Supersymmetry at the LHC

Transcription

1 Supersymmetry at the LHC Howard Baer Florida State University SUSY at LHC SUSY signatures SM backgrounds GEANT figure msugra : ~ g m 0 = 1000 GeV, m 1/2 = 500 GeV, A 0 = 0, ~ ul ~ t1 t - W + b ( jet4, s ( jet5, ~ ( jet3, W2+ + b ~ W1+ + Z ~ Z1 + cuts: optimizing signal/bg LHC reach for SUSY beyond discovery: precision measurements tan β = 35, µ > 0 ~ Z 2 + u ( jet6, E T = 1196 GeV) ~ Z1 + h E = 113 GeV) T b ( jet1, E = 206 GeV) E = 79 GeV) + -c - ( jet2, E T = 320 GeV) T b T E = 536 GeV) -T νν + + miss W τ ν + E T = 380 GeV e ν ~ Z1 b-jet 2 b-jet 1 m g~ = 1266 GeV m ~u = 1450 GeV b-jet 3 L m ~t = 1026 GeV 1 m ~Z = 410 GeV 2 m ~ = 214 GeV Z jet 6 1 m h = 119 GeV b-jet 4 S. Abdullin, A. Nikitenko jet 5 ~ Z1 S. Abdullin Oct Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

2 SUSY signatures at LHC g g, g q, q q production dominant for m < 1 TeV lengthy cascade decays of g q are likely events characterized by multiple hard jets, isolated and non-isolated leptons es and µs, and E T from Z 1 or G or νs escaping many jets are b (displaced vertices due to long B lifetime) and τ (1 or 3 charged prongs) jets one way to classify signatures is according to number of isolated leptons Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

3 Classify event topologies according to isolated leptons E T + jets 1l+ E T + jets opposite sign (OS) 2l+ E T + jets same sign (SS)2l+ E T + jets 3l+ E T + jets 4l+ E T + jets 5l+ E T + jets Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

4 Backgrounds to SUSY events at LHC numerous SM processes give same signature as SUSY! SM BGs include: QCD: multi-jet qq, q q, qg, gg production where E T comes from mis-measurement, cracks, etc. t t, b b, c c W or Z+ multi-jet production WW, WZ, ZZ production, where Z ν ν or τ τ all of above embedded in Isajet, Pythia, Herwig four particle processes: e.g. t tt t, ttbb, etc. WWW, etc. the 2 n for n > 2 processes usually need CalcHEP/Madgraph overlapping events; fake b-jets; fake leptons, etc Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

5 Background issues The BGs must be estimated using full event simulation jet broadening, interaction of particles with detectors Must also simulate detector: GEANT or toy or... If possible, use complete 2 n-body matrix elements matching of PS and HO-ME results? avoid double counting VECBOS, AlpGEN, MCNLO, etc. NLO QCD corrections? matching the data: how well do we know SM BG rates? first order of business at LHC: re-discover the SM! calibrate detectors using Z+jets, W+jets, t t production Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

6 Example: calculate SUSY reach of LHC for 10, 100 fb 1 Cuts and pre-cuts: E T > 200 GeV N j 2 (where p T (jet) > 40 GeV and η(jet) < 3 Grid of cuts for optimized S/B: N j 2 10 E T > GeV E T (j1) > GeV E T (j2) > GeV S T > muon isolation S > 10 events for 100 fb 1 S > 5 B for optimal set of cuts Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

7 Sparticle reach of LHC for fb m 1/ msugra with tanβ = 10, A 0 = 0, µ > 0 Z l + l - 2l OS 1l 4l γ 0l 2l SS 3l m(u ~ L )=2 TeV m(g ~ )=2 TeV E T miss m 0 m 1/ msugra with tanβ = 30, A 0 = 0, µ > 0 3l 2l OS Z l + l - 1l 4l γ 0l 2l SS m(u ~ L )=2 TeV m(g ~ )=2 TeV E T miss m 0 HB, Balazs, Belyaev, Krupovnickas, Tata: JHEP 0306, 054 (2003) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

8 Old sparticle reach of LHC for 10 1 fb incl. 2l and 3l 1l 800 0l 1l 800 0l tan β = 2, µ < 0 tan β = 10, µ < SS 2l,0j 3l,0j 1l 0l 3l OS SS 3l OS 2l,0j 3l,0j l,0j 2l,0j OS 3l,0j 1l 0l 3l SS tan β = 2, µ > 0 tan β = 10, µ > 0 3l SS OS 3l,0j m1/2 m 1/ m 0 m 0 HB, Chen, Paige, Tata: PRD53, 6241 (1996) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

9 Sparticle reach of LHC for 10 1 fb; RPV with Z 1 cds HB, Chen, Paige, Tata: PRD55, 1466 (1997) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

10 Sparticle reach of CMS; various Ldt miss msugra reach in E T + jets final state A 0 = 0, tanβ = 35, µ > 0 g ~ (3000) h(123) 3 years, high lumi (300 fb -1 ) m1/2 g ~ (2500) 1 year, high lumi (100 fb -1 ) q ~ (2000) q ~ (2500) g ~ (2000) 1 year, low lumi (10 fb -1 ) Charged LSP g ~ (1500) 1 month, low lumi (1 fb -1 ) g ~ (1000) g ~ (500) q ~ (1000) q ~ (1500) q ~ (500) h (114) mass limit Chargino Searches at LEP No symmetry breaking m 0 Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

11 Sparticle reach in AMSB model m 3/2 (TeV) m m Z ~ 2 m = 2 TeV g ~ e ~ R tanβ = 35, µ > 0 0 l 1 l OS SS 3 l m = 2 TeV u ~ R m 0 Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

12 Sparticle reach in GMSB model: various model lines Model NLSP Tevatron LHC Line (25 fb 1 ) (10 fb 1 ) A Z 1 B Λ = 115 TeV, Λ = 400 TeV Z 1 γ G m g/ q 0.87 TeV, m g/ q 2.8 TeV, llγγ + E miss T γγ + E miss T B τ 1 Λ = 53 TeV, Λ = 150 TeV m g/ q 0.82 TeV, Clean channels 3l + 1τ2l + 1τ3l m g/ q 2.0 TeV, 3l + E miss T +2τ1l + 3τ2l Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

13 Sparticle reach of all colliders and relic density 1600 msugra with tanβ = 10, A 0 = 0, µ > 0 Ωh 2 < LEP2 excluded 1600 msugra with tanβ = 45, A 0 = 0, µ < 0 Ωh 2 < LEP2 excluded m 1/ LHC m 1/ LHC 600 LC LC LC LC Tevatron 200 Tevatron m m 0 HB, Belyaev, Krupovnickas, Tata: JHEP 0402, 007 (2004) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

14 Sparticle reach of colliders plus DM DD/IDD 1600 msugra, A 0 =0 tanβ=10, µ> msugra, A 0 =0, tanβ=45, µ< Z ~ 1 not LSP LHC DD µ not LSP Z ~ 1 DD m 1/ m 1/ LHC 600 LC LC LC LC500 µ 200 TEV no REWSB LEP m 0 Φ(p - )=3x10-7 GeV -1 cm -2 s -1 sr -1 Φ(γ)=10-10 cm -2 s -1 Φ sun (µ)=40 km -2 yr -1 (S/B) e+ =0.01 m h =114.4 GeV 0<Ωh 2 <0.129 σ(z ~ 1 p)=10-9 pb 200 TEV no REWSB LEP m Φ(p - )=3e -7 GeV -1 cm -2 s -1 sr -1 (S/B) e+ =0.01 Φ(γ)=10-10 cm -2 s -1 Φ sun (µ)=40 km -2 yr -1 m h =114.4 GeV Φ earth (µ)=40 km -2 yr -1 σ(z ~ 1 p)=10-9 pb 0< Ωh 2 < HB, Belyaev, O Farrill, Krupovnickas: JHEP 0408, 005 (2004) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

15 Reach of Atlas for SUSY Higgs: 300 fb 1 Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

16 Precision measurements at LHC M eff = E T + E T (j1) + + E T (j4) sets overall m g, m q scale m(l l) < m ez2 m ez1 mass edge m(l l) distribution shape combine m(l l) with jets to gain m(l lj) mass edge: info on m q further mass edges possible e.g. m(l ljj) Higgs mass bump h b b likely visible in E T + jets events in favorable cases, may overconstrain system for a given model methodology very p-space dependent some regions are very difficult e.g. HB/FP Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

17 Paige, Hinchliffe et al. case studies: examined many model case studies in msugra, GMSB, high tanβ... classic study: pt.5 of PRD55, 5520 (1997) and PRD62, (2000) m 0, m 1/2, A 0, tan β, sign(µ) = (100, 300, 0, 2, 1) in GeV dominant g g production with g q q L qq Z 2 q 1 q 2 l 1 l q1 q 2 l 1 l 2 Z1 (string of 2-body decays) can reconstruct 4 mass edges; allows one to fit four masses: m ql, m ez2, m l, m ez1 to 3 12% can also find Higgs h in the SUSY cascade decay events if enough sparticle masses measured, can fit to MSSM/SUGRA parameters Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

18 M eff = E T (j1) + E T (j2) + E T (j3) + E T (j4)+ E T rough estimate of m g, m q can be gained from max of M eff dσ/dm eff (mb/400 GeV) M eff Atlas TDR (F. Paige) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

19 m(l + l ) mass edge from Z 2 l + l Z1 kinematically, m(l + l ) < m e Z 2 m e Z 1 for Z 2 l + l (l + Z 1 )l, have m(l + l ) < m ez2 1 m2 l 1 m2 ez 1 m 2 m Z2 e 2 l < m ez2 m ez1 400 signal SM backg SUSY backg events/4 GeV/30 fb m ll Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

20 m(l + l q) mass edge from q q Z 2 q L q Z 2 q l ± l ql ± l Z Events/20 GeV/100 fb m llq Atlas TDR (F. Paige) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

21 m(lq) mass edge from q q Z Events/20 GeV/100 fb m lq Atlas TDR (F. Paige) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

22 m(lq) mass edge from q q Z Events/20 GeV/100 fb m llq Atlas TDR (F. Paige) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

23 m(b b) Higgs mass bump in SUSY jets + E T events signal SM backg SUSY backg Events/8 GeV m bb Atlas TDR (F. Paige) Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

24 Case study of SUSY in the focus point region of msugra m 0 3 TeV so squarks/sleptons decouple m g 1 TeV and µ 226 GeV so W 1, Z2 light SUSY production: soft ( W 1 + W, W ± Z 2 ) and hard ( g g) component HB/FP Sparticle Masses Mass m g ~ m Z ~ 1 m~ Z 2 m~ Z 3 m~ Z 4 m W ~ 1 m ~ W 2 m g ~ 500 m~ Z 4, m W ~ 2 m~ Z 2, m~ Z, m W ~ m 1/2 m~ Z 1 HB, Barger, Shaughnessy, Summy and Wang Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

25 FP case study: cross sections HB/FP Cross Sections W ~ 1 Z~ Z ~ 2 Z~ 3 W ~ 1 Z~ 2 W ~ 1 Z~ 1 W ~ 1 W~ 1 W ~ 1 Z~ 2 W ~ 1 Z~ 1 W ~ 1 Z~ 3 σ (fb) 1 g ~ g ~ Z ~ 1 Z~ 3 W ~ 1 W~ 1 Z ~ 1 Z~ 2 Z ~ 2 Z~ 2 Z ~ 2 Z~ Z ~ 2 Z~ 2 Z ~ 1 Z~ 2 Z ~ 1 Z~ m g ~ Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

26 Apply cuts set C1 E T > max(100 GeV, 0.2M eff n j 4; S T > 0.2 E T (j1, j2, j3, j4) > 100, 50, 50, 50 GeV dσ/dm eff (fb/gev) Effective Mass Cuts C1 FP(3050,400,0,30,1,175) QCD jets tt W+jets Z+jets WW, WZ, ZZ Sum of Backgrounds M eff Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

27 n(jets) distribution No. of Jets Cuts C1 FP(3050,400,0,30,1,175) QCD Jets tt W+jets Z+jets WW, WZ, ZZ Sum of Backgrounds σ (fb) # of Jets Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

28 n(b jets) distribution No. of b-jets (60% eff.) Cuts C1 FP(3050,400,0,30,1,175) QCD Jets tt W+jets Z+jets WW, WZ, ZZ Sum of Backgrounds σ (fb) # of b-jets Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

29 n(leptons) (isolated) distribution No. of Isolated Leptons Cuts C1 σ (fb) FP(3050,400,0,30,1,175) QCD Jets tt W+jets Z+jets WW, WZ, ZZ Sum of Backgrounds # of Leptons Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

30 n(leptons) (isolated) distribution No. of Isolated Leptons Cuts C1 σ (fb) FP(3050,400,0,30,1,175) QCD Jets tt W+jets Z+jets WW, WZ, ZZ Sum of Backgrounds # of Leptons Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

31 Augmented effective mass A T n(jets) 7 n(b jets) 2 Augmented Effective Mass Cuts C1, n b-jets >=2 (60% eff.) FP(3050,400,0,30,1,175) QCD jets tt W+jets Z+jets WW, WZ, ZZ Sum of Backgrounds dσ/da T (fb/gev) A T Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

32 Augmented effective mass A T n(jets) 7; n(b jets) 2; A T > 1400 GeV signal way above BG; purely from g g production extract m g from total rate to 8% TH 100 fb -1 error TH ±15% TH ±15% ±100%BG BG σ (fb) LEP2 excluded m g ~ Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

33 Same flavor/opposite sign dilepton mass distribution cuts C1; n(leps) 2; n(jets) 4; n(b jets) 2; A T > 1200 GeV two mass edges stand out Z ~ 2 - Z~ 1 Z ~ 3 - Z~ 1 dσ/dm ll (fb/gev) m ll Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,

34 Conclusions SUSY at LHC event signatures backgrounds cuts reach precision measurements We now have a good idea of what SUSY will look like at the LHC for many SUSY models in 2008, the road to discovery begins at the LHC: time to either discover or rule out supersymmetry at the weak scale, and resolve the physics behind electroweak symmetry breaking! Howie Baer, SUSY at LHC, lecture 3: Karlsruhe, July 25,