Latest Physics Results from ALEPH Paolo Azzurri

CERN - July 15, 2003

P.Azzurri - Latest physics results from ALEPH

Whats new ?

QCD Studies

Four fermions & Gauge Couplings

Jet reconstruction & radiative Z peak

SUSY searches Conclusions & Prospects

P.Azzurri - Latest physics results from ALEPH

QCD studies

P.Azzurri - Latest physics results from ALEPH

S @ 91-209 GeVNLO + NLL TheoryTheory syst error evaluated with the lepwg method (uncertainty band method)Consistent analysis at all energies using six event shape variablesin hadronic events

P.Azzurri - Latest physics results from ALEPH

Two-dimensional BE correlationsSelection of two-jet events with large thrustqqp2p1String = Pion sourceQ= Dp= p1 - p2QL : longitudinal component of DpQT : transverse component of DpData/MC double ratio of the distribution of like-sign tracks to reference samples

P.Azzurri - Latest physics results from ALEPH

Two-dimensional BE correlationsLund Model predicts RT

Rapidity gaps in gluon jetsFrom OPAL proposal to test CR at Z peak

P.Azzurri - Latest physics results from ALEPH

Rapidity gaps in gluon jetsNew ALEPH measurement as a function of the rapidity gap (data-MC)/MC

P.Azzurri - Latest physics results from ALEPH

Four fermions & Gauge Couplings

P.Azzurri - Latest physics results from ALEPH

Zee production New analysis of the hadronic decay channeleeqq: 4f signal defined by lepwg convention

Selection efficiency=24%, purity =82%

P.Azzurri - Latest physics results from ALEPH

W-pair productionConsistent event selections at all energies 183-207 GeVMore stringent evaluationsof systematic uncertaintiesLatest data reprocessingand event reconstructionsFINAL !

P.Azzurri - Latest physics results from ALEPH

W decay couplingsLepton non-universality

P.Azzurri - Latest physics results from ALEPH

BE correlations in W pairsW pairs Double ratio: four jet decays compared to two mixed hadronic parts of semileptonic decays4q2q2q

P.Azzurri - Latest physics results from ALEPH

BE correlations in W pairsFit double ratio to:unlike sign pairslike sign pairs

P.Azzurri - Latest physics results from ALEPH

BE correlations in W pairsDouble differenceComplementary measurement: like sign pairsunlike sign pairs

P.Azzurri - Latest physics results from ALEPH

Triple Gauge CouplingsNew multi-parameter fits with correct O() treatment in W-pair analysis W pairs, single W and single photonscombined

P.Azzurri - Latest physics results from ALEPH

Generic Triple Gauge Couplingsupdated

P.Azzurri - Latest physics results from ALEPH

Generic Triple Gauge CouplingsT.L.Barklow et al. hep-ph/9704217NEW !

P.Azzurri - Latest physics results from ALEPH

Quartic Gauge CouplingsAnalysis of acoplanar photon pairs with high transverse momentum ( final state)

P.Azzurri - Latest physics results from ALEPH

Jet reconstruction improvements& radiative Z peak

P.Azzurri - Latest physics results from ALEPH

Rescaled di-Jet mass Radiative Z event:Jet angles and jet velocities are the fundamental ingredients ofradiative Z and W mass measurements with kinematic fits

P.Azzurri - Latest physics results from ALEPH

Jet velocity & massLast jet reconstruction(with ECAL cleaning)Z peak jets boost(T>0.8)

P.Azzurri - Latest physics results from ALEPH

Simulation of forward charged tracksLoss of forward tracks in data(nuclear interactions in Vdet material)Year 2000 Z peak hadronic eventsAffects regions with at low polar angle(4% max deficit in forward directions)Deficit parametrized as a functionof the track cos and PT

Monte Carlo tracks corrected

P.Azzurri - Latest physics results from ALEPH

Radiative Z peakUnbinned likelihood fit to a pdf built with a fit to the MC reference

P.Azzurri - Latest physics results from ALEPH

SUSY searches final results

P.Azzurri - Latest physics results from ALEPH

Constraints on the MSSMImprovement of the selectron searchin the gaugino regionNew scan of low tan with stau mixing(without Higgs constraints)limits on the LSP massCombination of searches for charginos, neutralinos, sleptons, higgs

P.Azzurri - Latest physics results from ALEPH

Limits on the LSP mass with stau mixingLSP limit at 95% CLwith any stau mixing

P.Azzurri - Latest physics results from ALEPH

Conclusions & Prospects

Searches for new physics completed with the LSP limitsMany Standard Model analyses completed or close to being published ALEPH is coming to an end

Archiving of ALEPH data and Monte Carlo (~3Tb) for long term analysis completed (June 2003)

P.Azzurri - Latest physics results from ALEPH

Two-dimensional BE correlationsComparison with other LEP experiments

P.Azzurri - Latest physics results from ALEPH

BE correlations in W-pairsFit results without fixing the source radius

P.Azzurri - Latest physics results from ALEPH

Triple Gauge CouplingsW-pairs, single W and single photonscombined

P.Azzurri - Latest physics results from ALEPH

Quartic Gauge Couplings

P.Azzurri - Latest physics results from ALEPH

Jet velocity & massZ peak jets boost(T>0.8)Jet boost (and mass) calibrated !ECAL cleaningwith full egs simulation:Last jet reconstructionwith ECAL cleaning

P.Azzurri - Latest physics results from ALEPH

Radiative Z peakMain effective changes wrt observation large data/MC shift :

Strict cut on beam background ECAL cleanning in jetsRemoval of low energy neutralsCorrection of forward tracks

P.Azzurri - Latest physics results from ALEPH

NLO + NLL (next to leading logarithmic (resummation)) TheoryTheor syst errors evaluated with the lepwg method (uncertainty band method)Consistent analysis at all energies using 6 ev shape variables :T, y23, rho (heavy jet mass), BW, BT (wide and total jet broadening), C parameterStandard Goldhaber parametrization results on source sizes depend strogly on the analysis method such as the reference sampleLund Model predicts RT data shows an effect All MC models w/o CR, tuned at same precision levelOPAL at 1.5 gap with btag (instead of softest jet=gluon) consistent with no-CR MCUniform analysis at all energiesNew processing reconstructionMore stringent evaluations of syst uncertaintiesnearly final results for W-pairs.Update of 2001 results. New reprocessed data & mc. New WW reconstruction. O(alpha) corr.Important for mZ & mW kinematic fits of di-jet masses ! dont confuse the jet mass(=velocity) with the di-jet rescaled massThrust >0.8.Discrepancies with low en photonsRef samples : unlike sign pairs (extra resonance corr) / mixed events pairs (less event kinematical corr) - Care to compare same analysis method between lep experiments. (DLO done before aleph)Consistent reco with W mass analysiswinter 2003 mW reco + syst