Transcript Document
TESTING THE STANDARD MODEL AT THE DØ EXPERIMENT -at present and in the future Tulika Bose for the Columbia-D group 10/12/01 T.Bose 1 Outline The Standard Model HEP’s burning questions The Fermilab Tevatron The D experiment Acknowledgement: Hal Evans – for letting me steal many of his slides! 10/12/01 T.Bose 2 Particles and forces Force Boson Mass [GeV] Strength Gravity G 0 10-39 Leptons E-M 0 10-2 Weak W 80.419 10-5 e Z0 91.1882 Strong g 0 10-1 (MZ) E-W Sym H0 >113 mf2 Particle Chg [e] Mass [MeV] e 0 O(<eV) -1 0.5 105 1777 Quarks u c t +2/3 1–5 1300 d s b -1/3 3–9 150 174300 4400 3 Standard Model –the good and the bad… Hugely successful ! But lots of problems/unanswered questions : 19 arbitrary parameters The origin of mass ? Matter/antimatter asymmetry? Gravity ? The Feedback Loop Trash Particle Theory HEP Experiments Beyond the SM ??? 10/12/01 T.Bose 4 The question of mass Why is there mass ? Why do some particles have mass while others are massless? Why does, say a top quark, have about 40 times as much mass as a bottom quark? etc. Electric EM Magnetic Electroweak Weak 10/12/01 T.Bose 5 HEP’s Most Wanted Invents a set of particles with very special properties their interaction with all the standard particles mass + one new particle – the Higgs boson But where is the Higgs??? 10/12/01 T.Bose 6 Higgs in cartoons 10/12/01 T.Bose 7 What’s the matter with antimatter ? = Right after Big Bang Matter Antimatter But we exist!!! Where did the anti-matter go? But some asymmetry between matter and antimatter connects the Universe’s matter dominance with elem. pcles Proton decay Rapid expansion 10/12/01 T.Bose 8 Theoretical framework : CKM matrix atleast 6 quark flavors complex phase Quarks CP Violation in B0, K0 decays…, Mixing (t ) B 0 ACP B B J / K S B J / K S 0 0 J / K S 0 0 0 0 J / K S 0 Is it zero or non-zero Leptons Neutrino Oscillations: neutrino mass, mixing & CP accomodates but does not explain it!!! SM amount of not enough to account for matter dominance Alternate models include other CP viol. effects experiments sensitive to physics beyond the SM 10/12/01 T.Bose 9 The gravity of the situation Hierarchy problem 10/12/01 T.Bose 10 SUSY to the rescue??? Supersymmetry adds a Superpartner for every SM pcle and 5 Higgs: h0, H0, A0, H± Simplest SUSY models require Mh < 135 GeV (!!!) Standard Model Particle S qL , qR ½ ½ ½ L , R L W , Z , 0 0 0 0 h ,H , A ,H g 1 0 1 Superpartners Sparticle S ~ ,q ~ q L R ~ ~ L , R ~ L ~ 1 , ~ 2 0 0 0 0 ~ 1 , ~ 2 , ~ 3 , ~ 4 ~ g 0 0 0 ½ ½ ½ 11 Answers??? new interactions analogous to the ‘color’ force new technicolor fermions like quarks at TeV scale SM particles interact with techi-fermions : the interaction mass to the SM pcles 10/12/01 T.Bose Hierarchy problem solved! 12 Large extra dimensions ?? String Theory Collision energy disappears Non-conservation of energy sign of new physics 10/12/01 T.Bose 13 The strategy Take your favourite beyond the SM theory: it looks like the SM at low energies , differences only at high E small corrections to SM predictions We need to look more precisely and at higher energies 10/12/01 T.Bose 14 The truth is out there… Precision measurements: Electroweak Physics: large sample of W & Z bosons W mass (dM(W) ~ 30 MeV/c2) W width, W/Z production properties tri-linear gauge boson couplings Any deviation new physics ! Top Physics: top only produced at the Tevatron top mass (dM(top) ~ 2.8 GeV/c2) top pair production cross-section single top production W mass + Top mass constrain Higgs mass 10/12/01 T.Bose 15 The beauty of physics - Large rate: ( p p bb) 150 b at 2 TeV (e e bb) 7 nb at Z0 (e e B B) 1 nb at (4S) – All species, including Bs, Bc, b, produced CP violation and CKM angles Bs mixing Cross sections Rare decays 10/12/01 T.Bose 16 Tevatron Fermilab Tevatron Circumference: 4 mile 20 feet underground ECM=2 TeV p p collisions Underlying Event g d u u q q d u p (E = 1 TeV) 10/12/01 p (E = 1 TeV) u Hard Scatter T.Bose 17 Tevatron Protons Antiprotons 1. H- Source produce 1. p-Ni p’s 2. Linac 400 MeV 2. Accumulator 8 GeV 3. Booster 8 GeV 3. Main Injector 150 GeV produce 4. Main Injector150 GeV 4. Tevatron 980 GeV 5. Tevatron 5. Recycler recovery 980 GeV 18 Tevatron upgrade Linac upgrade, main injector, new antiproton storage ring Tot. Anti-p (x1012) Bunches Ib 92-96 IIa 01-03 IIb 03-07… 0.3 1.1 4-11 6x6 36x36 140x103 Spacing [ns] 3500 396 132 E-CM [GeV] 1800 1960 1960 Typ. Lumi. [cm-2s-1] (x1032) 0.016 0.86 2–5.2 Lumi/week pb-1 3.2 17.3 40–105 Tot Lumi fb-1 0.125 2 15–20 2.5 2.3 1.9–4.8 Int’s/X’ing 10/12/01 Extensive upgrade of the D detector 19 10/12/01 The layers General purpose high energy physics detector T.Bose 20 The international coalition >500 people from ~ 50 institutions (17 countries) Run I (’92-’96) ~ 104 publications… EW Physics Top Physics Top quark co-discovered (w/ CDF) March 95 New Phenomena B Physics QCD Run II started March 1, 2001 ! Detector rolled in. All component detectors installed Electronics : final production/installation 10/12/01 T.Bose 21 On the home front Faculty Post-docs Graduate students Hal Evans John Parsons Mike Tuts Leslie Groer Christos Leonidopoulos Georg Steinbrueck Tulika Bose Shaohua Fu Mingcheng Gao Burair Kothari Jovan Mitrevski Responsibilities Hal Evans L2 muon trigger, Si Track Trigger, B phys group co-convener, Run 2b Cal. Trigger Upgrade leader Leslie Groer Detector Commissioning John Parsons Top/Higgs group Georg Steinbrueck Electroweak group co-convener Mike Tuts Calorimeter electronics, Run 2a upgrade co-leader 22 D upgrade Central Scintillator Forward Minidrift chamb’s 10/12/01 Forward Scint Central PDTs Shielding Calorimeter Tracking: Solenoid,Silicon,Fiber Tracker,Preshowers New Electronics,Trigger,DAQ T.Bose 23 10/12/01 The real thing! T.Bose 24 Tracking Readout Charged Particle p=qBR VB B n+ - + 50 m - + n SiO2 - + Si Detector 300 m p+ reverse biased diode Si wafers: charged pcle passes thru Si electrons & holes charge collected on strip readout pcle position points for track fit Ionization of atoms by charged particles : electrons knocked out trajectory deduced by measuring ionization at many points along the path curvature of track measured particle momentum ; amount of ionization per unit length (dE/dx) depends on particle type, p particle type identified 10/12/01 Tulika Bose 25 Tracking upgrade • • • Silicon Microstrip Tracker (SMT) Central Fiber Tracker (CFT) 2T superconducting solenoid 26 SMT Silicon Microstrip Tracker (SMT) 6 Barrels : 4 layers of Si microstrip detectors axial strips (10m resolution) Layers 1, 3: double-sided 90o strips (30m res.) (single-sided on 2 outer barrels) • Layers 2, 4: double-sided 2o stereo (15m res.) •793k Channels •SVX IIe Readout • L2 Trigger (’02) • 12 F-disks & 4 H-disks 27 SMT & CFT SMT high resolution measurements of particle tracks near the beam pipe (10m res.) measurement of charged particle momenta measurement of secondary vertices for identification of b-jets from top, Higgs, and for b-physics CFT (Scintillating fiber tracker) Fibers (830 m) -Axial & Stereo (±3o) on 8 concentric cylinders light from the fibers converted into electrical pulses by Cryogenic (LHe) Photon Detectors (new) VLPC Readout: ~77k Channels (SIFT + SVX IIe) Hit Resolution (~100 m) 28 Calorimeters Calorimeter high density material: particles slow down & stop energy deposited measured showers shape of shower distinguishes e, from hadrons electromagnetic : electrons, positrons, photons hadronic: hadrons which penetrate EM Cal. Detector unchanged from Run I (U-LAr) New electronics to cope with BX frequency 10/12/01 29 Chasing muons Muon detectors tracking muons, measure momentum drift chambers • • • • parallel anode wires stretched between two cathode planes elec liberated by ionization moves towards anode energy gain further ionization avalanches of elec & +ions drift time (collection time of avalanches)measure of position scintillation counters • excitation of atoms by ionizing particlesluminescence • light converted into electrical pulses by Visible light photon counters 30 Pictures Silicon Detector Fiber Tracker Muon Detector 31 Physics Rates Physics Rates Process X-Sect or BR Beam X’ing 7.5 MHz (132ns) Inelastic pp pp bb ( y 1) pp WX pp ZXbbX p p tt W bW b - e/ + jets only jets p p W/Z H(*) e/ b b qq bb Rate (L=2x1032) 50 mb 50 b 10 MHz 10 kHz 22 nb 1 nb 4.4 Hz 0.2 Hz 7.2 pb ~100% 35% 44% 5 / hour 425 fb 22% 56% 7 / day * M(H) = 100 GeV 32 Signal Vs. Background Signals High PT Leptons W/Z, b... High ET Jets Massive Objs ~~ pp t t X bbjj T ~ ~ ; ~ ~ 0 , qq ~0 t b 1 1 1 1 Missing ET ’s, LSP Displaced Vertices b’s... Backgrounds Low ET Jets ET Balanced pp qqgX No High PT Leptons No Displaced Vertices 33 Where is the needle? Out of every trillion proton-antiproton collisions, about ten top-antitop quark pairs are produced!!! 34 D Trigger System Crossing frequency 7MHz p p But data acquisition rate is 50 Hz New 3 Level Trigger System L1 7 MHz L2 L3 10 kHz Decision time 1 kHz Decision time 50 Hz Decision time 25ms 100s 4.2s •Single Sub-Det’s • Towers, Tracks, ET-miss • Some correl’s •Correlations • Calibrated Data • Physics Objects e,,j,,ET-miss •Simple Reco • Physics Algo’s • Not deadtimeless 35 L1 & L2 Detector Level 1 7 Mhz Level 2 10 khz 1 khz CAL L1Cal L2Cal c/f PS L1PS L2PS CFT L1CTT L2CTT SMT MU FPD Lumi L2STT L1Mu L2Mu L1FPD Framework Global L2 Level 3 36 The importance of beauty Some Run II physics programs: Search for the Higgs Boson ( H bb ) Studies of the top quark ( t Wb) B Physics (CP violation etc.) Search for new particles b quarks appear in the final state Tagging of b-quark jets is of utmost importance ! 37 Impact parameter B Decay Products B-Hadron: Flight Length ~ mm’s Collision Decay Vertex Impact Parameter Interesting physics is tagged by b-quarks Impact parameter is a good b-tag Need sensitivity at level of 10's of microns CFT: (100m res.) , SMT (10m res.) 38 Trigger thresholds Momentum Resolution Evts Trig Cut Interesting evts High PT Bgrd dominated by Low PT Bgrd Signal (magnified) soft thresholds allow a fraction of the particles with pT below threshold to fire (BAD!) PT increase in trigger rate sharp threshold cuts out this background below threshold decrease in trigger rate (VERY GOOD!) precise tracking more efficient use of the data acquisition bandwidth 39 Physics benefits New Phenomena increase Higgs sensitivity 20% ZHbb double sensitivity hAbbbb Top Trigger on Zbb (increase yield x6) Cut Mt systematics in half B-Physics Increase BKS yield by 50% 40 Silicon Track Trigger FRC Define search region in Si Tracks from CFT Data from SMT detectors STC Associate clusters to tracks Form Clusters TFC Re-fit track with Si clusters Global L2 Trigger 50s time budget via L2CFT impact parameter trigger ; 15m at PT=15GeV improved momentum resolution: (factor 2-3) Res ~ 30m at PT=2GeV sharper thresholds 41 The STT Integration 42 Status Dates Tevatron DØ 1/Mar/01 Official Run II Start Detector Open 3/Apr/01 First Colliding Beam (1x8) Timing In Detectors 27/Apr/01 36x36 stores Final mu-chamber gas 3-17/May/01 2-week shutdown All Si cabled – Close det. May-Aug/01 36x36 stores w/ shutdowns Install electronics as avail Jul/01-Sep/01 L2 Cal and Muon Oct/01-Nov/01 1-month shutdown Fully instrument Nov/01-2003 2 fb-1 Run IIa Jun/2002 STT installed 2003 Long Shutdown Install new silicon, etc. 2003-2007 Run IIb >15 fb-1 10/12/01 T.Bose 43 Status Dates Action ~ July 26 By August 15 NOW Run until ~ Oct 8 Oct 8 - Nov 16 November December & January 2002 10/12/01 Continue 36 x 36 running With detector as described before. • Increase L3 rate from 4 Hz to Done In Progress ~100Hz Done • Complete L1 Cal •Take Start bringing up L2 trigger data & commission Offlinepartially software In Preparation Install AFE8 boards & other with real data; Calibration & completion Alignment 36x36 stores Commission CFT & L1 track trigger 36x36 fine tune & stabilize; stable operation T.Bose 44 Data! Z ee 10/12/01 Muon T.Bose 45 Di-muon candidate 10/12/01 T.Bose 46 Outlook Exciting times ahead! D is the place to be at! DØ vs. The Standard Model Precision (2 fb-1) Searches (20 fb-1) Quark M vs Weak (2 fb-1) MW 30 MeV HSM 180 sin2 0.03 Mt 1.6 GeV tan,MA most 5 xs 30 |Vtb| 12% rare top 10–40 K*+- 700 evts etc… etc… etc… 47 I.P. resolution with STT • I.P. Resolution ~ 30 m at pT=2GeV ~ 15 m at pT=15GeV Tulika Bose 48 Momentum resolution • Si precision ~ 10 m , CFT precision ~ 100 m • improved momentum resolution: (factor 2-3) Tulika Bose 49 Improved rates 50