Latest Physics Results from ALEPH Paolo Azzurri CERN - July 15, 2003

P.Azzurri - Latest physics results from ALEPH2 What’s new ? QCD Studies Four fermions & Gauge Couplings Jet reconstruction & radiative Z peak SUSY searches Conclusions & Prospects

QCD studies

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH4 α GeV NLO + NLL Theory Theory syst error evaluated with the lepwg method (uncertainty band method) Consistent analysis at all energies using six event shape variables in hadronic events FINAL !

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH5 Two-dimensional BE correlations Selection of two-jet events with large thrust q q 22 11 String = Pion source Q=  p= p 1 - p 2 Q L : longitudinal component of  p Q T : transverse component of  p Data/MC double ratio of the distribution of like-sign tracks to reference samples Reference of mixed pions from different events Reference of unlike-sign pions from the same event

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH6 Two-dimensional BE correlations Lund Model predicts R T <R L Fit double ratio to: source size and strength depend on the reference sample !

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH7 Rapidity gaps in gluon jets From OPAL proposal to test CR at Z peak rapidity gap with no charged particles rapidity gap q q gluon – jet (softest) High purity quark jets : data/mc agreement Jets with 1.5 rapidity gap MC with CR (GAL) MC without CR The charge of the third softest jet (most likely gluon) is sensitive to CR models

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH8 Rapidity gaps in gluon jets New ALEPH measurement as a function of the rapidity gap Tested CR models not in agreement with data at all rapidity gaps (overestimate of CR effects) Models with no CR agree with data only at zero rapidity gap : data shows an effect ! (data-MC)/MC

Four fermions & Gauge Couplings

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH10 Zee production New analysis of the hadronic decay channel eeqq: 4f signal defined by lepwg convention Selection efficiency=24%, purity =82%

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH11 W-pair production Consistent event selections at all energies GeV More stringent evaluations of systematic uncertainties Latest data reprocessing and event reconstructions FINAL !

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH12 W decay couplings Lepton non-universality Lepton universality

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH13 BE correlations in W pairs W pairs Double ratio: four jet decays compared to two mixed hadronic parts of semileptonic decays MC BEI = BE Inside W decay MC BEB = BE Between W decays 4q 2q

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH14 BE correlations in W pairs disfavoured at the 3.7 sigma level Fit double ratio to: unlike –sign pairs like –sign pairs

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH15 BE correlations in W pairs Integral of the BE enhancement disfavoured at the 3.3 sigma level Double difference Complementary measurement: like –sign pairs unlike –sign pairs

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH16 Triple Gauge Couplings New multi-parameter fits with correct O(α) treatment in W-pair analysis W pairs, single W and single photons combined 1-D, 2-D & 3-D 95% CL contour limits

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH17 Generic Triple Gauge Couplings NEW ! updated

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH18 Generic Triple Gauge Couplings Form Factor for Vector Resonance Enhancement of mass & width of technirho T.L.Barklow et al. hep-ph/ excluded at 95% CL For at 95% C.L. NEW !

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH19 Quartic Gauge Couplings Analysis of acoplanar photon pairs with high transverse momentum (ννγγ final state) 95% CL:

Jet reconstruction improvements & radiative Z peak

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH21 Rescaled di-Jet mass Jet 1 Jet 2 Radiative Z event: Jet angles and jet velocities are the fundamental ingredients of radiative Z and W mass measurements with kinematic fits

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH22 Jet velocity & mass Last jet reconstruction (with ECAL cleaning) Z peak jets boost (T>0.8) Jet boost (and mass) now well calibrated ! Removing low energy neutrals (<1.5 GeV, and <2 GeV if mixed)

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH23 Simulation of forward charged tracks Loss of forward tracks in data (nuclear interactions in Vdet material) Year 2000 Z peak hadronic events Affects regions with at low polar angle (4% max deficit in forward directions) Deficit parametrized as a function of the track cosθ and P T Monte Carlo tracks corrected

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH24 Radiative Z peak Systematic uncertainties Unbinned likelihood fit to a pdf built with a fit to the MC reference

SUSY searches final results

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH26 Constraints on the MSSM Improvement of the selectron search in the gaugino region New scan of low tanβ with stau mixing (without Higgs constraints) limits on the LSP mass Combination of searches for charginos, neutralinos, sleptons, higgs

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH27 Limits on the LSP mass with stau mixing LSP limit at 95% CL with any stau mixing NEW ! improved Summary of LSP limits

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH28 Conclusions & Prospects ALEPH is coming to an end … ☼Searches for new physics completed with the LSP limits  Many Standard Model analyses completed or close to being published  Archiving of ALEPH data and Monte Carlo (~3Tb) for long term analysis completed (June 2003)

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH29 Two-dimensional BE correlations Comparison with other LEP experiments

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH30 BE correlations in W-pairs Fit results without fixing the source radius

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH31 Triple Gauge Couplings W-pairs, single W and single photons C.L. O(α) correction sytematic now evaluated as the difference between schemes

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH32 Quartic Gauge Couplings

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH33 Jet velocity & mass Z peak jets boost (T>0.8) Jet boost (and mass) calibrated ! ECAL cleaning with full egs simulation: Last jet reconstruction with ECAL cleaning

CERN - July 15, 2003P.Azzurri - Latest physics results from ALEPH34 Radiative Z peak Main effective changes wrt observation large data/MC shift : Strict cut on beam background ECAL cleanning in jets Removal of low energy neutrals Correction of forward tracks