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Tracey Berry (n ée Pratt) University of Liverpool

IOP HEPP Conference 2005. Exotics!. Tracey Berry (n ée Pratt) University of Liverpool. Talk Structure. Motivation Exotics Physics Searches* Signature based, Model based Where Results Summary. Disclaimer! Only a very small selection of Exotics results are presented here!

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Tracey Berry (n ée Pratt) University of Liverpool

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  1. IOP HEPP Conference 2005 Exotics! Tracey Berry (née Pratt) University of Liverpool IOP HEPP Conference, Dublin March 2005

  2. Talk Structure • Motivation • Exotics Physics Searches* Signature based, Model based • Where • Results • Summary • Disclaimer! Only a very small selection of Exotics results are presented here! • See other talks for more details. IOP HEPP Conference, Dublin March 2005 (Summary/Outlook) B physics!!!** • Future/Outlook(?) Experiments

  3. “Exotic” Physics : Why ? The SM describes experimental measurement very well, but raises crucial questions In the SM, EW symmetry breaking is responsible for giving rise to massive particles. The broken symmetry arises from a Higgs scalar field. Where/what is the Higgs boson ? Is it a fundamental scalar field? Or is the symmetry broken through a dynamical interaction ? topcolor unobserved Higgs boson technicolor (H→ qTqT) Technicolor H→ qTqT Supersymmetry Hierarchy problem MEW << MPl ? “Little” hierarchy Extra-dimensions • Questions which the SM (or SM + SUSY) does not answer : • “Replication” of three families ? • Particle masses & their hierarchy ? Compositeness ? Superstrings ? Extra-dimensions ? IOP HEPP Conference, Dublin March 2005 Dynamical Breaking of EW excited electrons: the hierarchical structure of the SM fermion families could be taken as an indication of quark and lepton substructure. One would therefore expect excited states of q’s and l’s to be produced in high energy collisions In a compositeness model, the new, strong interactions that binds the constituents (preons) may be expected to produce excited electrons strongly, with fairly large cross-sections. The Standard Model of electroweak and strong interactions continues to describe experimental measurement very well. In the Standard Model, electroweak symmetry breaking is responsible for giving rise to massive particles. The broken symmetry arises from a Higgs scalar filed and as yet unobserved Higgs boson. An alternative explanation for the broken symmetry is through a dynamical interaction known as technicolor, where the Higgs boson is replace by states of two techniquarks, called technipions, bounds by the technicolor force. A recent walking technicolor model predicts color singlet technirho production in high energy PbarP collisions throught a s-channel qbarq annihilation. This technirho can decay to technipions and to bosons , with a relatively high production cross section.

  4. G g,q f,V g,q f,V Signature Based Searches Exotic • Dilepton: ee, mm, tt (signature based) • gg, diEM (ee+gg), • Trileptons and include SUSY if time?! (model based) • e* (signature based) • Leptoquarks - e nu , mu nu etc.. (model based) • B physics (signature based)??? • WH (signature based) • H++ (signature based) • Bmu (signature based) (SUSY?!) • Other searches : CHAMPS, monopoles • Signature Based Search Strategy • Select signature, e.g. ee, mm, tt • Compare data to expectation from Standard Model • any deviation could indicate evidence of new physics • Interpret results in context of specific models Spin-0 RPV sneutrinos Spin-1 Z‘ bosons Spin-2 Extra dimensions n Z' IOP HEPP Conference, Dublin March 2005 *being very selective: not covering SUSY searches (initial signature motivated by some model) requires understanding backgrounds • Why? • initial signature motivated by some model • apply same search results to several models • How? • search for a particular signature • understand backgrounds • provide cross section limits: try to be as • generic/model-independent as possible • - study acceptance as a function of spin • interpret in context of specific models •  applicable to future models! • Signatures?ee •  • jj •  •  + ET occurs naturally in extensions of SM towards GUT scale e.g. “E6” models

  5. Signature Based Searches Exotic • Dilepton: ee, mm, tt (signature based) • gg, diEM (ee+gg), • Trileptons and include SUSY if time?! (model based) • e* (signature based) • Leptoquarks - e nu , mu nu etc.. (model based) • B physics (signature based)??? • WH (signature based) • H++ (signature based) • Bmu (signature based) (SUSY?!) • Other searches : CHAMPS, monopoles • Signature • Single leptons • Dileptons: ee, mm, tt • gg, diEM (ee+gg) • Low mass m+m- • Same-sign: em, ee, mm IOP HEPP Conference, Dublin March 2005 *being very selective: not covering SUSY searches • Why? • initial signature motivated by some model • apply same search results to several models • How? • search for a particular signature • understand backgrounds • provide cross section limits: try to be as • generic/model-independent as possible • - study acceptance as a function of spin • interpret in context of specific models •  applicable to future models! • Signatures?ee •  • jj •  •  + ET

  6. e+/- p 920 GeV 27.5 GeV Lepton Search Experiments LEP, CERN, Geneva Tevatron, Fermilab, USA HERA, DESY, Hamburg CERN: world's largest particle physics laboratory H1 p e- e- e+ CDF p p D0 Tevatron: Highest energy collider operating in the world! LEP I √s = 91 GeV LEP II √s =136-208 GeV World’s only ep collider HERA Run I: L 130pb-1 √s =320 GeV L = ~ 70ish pb-1 Run I √s = 1.8 TeV Run II √s = 1.96 TeV Run I √s = 320 GeV Run II √s = 320 GeV IOP HEPP Conference, Dublin March 2005 is HERA now e- ? – see picture! – add experiments on CERN picture?1 Ldelivered ~400/pb Run I (1992-1996) √s  1.8 TeV, 110 pb-1 Run II (2001-2009) √s 1.96 TeV Physics Analyses use ~200-345pb-1 collected between 02/02 and 07/04 Run II (2001-2009) √s 1.96 TeV Physics Analyses use ~ 200/pb collected between 03/02 and 09/03 diphoton search 300/pb and ability to set improved limits on new physics

  7. Is this just H1 data – or combined in tables? = COMBINED e+ or e- now? HERA? HERA I Lepton Searches Updated Run II results and check Run I too Signature • isolated high pT e or m • pT,miss • jet with high pT Confirmed or not by Zeus/? Interpreted?! Main SM contribution from W production 94-04 e±p, L=171pb-1, PTX>25GeV Total includes 53pb-1 Run II e (obs / exp) 10 / 2.7±0.5 5 / 0.8±0.2 m (obs / exp) 6 / 2.6±0.5 0 / 0.9±0.1 • H1 observes an excess: • e channel in Run I & Run II data • channel only in Run I data Excess not observed by ZEUS IOP HEPP Conference, Dublin March 2005 Imporatnt/Crucial to understand backgrounds very well 94-04 Run I e±p + 53pb-1 Run II e+p: L=171pb-1 Total Run II(53pb-1) e (obs / exp) 10 / 2.7±0.5 5 / 0.8±0.2 m (obs / exp) 9 / 2.9±0.5 1 / 0.9±0.1

  8. Tevatron High Mass Dilepton Searches Signature based approach: look for deviations from SM expectation ∫Ldt = 250 pb-1 ee mm both-central or central-forward ee both-forward tt IOP HEPP Conference, Dublin March 2005 *Talk by Muge

  9. ∫Ldt = 200 pb-1 Z’SM 600 GeV Tevatron Dilepton Z' limits search for spin-1 resonances HERA/LEP? (GeV/c2) Why so low – what luminosity? for 680 D0 results and lum used for all? IOP HEPP Conference, Dublin March 2005

  10. G g,q f,V g,q f,V Tevatron Dilepton & ggResonance Searches search for spin-2 resonances Randall-Sundrum model 1extra compactified/warped dimension in which gravitons can propagate BR(G→gg) = 2*BR(G→ee) ll/gg has largest acceptance at low/high mass Some searches better to perform a diEM (ee+gg) search IOP HEPP Conference, Dublin March 2005

  11. Tevatron Dilepton + gg Searches search for spin-2 broad σ change ADD extra dimensional model many large extra dimensions in which gravitons can propagate In some models improvements if angular in addition to invariant mass information is used What Ms value is the D0 picture for? Interference ED term Background Parameterise sin terms of h = / Ms4 : s = sSM+ h sINT + h2 sKK + sBG LEP results? Translate hG95% limits to 95% CL lower limits on Planck scale MS, in TeV, in Hewett formalism: Ms > 1.22/1.10 (l=+/-1) TeV Run II Ms > 1.28 (l=+1) TeV Run I + II IOP HEPP Conference, Dublin March 2005 • , dimensionless parameter, 1 200 pb-1 CDF ee (CC+CP) Ms > 0.959/0.987 (l=+/-1) TeV Run II Use templates to fit to the data

  12. Tevatron Bs Search for new physics in dilepton low mass invariant mass region SM box Penguin BR could be enhanced from new physics: loop decays (MSSM, mSugra) or direct (RP) Challenging: SM prediction is 3.4 x 10-9 ... Higgs mediated where Higgs allows flavour violation SM signal x 10 5 SUSY Loop RPV Tree Complementary to other SUSY searches →indirect method IOP HEPP Conference, Dublin March 2005

  13. Dimuon searches at the low mass extreme! Complementary to other SUSY searches, indirect Tevatron Bs hep-ph/0411216 Now 8fb-1 SM expectation CDF (171pb-1) Expect: 1.05 ± 0.30 Obs : 1 D0(240pb-1) Expect: 3.7 ± 1.1 Obs: 4 New result?! – add Belle limit? *Talk by Sinead Farrington IOP HEPP Conference, Dublin March 2005 Combined: BR(Bs) < 2.7 x 10-7 BR(Bd )< 1.5 x 10-7 (CDF) 90% CL • 78 fb^{-1} • Belle. No candidate events have been found. Upper limits on the branching fractions are calculated at the 90% confidence level: • B(B^0 -> mu^+ mu^-) < 1.6 x 10^{-7}

  14. H++ e+ l  l- Same-sign (l+l+) Resonances ? Signature like-sign ee, , tt (65pb-1) em (118pb-1) 0.3 corresponds to a coupling of electromagnetic strength. E.g. H±±:Single H±±L,R production at H1 e+  e-H++ via e+  e- H++ No evidence for doubly-charged Higgs production observed Model: the Higgs triplet couples to leptons of the i'th and j'th generation via Yukawa couplings hL,Rij. H++  ee only MH=139 GeV H++em only MH=140 GeV IOP HEPP Conference, Dublin March 2005 • Assuming H++  ee only : lower mass limit H±±L,R = MH=139 GeV • Assuming H++ -> em only : lower mass limit H^{\pm\pm}_{L,R} = 140 GeV for a value h_{ee}^{L,R} = 0.3. • Influence on Bhabha scattering at LEP  Constraints at M > 200 GeV • limits on the h_{ee}^{L,R} and h_{e mu}^{L,R} Yukawa couplings as a function of the H^{\pm\pm}_{L,R} mass are derived Appear in L- R symmetric models : SU(2)L x SU(2)R broken by Higgs triplet (or extended Higgs sector by a triplet with Y=2). Might explain small (Majorana)  masses.b H1 2e & 3e events at high M : only one 2e evt fulfils charge requirement Run II should probe masses up to 180 GeV H++ couples to fermions via unknown Yukawa couplings hij, not related to masses SUSY L – R models predict low H++ masses, below  1 TeV

  15. Same-sign (l+l+) Resonances? • Single production at LEP & Hera • Also pair production • at LEP :H  ee, , , e, e,  considered: MH > 98.5 GeV • dominates at Tevatron ee e IOP HEPP Conference, Dublin March 2005 • Influence on Bhabha scattering at LEP  Constraints at M > 200 GeV Appear in L- R symmetric models : SU(2)L x SU(2)R broken by Higgs triplet (or extended Higgs sector by a triplet with Y=2). Might explain small (Majorana)  masses.b H1 2e & 3e events at high M : only one 2e evt fulfils charge requirement Run II should probe masses up to 180 GeV H++ couples to fermions via unknown Yukawa couplings hij, not related to masses SUSY L – R models predict low H++ masses, below  1 TeV

  16. e,  u,d Model-Based Searches • Model Based Search Strategy • select particular model, e.g. leptoquarks • search for particular signature/s predicted by the specific model • compare data to expectation from Standard Model • interpret results in context of the specific model Leptoquarks Additional symmetry between leptons and quarks LQ Signature High pt isolated leptons and/or ET + jets IOP HEPP Conference, Dublin March 2005

  17. Model-Based Searches • Model Based Search Strategy • Leptoquarks • SUSY • CHAMPS • Non-SM Higgs • Monopoles IOP HEPP Conference, Dublin March 2005 • Technicolour, Trileptons - SUSY • CHAMPS***

  18. e e e,  u,d Leptoquarks Additional symmetry between leptons and quarks Generation refers to lepton generation • Branching Ratiounknown, convention: • β=1 means 100% BR(LQ→l±q) • β=0 means 100% BR(LQ→q) 1st generation LQ • Complementarity between world’s accelerators: • HERA, LEP and Tevatron • At Tevatron: independent of coupling λ aEM 290 GeV IOP HEPP Conference, Dublin March 2005 Apparent symmetry between the lepton & quark sectors: common origin ? • A search for scalar and vector leptoquarks coupling to first generation fermions is performed in the H1 experiment using data collected from 1994 to 2000. • No significant evidence for the direct production of such particles is found in a data sample with a large transverse momentum final state electron or with large missing transverse momentum, and constraints on leptoquark models are established. • For leptoquark couplings of electromagnetic strength, leptoquark masses up to 290 GeV are ruled out.

  19. tl + th njet>= 2 YT=PT(l)+PT(th)+ET>85 GeV/c MT(l,ET) < 35 GeV/c2 3rd generation LQ channel: tlthjj (one leptonic, one hadronic decayed t’s) (final state: ttbb, same as the RPV Stop search signature) expect 4.8 ± 0.7 events, observed 5 events for b=1, CDF: Run II, MLQ > 129 GeV/c2 IOP HEPP Conference, Dublin March 2005

  20. SUSY: GMSB: gg+MEt Supersymmetry (SUSY) theory • solves Hierarchy Problem • which introduces a new symmetry between fundamental particles • Gauge-Mediated SUSY Breaking models (with gauge interactions communicating the symmetry breaking) GMSB : gravitino G is the lightest supersymmetric particle (LSP). Signature GMSB can produce gg and large MEt. • MET is common signature for SUSY signals because it could indicate the escape of a non-interacting SUSY particle (like LSP) from the particle detector. • The LSP signals are of particular interest, as they provide a natural explanation for the "Dark Matter“. ~ *See ‘New Physics’ parallel session for more detailed description of SUSY and SUSY searches. IOP HEPP Conference, Dublin March 2005 • In Supersymmetry (SUSY) theory, which introduces a new symmetry between fundamental particles, Gauge-Mediated SUSY Breaking models (with gauge interactions communicating the symmetry breaking) can produce events which decay down to the lightest neutralino into the photon and gravitino, the SUSY partner of the graviton, where gravitino is the lightest supersymmetric particle (LSP). GMSB can produce a final state of two photons and large unbalanced (missing) transverse energy MET. MET is often used as a pointer to possible SUSY signals because it could indicate the escape of a non-interacting SUSY particle (like LSP) from the particle detector. The LSP signals are of particular interest, as they provide a natural explanation for the "Dark Matter", known to pervade our universe, and help us to understand the fundamental connection between particle physics and cosmology. (the SUSY partner of the graviton)

  21. GMSB gg+MEt Signature gg+MEt • For MET > 45 GeV • 0.21+-0.05+-0.14 events are predicted.     • The total expected number of background events is 0.60 +0.50-0.26(stat) +-0.28(syst) Optimise the expected 95% C.L. cross section upper limit using the expected numbers of background events. Expect the best limit comes from an additional cut of MET > 45 GeV. IOP HEPP Conference, Dublin March 2005 Using the expected numbers of background events we estimate the expected 95% C.L. cross section upper limit for optimization. We expect the best limit comes from an additional cut of MET > 45 GeV. • By mass relations in the model neutralino mass < 93 GeV and Lambda < 69 TeV are excluded.

  22. GMSB gg+MEt Signature 2 isolated central g with Et>13 GeV+ MEt > 45 GeV Total expected number of background events 0.60+0.50-0.26(stat)±0.28(syst) No events observed Lower mass limit on the lightest chargino =168 GeV at NLO. IOP HEPP Conference, Dublin March 2005 Using the expected numbers of background events we estimate the expected 95% C.L. cross section upper limit for optimization. We expect the best limit comes from an additional cut of MET > 45 GeV. • By mass relations in the model neutralino mass < 93 GeV and Lambda < 69 TeV are excluded. CDF+D0 combined result?

  23. CHAMPS CHArged Massive Stable Particles Feynman diagram? what pt of muons? what mass is massive? better speed plot? • Signature • electrically charged, • massive: speed << c • lifetime long enough to decay • outside the detector 100 GeV Staus 100 GeV Higgsion-like Chargino 100 GeV Gaugino-like Chargino • Event Selection • 2 isolated m Pt>15 GeV/c • speed << c SM exp 0.66±0.06 Observed 0 0.62pb No excess of events observed Strictest Tevatron limits to date 0.06pb IOP HEPP Conference, Dublin March 2005 Limits: from 0.06pb to 0.62pb, depending on the stau mass Limits vary from 0.06pb to 0.62pb depending on the stau mass mm with speed and Mmm inconsistent with beam-produced muons No SM background! Limits set on cross-section for pair produced stable stau leptons

  24. CHAMPS+SUSY Feynman diagrams? Same data used to set mass limits on stable charginos higgsino-like chargino gaugino-like chargino 390pb-1 174 GeV 140 GeV Best limits to date for stable charginos IOP HEPP Conference, Dublin March 2005 140 GeV for higgsino-like chargino 174 GeV for gaugino-like chargino

  25. HW Searches qq→W±H→W±W*W*→l±l±n Signature high-pT isolated like-sign (LS) dilepton events Event Selection pT2>16 (18) GeV/c and pT12 >35 GeV/c for the MH <160 GeV/c2 (>160 GeV/c2) IOP HEPP Conference, Dublin March 2005 • We search for neutral Higgs production associated with the W boson using high-pT isolated like-sign (LS) dilepton events in the 193.5 pb^-1 CDF Run II data. We first study the background components in our base-line like-sign sample which is created by requiring the leading lepton p_T > 20 GeV/c and the second lepton p_T > 6 GeV/c, and confirm that, overall, the entire sample is consistent with out background expectation. Based on the S/sqrt{B} calculated from signal Monte Carlo's and our background expectation, the signal region is then determined in the plane of the second lepton p_T (p_T2) versus the vector sum of p_T's of the two leptons(p_T12). The signal region is p_T2 > 16 (18) GeV/c and p_T12 > 35 GeV/c for the Higgs masses < 160 GeV/c**2 (> 160 GeV/c**2). No event is found, while the total background is expected to be 0.95 +- 0.61(stat) +- 0.18(syst) events, the 110 GeV/c**2 bosophilic (fermiophobic) Higgs to be about 0.06 events assuming the same production cross section as the Standard Model Higgs, and the 160 GeV/c**2 Standard Model Higgs to be about 0.03 events. We set cross section upper limits sigma(WH) * BR(H->WW) < 12 pb at 95% C.L. for the 110 GeV/c**2 Higgs and 8 pb for the 160 GeV/c**2 Higgs. The analysis is structured from simple techniques only: conventional isolation, high-p_T lepton identification, and simple kinematical requirements to define the signal region. There are no signal-specific cuts such as missing E_T and other topological cuts. The present result therefore provides a conservative physics interpretation. In base sample: confirm that, overall, the entire sample is consistent with out background expectation

  26. HW Searches MH>160 GeV/c2 • the 110 GeV/c**2 bosophilic (fermiophobic) Higgs to be about 0.06 events assuming the same production cross section as the Standard Model Higgs, and the 160 GeV/c**2 Standard Model Higgs to be about 0.03 events. Total background is expected to be 0.95± 0.61(stat) ± 0.18(syst) events Expected Signal: 0.06 events MH =110 GeV/c2 bosophilic (fermiophobic) Higgs 0.03 events MH = 160 GeV/c2 Standard Model Higgs 18 35 <12 pb for MH 110 GeV/c2 No event is observed <8 pb for MH 160 GeV/c2 IOP HEPP Conference, Dublin March 2005 • set cross section upper limits sigma(WH) * BR(H->WW) < 12 pb at 95% C.L. for the 110 GeV/c**2 Higgs and 8 pb for the 160 GeV/c**2 Higgs.

  27. Monopole Searches • g=nhc/2e = ngD • assumes fundamental charge is e, - maybe e/3, 2e/3…? • → minimum magnetic charge could be gD, 2gD, 3gD, 6gD • H1 performed first search for monopoles in e+p collisions • Search for monopoles that have been stopped in the Al beam pipe • Use a section of H1 beam-pipe around the interaction zone • 1995-1997. Exposed to integrated luminosity 60pb-1 60cm long 5cm radius 2mm thick • Sliced into 15 longitudinal strips • Pass samples through a SQUID magnetometer IOP HEPP Conference, Dublin March 2005

  28. H1 Monopole Searches Signature distance Persistent Current Magnetometer sensitive to g>~0.2gD No repeatable monopole signal seen IOP HEPP Conference, Dublin March 2005

  29. Tevatron Dirac Monopole Searches Signature • Large pulses in Time of Flight (TOF) • Large ionization in drift chamber (COT) • No curvature in r-phi • Curvature in r-z (not used in analysis) IOP HEPP Conference, Dublin March 2005 Developed a dedicated trigger for Monopoles

  30. CDF assumes a Drell-Yan like cross section (Giacomelli and Patrizii, hep-ex/0302011) Monopole Search Results IOP HEPP Conference, Dublin March 2005

  31. Summary • Many searches are for new physics are underway • At a variety of different experiments • Different methods used • search for specific models • signature based searches • Several interesting results have been observed Looking forward to future results! IOP HEPP Conference, Dublin March 2005

  32. SM Higgs Technirho Technicolour ˉ ,c • Can search for Technicolor in many signatures • This search explores same signature as SM Higgs (lνbq) What are results? Remove this slide! IOP HEPP Conference, Dublin March 2005

  33. HERA I Multi-lepton Searches Signature Main SM contribution from g-g collisions Multi-leptons Good agreement with SM in m and t channels Excess in multi-e channel at high invariant mass Updated RUN II & Run I results?! Open to interpretion - /model IOP HEPP Conference, Dublin March 2005 • M >100 GeV 99-00 e±p, L=70.9pb-1 2e (obs / exp) 3 / 0.25 ± 0.05 3e (obs / exp) 3 / 0.23 ± 0.04 Interestingly: Neither H1 nor ZEUS saw mm events with Mmm>100 GeV! Run II data being studied – blessed?! 3 high invMass mm events – see Aweys talk

  34. ZEUS Tau search Update results?! IOP HEPP Conference, Dublin March 2005

  35. Excited/Exotic e excited electrons: the hierarchical structure of the SM fermion families could be taken as an indication of quark and lepton substructure. One would therefore expect excited states of q’s and l’s to be produced in high energy collisions In a compositeness model, the new, strong interactions that binds the constituents (preons) may be expected to produce excited electrons strongly, with fairly large cross-sections. Expected in many compositeness models Signature at Tevatron: pp→ee*→ee ZEUS/Hera contact interaction gauge mediated The cross section depends on the e* mass and the compositeness scale, . Very little background 3 candidate events The excited fermions also have gauge interactions. If the decay via gauge interactions dominates the total width, the e* can be detected as a narrow egamma mass resonance. 344 GeV IOP HEPP Conference, Dublin March 2005 • This signature based search with a resonance in the e gamma channel is geared toward the production of excited or exotic electron as in the following reaction p + pbar --> e* + e --> e gamma + e. Excited electrons are expected in many compositeness models. We use a model for excited fermions based on their coupling to quarks and leptons via contact interaction that is described by an effective four-fermion Lagrangian (Baur, U. Phys Rev D 42, 3). The cross section for this model depends on both the e* mass and the compositeness scale, Lambda. In both models the cross section depends on both the e* mass and the compositeness scale, Lambda. Model dependent acceptances here for each model Interpretation of limit Excited electrons are expected in many compositeness models. Model 1: based on excited fermions coupling to quarks and leptons via contact interaction, described by an effective four-fermion Lagrangian (Baur, U. Phys Rev D 42, 3). Model 2: excited electrons produced via gauge mediated interaction (Baur, U. Phys Rev D 42, 3).

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