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Status of New Physics Searches at the Tevatron DIS 2011 Newport News, VA Status of New Physics Searches at the Tevatron Craig Group (University of Virginia and Fermilab) on behalf of the CDF and D0 experiments… Outline Searches at the Tevatron • The Tevatron, CDF, and D0 • Dilepton/diphoton resonances • Diboson resonances • Complex final states (MET, jets, H.F.) • Higgs (SM) • Higgs (non‐SM) DIS2011 C. Group ‐ Review of Searches at the Tevatron 2 The Tevatron at Fermilab The Tevatron currently provides the high energy proton‐anproton collisions: Ecm = 1.96 TeV CDF DO Tevatron DIS2011 C. Group ‐ Review of Searches at the Tevatron 3 The Tevatron is… …and has been a Discovery Machine! Results shown today include 4‐8 ‐1 Single Top Rare Bs decays Diboson Channels Y(4140) Bs ΦΦ Charm mixing ZZ WZ Z+b Bs‐mixing Exclusive charm Exclusive ee Top Quark DIS2011 C. Group ‐ Review of Searches at the Tevatron 4 Dilepton Final States Old‐fashioned bump hunt in Mee distribuon: CDF: 5.7‐1 ‐Z producon and decay into ee/µµ precisely measured D0: 5.4‐1 ‐Lepton ID/Reco and Trigger efficiencies high and very well understood ‐Background low and easily determined (QCD fakes) ‐Clean events PLB 695, 88 (2011) CDF Public Note 10405 DIS2011 C. Group ‐ Review of Searches at the Tevatron 5 Dilepton Final States Old‐fashioned bump hunt in Mee distribuon: CDF: 5.7‐1 ‐Z producon and decay into ee/µµ precisely measured 2 D0: 5.4‐1 ‐Lepton ID/Reco and Trigger efficiencies high and very well understood = 960 GeV/c ‐Background low and easily determined (QCD fakes) Mee ‐Clean events PLB 695, 88 (2011) CDF Public Note 10405 event ever recorded! dilepton the highest DIS2011 C. Group ‐ Review of Searches at the Tevatron 6 Dilepton Final States No obvious resonant structure limits on exoc models: ex. Z’, RS Graviton PLB 695, 88(2011) CDF Public Note 10405 M(ZSSM) > 1023 @ 95% CL M(RSG) > 907 (k/MPl=0.1) @ 95%CL Best limit in this channel! 927 with fixed k‐factor DIS2011 C. Group ‐ Review of Searches at the Tevatron 7 Dilepton Final States ‐1 CDF has searched the Mμμ distribuon as well: CDF:4.6 PRL 106, 121801 (2011) Limits are derived for other scenarios (2.3‐1) Sneutrino: up to 866 GeV/c2 (λ2BR = 0.01), 2 RS graviton: up to 921 GeV/c (K/MPL = 0.1) Best limit in this channel! DIS2011 C. Group ‐ Review of Searches at the Tevatron 8 Dilepton + Diphoton Final States Sensivity to the Graviton is improved by combining searches in Mee and Mγγ. Graviton KK excitaon mass limits: 2 560‐1050 GeV/c for 0.01 ≤ k/MPL ≤ 0.1 PRL 104, 241802 (2010) Excess at 450 GeV/c2 (diphoton) ‐ 2.3σ significance DIS2011 C. Group ‐ Review of Searches at the Tevatron 9 Dilepton + Diphoton Final States Phys.Rev.D83:011102,2011 Combined with dielectron channel gives the most 2 stringent limits to date (M(RSG) > 963 GeV/c k/MPL = 0.1) 2 604‐1055 GeV/c for 0.01 ≤ k/MPL ≤ 0.1 (variable k‐factor) 1089 for k/MPL for fixed k‐factor CDF Public Note 10405 See details and most recent Graviton results from John Strologas (Wed. session of EWK/BSM Working group talks) DIS2011 C. Group ‐ Review of Searches at the Tevatron 10 New W’ Result Search for heavier versions of the EW gauge boson: simple final state with lepton and neutrino Pushing the envelope by going up to energies far from benchmarks! Understanding of the SM tails very important. No excess observed‐ 95% CL limit mW’ > 1.1TeV Phys.Rev.D83:031102,2011 (CMS limit already at 1.6 TeV!) DIS2011 C. Group ‐ Review of Searches at the Tevatron 11 Diboson Producon •Diboson producon is one of the least tested areas of the SM •The triple gauge verces are sensive to physics beyond the SM •SM diboson producon share many characteriscs and represent background to Higgs and SUSY searches See details and most D0 Diboson results from Joe Haley (Thurs. session of EWK/BSM Working group talks) DIS2011 C. Group ‐ Review of Searches at the Tevatron 12 Diboson Searches Limits from combining: Search sensivity increased by spling into high mass/low lνjj, lljj, and tri-leptons. mass regions arXiv.org:1011.6278 (acc by PRL) Tri‐leptons: PRL 104, 061801 (2010) 4.1‐5.4 ‐1 DIS2011 C. Group ‐ Review of Searches at the Tevatron 13 Vector‐like Quarks Q decays into W/Z +q Final state of lepton(s), MET and at least 2 jets 5.4 fb-1 Single lepton Q Use MT (lepton plus MET) and Mllj masses and search for evidence of the Qv decay. dileptons QV→Wq QV→Zq PRL 106, 081801 (2011) DIS2011 C. Group ‐ Review of Searches at the Tevatron 14 W+jj arXiv:1104.0699 •Special Wine & Cheese seminar: 3.2 sigma excess! •CDF has an excess in the dijet mass for W+2 jet events above the W mass peak. •If fit to Gaussian of with of mass resoluon the significance can be calculated as 3.2 sigma •Not consistent with SM Higgs, not seen in Z+jets •Provisionally accepted by PRL within 48 hours of submission Analysis web page: hp://www‐cdf.fnal.gov/physics/ewk/2011/wjj/ DIS2011 C. Group ‐ Review of Searches at the Tevatron 15 More Exoc Final States Photon + MET + b‐jet + lepton : γ • Leading background is Standard Model t-tbar + γ. • Search for deviation from the Standard Model, and measurement of the ratio of the cross section: γ- ttbar/ ttbar. Possibly the smallest cross‐secon measured! CDF Public Note 10270 No excess observed, σ(ditop+γ) =0.18 ±0.07 pb 6.0 ‐1 R(γ/) = 0.024 ± 0.009 DIS2011 C. Group ‐ Review of Searches at the Tevatron 16 More Exoc Final States MET + leptonic jet (exoc SUSY) 5.8 ‐1 – hidden sector weakly coupled to SM parcles – Force carrier in the hidden sector: dark photon – Dark photon decays to highly collimated SM parcles • Signature: two leptonic jets and MET • Leptonic jet ‐ regular lepton + addional track(s) of opposite charge near the lepton NOTE: efficiency times acceptance varies over range of masses due to hadronic decays. PRL, 105, 211802 (2010) DIS2011 C. Group ‐ Review of Searches at the Tevatron 17 More Exoc Final States 4th Generaon: t’ Exoc 4th generaon quarks t’‐> tX, where X is a dark maer candidate (w/ Dark Maer) • J.Feng et al, arXiv:1002.3366 • Other scenario: stop ‐> top + neutralino •Signature: bar + large MET 4.8 ‐1 •Dominant background, bar and W+jets Strategy: CDF Public Note 10374 1) fit background + signal transverse mass distribuon 2) Opmize the MET cut for different points 3) Test modeling of background is in control regions Control region Control region Signal region CDF Public Note 10374 DIS2011 C. Group ‐ Review of Searches at the Tevatron 18 More Exoc Final States 4th Generaon: b’ Current limits push 4th generaon down‐type quark to be above m(top)+m(W) Final state comprising top and extra W’s Lepton+jets signature ‐ high acceptance due to hadronic decaying W’s Fit to HT = Σ(Jet ET + lepton ET + MET) Across different jet mulplicity bins 5‐jets 6‐jets 7‐jets Mb’>375 GeV Exclude b’ < 385 GeV/c2 @95% CL arXiv:1101.5728 DIS2011 C. Group ‐ Review of Searches at the Tevatron 19 Exoc Searches Summary The search for new physics at the Tevatron continues… • The Tevatron has been performing very well • Very Large Dataset! • Some limits are still the best! • The CDF and D0 collaborations are pushing: – for better and improved limits on particles production • Small cross-section phenomena now accessible due to large luminosity – to exercise most techniques applicable • LHC is surpassing the Tevatron quickly as expected, but surprises might still come from CDF and D0…. More search results and details: – http://www-cdf.fnal.gov/physics/exotic/exotic.html – http://www-d0.fnal.gov/Run2Physics/WWW/results/np.htm DIS2011 C. Group ‐ Review of Searches at the Tevatron 20 Higgs Searches at the Tevatron DIS2011 C. Group ‐ Review of Searches at the Tevatron 21 Higgs Searches: The basics ZH → llbb WH → lνbb ZH → ννbb H → WW → lνlν Note: These are the most sensive channels but all non‐negligible producon and decay modes are considered. DIS2011 C. Group ‐ Review of Searches at the Tevatron 22 Higgs Producon Rates About 1000 Higgs events expected to be produced at the Tevatron in the full dataset! (10 ‐1) DIS2011 C. Group ‐ Review of Searches at the Tevatron 23 2 Results: Low Mass (MH = 115 GeV/c ) Channel CDF D0 Limit x SM Limit x SM (expected) (expected) WH → lνbb 3.5 4.8 ZH → ννbb 4.0 4.0 (New!) ZH → llbb 5.5 5.7 H → WW → lνlν 10.8 (New!) 8.6 (New!) ZH+WH → jjbb 18 19.9 H → ττ 15 (New!) 12.8 (New!) H → ϒϒ 20.8 11 (New!) DIS2011 C. Group ‐ Review of Searches at the Tevatron 24 High Mass (HWW) • Most important channel for MH> 125 GeV • Contributes down to 115 GeV Spin correlaon: Main challenge: to distinguish signal Leptons go in the same direcon from EWK WW pair production. W+ H + W+ μ W‐ Signal x 10 ν ‐ W‐ e Backgrounds ν Dilepton opening angle is the strongest background discriminant DIS2011 C. Group ‐ Review of Searches at the Tevatron 25 Tevatron Combinaon One experiment is not enough – need to combine CDF and D0 results! High mass result featured on PRL First published cover page Standard Model Higgs exclusion since LEP! DIS2011 C. Group ‐ Review of Searches at the Tevatron 26 But, one experiment is enough! CDF and D0 have obtained single experiment exclusion at high mass! DIS2011 C.
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