Searches for (non-susy) Exotics at HERA Linus Lindfeld, University of Zürich UNIVERSITAS TURICENSIS MDCCC III Int. Conference on Supersymmetry and the Unification of Fundamental Interactions Irvine, California, USA June 27, 2006 on behalf of the collaborations H and ZEUS L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006
Latest HERA luminosity harvest Searches for exotic signatures: Possible new physics: Outline Isolated leptons with pt Anomalous single top viat FCNC Multi-lepton events Doubly charged Higgs Multi-jets with pt Excited neutrinost Sorry, there are yet no new HERA results about... Isolated high-pt µ or τ + jet Resonances in high-q 2 NC/CC Lepton Flavour ViolationT Leptoquarks L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006
HERA with H and ZEUS s = 320 GeV e - /e + 27.6 GeV 920 GeV p e - p Luminosity seen by H (ZEUS similar): HERA I (994-2000) e + p: L ~ 5 pb e p: L ~ 5 pb e - p e + p e + p 2005: luminosity record from 2003 on: longitudinally polarised lepton beam 2000: HERA I ending HERA II (2003-now) e + p: L ~ 50 pb e p: L ~ 40 pb 2002-03: HERA II startup now more than 300 pb of data for each experiment! L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 3
Isolated leptons and (H) hadronic final state, = 29 GeV = 44 GeV Excess at high! isolated electron, = 37 GeV isolated electron hadronic final state Dominant SM process: W-Production at Q 2 ~0 (Photoproduction) e γ, Z 0 q p W + e q l + ν l low isol. lepton σ ~ pb x BR(W leptons)~30% 2 2 HERA I (8 pb ) e + p Combined Electron and Muon N data = 8 N SM = 2.4.7 + 0 20 40 60 80 P T / GeV L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 4 Phys.Lett. B56 (2003) 24-257 Review to HERA I analysis (8 pb of e ± p data): An excess of e + p data events is observed at large hadronic transverse momentum ( > 25 GeV): e: 5 /.8±0.3 µ: 6 /.7± 0.3
Isolated leptons and (H) Total analysed luminosity from HERA I + II datasets : 279 pb 2 H Data (prelim.) All SM Signal + l+p T events at HERA 994-2004 (e p, 58 pb ) N Data = 28 N = 8.5 ± SM 2.6 2 l+p T events at HERA 998-2005 (e p, 2 pb H Data (prelim.) All SM Signal N Data = 2 N SM = 5.8 ± 2.2 58 pb e + p 2 pb e p - ) 0 20 30 40 50 60 70 80 P T e and µ channels H (prelim.) e channel µ channel 279 pb obs. / exp. (W-cont.) obs. / exp. (W-cont.) Full sample 30 / 27.2 ± 3.8 (68%) / 7.2 ±. (8%) > 25 GeV / 4.7 ± 0.9 (69%) 6 / 4.3 ± 0.7 (78%) e p (2 pb ) 2 / 2.4 ± 0.5 (62%) 0 / 2.0 ± 0.3 (76%) e + p (58 pb + ) 9 / 2.3 ± 0.4 (80%) 6 / 2.3 ± 0.4 (78%) 0 20 30 40 50 60 70 80 P T e and µ channels In 279 pb of e ± p data the excess is observed in e + p data only, not in e p!? Does ZEUS see the same? Is there a theoretical concept for this? FCNC-top, SUSY? L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 5
Isolated leptons and (ZEUS) Short answer: No, ZEUS does not see a significant excess of isolated lepton events in HERA I+II e ± p data! e jet e jet ZEUS (prelim.) e channel µ channel obs. / exp. (W-cont.) obs. / exp. (W-cont.) Y View 2 GeV < < 25 GeV 249 pb : 5 / 3.5 ± 0.4 (58%) 26 pb : 2 /.4 ± 0.2 (68%) ZR View > 25 GeV 249 pb : 4 / 4.4 ± 0.5 (6%) 26 pb : 2 /.4 ± 0.2 (86%) e p 43 pb : 3 / 2.86 ± 0.46 (53%) 26 pb : 2 /.4 ± 0.2 (86%) e + p 6 pb +0.2 : /.5 (78%) L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 6 0.3
Anomalous top production via FCNC HERA I analyses have set limits on κ tuγ and v tuζ ZEUS FCNC isolated lepton plus signature v tuz 0.8 0.6 κ tuγ v tuz exclusion region ZEUS (prel.) 94 00 M top =70 GeV M top =75 GeV M top =80 GeV Excluded by CDF κ tcγ =v tcz =0 anomalous magnetic coupling γ anomalous Z vector coupling Ζ large 0.4 0.2 LEP prel. (Born Level) H 94 00 M top =75 GeV Anomalous top production via FCNC may cause observed excess, but it gives no explanation for e + p/e p asymmetry HERA is competitive! 0 0 0.2 0.4 0.6 0.8 HERA I (7 pb ): H upper limit σ(ep et) < 0.55 pb is weaker than ZEUS limit due to excess! L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 7 [Eur.Phys.J. C33 (2004) 9-22] κ tuγ
Isolated tau leptons and (H) it's very difficult to identify tau leptons at HERA H τ + P T dedicated analysis needed! candidate with large P T τ τ R ing Z Y P T = 59 GeV P τ T = 4 GeV P T = 5 GeV Tau-identification (hadronic decays only) based on jets with low track multiplicity and narrow pencil-like shape L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 8
Isolated tau leptons and (H) 53 pb e + p 25 pb e p H (prelim.) τ + 279 pb obs. / exp. Total 25 / 24.2 > 25 GeV 3 / 0.74 e p (25 pb ) 3 / 0.35 e + p (53 pb + ) 0 / 0.40 +4.20 5.80 +0.9 0.6 +0. 0.08 +0. 0. Remarkable events with an isolated tau lepton and is observed at high in e p data! L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 9
Isolated tau leptons and (ZEUS) 2 ZEUS 94-00 data Single Top MC SM W only HERA I e ± p data 30 pb : overflow -2-3 -4 0 D > 0.95 2 3 -log(- D ) D>0.95-2 D: discriminator variable to separate τ-jets from q-jets tau candidate, p =39 GeV T Preselection: 7 / 2.2 D > 0.95: 3 / 0.4 > 25 GeV: 2 / 0.2 > 40 GeV: / 0.07 +0.39-0.58 +0.2-0.3 +0.05-0.05 +0.39-0.58 P T -3 0 20 40 60 80 0 had Phys.Lett. B583 (2004) 4-58 P T Slight excess in the tau channel! Results from HERA II still to come... L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006
Multi-Lepton (H) Spectacular multi-lepton events with very high invariant masses are detected! M eµ > 20 GeV Dominant SM process is elastic γγ scattering e e 2 eee 2 eµµ γ, Z 0 l low and γ, Z0 l low inv. mass p -2 0 20 40 60 80 0 20 40 60 80 M 2 L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006-2 0 20 40 60 80 0 20 40 60 80 M e µ
Multi-Lepton (H) H Data (prelim.) DIS+Compton Pair Production 3 2 e + p (56 pb ) 2+3 leptons 3 2 e p (9 pb ) 2+3 leptons Covered analysis topologies: 2 leptons: ee, µµ, eµ 3 leptons: eee, eµµ -2 0 20 40 60 80 0 20 40 60 80 Σ P T -2 0 20 40 60 80 0 20 40 60 80 Σ P T The excess of multi-electron events at high Σ is seen in HERA I data. [Eur.Phys.J. C3 (2003) 7-29] New HERA II data is compatible with SM expectation (Σ is the scalar sum of the lepton transverse momenta) H Preliminary 275 pb Σ > 0 GeV Data SM HERA I+II (275 pb ) 4. ± 0.2 e + p (56 pb ) 4 0.6 ± 0. e p (9 pb ) 0 0.5 ± 0. L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 2
Multi-Lepton (ZEUS) eee event in HERA I... events 2 ZEUS ZEUS (prel.) 94-00 GRAPE+NC+QEDC NC+QEDC QEDC -2 0 20 40 60 80 0 20 40 M 2 M 2 : inv. mass of two electrons with highest inv. mass HERA I analysis (30 pb ) events with two or more electrons: Type data SM all 27 248.5 ± 3.9 E T,e > 30 GeV 8 7. ± 0.3 M 2 > 0 GeV 2.4 ± 0.09 Event yield is compatible with SM L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 3
Doubly charged Higgs (H) Dedicated search for ee, eµ or eτ pairs with equally charged leptons (=beam charge) σ x BR (pb) cross section H H ±± e ± τ ± H ±± e ± e ± L,R h ee Excluded by LEP electron channel Excluded by CDF, h R ee Excluded by CDF, h L ee Excluded by H H Excluded via Bhabha Scattering OPAL BR(H ±± e ± e ± )=0% Excluded by OPAL H ±± e ± µ ± HERA I analysis (8 pb ): ee: 3 / 2.45 ± 0. Results: eµ: / 4.2 ± 0.44 eτ: / 2.07 ± 0.54 lower limit on mass of H ++ assuming exclusive coupling h eµ,eτ =0.3 to eµ (eτ) at 4 GeV (2 GeV) [Subm. to Phys.Lett.B, hep-ex/0604027] h L,R eµ 80 0 20 40 M H Excluded by LEP muon channel Excluded by CDF, h L eµ Excluded by H 4 GeV BR(H ±± e ± µ ± )=0% H 80 0 20 40 M H h L,R eτ h eµ =0.3 80 0 20 40 60 M H Excluded by LEP tau channel 2 GeV Excluded by H h eτ =0.3 BR(H ±± e ± τ ± )=0% H 80 0 20 40 M H L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 4
e ν W ± q(x) p ν, (e) γ, Z, (W ± ) q Excited neutrinos (H) Signature: neutral lepton-boson resonance (CC-like) extra jets besides ν* decay products Feature: cross sections are O( 2 ) larger in e p collisions due to favourable valence u-quark and helicity enhancement in CC L int = 2Λ F R σµν τa gf 2 W µν a }{{} SU(2) + g f Y 2 B µν }{{} U() 2 Ga µν F L }{{} SU(3) + g s f s λ a ν* e* Hagiwara et al, ZPC 29 (985) 5. Boudjema et al, ZPC 57 (993) 425. boson couplings to fermion F and excited fermion F*: C γff = 2 (fi 3 + f Y 2 ) C ZFF = 2 (fi 3 cotθ W f Y 2 tan θ W) C WFF = f 2 2 sinθ W C γνν = 4 (f f ) C γee = 4 (f + f ) photon coupling to νν* only for f f' photon coupling to ee* only for f f' L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 5
Excited neutrinos (H) Analysis reaches 80-90% (~70%) acceptance assuming f= f' (f=+f') by covering the channels: Decay: ν νγ ν νz ν qq ew qq Signature: photon + + multijet e + multijet SM Bkg: radiative CC CC (multijet) NC (multijet) ν νγ ν νz ν qq ew qq γ jet jet jet jet ν ν e L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 6
Excited neutrinos (H) 5 4.5 4 3.5 3 2.5 2.5 0.5 Extended domain for ν* production explored! for f= f' and f/λ=/m ν* M ν < 88 GeV excluded * H Preliminary - Search for ν νγ 0 50 0 50 200 250 300 350 M ν* ) f / Λ (GeV ν νγ ν νz ν qq ew qq -2-3 H Data (prelim.) All SM Processes - - H Preliminary ν* limit 4 pb (e p) f = - f H 98-99 5 pb LEP (L3) e p, 4 pb 25 20 5 0 50 0 50 200 250 300 350 M ν* f / Λ = /(M ) ν* 0 20 40 60 80 200 220 240 260 M ν* 5 * H Preliminary - Search for ν νz qq H Data (prelim.) All SM Processes 0 20 40 60 80 200 220 240 260 M ν* L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 7 ) - f / Λ (GeV -2-3 e p, 4 pb 40 35 30 25 20 5 5 - H Preliminary ν* limit 4 pb (e p) f = + f H 98-99 5 pb LEP (L3) H Preliminary - Search for ν* ew qq 0 50 0 50 200 250 300 350 M ν* f / Λ H Data (prelim.) All SM Processes = /(M ) ν* - e p, 4 pb data/sm : 2 /.6 ± 2.5 88 / 8 ± 5 36 / 8 ± 22 88 GeV
Summary Excess of isolated leptons observed at H in old and new e + p data e + p/e p asymmetry apparent No such excess at ZEUS with Tau leptons + pt : Slight excess in both experiments Remarkable high-pt multi-lepton events observed Competitive new limits on doubly-charged Higgs New domain explored for a possible excited neutrino production and limits extended L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 8
Outlook H Integrated Luminosity / pb 500 400 300 200 electrons positrons projected HERA-2 watch out for the data still to come! HERA 0 0 0 500 00 500 Days of running L. Lindfeld, Uni Zürich SUSY'06, Irvine June 6, 2006 9