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Searches for. New Particles and Phenomena. at CDF. Chris Hays, Duke University for the CDF Collaboration. Fermilab Frontier. Structure of Matter. Interaction Time Scale. 10 -20 sec. 10 -24 sec. 10 -28 sec. 10 -32 sec. 10 -36 sec. 10 -40 sec. 10 -44 sec. Atom. Nucleus.
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Searches for New Particles and Phenomena at CDF Chris Hays, Duke University for the CDF Collaboration
Fermilab Frontier Structure of Matter Interaction Time Scale 10-20 sec 10-24 sec 10-28 sec 10-32 sec 10-36 sec 10-40 sec 10-44 sec Atom Nucleus particle string? 10-11 m 10-15 m 10-19 m 10-23 m 10-27 m 10-31 m 10-35 m Distance Scale ( ) ( ) ( ) u d c s t b Chiral Color? SU(3) g Right-handed Weak Force? Axigluons? ( ) ( ) ( ) Supersymmetry? Grand Unification? SU(2) e ne m nm t nt Leptoquarks? W,Z Monopole? Strong Gravity? Z'? H++? Electroweak Unification q*? e*? Higgs? Extra Dimensions? U(1) Technicolor? Unitarity violation (WW scattering) g Strings? H0? Compositeness? History of the Universe Age of Universe 10-20 sec 10-28 sec 10-36 sec 10-44 sec 104 sec 10-4 sec 10-12 sec 104 TeV 108 TeV 1012 TeV 1016 TeV 10-8 TeV 10-4 TeV 1 TeV Temperature of Universe
m END WALL 2.0 HADRON = 1.0 n CAL. 0 30 SOLENOID 1.5 1.0 = 2.0 n COT END PLUG HADRON CALORIMETER END PLUG EM CALORIMETER .5 = 3.0 n 0 3 0 2.5 0 .5 1.0 1.5 2.0 3.0 m Intermediate silicon Inner silicon 1 or 2 layers 6 layers CDF Detector Reconstructed Objects MUON UPGRADE (CMP) STEEL CENTRAL MUON (CMU) MUON EXTENSION (CMX) CENTRAL HAD. CALORIMETER CENTRAL EM CALORIMETER h=1.0 q or g “jet” g e m
Excited Electrons Composite electrons have excited states Excited electron decays to e+g Zg dominant background Expect 1 event with mee= Z Observe 1 event (mee= Z), 0 events (mee = Z)
Doubly-Charged Particles X++/-- e+/- e+/- ( ) H0 H+ H++ Doubly-charged Higgs L-R symmetric model: m SU(2)LxSU(2)R m m ~ l nL l m Explains light neutrino masses NR 0 events observed Search mass windows Z ee W+jet
Doubly-Charged Particles m+/- m+/- X++/-- Cosmic rays dominant background W+jets dijets CDF RUN II PRELIMINARY cosmics Expect 0.9±0.2events (mass>80 GeV) 2 events observed: m=160, 760 GeV H++/-- mass > 110 GeV (LEP: > 100 GeV)
Dijet Mass Search Sensitive to variety of new physics Probes highest available energies Excludes axigluon mass < 1.1 TeV
Dilepton Mass Search Search for neutral resonances Graviton Theory with 1 extra dimension Z’ Run 1: > 690 GeV
Long-Lived Charged Particles Search for heavy, slow particles 4th generation quarks “stable” supersymmetric top quarks DTOF>2.5 ns Tracks with long flight time (>d/c) Expect 2.9±3.1 events, observe 7 stop mass > 108 GeV (LEP: > 95 GeV)
Leptoquarks Directly couple quarks to leptons Predicted by Grand Unified Theories One LQ per generation at low mass LQ qe (qn) pp LQ qe (qn) qqee qqen Expect 3.4±3.2 events, observe 0 Expect 1.9±1.3 events, observe 1 CDF+DØ Run 1: mLQ > 242 GeV DØ Run 1: mLQ > 204 GeV MLQ>230 GeV MLQ>177 GeV
Leptoquarks LQ qn pp LQ qn Sensitive to leptoquarks of all 3 generations 2 jets + Missing Energy challenging experimental signature Many Standard Model, detector backgrounds Requires understanding of calorimeter noise and cracks qqnn W, Z + jets QCD multijet production DØ Run 1: mLQ > 98 GeV
Diphoton Search Gauge-mediated supersymmetry breaking predicts ggET signature c1 No excess at high ET for g ET> 25 GeV Gg pp c1 Gg Diphoton sample understood ...or for g ET> 13 GeV
Still Searching... Past year of data has provided increased sensitivity to new physics Supersymmetry Compositeness Technicolor Chiral color Right-handed weak force ...and new particles Excited electrons Diquarks Doubly-charged Higgs Gravitons Leptoquarks Supersymmetric top quarks Coming year will provide even more sensitivity to new physics and particles SUGRA (Bsmm) chargino, neutralino (trileptons) stop, LQ (2 jets + ET, with heavy flavor tagging) magnetic monopoles
gET Search Variety of new physics with gET signature Supersymmetry Clean up ET Large Extra Dimensions Clean up photons Observed events consistent with background prediction