IOP HEPP Conference 2005 Tracey Berry ne Pratt

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

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. Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 2

“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 ? technicolor (H→ q. T) Hierarchy problem MEW << MPl ? Supersymmetry Extra-dimensions Questions which the SM (or SM + SUSY) does not answer : • “Replication” of three families ? Compositeness ? Superstrings ? • Particle masses & their hierarchy ? Extra-dimensions ? Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 3

Signature Based Searches Signature Based Search Strategy • Select signature, e. g. ee, , • 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 n Tracey Berry University of Liverpool Spin-1 Z‘ bosons Z' Spin-2 Extra dimensions G g, q IOP HEPP Conference, Dublin March 2005 f, V 4

Signature Based Searches Signature • Single leptons • Dileptons: ee, , - , di. EM (ee+ ) - Low mass + - Same-sign: e , ee, Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 5

Lepton Search Experiments LEP, CERN, Geneva CERN: world's largest particle physics laboratory e- H 1 CDF p p D 0 Tracey Berry University of Liverpool p e- e+ LEP I √s = 91 Ge. V LEP II √s = 136 -208 Ge. V HERA, DESY, Hamburg Tevatron, Fermilab, USA Tevatron: Highest energy collider operating in the world! Run I √s = 1. 8 Te. V Run II √s = 1. 96 Te. V IOP HEPP Conference, Dublin March 2005 e+/27. 5 Ge. V p 920 Ge. V World’s only ep collider Run I √s = 320 Ge. V Run II √s = 320 Ge. V 6

HERA I Lepton Searches Signature • isolated high p. T e or • p. T, miss • jet with high p. T Main SM contribution from W production 94 -04 e±p, L=171 pb-1, PTX>25 Ge. V Total includes 53 pb-1 H 1 observes an excess: Run II e channel in Run I & Run II data e (obs / exp) 10 / 2. 7± 0. 5 5 / 0. 8 0. 2 channel only in Run I data Excess not observed by ZEUS (obs / exp) 6 / 2. 6± 0. 5 0 / 0. 9 0. 1 Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 7

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

Tevatron Dilepton Z' limits search for spin-1 resonances ∫Ldt = 200 pb-1 Z’SM 600 Ge. V (Ge. V/c 2) SM couplings ee ee+ CDF 750 735 815 394 780 680 D 0 E 6 CDF(ee+ ) ZI Zχ Zψ Zη 610 670 690 715 D 0 (ee) 575 640 650 680 Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 9

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

Tevatron Dilepton + 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 Interference ED term Background Parameterise s in terms of h = / Ms 4 : s = s. SM + h s. INT + h 2 s. KK + s. BG Translate h. G 95% limits to 95% CL lower limits on Planck scale MS, in Te. V, in Hewett formalism: Ms > 1. 22/1. 10 ( =+/-1) Te. V Run II Ms > 1. 28 ( =+1) Te. V Run I + II Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 11

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, m. Sugra) 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 Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 12

Tevatron Bs hep-ph/0411216 Now 8 fb-1 CDF (171 pb-1) Expect: 1. 05 ± 0. 30 Obs : 1 D 0(240 pb-1) Expect: 3. 7 ± 1. 1 Obs: 4 Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 SM expectation *Talk by Sinead Farrington 13

Same-sign (l+l+) Resonances ? Signature like-sign ee, , (65 pb-1) e (118 pb-1) 0. 3 corresponds to a coupling of electromagnetic strength. E. g. H±±: Single H±±L, R production at H 1 e+ e-H++ e+ l H++ l- 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 h. L, Rij. Tracey Berry University of Liverpool H++ ee only MH=139 Ge. V H++ e only MH=140 Ge. V IOP HEPP Conference, Dublin March 2005 14

Same-sign (l+l+) Resonances? • Single production at LEP & Hera • Also pair production • at LEP : H ee, , , e , considered: MH > 98. 5 Ge. V • dominates at Tevatron ee Tracey Berry University of Liverpool e IOP HEPP Conference, Dublin March 2005 15

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 Signature High pt isolated leptons and/or ET + jets Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 LQ e, u, d 16

Model-Based Searches Model Based Search Strategy • Leptoquarks • SUSY • CHAMPS • Non-SM Higgs • Monopoles Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 17

Leptoquarks Additional symmetry between leptons and quarks Generation refers to lepton generation Branching Ratio unknown, convention: β=1 means 100% BR(LQ→l±q) β=0 means 100% BR(LQ→ q) 1 st generation e, LQ u, d Complementarity between world’s accelerators: • HERA, LEP and Tevatron • At Tevatron: independent of coupling λ a. EM ee 290 Ge. V Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 18

3 rd 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 =1, CDF: Run II, MLQ > 129 Ge. V/c 2 Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 19

SUSY: GMSB: +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 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. Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 20

GMSB +MEt Signature +MEt 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 Ge. V. Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 21

GMSB +MEt Signature 2 isolated central with Et>13 Ge. V + MEt > 45 Ge. V 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 Ge. V at NLO. Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 22

CHAMPS CHArged Massive Stable Particles Signature • electrically charged, • massive: speed << c • lifetime long enough to decay outside the detector 100 Ge. V Staus 100 Ge. V Higgsion-like Chargino 100 Ge. V Gaugino-like Chargino Event Selection -2 isolated Pt>15 Ge. V/c -speed << c SM exp 0. 66± 0. 06 Observed 0 0. 62 pb No excess of events observed Strictest Tevatron limits to date Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 0. 06 pb 23

CHAMPS+SUSY Same data used to set mass limits on stable charginos higgsino-like chargino gaugino-like chargino 390 pb-1 174 Ge. V 140 Ge. V Best limits to date for stable charginos Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 24

HW Searches qq→W±H→W±W*W*→l±l± Signature high-p. T isolated like-sign (LS) dilepton events Event Selection p. T 2>16 (18) Ge. V/c and p. T 12 >35 Ge. V/c for the MH <160 Ge. V/c 2 (>160 Ge. V/c 2) Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 25

HW Searches MH>160 Ge. V/c 2 Total background is expected to be 0. 95± 0. 61(stat) ± 0. 18(syst) events Expected Signal: 0. 06 events MH =110 Ge. V/c 2 bosophilic (fermiophobic) Higgs 18 35 0. 03 events MH = 160 Ge. V/c 2 Standard Model Higgs <12 pb for MH 110 Ge. V/c 2 No event is observed Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 <8 pb for MH 160 Ge. V/c 2 26

Monopole Searches • g=nhc/2 e = ng. D • assumes fundamental charge is e, - maybe e/3, 2 e/3…? • → minimum magnetic charge could be g. D, 2 g. D, 3 g. D, 6 g. D H 1 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 H 1 beam-pipe around the interaction zone • 1995 -1997. Exposed to integrated luminosity 60 pb-1 60 cm long 5 cm radius • Sliced into 15 longitudinal strips • Pass samples through a SQUID magnetometer 2 mm thick Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 27

H 1 Monopole Searches Signature distance Persistent Current Magnetometer sensitive to g>~0. 2 g. D No repeatable monopole signal seen Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 28

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) Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 29

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

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! Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 31

SM Higgs Technicolour ˉ Can search for Technicolor in many signatures Technirho This search explores same signature as SM Higgs (lνbq) , c W R Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 32

HERA I Multi-lepton Searches Signature Main SM contribution Multi-leptons from - collisions Good agreement with SM in and channels Excess in multi-e channel at high invariant mass Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 33

ZEUS Tau search Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 34

Excited/Exotic e Expected in many compositeness models Signature at Tevatron: pp→ee*→ee The cross section depends on the e* mass and the compositeness scale, . contact interaction Z gauge mediated Very little background 3 candidate events 344 Ge. V Tracey Berry University of Liverpool IOP HEPP Conference, Dublin March 2005 35