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CDF Searches for at High Diphoton and Dilepton Masses

New Physics. CDF Searches for at High Diphoton and Dilepton Masses. Motivation - Alternatives to SUSY Introduction to the Tevatron and CDF Dilepton ( ee , mm * ) and gg Event Selection Comparison of Background Expectation to Data Spin Dependent Acceptances

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CDF Searches for at High Diphoton and Dilepton Masses

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  1. New Physics CDF Searches for at High Diphoton and Dilepton Masses • Motivation - Alternatives to SUSY • Introduction to the Tevatron and CDF • Dilepton (ee, mm*) and gg Event Selection • Comparison of Background Expectation to Data • Spin Dependent Acceptances • Preliminary Results • Summary and Conclusions Tracey Pratt Liverpool University * searches presented by A. Anastassov SUSY 2004, Tsukuba, Japan

  2. ADD Taking compact space to be very large Gravity freely propagates in the many large extra dimensions (n=2-7) MPl2 = VnMPl(4+n)(2+n) To solve hierarchy: G MPl(4+n) ~ 1 TeV Alternatives to SUSY to Solving the Hierachy Problem (MEW << MPlanck?) Extra dimensional (ED) solutions RS Curvature of the extra dimension compactified Planck TeV brane 1 highly curved extra dimension Torus Gravity localised in the ED Vn = 2Rcn Scale of physical phenomena on the TeV-brane is specified by the exponential warp factor: = MPle-kRc ~ TeV if kRc ~11-12.  requires Rc ~ 10(30/n–19) m for n  2, Rc < 1 mm hep-ph 9803315 hep-ph 9905221 SUSY 2004, Tsukuba, Japan

  3. l- q l- q l- g /Z0 KKn KKn + + l+ q l+ q g l+ q l+ KKn q l- g l+ KKn g l- l+ l+ l+ l- l- l- Search for ED? q • Deviations in cross sections () and angular distributions from SM processes caused by graviton exchange Resonance in RS model and broad change in  in ADD model q Dilepton Channel Diphoton Channel Z/ Standard Model l- Extra Dimensions • Low backgrounds • Clean experimental signature • Also search for other physics models SUSY 2004, Tsukuba, Japan l+ q /Z gg initiated process q l- gg initiated process

  4. l+ X? l- l- l+ l+ l- l- Other New Physics Searches in Dilepton Channels Also set limits on new physics • Z' (E6 and Little Higgs) (Spin-1) • RPV sneutrinos (Spin 0) • Perform general searches comparing data to expectation • Determine spin dependent acceptance and .BR • Interpret data according to many new models! X X? X? • Z' occurs naturally in extensions of SM towards GUT scale, e.g. “E6” models • M(Z')>570 GeV for E6 models (depends on exact model: • couplings to quarks and leptons) • M(Z')>750 GeV for SM coupling • (D0 M(Z')>719 GeV, 122 pb-1) Search Strategy SUSY 2004, Tsukuba, Japan

  5. CDF @ Tevatron pp Collider Highest energy collider operating in the world! CDF p p D0 Run I (1992-1996) √s  1.8 TeV, 110/pb Run II (2001-2009) √s 1.96 TeV Physics Analyses use ~ 200/pb collected between 03/02 and 09/03 days SUSY 2004, Tsukuba, Japan Ldelivered ~400/pb and ability to set improved limits on new physics

  6. mm 2 isolated m PT>20 GeV |m1|<1, |m2|<1.5 Cosmic ray rejection cuts Search Selection Muon System Central Calorimeters || < 1 || < 1.5 || < 1 • ee • 2 two isolated e, ET > 25 GeV • 2 central e (CC) • or 1 central and 1 forward e (CP) Plug Calorimeter 1<||<3 Solenoid COT gg 2 isolated g ET>15 GeV 2 central g (CC) Time-of-Flight Silicon Tracker Perform searches compare to bkdgs and apply to new physics models SUSY 2004, Tsukuba, Japan

  7. High Mass Dielectrons 371 GeV CC+CP Typical CC event PP CDF6343 SUSY 2004, Tsukuba, Japan We find good agreement with the Standard Model expectation and thus set an upper limit on the production cross section (times branching ratio) for the production of particles leading to this signature. We do this separately for spin-0, spin-1 and spin-2 particles since the experimental acceptance depends on the spin. We then interpret this cross section limit in terms of physics beyond the Standard Model: Z', RS Gravitons, sneutrino, technicolor, Little Higgs. The main source of background is Drell-Yan. Jets being misidentified as electrons (labelled "QCD") are another important source of background.

  8. High Mass Dimuons Total of ~ 7500 dimuon candidates in 200 pb-1 data High mass dilepton spectra is consistent with background prediction SUSY 2004, Tsukuba, Japan

  9. Dilepton Angular Distributions mm cos* in Collins-Soper frame SUSY 2004, Tsukuba, Japan can I say that these are … - what deviations would we expect though?! Results consistent with the background

  10. High Mass Diphotons • Backgrounds • Standard Model diphoton production • Fakes: -jet and jet-jet, • where jet fragments into a hard p0 Total Background 405 GeV/c2 SUSY 2004, Tsukuba, Japan Search selection 2 isolated m ET>15 GeV, ||<1

  11. Highest Mass Event SUSY 2004, Tsukuba, Japan

  12. Spin-dependent Acceptance Angular distribution and therefore acceptance of decay products depends on the spin of the decaying particle. spin-0 spin-1 spin-2 SUSY 2004, Tsukuba, Japan The following plots show the efficiency times acceptance of detecting a particle decaying into a electron-positron pair as function of the mass. Since the spin of the particle changes the angular distribution of the decay particles we consider the possible spin of any new particle separately: spin-0 , spin-1 and spin-2.

  13. ni i L(/)=i i e ni! L()/(4x10-14 GeV-4) 95 % • 95%= N95% AÕ || (x10-11GeV-4) New Physics Limits spin-1 Bayesian method with flat prior probability 95 % C.L. upperlimits on .BR(G→) are placed using ± 3 search windows around MG • Observed limit consistent with expectation • Applicable to any new possible future theory 95 % C.L. upperlimits on .BR(X→ll) for spin-0,1,2 and lower limits on string scale are placed using binned likelihood method 1sigma error and 2 sigma error on the expected limit ni : observed events mi= a Nisig + Nibkg (Resonant particles) mi= Nisig() + Nibkg (LED spectrum) Repeat the pseduoexperiment 1000 times. The value of each bin is chosen randomly from Poisson distribution which has the mean value of the expected background. Likelihoods are integrated to give the final limits, taking into account the signal and background systematic uncertainties Sources of systematic uncertainties: Luminosity (6%) Acceptance (PDF, MC statistics..) Energy/Momentum scale resolution Selection Efficiencies Background statistics and normalisation N95%=95%Nsig 95 % CL upper limits on sigma*BR for spin-0,1,2 used to set limits (all except LED – limit set using binned likelhood method) SUSY 2004, Tsukuba, Japan 1and 2  error spin-1 1and 2  error on the expected limit 1) Scan through h, and at each point, reminimise L w.r.t nSM and nBG. 2) Plot L 3) 95 % C.L. result is the value of h such that 95 % of area under the likelihood function lies between it and 0. detector description,..)

  14. l- q l- q l- g /Z0 KKn KKn + + q l+ q g l+ l+ Randall-Sundrum Graviton Dilepton Channel 470 GeV/c2 620 GeV/c2 gg initiated process   Clean experimental signature. Low backgrounds ee K/Mpl 0.1 620 0.05 470 0.02 310 0.01 200 ee has largest acceptance at low mass has largest acceptance at high mass BR(G→) = 2 * BR(G→ee) for k/M_Pl=0.05 masses less than 500 GeV are ruled out at 95% C.L.. SUSY 2004, Tsukuba, Japan Randall-Sundrum gravitons are excluded by these data in the plane of coupling (k/MPl) versus effective graviton mass. E.g. for k/M_Pl=0.05 masses less than 500 GeV are ruled out at 95% C.L.. Add Run I limits?! Scale of physical phenomena on the TeV-brane is specified by the exponential warp factor: = Mple-kRc ~ TeV if kRc ~11-12. Scale of physical phenomena on the TeV-brane is specified by the exponential warp factor: = Mple-kRc ~ TeV if kRc~11-12.

  15. Large Extra Dimensions ee Set a limit on the effective Planck scale (Ms4) in ADD model Generate MC templates for each piece independent of the choice of  and Ms4. Parameterise the cross section in terms of h = /Ms4 (*=±1) s =sSM+h sINT+ h2 sKK A 3 parameter (nSM, nBG,h) unbinned likelihood function is used to extract h * 987 959 D0 1.28 GeV (GRW) 128 pb-1 ee/ CDF Run I: 780 768 SUSY 2004, Tsukuba, Japan Gupta et. al. hep-ph/9904234 Compare to D0 limits!

  16. Spin-1 Dilepton Limits Z' bosons CDF Run L(pb-1) Mass Limit @ 95 % Z' SM eemm Run IA(92-93) 20 505 Run IB(94-94) 90 640 590 IIA (winter 04) 200 750 735 • Sequential Z`: Reference model • with SM-like couplings to fermions • Free parameter M(Z`) Run I limits exceeded! E6 Z' Technicolor • E6 Model Z`:del Aguilia et al., Nuc Phys B287 (87) • Unification of strong and EWK forces at GUT • E6→(SO(10)→SU(5)xU(1))xU(1) • Z` = Z sinE6 + Z cosE6 • Z,ZIE6 = sin-1√3/8, sin-1√5/8 RPV sneutrinos SUSY 2004, Tsukuba, Japan

  17. Spin-1 Dilepton Limits Little Higgs Z' Solve fine-tuning and hierarchy by canceling divergences of Higgs mass SU(2) ZH coupling parameter cot mm Technicolor First limits set! Littlest Higgs ZH (→ee) M(ZH)>800 GeV/c2 for cot=1.0 M(ZH)>755 GeV/c2 for cot=0.9 RPV sneutrinos Arkani-Hamed, Cohen, Georgi, Phys. Lett. B 513, 232, 2001 Han, Logan, McElrath, Wang, Phys. Rev. D 67, 095004, 2003 SUSY 2004, Tsukuba, Japan

  18. Spin-0 new physics limits RP sneutrino l+   ` : square of coupling to initial state x BR = proportional to the cross-section `  l- ee SUSY 2004, Tsukuba, Japan

  19. Summary and Conclusions • Many searches for new physics at CDF are underway • Presented: preliminary results in high mass ee++ (200 pb-1) • Surpassed the sensitivity and results of Run I high mass dilepton searches • Limits shown either exceed any published results of direct searches or are the first limits ever! • Lots more CDF data to analyse • Combined results and publications are on the way .BR upper and mass lower limits on various new physics models @ 95 % using 200 pb-1 of CDF II high mass ee++ data Many new exciting results from CDF and more coming soon! SUSY 2004, Tsukuba, Japan

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