Physics results from ALEPH (Summer Conferences 2002) Andrea Venturi INFN Pisa and CERN On behalf of the ALEPH Collaboration LEP Physics Jamboree Jul 22 nd 2002

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN2 LEP II Outline LEP I ’s branching ratios Charm gluon splitting  s from event shape Standard Two photons ee  Zee  ee Colour reconnection studies Searches for new physics single top production LSP limits stop into gluino LSP non-standard Higgs Only ’s final states “Complete” LEP II or LEP I datasets used for (almost) all the results Results are preliminary unless published Exclusion limits at 95% CL

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN3 LEP I: Branching Ratios New results with the full LEPI statistics: ~330k  pairs Classification of each  decay according to number of tracks,   ’s and particle id: 13 classes (e,,h,h 0,h2 0,…,3h,3h 0,…) Improved treatment of MC corrections and systematic evaluation, especially ’s and  0 ’s Results corrected for the  decays into K’s,’s and ’s using previous analyses (ALEPH and CLEO)

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN4 Lepton universality tested within 2-3 per mille LEP I: Branching Ratios Lepton universality: B  and B  translated into electron BR WA and  lifetimes and  mass used

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN5 Vector spectral functions from  0, 3 0, 3 0 BR’s and mass distributions LEP I: Branching Ratios Hadronic contribution to g-2 radiative corrections An example: ee    cross section from BR(    0 )

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN6 3 jets events with a lepton in the least energetic jet NN with 6 variables to increase signal purity: ~25% e, ~18%  Main systematics: –Lepton id –Charm jet simulation –BR(c  l) g cc (e)=(2.990.280.41) % g cc ()=(2.900.380.74) % LEP I: gluon splitting into charm g cc =(2.98  0.48) % WA: (2.96  0.38)%

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN7 Results from the full LEP I+LEP II ALEPH data set 6 event-shape variables used: T, M H 2, B W, B T, C, -log y 3 Fit with O(  s 2 ) + NLLA Good agreement with  s running LEP I + LEP II:  s from event-shape variables running to M Z and combining:  s (M Z )=0.12110.0047

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN8 Measurements with LEP II data LEP II:     and  K  K - Prediction Rescaled x2 Angular distributions W  distributions  

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN9 D * from D 0 + soft pion Measurement “direct” and “single- resolved” contributions D * cross sections vs p t and  (ee  ee cc) LEP II: D * X direct Single-resolved Frixione et al. (2000) Rapidity

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN10 D * X and (eeeecc) Transverse momentum

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN11 New results: A b FB, Q udsc FB and R c LEP II: 2 fermions production: HF results E CM (GeV)SM 205A b FB     Q udsc FB 0.0051 0.0039 E CM (GeV)RcRc SM 0.033  0.035  0.037  0.029  : 3.5  all: 2.3 

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN12 New analysis Signal definition according to LEP WG (phase space cuts): –M  > 60 GeV –Forw electron < 12 o –bckw elect: E>3 GeV, 12 o <<168 o Selection efficiency: (362)% 16 events selected ( GeV) (1.9 expected bkg) LEP II (4f): eeZee  ee cross section (eeZee  ee)=57  14  4 fb (average from 183 to 207 GeV)

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN13 Colour singlets can be created across decay products of different W’s: we cannot ask ourselves which W a particle comes from. Interesting to better understand non-perturbative QCD, worrying for the W mass measurement Larger effects at the end of the parton shower and in the non-perturbative part  MC models ALEPH preliminary results from: –Charged particle multiplicity and momentum spectrum analysis Real data are compared to different MC models using WW4q and WW lqq events –Particle flow analysis in WW4q (started by L3) Particle multiplicity between jets from the same and different W’s are compared to MC models with and without Colour Reconnection –Variation of the W mass measurement when soft particle (momentum cut) are discarded from jet reconstruction Looking for Colour Reconnection in WW4q events: preliminary results

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN14 M W with CR models % of reconnected events Mass shift in MeV In SKI model P reco is controlled by the parameter K i SKI model predictions Model M (MeV) Herwig CR~30 Ariadne 2 CR70-80 Rathsman (GAL)30-40

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN15 CR: Charged Particle spectra 1GeV10 GeV X p =p/E beam JETSET vs others

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN16 In WW 4q events particles are projected to the closest inter-jet plane and angles w.r.t. jet are measured Inter-jet angles are normalized to 1 Distribution is folded and binned ratio is done: R n = one bin from 0.2 to 0.8 CR: Particle flow between W’s R n =1.0950.014(stat) 0.006(syst) 0.006(extrap) extrapolated to 189 GeV (A+B)/ (C+D) 0=

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN17 R n measured in data is compared with MC predictions from different models with and without CR R n (data)= 1.0950.014(stat) 0.006(syst) 0.006(extrap) Background, BE and detector systematics are included. Fragmentation is not included CR: Particle flow between W’s SKI model Model parameter K i Bias induced by MC tuning has not been evaluated yet R/ tot k i =2.3

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN18 CR is expected to affect mainly low momentum particles and particles away from the jet core CR from the W mass Measure the variation of the W mass obtained removing progressively low momentum particles (pcut analysis) or “far away” particles (cone analysis) The following results have been obtained with the pcut analysis The slope of the W mass measurement is compared to the MC predictions. Mass shift Momentum cut

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN19 Ariadne2 (CR) model predicts a fairly large mass shift (~70-80 MeV) but quite insensitive to momentum and cone cuts CR from the W mass Semileptonic events control sample Very preliminary results: conservative systematics and bias improved “calibration” studies to be done Fully hadronic events

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN20 VERY preliminary study Relative error variation wrt no P cut analysis It is sensitive to CR It can differentiate models –In particular AR2 CR from the W mass statistical error

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN21 Final results (CERN-EP/ ): From SM to new physics: ’s final states Single photon N = 2.86  0.09 ee  XY  YY:  < 0.25 – 0.05 pb Super-light gravitino > eV Gravity with extra dimension: graviton mass limit: M D > 1.26 – 0.57 TeV (d=2-6) Acoplanar photons ee  XX  YY:  < 0.1 – 0.04 pb ee  o 1  o 1  : M  > 98.8 GeV Collinear photons Gravity with extra dimension: string scale Contact interactions:  6 > 1.35 TeV,  7 > 0.74 TeV,  8 > 21.4 GeV Excited electron: M > 213 GeV (f  = 1)

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN22 Final results with full LEPII data –CERN-EP/ Multijet (with one b) final state (with or without leptons) ~ 3% (lepton), ~ 13.5% (hadron) including BR’s Single top production limits 24 candidates in data (20.1 expected) BR(tZc)+BR(tZu)<14% (95% CL) (no  coupling, m top =174 GeV) ALEPH limits

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN23 Small mass differences with mass unification only if M 2 very large More “natural” with AMSB Dedicated analysis to cover the hole between: –Long-lived charginos: search for heavy stable charged particles –Chargino’s decay products can trigger DAQ Search for ISR  plus soft tracks compatible with  +   production and decay Charginos nearly degenerate with neutralino Gaugino region Higgsino region M  > 88 GeV (heavy sfermions) (Phys. Lett B533 (2002) 223)

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN24

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN25 Framework : MSSM –LSP =    –Mass unification “Standard” analyses: –Chargino and Neutralino searches –Squarks and sleptons –Higgs Boson If stau mixing   is let free –      can be dominating – m(   ) can be small: soft ’s in final state Additional searches: ee        acoplanar ’s pairs (large m), ISR +soft tracks (small m) ee              single  (small m) ee            ’s final state LSP mass: toward an absolute limit

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN26 LSP limit I – chargino 3-bodies II – chargino 2 - bodies ’s final states Charginos + ISR Selectrons m 1/2 vs m 0 An example:=-1000 GeV tan=35:    tan=35    tan=35    Standard analyses New  analyses ISR  analysis M LSP > 41.6 GeV

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN27 Very preliminary Y2K data only Gluino is LSP can be produced at LEP II R-parity conserved  R-hadrons s-top decays into gluino LSP MC simulation –gluino parton shower in PYTHIA –R-hadrons interact as heavy pions Missing energy is not always present Selection of acoplanar jets –depends on M –efficiencies: % –4f background is subtracted

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN28 Flavour-independent Higgs boson search (CERN-EP/ ) Only HZ  qqqq analysis has been modified with respect to the standard Higgs boson search –No b-tagging + estimators of WW and HZ hypothesis Search of Higgs boson with non-standard decays M H GeV BR(had)* SM BR SM M H > GeV M H > GeV Hadronic final state limits  final state limits BR(had)+ BR= 1 : M H > GeV

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN29 Search for decays of a Higgs boson (CERN-EP/ ): –LEP I + LEP II Looking for events with two ’s +: –Missing energy (H) –2-4 charged tracks (Hll) –> 5 tracks (Hqq) Search of Higgs boson with non-standard decays Fermiophobic Higgs: M>105.4 GeV

Jul 22nd 2002Physics results from ALEPH - Andrea Venturi - INFN Pisa / CERN30 ALEPH is still obtaining interesting results from LEP I data searchesExclusion limits from searches are becoming more and more general More exotic models have been explored Progress in understanding the main systematics of the W mass measurement (LEP-wide joint effort) See you in Winter 2003 with other (final) results: 4f cross sections, searches, W mass, … Summary and conclusions