply upper cut on the 2nd jet energy to reduce combinatorics due to jets coming from squarks. Generated value: M( g~ ) = GeV 10 fb -1 April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 37

38 Gluino-sbottom at 300 fb -1 Analysis repeated, with cuts reoptimised, to get resolutions below the 10 % level: B sbottom gluino April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 38

Point G with 300 fb -1 Heavier sparticles (M ~ g 900 GeV, M ~ b 750 GeV M q ~ 800 GeV ) lower SUSY cross section (6 pb) ~ Higher tanβ : larger χ 0 τ + τ ~ χ 0 2 1 branching ratio,

39 Point G with 300 fb -1 Heavier sparticles (M ~ g 900 GeV, M ~ b 750 GeV M q ~ 800 GeV ) lower SUSY cross section (6 pb) ~ Higher tanβ : larger χ 0 τ + τ ~ χ branching ratio, lower l + l - signal 300 fb -1 SM Need high statistics to reconstruct invariant mass peaks. miss E T > 250 GeV April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 39

40 Gluino-squark reconstruction squark gluino G Fit result ~ M(d L )=M(s ~ L )=778.0 GeV generated M(g)=860.8 ~ GeV M(u ~ L )=M(c ~ L )=773.9 GeV April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 40

41 miss Conclusion SUSY (jets+e T ) triggers in CMS: first GEANT + full reconstruction study. Good efficiency both at low and high lumi (mass), even with R-parity violation. Inclusive CMS SUSY reach, quite indep. of the choice of parms.: TeV for ~ q and g ~ (300 fb -1 ). MSSM heavy Higgs bosons decaying in charginos and neutralinos: extend the reach in the low tanβ part of the tanβ-m A plane. Full analysis of msugra points B and G show good resolution (below 10%) on M~ b, M q ~, M g ~, already with 10 fb -1 at p.b (300 fb -1 at p.g). April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 41

42 CMS reach on msugra mass plane Systematic studies Signal +/- 30% Background +100% / -50% April 14, 2003 Stefano Villa Discovery potential for SUGRA/SUSY at CMS 42

Supersymmetry at the LHC: Searches, Discovery Windows, and Expected Signatures

Supersymmetry at the LHC: Searches, Discovery Windows, and Expected Signatures Darin Acosta representing ATLAS & Outline Introduction to SUSY, LHC, and the Detectors Non-Higgs sparticle searches: Trigger