Non-SUSY Searches at Tevatron

Transcription

1 Non-SUSY Searches at Tevatron Jieun Kim Kyungpook National University for the CDF and D0 collaborations DIS2006 (Apr 20 ~ 24, 2006, Tsukuba) 1

2 Outline (Search & Signature) Chicago New Gauge Bosons Z Z, W W ( sequential Z, Z Zψ,Ζη,Ζχ,Ζι ) Compositeness New Fermions - ee, µµ, ττ, eν - ee, µµ ( t, t μ*, q* ) -lν+ jets, µµγ, ee+jet Extra Dimension ( LED, TeV-1ED, & WarpedED ) - ee, µµ, γγ, jet + ME T P Tevatron Collider CDF s 1.96 TeV D0 P Leptoquarks -( ll, lν, νν ) + jet jet Anomalous Diphoton+X Production -X = e, µ, γ recorded to delivered lum. ratio : 80 to 90% ~1.2 fb -1 on tape for each experiment 4 to 8 fb -1 expected in to 1 fb -1 for results presented here 2

3 Z (heavy neutral gauge boson) e, lep µ, q e - τ q Dilepton Channel e, lepµ, e + τ The majority of extensions to the SM predict new gauge interactions, many of which naturally result in the prediction of neutral bosons, such as a highly massive Z particle : Sequential Z (SM coupling), Ζψ, Ζη, Ζχ, Ζι in GUT E(6) Model Generated from q q annihilation from p p collision at 1.96 TeV Looking for resonances decaying to leptons provides very clean signature even in a hadron collider Search X ( pp X ll ) directly by comparing observed and expected background invariant mass distribution - Background contributions ( Drell-Yan, QCD, cosmic, τ + τ, tt, WW, WZ ) 3

4 Dilepton Mass Dist. q e - e, µ, lep τ ee, 819 pb -1 q e, lepe + µ, Very good agreement between data and prediction for full mass region and high mass signal region. τ Both D0 and CDF have no significant Excess ττ, 195 pb -1 µµ, 400 pb -1 4

5 Z Limits (95% CL) (unit : GeV) Sequential Z (SM Couplings) ee µµ ee+µµ ττ CDF (820 pb -1 ) 850 CDF with cosθ (450 pb -1 ) 845 CDF (200 pb -1 ) DØ ( pb -1 ) E6 Z I Zχ Zψ Zη CDF with cosθ (ee, 450 pb -1 ) CDF (ee+µµ, 200 pb -1 ) DØ (ee, 200 pb -1 ) Search for decays : Z e + e Use dielectron mass M ee and cosθ* L dt = 450 pb -1 θ* : Scattering angle in Collin-Soper frame q e - θ q Adding cosθ is equivalent to adding 25% more data for the sequential Z e + 5

6 Compositeness o o o o Look for effects due to preons, the fundamental constituents of quarks and leptons The effects are parameterized in terms of Λ, the compositeness scale the search compared invariant mass and scattering angle of data with SM expections, Λ : compositness scale (TeV) 2 d σ * dm dcosθ = f SM I + Λ where I and C are input from theory and express the possiblity of constructive / destructive interference 2 C + 4 Λ o No excess wrt SM -> limits (95% CL) on the models D0 ( μμ, 400pb -1 ) D0 ( ee, 270 pb -1 ) CDF ( ee, 450 pb -1 ) ee and μμ combination in progress 6

7 W e, q e W µ, τ lep o Additional charged heavy vector boson Left-Right Symmetric Model: SU(2) L xsu(2) R xu(1) Y (SU(2) R W ) q ν, ν µ, ν τ e lep + (light & stable) o High P T e + ME T Compare M T distribution Highest M T events at 524 GeV/c 2 No excess over background (SM coupling) Limit: M(W SM )> 788 GeV/c 2 Run I results : M(W SM )> 754 GeV/c 2 CDF 7

8 Excited Muon ( μ* ) signature : μμγ EW decays: μ* -> μ + gauge boson CI decays: μ* -> μ + ff Three parameters: Contact Interaction (CI) -m μ* -BR(μ* -> μγ) - Λ: compositness scale L=377 pb -1 Λ (TeV) CDF Run II Preliminary -1 L dt = 371 pb 371 pb % C.L. 1 Exclusion Region (GeV) M µ* m μ* > 618 GeV Λ=1 TeV m μ* > 800 GeV Λ=1 TeV CI decay taken into account in the calculation of BF(μ* ->μγ ) Assume that decays via contact interactions can be neglected, only EW decays 8

9 Excited Quark ( q* ) signature : Z(ee)+jet Heavy resonances decaying into a quark and a gauge boson may signal the existence of excited quarks and thereby indicate a possible substructure Low BR(Z->ee), but the high luminocity offered in RunII present preliminary results for the first time on this final state M Zq resonant 376 pb -1 M q* > % CL 9

10 4th Generation Quark ( t ) signature : lν + 4jets heavy top (t') quark pair production decaying to Wq final states ( t -> Wq ) signature : lepton + MET + jets reconstruct the mass of the t' quark 2D-fit of the observed (HT, Mreco ) distribution to discriminate signal from SM backgrounds exclude SM 4th generation t' quark with mass below 258 GeV at 95% CL 760 pb-1 10

11 Extra Dimensions (ED) Alternatives to SUSY for resolving the hierarchy problem (M EW << M Plank?) In this model, gravition can propagate in additional spatial dimensions Models with n extra spatial dimensions G Large ED(LED) : n>0 (n>2) compactified M 2 Pl ~Rn M n+2 D, M D : string scale g,q f g,q f TeV -1 ED : Graviton n>=1 (n=1) Exchange M c : compactification scale Gauge Boson Exchange Warped ED (RS): n=1, highly curved k/m Pl, k: curvature scale g,q g,q G jet ee µµ γγ jet(s)+e T γ +E T Graviton Exchange Graviton Emission Boson Exchange Signature ll, γγ Jets + MET dielectron LED Model LED, RS TeV -1 ED At the Tevatron, searched LED : ee, µµ, γγ, jet+met TeV -1 ED : ee RS : ee, µµ, γγ Graviton Emission 11

12 LED ( graviton emission ) : Jet + ME T Direct production of graviton qq, qg, gg-> gg, qg : a single energetic jet + large ME T L ~ 368 pb -1 One central jet p T > 150 GeV ME T > 120 GeV g,q g,q G jet heavy G escapes to extra D large MET recoil jet very energetic n : number of Extra Dimensions M D : effective Planck scale SM background 265 ± 30 events Data 263 events n=5 M D >0.85 TeV n=6 M D >0.83 TeV 12

13 RS Graviton & TeV-1 1 ED : ee, µµ, γγ L= 345 pb -1 M G > 690 GeV/c 2 Predicted Background L= 200 pb -1 TeV -1 ED signal for η C =5.0 TeV -2 L= 275 pb-1 M G > 785 GeV/c 2 TeV -1 ED : Gauge Boson Exchange Set Limit on M C via η C Lower Limit on compactification scale: RS gravitons are excluded by these data in the plane of coupling (k/m Pl ) versus effective graviton mass. M C > 1.12 TeV at 95% CL World Limit(incl. LEP indirect search limit) : M C > 6.8 TeV at 95% CL 13

14 Leptoquarks (LQ) Color-triplet particles coupled both quarks and leptons Predicted in many extensions of SM(GUT, Superstring, compositeness, technicolor etc..) Carry both lepton and color quantum numbers LQs can be scalar (spin=0) or vector (spin=1) : SLQ or VLQ Couple only to fermions of same generation due to no FCNC & helicity supp. decay At the Tevatron, pair-produced by gg fusion or q qbar annihilation Decay channel is controlled by β = BR (LQ lq ) jet jet lepton lepton ( lq)( lq) β=1 β=0.5 β=0 14

15 SLQ (β=0) pp -> LQLQ -> ννjj : 2 acoplanar jets + ME T Main background : -Z(νν)+jets -W(lν)+jets - QCD multijets L ~ 191 pb -1 L ~ 310 pb -1 2 central jets p T > 40, 25 GeV p T > 60, 50 GeV MET > 60 GeV > 80 GeV no isolated track, no electron or muon cuts on ΔΦ(MET, jet) to remove SM and QCD background DATA SM 118.3± β = 0 M LQ > 136 CL β = 0 M LQ > 117 CL 15

16 1 st st and 2 nd generation SLQ (combined) o 1 st Gen : eejj,,eνjj, ννjj o 2 nd Gen : µµjj,ννjj,µνjj 200 pb pb pb -1 For β =1, I generation CDF: Run II, M LQ > 235 GeV/c 2 D0: Run I + II, M LQ > 256 GeV/c 2 for β =1, II generation CDF: Run II, M LQ > 224 GeV/c 2 D0: Run I+II, M LQ > 251 GeV/c 2 16

17 VLQ3 3rd Gen. LQ (Vector & Scalar) (β=1)( Br (VLQ3 -> τ b) = 100% (β=1) τ l + τ h P T (l) > 10 GeV/c, P Τ (τ h ) > 15 GeV/c opposite sign of lepton and tau E T >10 GeV H T = P T (l) + P Τ (τ h ) + P T (jet) +E T >400 GeV/c n jet >= pb -1 removal of conversions, cosmics, and DY Channel : τ l τ h j j (one leptonic, one hadronic decayed τ s) SLQ3 final state: ττbb, same as the RPV Stop search signature 322 pb pb -1 for β=1, CDF: Run II, M VLQ3 > 344 GeV/c 2 for β=1, CDF: Run II, M SLQ3 > 151 GeV/c 2 17

18 Anomalous Diphoton + X Production (X= e, µ, γ ) Searches based on the final state signature diphoton trigger: E T >12 (isolated), E T >18 GeV 2 central photons η < 1 E T >13 GeV γγ+e,μ ( L ~ 683 pb -1 ) one electron E T > 20 GeV one muon p T > 20 GeV γγ+γ ( L ~ 1020 pb -1 ) A third photon η < 1 E T >13 GeV γγγ 0.7 ± 0.1 Fakes 1.2 ± 0.6 Total 1.9 ± 0.6 Observed 4 18

19 Conclusion 1. Current results based on 0.2 ~ 1 fb At present, ~ 1.2 fb -1 on tape 3. World best Limits on Z, LQ, LEDs etc.. 4. Second stage of analysis with ~ 1fb -1 data 5. At the end of 2009, we may have 4 ~ 8 fb So far, ~ 10% of data analyzed from expected data till Expect real discoveries!!??

20 Back up 20

21 CDF Detector Silicon tracking detectors Central drift chambers (COT) Solenoid Coil EM calorimeter Hadronic calorimeter Muon scintillator counters Muon drift chambers Steel shielding η = 2.8 η = 1.0 η = 2.0 θ η = log(tan(θ 2)) 21

22 D0 Detector 22

23 Generic Z Z : Z Z e + pb -1 o 2004 paper by Carena et al defines 4 general model classes (PRD70:093009,2004): B-xL, q+xu, 10+x5, d-xu Within each class, Z defined by: mass M Z, strength g z, parameter x o Comparisons to LEP 2 possible: q+xu, 10+x5, d-xu more exclusion than LEP II As well as LEP II for B-xL More sensitive than LEP to low g z couplings LEP II excluded below line 23

24 Z ee (819 pb -1 ) highest mass event at 491GeV central ( eta <1.1) + plug (1.2< eta <3.0) M ee = 491 GeV/c 2 central-central 24

25 Limits for e* eγ Limits in parameter space of f/λ (GM model) and M e* /Λ(CI model) In GM model, M e* > 430 GeV for f/λ ~ 0.01 GeV -1 (95% CL) In Compositeness model, M e* > 906 GeV for M e* = Λ (95% CL) 25

26 LED ( graviton exchange ) : ee + γγ Gravity effect is parametrized by η G 2 d σ = * dm dcosθ ee, γγ invar iant Scatt. angle f SM + f int η G + f KK Functions of M & cosθ* determined by theory η 2 G QCD SM prediction Signal prediction Fit M ee,m γγ and cosθ * Data consistent with background expectation Bayesian likelihood fitting set 95% CL on η G 95% CL mass limits on Fundamental Planck Scale(M D ) (in TeV) η G : effective x-section parameter (=F/M D4 ) F is a model dependent dimensionless parameter ~ 1 GRW: F = 1 HLZ: F = log(ms2/m2), n =2 F = 2/(n-2), n > 2 Hewett: F = 2 λ/π, λ = ±1 L (pb -1 ) 200 CDF 246 D0 275 D0 Final state ee μμ ee+γγ GRW [1] n= n= HLZ[2] n=4 n= n= Hewett[3] n=7 Λ=+1/λ= / / /1.21 RunI+RunII 26