Searches for Resonances in dilepton final states PANIC

Searches for Resonances in dilepton final states PANIC 2008 9 th-14 th November 2008, Eilat, ISRAEL A. Canepa for the CDF Collaboration November 10 th 2008 A. Canepa 1

Outline § Lepton flavor conserving models § New U’(1), Extra-dimensions § Lepton flavor violating models § SUSY § Maximal Flavor Violation models Peak luminosity, 321 1030 cm-2 s-1 Tevatron Collider In this talk ! The current energy frontier ! § Proton-antiproton collider § s = 1. 96 Te. V at t = 396 ns 2003 November 10 th 2008 A. Canepa 2005 2008 2

CDF at Tevatron Muon chambers Central HAD Calorimeter Central EM Calorimeter Central Outer Tracker Silicon Tracker Central Shower Max (CES) Data for the searches collected with single muon (electron) trigger at p. T (ET) > 18 Ge. V November 10 th 2008 A. Canepa 3

Z’ (I) New U’(1) spontaneously broken new massive Z’ boson coupling to SM fields 2. 3 fb-1 Used for normalization to data Optimized calibration of COT p. T correction using E/p p. T scale from Z Events with two muons p. T > 30 Ge. V § Main backgrounds from § EWK processes § Cosmic rays § Kaons and jet mis. ID as leptons Di-mass resolution constant in m -1 Data statistically consistent with the SM expectations (p-value 6. 6%) November 10 th 2008 A. Canepa 4

Z’ (II) Likelihood fitter 95% C. L. upper limit on the number of signal events § § § 35 bins in search region m -1 < 10 Te. V-1 Resonant pole width = 2. 8% M Assume no interference between SM Z/ * and Z’ SM like Z’ m > 1. 03 Te. V/c 2 at 95% C. L November 10 th 2008 A. Canepa 5

Z’ ee § Energy scale from Z Events with two electrons ET > 25 Ge. V Main backgrounds from § EWK processes § jet mis. ID as leptons 2. 5 fb-1 2. 5 significant excess in [228; 250] Ge. V November 10 th 2008 A. Canepa SM like Z’ m > 966 Te. V/c 2 at 95% C. L 6

G RS model of warped extra-dimensions gravitons propagating in the bulk KK tower of excited modes couple to SM fields Scale of the model ~ MPl e-k R k = curvature of space-time Coupling ~ 1/ Graviton @ k/MPl = 0. 1 m > 850 Ge. V/c 2 at 95% C. L November 10 th 2008 A. Canepa 7

sneutrino SUper. SYmmetry New boson (fermion) partner for each SM fermion (boson) Lepton (or baryon) number violation allowed in theory sneutrino @ 2 BR = 0. 01 m > 810 Ge. V/c 2 at 95% C. L “Single” coupling dominance November 10 th 2008 A. Canepa 8

sneutrino e , , e (I) § To probe lepton flavor violation decay, select events with taus decaying hadronically! New algorithm for ID of energetic hadronic taus Calibration of CES detector to improve resolution of tau visible momentum Response of hadronic calorimeter tuned to data November 10 th 2008 A. Canepa 9

sneutrino e , , e (II) Events with one muon (electron) p. T (ET) > 20 Ge. V and one hadronic tau Visible ET > 25 Ge. V § Major backgrounds § § 1. 0 fb-1 EWK and W+jet jets and mis. ID as leptons Background in signal region extrapolated from low mass region e November 10 th 2008 A. Canepa e 10

sneutrino e , , e (III) Data statistically consistent with the SM expectations in all search channels Mass cut derived from best expected limit BR excluded at 95% C. L in the 10 -2: 10 -1 pb range e November 10 th 2008 A. Canepa e 11

0 LS leptons (I) SM + Max Flavor Violation SM + scalar doublet Expect high cross sections Weak experimental limits ! Events with 2 LS muons (electrons) p. T (ET) > 20 Ge. V, MET > 20 Ge. V, 1 b-tagged jet 2. 0 fb-1 SIGNAL 2 like-sign leptons, 2 neutrinos, 1 b-jet and 0, 1 or 2 light jets November 10 th 2008 A. Canepa 12

0 LS leptons (II) Binned likelihood fit of jet multiplicity to extract the signal § § Assume + heavy not accessible at Te. V real and 31= 13 § 0 ut dominant decay Exclude natural values of ξ=1 at low masses November 10 th 2008 A. Canepa 13

Summary CDF explored up to 2. 5 fb-1 of Tevatron collision data searching for high mass resonances decaying into leptons No signal of New Physics seen World best limits set on Z’, RS gravitons, sneutrino More data to be analyzed in the next years! For updates, http: //www-cdf. fnal. gov/physics/exotic. html November 10 th 2008 A. Canepa 14