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Emmanuelle PEREZ CEA-Saclay, DSM / DAPNIA / Spp

Searches for New Phenomena : Where do we stand …. 5 th Rencontres du VietNam – New Views in Particle Physics Hanoi, 5-11 August 2004. and what we might learn within the coming years …. Emmanuelle PEREZ CEA-Saclay, DSM / DAPNIA / Spp. 10 August 2004. Rencontres du VietNam, Hanoi.

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Emmanuelle PEREZ CEA-Saclay, DSM / DAPNIA / Spp

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  1. Searches for New Phenomena : Where do we stand … 5th Rencontres du VietNam – New Views in Particle Physics Hanoi, 5-11 August 2004 and what we might learn within the coming years … Emmanuelle PEREZ CEA-Saclay, DSM / DAPNIA / Spp 10 August 2004 Rencontres du VietNam, Hanoi

  2. Searches for New Physics : why, where, how… Mechanism of the EW symmetry breaking ? •  Higgs (i.e. fundamental scalar) ? Find it… •  structure of the Higgs sector ? •  solution of the hierarchy problem ? • no Higgs ?Dynamical breaking ?( H ~ condensate ) extra-dimphysics ? ( H ~ Gauge Field|4d ) #doublets, triplets ? CP ? SUSY  MPl ? “Little Higgs”   10 TeV ? extra dimensions  no hierarchy ? In most scenarios, new physics is expected at the TeV scale. Also hoped for, that NP might answer some of the questions unexplained by the SM. Various strategies to track new physics, e.g. : - high precision measurements ( need good theoretical control ) - rare decays (K & B) , LFV processes - searches for Dark Matter - searches at high energy colliders Tevatron, HERA - model driven searches - exploit at best the experimental knowledge of our detectors Some complementarities between these different approaches. Rencontres du VietNam, 08/04

  3. Good performances of our facilities ! _ H1 & ZEUS Tevatron pp, s = 1.96 TeVCDF & D0 ep, s = 320 GeV HERA Run I (92-96) :  110 pb-1 / exp until summer 2000 : 120 pb-1 / exp Restart in may 2001   0.6 fb-1 delivered Serious background problems at the restart (fall 01) Tevatron Run II Required time, now solved 2004 1032 cm2 s-1 threshold broken on July 16th ! 1032 cm2s-1 HERA is now operating with twice the 2000 peak lumi 6.1031 HERA-II Peak lumi Peak lumi average (e+ p) 2.1031 2003 2002 Jan 02 Jan 03 Jan 04 HERA-II analyses : up to  50 pb-1 Analyses presented here  200 pb-1 of Run II data (2002 & 2003) NB: expect several new results in the coming weeks ! some with up to  350 pb-1 ! + LEP data ! Very relevant constraints on NP ! some final combinations are still to come Rencontres du VietNam, 08/04

  4. Hunting the SM Higgs Boson • Status : (LEP EW WG, April 2004) Direct searches at LEP  MH > 114.4 GeV @ 95% C.L. EW fits ( latest Mtop = 178.0  4.3 GeV) : MH < 237 GeV LEP final combination for MSSM Higgs coming soon… (new Mtop required new databases with , BR etc…) LEP is finalizing investigations of non-standard scenarios (invisible h, bosophilic Higgs, CP-violation…) • Until the start-up of (physics at) LHC, Higgs searches • are in the hands of the Tevatron experiments : “Light” Higgs, M < 130 GeV :  ( pb ) a few 10-1 pb H  bb gg  H • Best S/B in leptonic W/Z decays • Large bckgd from W/Z + jets  b tagging ! • Importance of a good mass resolution ! HW H bb “Heavy” Higgs, M > 130 GeV : H  WW H  WW(*) Clean dilepton + ET,miss signature MH (GeV) E. Perez

  5. 8.5 4.4 fb-1 Tevatron Searches for a light SM Higgs WH  bbl with l = e, First analyses exist ! CDF Run II Prelim., 162 pb-1 Exp. limit Exploit kinematics and topology, require 1 (2) b-tag in D0 (CDF) Obs. limit (WH) x BR < 5 pb for MH = 115 GeV Still a factor ~ 50 larger than SM predictions ! SM prediction (also T  WT lbb) • Full GEANT simulation, 396 ns, RunIIb Si. • experience from current data (bckgd, (Mbb)) Updated sensitivity study (impact of cancellation of Si. upgrades still to be assessed) Fermilab-Pub-03/320-E Challenging anyway ! End 2008 : between 4 & 8 fb-1 No “golden” channel … 10 8.5 Integrated Lumi (fb-1) (reasonably) optimistic 5 4.4 conservative Combining WH & ZH, D0 & CDF 09 05 06 07 08 Rencontres du VietNam, 08/04

  6. e Tevatron Searches for a Heavy SM Higgs Final states investigated : ee + ET,miss, e + ET,miss,  + ET,miss (combined ll + ET,miss in the CDF analysis) ( H  WW* ) L 160 – 200 pb-1 Backgrounds from W + jet(s), Z/DY, WW Exploit spin correlations : leptons small No excess w.r.t. SM predictions… x-section enhanced w.r.t. SM via heavy 4th generation quarks in the ggH loop Will soon be sensitive … Higgs = condensate RtL (H) x BR(H  WW) < 5.6 pb for MH = 160 GeV i.e. a factor ~ 20 larger than SM predictions SM Higgs : need ~ 4 fb-1 for sensitivity @ 95% CL Rencontres du VietNam, 08/04 E. Perez

  7. SUSY & Non standard Higgses • Higgs in SUSY models : extended Higgs sector h, H, A, H  MSSM constraints Mh < 135 GeV Two free parameters, e.g. MA and tan = vu/vd • Often : one Higgs  looks like HSM • Else : low (W+Higgs) but (Higgs+bb) • enhancedat large tan  4b ! • Difficult cases : SM = H heavy, orbb • look for A  , use partially reco’ed mass  95% CL sensitivity over the allowed M range _   e/ + had. _ For tan = 30, sensitivity still a factor ~ 10 away from MSSM • Doubly charged Higgses : D0, hep-ex/0404015 CDF, hep-ex/0406073 CDF Run II 240 pb-1 H++ appear in e.g. 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. 136 GeV Evidence of 0 at the Heidelberg-Moscow experiment ? H++ couples to fermions via unknown Yukawa couplings, not related to masses. SUSY L–R models predict low H++ masses, below  1 TeV 113 GeV • Search for (high mass) same-sign dileptons (CDF also searched for quasi-stable H++ , M > 134 GeV) Rencontres du VietNam, 08/04

  8. expt H1 ( 115 pb-1) selection 2e, M12 > 100 GeV 3 / 0.30  0.04 3e, M12 > 100 GeV 3 / 0.23  0.04 H++ and the HERA multilepton events Events with  2 leptons in final state. Mainly produced via  H1 data 94-00 : excess of 2e+3e events at high M12 = mass of two highest PT e No such excess seen in ZEUS data obs. / exp. H1 94-00 data The H1 evts are not consistent with (different angular ranges in both analyses) H1,EPJ C31 (2003) 17 e  H++ (e)  ee(e) H1 analysis extended to include 45 pb-1 of 03-04 data 163 pb-1 H1 Prelim., HERA I+II Extended to other 2l & 3l topologies : ee, , e, eee, e, ee • no new 2e / 3e evt at M12 > 100 GeV • (but one high mass 3e event …) • one e event at M > 100 GeV   Altogether, at PT > 100 GeV : Nobs = 4, Nexp = 0.61  0.11 2l + 3l e Rencontres du VietNam, 08/04 E. Perez

  9. Hunting Supersymmetry… For the last  20 years, SUSY has been “the standard non-standard theory”… • Provides a technical solution for the “hierarchy” problem • The only symmetry which prevents to add a mass term m2 H+H • Unification of couplings : works well with SM + SUSY • Possibly provides an additional source of CP Different models and phenomenology depending on : - the SUSY breaking mechanism(gravity mediated, or gauge interactions, anomalies ?) - whether or not the LSP (Lightest Supersymmetric Particle) is stable  Typical signatures with ET,miss , or , or large multiplicities or etc… HERA LEP Tevatron Mass bounds  100 GeV NB: no model independent bound on the LSP mass SUSY might also manifest itself in precision measurements, rare decays, Dark Matter searches etc… Rencontres du VietNam, 08/04

  10. Run I SUSY : GMSB at the Tevatron Gauge Mediated SUSY Breaking : - naturally avoids large unwanted FCNC - revival of interest in GMSB following “the” CDF Run I event NB : LEP analyses made the GMSB interpretation unlikely - LSP = gravitino G ( < keV), pheno. depends on NSLP (10-6 expected !) ~ ~ When NLSP = Neutralino : 01  G Inclusive search for  + ET,miss – might come from 02 1 production (no spectacular eeET,miss event observed so far in Run II data) Large instrumental background(jets faking a ), determined from the data. NB : Tevatron will provide very relevant data for the jet 0 fragmentation… cf H   @ LHC !! Interpretation within a “minimal” GMSB model : 185 pb-1 (D0 Prelim, 185 pb-1) M(01) > 105 GeV M(1) > 192 GeV 01 mass (GeV) Similar results from CDF World best limit ! Rencontres du VietNam, 08/04 E. Perez

  11. ~ D0 : pair production of squarks, q  q 01 Z () + jets Large bckgd from multijet prod. ! search domain ~ q > 292 GeV, g > 333 GeV ~ ~ (roughly,   g, sleptons +   squarks ) SUGRA-like SUSY at the Tevatron LSP usually the 01. RPC  ET,miss ~ ~ • Pair production of q / g • large , Signature jets + ET,miss Interpretation within mSUGRA: (for some values of parameters) D0 Run II, Prelim., 85 pb-1 Better than in Run I… but still stronger LEP bounds in this very constrained model ! CDF : light sbottom squarks (156 pb-1) g pair production, g  bb1 ~ ~ ~ D0 Prelim., 147 – 250 pb-1 • Chargino + Neutralino production ( 02 1 ) •  trilepton final states • Low  x BR but clean signatures eel + el + l + same-sign  Need high L and combined analyses Getting close to the unexplored mSUGRA region ! NB : importance of  id. at large tan  Rencontres du VietNam, 08/04 E. Perez

  12. tan  New Physics Searches in rare decays (examples) • b  s   stops + charginos BR (SM) = (3.70  0.30) x 10 –4 Good agreement with CLEO & Belle : BR (exp) = (3.34  0.68) x 10-4 i.e. not much room for SUSY here … Note: SUSY constraints are model-dependent (mixing in the down squark sector) J/  • Bd,s +- SM  (3.4  0.5) x 10 -9 SM signal X 106  SUSY :  (tan )6 could reach 10-6 !  (1S,2S,3S) ’ M (GeV) _ Tevatron :  (bb)  100 b  sensitivity ! For Bd0 : Slightly better than Belle 2003 ! New CDF upper bounds on BR( Bs,d  ) : hep-ex/0403032 Submitted to PRL Br(Bd ) < 1.5 x 10-7 Br(Bs ) < 5.8 x 10-7 Similar sensitivity from D0 Rencontres du VietNam, 08/04

  13. from    had from e+e- had • Summer 03: revised analysis of CMD-2 data better agree with , but still… • exp. measurement of E821 using- : average value goes up a bit (+ & - combined) 0.5 ppm ! aexp = 11 659 208 (6) x 10-10 The muon anomalous magnetic moment (g-2) sensitive probe to New Physics … aHAD ? But uncertainties on the SM prediction : Disagree… Recent developments : • underestimation of isospin breaking corrections to the  data due to -0 mass • splitting? … controversial … (Davier, hep-ex/0312065; Ghozzi & Jegerlehner, DESY 03-155) • reevaluation of part of aLBL • would shift the expected value by ~ + 50 10-11 (Melnikov & Vainshtein, hep-ph/0312226) 1.4 2.7 • e+e- 4 at BaBar using ISR photons : • somehow in-between e+e- & , closer to  data … • (e+e-  ) by KLOE at DANE (s  1 GeV) : • confirms the other e+e- measurements … Winter 04 hep-ex/ 0407048 Still puzzling… but new data from BaBar and KLOE might help understand… Rencontres du VietNam, 08/04

  14. Encroaches on the “trileptons” domain of the Tevatron SUSY Searches and a In any case, aSUSY cannot be too large ! e.g. aSUSY < 80 x 10-10 (very conservative) aSUSY > 0 | aSUSY |  tan  / m2SUSY Martin & Wells, PRD67, 015002 (2003)  > 0 500 tan  = 50 M ( smuon ) tan  = 20 At large tan  : difficult to have chargino & sleptons both light 0 0 1000 M ( chargino ) Baltz & Gondolo, PRD67, 06503 (2003) If aSUSY“signal” is confirmed :  (p) (pb) 10-6 - upper bounds on M(chargino) & M(sleptons)  encouraging for collider searches although ’s and l might be too heavy for Tevatron… - encouraging fordirect0 CDM searches ~ 10-10 (squarks & Higgs not too heavy i.e. (p) not too small) NB : however can have large (p) while aSUSY  0 … CDMS II, Edelweiss II M ( LSP ) e.g. if aSUSY > 11 x 10-10 Rencontres du VietNam, 08/04 100 1000

  15.  from Sun (Antares, Icecube)  from Sun 100 100 fb-1 LHC 10 fb-1 LHC 10 fb-1 1 x 10-8 Bs  < 2 x 10-8 Run II 3-leptons CDMS II, Edelweiss II CDMS II, Edelweiss II Tri leptons Run II Constraints & Sensitivities on mSUGRA If DM = 01 : 2 bounds from WMAP 0.095 < LSP < 0.13 Very precise !! White domains allowed if 01 is only a part of the CDM “funnel”,   A “focus point”,   WW tan  = 10 tan  = 55 1000 LSP too large 1000 m0 (Gev) m0 (Gev) 100 • sfermion • exchange • - l coannihil. & ~ 10 100 100 1000 100 1000 m1/2 (GeV) m1/2 (GeV) ~ • -  co-annihilation • Requires m  O(10 GeV) aSUSY not too large Plots from L. Roszkowski hep-ph/0404052; bounds from V. Bertin et al. hep-ph/0204135, Run II Workshop hep-ph/0003154

  16. Relaxing universality : constraints on LSP much more easily fulfilled e.g. increase M1 or decrease M3 m( ) decreases  co-annihilation   Lower M3 q & g searches at the Tevatron not so severely constrained by LEP… ~ ~ • In some cases, might expect stable  or t Beyond Minimal SUGRA… mSUGRA is becoming very tightly constrained… But (examples of way-outs) : Belanger et al., hep-ph/0407218 ~ ~ • SO(10) SUSY Grand Unified Theories Large interest, e.g. in view of neutrino masses ! Minimal models not so severely constrained by LSP (lighter A) Yt = Yb = Y = Y 1st & 2nd gene. sfermions are heavy ! i.e. no effect on (g-2) Large tan  sensitivity of Bs  at the Tevatron ! Direct DM searches :   10-9 – 10-7 pb, i.e. encouraging May see   e in the difficult “funnel” region ! m2atm  m2t / MGUT e.g. Masiero & Vempati, hep-ph/0407325 • DM mainly consists of something else … (axions, gravitinos, axinos, Kaluza-Klein states,…) Stable stop above  100 GeV Search for charged slowly moving particles (TOF)  0  DM if Rparity = (-1)3B+L+2S is not conserved … Might affect rare decays e.g. K  For neutrinos : mechanism to generate (Majorana) mass terms At colliders : single production of SUSY particles, less Emiss Rencontres du VietNam, 08/04

  17. _ e PTX • (W prod)  1 pb ’131 = 0.3 M(sbottom) (GeV) H1 Collab., hep-ex/0405070 M(stop) (GeV) • Data not consistent • with t production (3 chan) • Other interpretations • considered e.g. FCNC top ~ Rp and the HERA events with lepton + PT,miss Rp Example : resonant stop production at HERA via ’131 Assume heavy gauginos & light sbottom. ~ ~ Dominant decay : t  b W  jet + P T,miss + W H1 Collab.,PLB 561, 241 (2003) Main bckd when W  l : HERA-I, 105 pb-1 : No such excess in ZEUS (but candidates in  channel) (HERA-I) HERA I & II, e &  H1 in HERA-II data (45 pb-1) : 8 new events, 3 at PTX > 25 GeV At PTX > 25 GeV : Nobs = 14 Nexp = 5.1  1.0 H1 Prelim., 163 pb-1 (includes e-p HERA-I data)  Stay tuned !!!

  18. e e ZEUS e+p 94-00 Lepton + Quark Resonances : Leptoquarks cf Rp squarks Apparent symmetry between the lepton & quark sectors ? Exact cancellation of QED triangular anomaly ? • LQs appear in many extensions of SM • (enlarged gauge structure, compositeness, technicolor…) • Connect lepton & quark sectors • Scalar or Vector color triplet bosons • Carry both L and B, frac. em. charge  (unknown) Yukawa coupling lepton-quark-LQ ej channel at HERA jj channel at Tevatron ZEUS, PRD68 052004 (2003) CDF Run II Prelim., 191 pb-1 Not an easy channel ! Look for a resonant peak in M spectra  reduced background Large bckgd, but well controled

  19. Constraints on 1st & 2nd generation Leptoquarks (LP’03) e = BR( LQ  eq ) D0 Run II + Run I : M > 253 GeV for =1  = BR (LQ  eq) • Tevatron probes • large masses for large • e independently of  • HERA better probes LQs with small  provided • that  not too small  Complementarity of both facilities CDF II Prelim, 198 pb-1 MLQ (GeV) NB : at HERA, e+ / e- + polarisation could help in disentangling the LQ quantum nbs 2nd gene,  = 1 2nd (and 3rd ) generation LQs also looked for at the Tevatron. For LQ  j, similar sensitivity as for LQ  ej. M(LQ2) > 241 GeV Rencontres du VietNam, 08/04 E. Perez

  20. Searches for new resonances : dilepton • New heavy gauge boson Z ’, e.g. L-R models, or E6 GUT inspired, Little HiggsZ’… • Kaluza-Klein gravitons in some extra-dim. models • (Color-singlet) technirho in Technicolor models … D0 & CDF searched for ee &  resonances : Main bckgds @ high M :  200 pb-1 q cotan  “Little Higgs” _ q ZH Z’ Run II direct bounds between 570 & 780 GeV CDF II Prelim, 200 pb-1 Z’ Bounds D0 Run II Prelim. For E6 inspired models, already competitive with indirect LEP bounds (430-670 GeV) SM couplings E6,  Z’H ee E6,  E6,  ee First constraints (direct) on “Little Higgs” models ! 780 GeV (although “minimal” models predict heavier ZH, 2-6 TeV) 95% CL 200 pb-1 E. Perez

  21. G(k) heavy, G(1) TeV Coupling of G(k) to SM fields  TeV (determined by some model param, k/MPl 0.1) Kaluza-Klein Gravitons Why is the gravity so weak, i.e. MPl >>> MEW ? All attempts  higher dim. space, with n compactified extra dimensions • “Localized gravity” on a “brane” at d  0 from our brane; propagation of gravity • in the extra dim is exponentially damped due to the (tuned) space-time metric Randall & Sundrum models; “usual” version : n=1, Rc Planck length PRL 83 (1999) 3370; PRL 83 (1999) 4690 • “Strong gravity” ; fundamental scale ~ TeV; gravity appears weaker in 4d because flux lines • are “diluted” in large extra dim. Large Rc 0.1 mm. Not excluded by gravity measurements • Arkani-Hamed, Dimopoulos, Dvali, PLB 429 (1998) 263 revived ideas from Antoniadis, PLB 246 (1990) 377. Graviton propagate in extradim  Kaluza-Klein modes In localized gravity : Spin 2 resonance  Coupling k/MPl  345 pb-1 For k / MPl = 0.1 : masses below 690 GeV ruled out at 95% C.L. ee Most stringent collider bounds so far. (also D0 Prelim, ee final states) G(1) mass (GeV)

  22. m2 = 0 = ( E2-p4d2 )-qT2  m4d2 = qT2 Kaluza-Klein Gravitons in Large Extra Dim Very different phenomenology if “large” extra dimensions. G(k) with quantized momentum qT = k/R in extra dim : R  0.1 mm i.e. 1/R  1 meV  Mass “continuum”, “first” states very light !! ADL Prelim., Summer 04 Coupling of G(k) to SM fields  1 / MPl  G(k) stable ! e+e-  G (k) • Direct production at colliders n=2 : MD > 1.6 TeV n=4 : MD > 0.9 TeV compensated by huge multiplicity of states 1 / MPl • Indirect effect on SM aplitudes due to virtual exchange : D0 Run II Prelim. 200 pb-1 ee &  SM + MS = 1.1 TeV Effective coupling : A  / MS4 QCD “fake” D0 Run II + Run I, ee &  : MS > 1.43 TeV Most stringent collider bound Tevatron 2 fb-1 MS up to  2 TeV Rencontres du VietNam, 08/04 E. Perez

  23. Conclusions The search for new physics is a very active field. Tevatron & HERA are working very well, the experiments might “see” something in the near future ! Constraints set on many models, often the most stringent up to date. The example of SUSY searches shows the nice complementarity between different experimental approaches : direct searches, rare decays, precision measurements, Dark Matter searches … “Searches” is a very rich field of physics. It is likely to remain the case – even more ? – after direct evidence for New Physics at (e.g.) the LHC ( if SUSY : consistent value for LSP, additional CP phases, mixing in the squark sector, possible relations with the  mixing etc …) No doubt that using most of the experimental data to reach the understanding we aim at will be fun ! Rencontres du VietNam, 08/04

  24. Backup & Divers… Rencontres du VietNam, 08/04

  25. -j- “Signature Based” Searches for NP Pionnered by DZero with the full Run I sample • (Quasi) “model-independent” search for new physics : • definition of objects (e, , , , jet, W, Z, …) • look at data vs SM in all “channels” with > 1 object • in each channel, find the part of  space with largest deviation (e.g. in M,  pT ) • quantify the agreement using “Gedanken” (Mock, MC) expts D0, PRD64, 012004 (2001) # Events Applied recently to the full sample of H1 data H1, contrib paper #195 H1 Prelim 2B 45 pb-1 • overall very good agreement H1 data / SM • retrieves the “lepton-jet-ET,miss” and • “multi-electron” anomalies • (dedicated analyses might be more sensitive) 3B HERA-II Requires a very good understanding of detector & backgrounds ! 4B Rencontres du VietNam, 08/04

  26. Excited quarks & other j-j resonances • Dijet resonances predicted in various models Narrow resonances compared to (Mjj)  10% Mjj • New fermions, e.g. excited quarks •  expect signal in q /Z, q W depending on fs vs f & f’ • new gauge bosons, Z’, W’(but signal mainly in the dilepton channels) • new massive colored bosons, e.g. SU(3)1 x SU(3)2 SU(3)QCD • ( chiral color, colorons, topgluons…) q q q* g g fs /  • Look for a narrow resonance in the di-jet spectrum : use a simple background • parametrization for d/dM and search for bumps  resolution CDF Run II, 75 pb-1, Prelim.  X BR (pb) • Axigluon & (flavor univ.) colorons : assuming (qqg) = (qqG) M > 1130 GeV First direct bound > 1 TeV !! 10 • Excited quarks : 1 M > 760 GeV (f=f’=fs=1,  = M) Resonance mass (GeV) 200 1100 Rencontres du VietNam, 08/04

  27. HERA events with isolated lepton + PT,miss HERA I data HERA I Rencontres du VietNam, 08/04

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