Recommended
More Related Content
What's hot
What's hot (20)
Viewers also liked
Viewers also liked (20)
Similar to Searches with LHC
Similar to Searches with LHC (20)
Recently uploaded
Recently uploaded (20)
Searches with LHC
- 1. Searches with LHC Gökhan Ünel U.C.Irvine ATLAS and CMS: general purpose LHC 27 km ring previously used for LEP e+e- UPHDYO VI ALICE: 2/09-7/09 2010 Heavy Ions LHCb: B-physics, CP-violation
- 2. SM ingredients 2 ‣Fermions as matter particles • Quarks & Leptons ‣Gauge group structure • gauge bosons as force carriers ‣EW Symmetry Breaking • mass via Higgs bosons ‣SM can not be the final theory: • Hierarchy problem: δH ~ MH • EW and Strong forces not unified ‣3+1 space-time • Arbitrary fermion masses & mixings • Arbitrary number of families • Unknown source of baryogenesis
- 3. 3
- 4. Gearing up 4 ‣LHC started running at √s=7 TeV starts in 30 March 2010 • mid November heavy ion run will start, followed by yearly shutdown • aims to reach 1000 pb-1 at 2011 • currently ~3.6 pb-1 delivered, ATLAS recorded ~96% of it ‣We are understanding the detector, and repeating the some of the earlier particle physics work ‣From 2013, LHC is to work at √s=14 (13?) GeV, with 100fb-1/year for a total of 300 fb-1
- 5. First results 5 Minimum-bias events: momentum spectra & particle multiplicities Measured over a well-defined kinematic region: ≥ 2 charged particle with pT > 100 MeV, |η| <2.5 No subtraction for single/double diffractive components Experimental error: < 3% Distributions corrected back to hadron level High-precision minimally model-dependent measurements Provide strong constraints on MC models
- 6. looking for ‘old friends’ 6 L2 trigger η(e+) = ‐0.42 PT(e+) = 34 GeV ron lect ate E id can d idates T E and on c ing Mu ss Mi ET,Miss=26 GeV W-> eν Z-> μμ
- 7. 7 dimuon distributions -1 J/ψ is one of the first “candles” for detector commissioning and early physics (B-physics, QCD). Provides large samples of low-pT muons to study μ trigger and identification efficiency, resolution and absolute momentum scale in the few GeV range From J/ψ mass peak and resolution reconstructed in the Inner Detector: -> absolute momentum scale known to ~ 0.2% -> momentum resolution to ~2 % in the few GeV region
- 8. 8 dimuon distributions -2 Simple analysis: LVL1 muon trigger with pT ~ 6 GeV threshold 2 opposite-sign muons reconstructed by combining tracker and muon spectrometer both muons with |z|<1 cm from primary vertex Looser selection: includes also muons made of Inner Detector tracks + Muon Spectrometer segments Distances between resonances fixed to PDG values; Y(2S), Y(3S) resolutions fixed to Y(1S) resolution
- 9. 9 dimuon distributions -3 PDG on Z: Z -> μμ Peak (GeV) 90.3 ± 0.8 Width (ΓZ unfolded)(GeV) 4.2 ± 0.8 work needed on alignment of ID and forward muon chambers, and on calorimeter inter-calibration, to achieve expected resolution 79 events
- 10. 10 Z cross-section measurement 125 events: 46 Z -> ee 79 Z -> μμ σ (Z ll) = 0.83 ± 0.07 (stat) ± 0.06 (syst) ± 0.09 (lumi) nb Dominant experimental uncertainty: σ (Z ee) = 0.72 ± 0.11 (stat) ± 0.10 (syst) ± 0.08 (lumi) nb lepton reconstruction and σ (Z μμ) = 0.89 ± 0.10 (stat) ± 0.07 (syst) ± 0.10 (lumi) nb identification
- 11. 11 Higgs remains unseen SM3 1 BF -1 10 -2 10 -3 10 Higgs Hunt -4 10 100 200 300 400 500 600 700 800 900
- 12. ATLAS Experiment overview 12 Hunt for the SM Higgs • SM contains massless chiral fermions, H → γγ • SSB via Higgs mechanism to induce mass • Higgs boson is not yet observed experimentally H → ZZ → 4l e/μ ➡ Its mass is not known H e/μ e/μ • Discovering Higgs is a major task Z e/μ ➡ above 5σ significance needed qqH → qqττ τ τ H τ τ 30fb-1 discovery in 1st year mH > 114.4 GeV for any H mass
- 13. SM to BSM 13 Fourth ‣Fermions as matter particles Family • Quarks & Leptons new quarks new leptons lepto-quarks new constituents composite models GUTs ‣Gauge group structure • gauge bosons as force carriers Super Symmetry Gauge G new gauge bosons Little Higgs ‣EW Symmetry Breaking • mass via Higgs bosons Dynamical Symmetry new scalars new EWSB Breaking disclaimer: 2HDMs Technicolor For the rest ‣3+1 space-time of the talk, a search based new dimensions RS Model ADD approach will Models be followed.
- 14. SM to BSM 14 Fourth ‣Fermions as matter particles Family • Quarks & Leptons new quarks new leptons lepto-quarks new constituents composite models GUTs ‣Gauge group structure • gauge bosons as force carriers Super Symmetry Gauge G new gauge bosons Little Higgs ‣EW Symmetry Breaking • mass via Higgs bosons Dynamical Symmetry new scalars new EWSB Breaking 2HDMs Technicolor ‣3+1 space-time new dimensions RS Model ADD Models
- 15. New constituents excited νs* SN 15 -AT LA S-2 00 4-0 47 predicted by: composite (preonic) models produced as: single (νν ∗ /ν ∗ e) via Z,W, γ q Z q ν∗ Z ν∗ q q γ γν ∗ decay via: boson + lepton:νγ, νZ, eW q ¯ q ¯ ν ¯ ν ¯ q ¯ q ¯ ν ¯ q W+ ν ∗ •Fast MC based study ¯ q e ¯ •scan neutrino mass: [500,..,2500] •consider 2 coupling possibilities: 9 •with and w/o νγ decay (same disc. limit) with 300fb-1 data 10 5 8 9 TeV @ 300GeV 10 4 7 2.5 TeV @ 2 TeV 10 3 6 10 2 5 10 4 1 3 -1 eW (W→jj e/μ ν) AND 10 2 eZ (Z→jj μμ) considered -2 10 0 500 1000 1500 2000 2500 3000 3500 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 *other excited fermions (e*,q*) also studied in earlier works but not reported here.
- 16. New quarks q=-1/3 singlets 16 predicted by: E6 GUT produced as: pairs from gluon (quark) fusion decay via: boson + light jet •Fast MC based study •scan new quark mass #D quarks/20GeV/year 16 14 Signal @ 600GeV SM background SM + Signal @ 600GeV •pair production is mixing independent 12 10 ¯ DD → ZjZj → 4 2j Significance (!) 8 6 4 2 10 0 200 400 600 800 1000 1200 1400 MZ,jet (GeV) Eur.Phys.J.C49:613-622,2007 1 35 35 500 600 700 800 900 1000 Events/100 fb /20 GeV 600 GeV PTjet>80 GeV 30 30 mD (GeV) -1 PTlep>20 GeV Luminosity (fb ) -1 25 25 PTmis>30 GeV 20 20 10 2 15 15 10 10 10 5 5 1 discovery in 1st year if D 0 500 1000 1500 2000 0 500 1000 1500 2000 -1 mass<500 GeV Mass (Z(ll) jet), GeV Mass (W(l!) jet), GeV 10 500 600 700 800 900 1000 Eur.Phys.J.C54:507-516,2008 mD (GeV)
- 17. New quarks q=2/3 singlets SN 17 -AT LA S-2 00 4-0 38 predicted by: Little Higgs produced as: single from W exchange decay via: boson + (t or b) jet •Fast MC based study qb → q T → q W b (ht, Zt) •function of T quark mass and t-T mixing •all 3 decay channels studied. 4 Zt → νjb 400 W b → νjb Events/40 GeV/300fb -1 Events/40 GeV/300 fb -1 3.5 ATLAS 350 ATLAS 300 T is observable with 300 fb-1: 3 2.5 250 •up to ~2.5 TeV via Wb, 2 200 •up to ~1.4 TeV via Zt. 1.5 150 at maximum t-T mixing 1 100 0.5 50 0 500 1000 1500 2000 0 500 1000 1500 2000 Invariant Mass (GeV) Invariant Mass (GeV)
- 18. New quarks doublets 18 predicted by: DMM produced as: pairs from gluon (quark) fusion decay via: W + jet (no FCNC) ¯ pp → u4 u4 ¯ or d4 d4 •Fast MC based study •scan new quark mass Invariant Mass for q4 •results for 100 fb-1 shown #q candidates / 25GeV / 1fb -1 signal+BG + u4 → W b signal VWjj (V=Z,W) Events / 20 GeV WWbb 20000 total background 2 10 WWbbj - pp ! t t pp ! W + jets 15000 - pp ! u4 u4 4 10000 10 5000 0 200 400 600 mj j b(GeV) •61σ signal from 320 GeV u4 300 400 500 600 700 q4 800 •13σ signal from 640 GeV u4 Eur.Phys.J.C57:621-626,2008 mWj (GeV)
- 19. New quarks & the Higgs hunt 19 100 BR Higgs Enhancement from new quarks 90 Phys.Lett.B669:39-45,2008 ! (pb) 80 SM quarks only 102 mq = 250 GeV 70 4 mq = 1000 GeV 60 4 10 50 40 1 30 20 10-1 10 100 200 300 400 500 600 700 800 900 g v4 m h (GeV) 0 h 200 300 400 500 600 700 800 q MD(GeV) g v4 ¯ compatibility w/ EW data Majorana ν4s mν4=100, 900 GeV me4=250 GeV http://projects.hepforge.org/opucem/ SM3 with mt=170.9 GeV mu4=360 GeV md4=260 GeV mh=115 GeV mh=115 GeV
- 20. New Charged Leptons AT 20 LAS -PH YS heavy lepton pair production by gluon fusion included as a new external process [23]. The detector response was simulated with the parametrized Monte Carlo program ATLFAST -20 [24], with default values of the parameters. 03 The note is organized as follows. In the next section the signal and the background -01 predicted by: Fourth family, E6 GUT, technicolor.. are described and relevant conditions to reduce the background contribution are pointed out. In section 3 the event selection is analyzed and the discovery potential is derived as 4 a function of ML and MZ in section 4. The gluon-gluon fusion cross section formula and produced as: pairs from gluon (quark) fusion its scale dependence is included in Appendices A and B, respectively. + + + (e ,µ+ ) decay via: boson + lepton q (e , µ ) jet jet g 0 0 Z 0 jet Z , Z’ + Z 0 jet ! , Z , Z’ L + L q •Fast MC based study L - Z 0 jet L- Z 0 jet •function of L, Z’ mass jet g jet - - q (e , µ ) - (e ,µ-) Figure 1: Charged heavy lepton pair pro- Figure 2: Charged heavy lepton pair pro- duction by Drell-Yan mechanism. The com- duction by gluon-gluon fusion mechanism. plete γ ∗ /Z 0 /Z interference was studied. 2. Signal and background description 2.1 The signal The Drell-Yan processes studied include q q anihilation into (γ ∗ /Z 0 /Z ) and their further ¯ decay into a pair of charged heavy leptons. For the gluon fusion process [20], Z and Z bosons decay into a pair of heavy charged leptons. Subsequently, the neutral current decay of each heavy charged lepton into an electron and two jets coming from the Z boson decay was considered: @ 100 fb -1 ¯ qq → γ, Z 0 , Z 800 GeV reach → L+ L− → (e, µ)+ Z 0 (e, µ)− Z 0 → (e, µ)+ (e, µ)− + 4 jets (2.1) + − − − 0 → L L → (e, µ) Z (e, µ) Z → (e, µ) (e, µ) + 4 jets (2.2) + 0 0 + Higher Z’ mass gg → Z , Z increases the L mass For simplicity, it was assumed here that the heavy lepton decays to one family of leptons (either e or µ) with a short lifetime. Limits on the mixing of a heavy lepton with a SM lepton are given in [25]. reach: Z’=2TeV, L=1TeV accessible
- 21. New Neutral Leptons JH 21 EP 081 0:0 74 ,20 08 . predicted by: Fourth family, E6 GUT, technicolor.. q v4 g v4 Z h q q ¯ v4 ¯ g v4 ¯ produced as: pairs from ν4 pair production cross section gluon (quark) fusion Z+h (mh = 500GeV) decay via: boson + lepton Z+h (mh = 300 GeV) Z only Define 3 benchmark points s1 s2 s3 ➡ at least 3 signal events required v4 100 100 160 ➡ early double discovery possible h - 300 500
- 22. Lepto-quarks SN 22 -AT LA S-2 00 5-0 51 predicted by: GUTs & composite models produced as: pairs + single from g-g (q) fusion decay via: e(type1) or ν(type2) + light jet •Fast MC based study for Scalar & Vector LQs •Coupling κ, λ=e (for V) •LQ-mass scanned @ 100 fb-1 1.2 TeV reach for S LQs 1.5 TeV reach for V LQs
- 23. SM to BSM 23 Fourth ‣Fermions as matter particles Family • Quarks & Leptons new quarks new leptons lepto-quarks new constituents composite models GUTs ‣Gauge group structure • gauge bosons as force carriers Super Symmetry Gauge G new gauge bosons Little Higgs ‣EW Symmetry Breaking • mass via Higgs bosons Dynamical Symmetry new scalars new EWSB Breaking 2HDMs Technicolor ‣3+1 space-time new dimensions RS Model ADD Models
- 24. New bosons Z′ AT 24 LAS -PH YS -PU B-2 00 predicted by: SO(10), E6.. GUTs, Little Higgs, EDs 6-0 24 produced as: from q-q annihilation decay via: fermion pairs •Full MC based study •1.5 & 4 TeV considered •CDDT parametrization shown •g is global coupling strength B-xL 10+x5 •x is fermion coupling •M is Z’ mass results with 100 fb-1 of data shown by G.Veramendi at Pheno 2005 d-xu q+xu
- 25. New bosons Z SN 25 -AT n LA S-2 00 7-0 65 predicted by: RS, ADD models produced as: from q-q annihilation pp → γ n /Z n → + − decay via: lepton pairs •FULL simulation based study 8 •3 Parameter sets to reproduce the 7 Set A fermion masses & mixings (A, B, C) Set B 6 •only electrons were reconstructed 5 Set C 4 Set A 4 10 Set A 10 3 2 Set B 102 3 10 10 Set C 1 10-1 DY 10-2 2 Excluded -3 10 10 -4 10 1000 2000 3000 4000 5000 6000 7000 8000 Set B 1 104 3 10 1 102 0 102 103 10 1 1 10 -1 10 10-2 -1 10 10 -3 10-4 1000 2000 3000 4000 5000 6000 7000 8000 Set C Discovery reach is about 6 TeV depending 104 10-2 10 3 102 10 on the model for 100fb-1 data. 1 10-1 -3 10 10 -2 1000 2000 3000 4000 5000 6000 7000 8000 10 -3 10-4 1000 2000 3000 4000 5000 6000 7000 8000
- 26. New bosons W`/ W AT 26 LAS -PH H YS -PU B-2 00 predicted by: SO(10), E6.. GUTs, Little Higgs, EDs 6-0 03 produced as: s channel from q-q’ annihilation ¯ decay via: top-b q q → W → tb → νbb •Fast MC based study •W-WH coupling via cotθ •WH mass 1 & 2 TeV considered Discovery plane for 300fb-1 data cot ! 2 WH " t b S/ B > 5 S > 10 1.5 compare to WH →eν from SN-ATLAS-2004-038 1 0.5 Discovery reach is 6.5 TeV depending on 0 1 1.5 2 2.5 3 3.5 4 the W-WH mixing. mWH (TeV)
- 27. SM to BSM 27 Fourth ‣Fermions as matter particles Family • Quarks & Leptons new quarks new leptons lepto-quarks new constituents composite models GUTs ‣Gauge group structure • gauge bosons as force carriers Super Symmetry Gauge G new gauge bosons Little Higgs ‣EW Symmetry Breaking • mass via Higgs bosons Dynamical Symmetry new scalars new EWSB Breaking 2HDMs Technicolor ‣3+1 space-time new dimensions RS Model ADD Models
- 28. New Scalars q=±2 lead to complex event topologies. SN 28 -AT In the present work, we consider the production and decay modes discussed above. The LA results will be presented as limits in terms of the couplings vL or vR , taking fixed reference S-2 values for the Yukawa couplings of the doubly charged Higgs bosons to the leptons. It will 00 then be a simple matter to re-interpret the results for different values of these Yukawa 5-0 couplings. We will assume a truly symmetric Left-Right model, with equal gauge couplings 49 gL = gR = e/ sin(θW ) = 0.64. Since the mass of the WR is essentially proportional to vR , predicted by: Little Higgs, LRSM as mentioned in the introduction, it will not be an independent parameter. We note that the existence of the Higgs triplet can also be detected in the decay channel ∆+ → W Z. This will not be studied here, as the signal is very similar to narrow produced as: pair via q-q annihilation & single via W fusion technicolor resonances which have been analyzed elsewhere [21]. the case of leptonic decays of the doubly-charged Higgs bosons decay via: lepton pairs golden channel and the background will be negligible (as for th 4 ). W+, ! + + + •Fast MC based study " Fig. 8 shows the contours of discovery, defined as observat •W+R & Δ++ mass scanned for min 10evts leptons are detected or +if! any 3 of the leptons are observed. ++ W, + mass reach for m(∆R ) increases at first, as the s-channel diag •e,μ & τ channels separately studied mass shell becomes the dominant contribution. However, for ve •results for 100(a) & 300(b) fb-1 shown contribution of this diagram is kinematically suppressed. Bein involving the WR , this channel is not sensitive to the mass of ++ Figure 1: Feynman diagrams for single production of ∆ pair production reach 1.1 TeV single production reach ~1.8TeV depending on mW+ depending on mZR with 3 and 4 leptons 4500 a b 3 Simulation of the signal and backgrounds 4000 The processes of single and double production of doubly charged Higgs are implemented 3500 in the PYTHIA generator [22]. Events were generated using the CTEQ5L parton distrib- ution functions, taking account of initial and final state 3000 interactions as well as hadroniza- M ZR (GeV) tion. The following processes were studied here: 2500 • qq → qqWR,L WR,L → qq∆++ → qq e+ e+ /µ+ µ+ + + R,L 2000 • qq → qqWR,L WR,L → qq∆++ → qq τ + τ + with one1500 + + R,L or both τ ’s decaying leptonically. 1000 4 500 0 600 800 1000 1200 1400 M !++ (GeV) R
- 29. New EWSB no scalar AT 29 LAS -TD R predicted by: Dynamical SB models, technicolor produced as: from q-q annihilation decay via: boson pairs •Fast MC based study •Scan ρT mass for different πT Discovery with 30fb-1 data possible depending on model parameters
- 30. New EWSB SUSY 30 Give up the (so far) observed “spin” asymmetry between matter and force carriers: partners for all SM particles • solves Fine Tuning, DM.. problems SUSY not observed: sparticles heavy: broken symmetry Rich phenomenology (even with Rparity): • large # of parameters: >100 in MSSM case* • many SB options: MSSM, mSUGRA, GMSB, AMSB.. Common properties: has 5 parameters has 6 parameters • cascade decays of sparticles to high pT objects , • stable LSP escapes undetected: large ETmiss . Look for: jets + ETmiss and leptons +jets + ETmiss * #parameters=124 given in SN-ATLAS-2006-058
- 31. 1 bb+jets 272 · 10 364 0 New EWSB mSUGRA SN 31 -AT 10-1 WMAP range L of Table 6: Efficiency of the cuts used for the reconstructionAS- the decay o 20 07 evaluated with ATLFAST events for low luminosity operation. The numbe - 4 to an integrated luminosity of 10 fb . The third column contains the0numb −1 9 10-2 ISAJET +MICROMEGAS the inclusive cuts on jets, b-jets, missing energy and effective mass. The fou mSUGRA’s LSP is DM candidate SOFTSUSY+MICROMEGAS number of events with two reconstructed top candidates which satisfy all ˜ 0 102000 -3 ˜ ¯ divided in those with the presence of the g → χ0 tt decay (signal), and th ˜ •model should be consistent with WMAP data χ1 2500 3000 3500 4000 4500 5000 m0 (GeV) (background). R parity imposes pair productionevents which passes the various selectionsχshown¯ Tab g → ˜ tb ˜ + in The number of is ˜˜ pp → g g mass term µ on the mSUGRA common conditions and an integrated luminosity of 10 fb−1 . The dominant running scalar − •Fast MCµ, and astudymass of 175 GeV. The inclusive cuts on jets, b-jets, missing energy and effecti 0, a positive based top grounds after the ¯ ˜ ˜ g→χ ¯ tb •m1/2-m0 parameterusing SOFTSUSY. 6) are the tt and two bb+jets production. The2.5 is required (last of Table space scanned hadronic decay of the latter is removed w GEs, the open squares n m0 . of the Right top quarks with ∆R < ¯ 0 and the dominant background remains the tt production, which is howeve ˜ ˜ g→χ ¯ tt of magnitude smaller than the signal. jets + ETmiss ISAJET 7.71 mt = 175 GeV, tan " = 54 A=0 GeV µ > 0 Invariant mass best selected tt pair 1000 Events/ 30 GeV / 10fb-1 m1/2 (GeV) 10 900 SUSY 800 8 700 tt 6 600 500 4 7 σ significance 400 with 1fb-1 of data 300 allowed region 2 ! > !WMAP 200 0 LEP excluded 100 ! < !WMAP -2 0 400 600 800 1000 1200 1400 0 1000 2000 3000 4000 5000 6000 7000 8000 MINV (GeV) m0 (GeV)
- 32. New EWSB GMSB SN 32 -AT LA S-2 00 1-0 04 Susy breaking scale close to weak scale •LSP is gravitino, FCNC is suppressed Reference points with different model parameters & NLSP •Fast MC based study @ G3 (NLSP is stau) •G3b: NLSP is quasi-stable q → χ0 q → ˜ q → τ (τ ) q → Gτ (τ ) q ˜ ˜1,2 ˜ •G3a: NLSP immediately decays ˜ leptons +jets + ETmiss Negligibly small SM background Excellent signal with few fb-1 in both cases G3b: stau detected in G3a: stau decays the muon chambers before detection but dips can be calculated & fit:
- 33. SM to BSM 33 Fourth ‣Fermions as matter particles Family • Quarks & Leptons new quarks new leptons lepto-quarks new constituents composite models GUTs ‣Gauge group structure • gauge bosons as force carriers Super Symmetry Gauge G new gauge bosons Little Higgs ‣EW Symmetry Breaking • mass via Higgs bosons Dynamical Symmetry new scalars new EWSB Breaking 2HDMs Technicolor ‣3+1 space-time new dimensions RS Model ADD Models
- 34. EDs graviton SN 34 -AT LA S-2 00 1-0 05 predicted by: all ED models produced as: from q-q annihilation, q-g/g-g fusion decay via: - (stable) ¯ gg/gq/q q → gG •Fast MC based study •#EDs=2,3,4 & ED scale scanned Events / 20 GeV !s = 14 TeV jW(e!), jW(µ!) 10 6 MPl(4+d)MAX(TeV) d=2 d=3 d=4 jW("!) 10 5 jZ(!!) 30fb-1 7.7 6.2 5.2 10 4 total background 100fb-1 9.1 7.0 6.0 signal #=2 MD = 4 TeV signal #=2 MD = 8 TeV 10 3 signal #=3 MD = 5 TeV ¯ signal #=4 MD = 5 TeV 10 2 q q → γG •lower rate, •lower sensitivity due to Zγ background 10 1 0 250 500 750 1000 1250 1500 1750 2000 ETmiss (GeV)
- 35. EDs Excited gluons SN 35 -AT LA S-2 00 6-0 02 predicted by:g*TEV-1 EDs (ADD) 1800 1200 !bb 1600 g* ! b b ¯ ∗ 1000 -1 produced as: from q-q annihilation qq → g → tt 1400 -1 Events/80 GeV/100 fb Events/40 GeV/10 fb Signal 1200 Signal → b¯ 800 Total backg Total backg 1000 decay via: heavy quark pairs 600 400 Reducible backg 800 600 b Reducible backg 400 200 200 1800 1200 0 400 600 800 1000 1200 g* !1600 b 1400 b 1800 •Fast MC based study! b b 0 1600 g* 1000 1500 2000 2500 3000 •g* mass scanned [1..3] TeV mg* (GeV) 1000 -1 mg* (GeV) 1400 -1 Events/80 GeV/100 fb Events/40 GeV/10 fb Signal 1200 Signal 800 Total backg Total backg (a) Reducible backg 1000 (b) Reducible backg 600 g. 3. Reconstructed mass peaks for g ∗ → b¯ including both signal and background b 800 600 ntributions for mass values of M = 1 and 2 TeV. The mass window used to cal- 400 400 ate200 significance is indicated in the figures. Luminosities of = 10 4 pb−1 and the 200 = 105 pb−1 are assumed for M = 1 and 2 TeV, 0respectively. g* ! t t g* ! b b 3 0 10 1000 1500 2000 2500 3000 400 600 800 1000 1200 1400 1600 1800 mg* (GeV) mg* (GeV) b¯ 140 Significance g* ! t t (b) 10 g* ! t t b 700 (a) ¯ 2 120 g. 3. Reconstructed mass peaks for g ∗ → b¯ including both signal and background tt Events/60 GeV/10 fb-1 600 Events/40 GeV/3 fb-1 Signal b 100 Signal 500 ntributions for mass values of M = Total backg 1 and 2 TeV. The mass window used to cal- 80 10 Total backg Reducible backg Reducible backg 400 late the significance is indicated in the figures. 60 Luminosities of = 10 4 pb−1 and = 105 pb−1 are assumed for M = 1 and 2 TeV, 40 300 respectively. 200 1 0 500 1000 1500 2000 2500 3000 3500 4000 100 20 140 M (GeV) fb-1g*as at function of mass for ∗ → b¯ and a lum Fig. 5.300(GeV) Significance allows reaching 3.3 gTeV with 5σ 700 0 400 600 800 1000 1200 g* ! t t 14001600 1800 0 120 600 ! t 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 b fb-1 600 mg* (GeV) m fb-1 100 5 g* −1
- 36. Summary 36 LHC has very rich discovery potential for (B)SM physics. •mostly published ATLAS results shown •ATLAS (& CMS) are currently taking data @ 7TeV Concentrated on a selection of discovery possibilities; •some models (e.g. micro BHs) not mentioned, •differentiation between models not shown, •boost to standard searches from BSM physics not shown. Some results with Fast MC were shown, •New analyses with full simulation ongoing for first 1fb-1, •Trigger aware studies immediately applicable to LHC data ? Next few years will be very exciting, stay tuned..
- 37. auxiliary slides 37 ATLAS weight 7 000 t diameter 25 m length 46 m B Field 2T year energy luminosity aimed ∫L (fb-1) physics beam time 2009/10 3.5+3.5 1x1032 1 protons - from July on ➠ 4*106 seconds ions - after proton run - 5 days at 50% efficiency ➠ TeV 0.2*106 seconds 2012 7+7 TeV 1x1033 10 protons:50% better than 2008 ➠ 6*106 seconds ions: 20 days at 50% efficiency ➠ 106 seconds 2013 7+7 TeV 1x1034 100 TDR targets: protons: ➠ 107 seconds ions: ➠ 2*106 seconds
- 38. 38 Fourth generation quarks (doublets) • What is it? ➡ SM does not give #families => not a true modification ➡ predicts 4 new heavy fermions with 1TeV > m >100GeV • Viable? Leptons Quarks 2 1 mt mντ δS = − log − log 3π 3π ➡ PDG considers only total degeneracy mb mτ u c t u4 ➡ SM3 & SM4 have same χ2 from fits, d s b d4 ➡ CKM has enough room for 4 row/column ➡ SM4 can accommodate heavier Higgs νe νµ ντ ν4 e µ τ e4 • Desirable? I II III IV ➡ CPV source (for BAU) ➡ Alternative EW SymBreaking ➡ Fermion mass hierarchy ➡ DarkMatter candidate • Discoverable? ➡ Tevatron: ongoing; b-Factories: indirectly; LHC: Find or refute !
- 39. BSM models: Exotics 39 ‣A brief summary of popular models: • Grand Unified Theories: - SM gauge group is embedded into a larger one like SO(10), to unify EW and QCD. - additional fermions and bosons predicted. • Little Higgs models: - spontaneously broken global symmetry to impose a cut-off ~10 TeV. - additional bosons and quarks introduced to cure the hierarchy problem. • Extra Dimensions: - Low Planck scale in d dimensional theory solves the hierarchy problem between EW and Gravitational couplings. - Excitations of SM bosons and fermions are predicted. ‣ These models do not exclude supersymmetry.