38. Herbstschule für Hochenergiephysik Maria Laach September 2006

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1 38. Herbstschule für Hochenergiephysik Maria Laach September Herbstschule Maria Ariane Laach Frey, MPI München Ariane Frey, MPI München Photo S.Bethke 1

2 Outline: Motivation: why e + e -, why linear Accelerator Detector requirements and concepts Examples from LDC ILC: SM Higgs Supersymmetry Precision Physics (top, ) Extra Dimensions, heavy Z Z LHC/ILC Synergy CLIC Lecture 1 Lecture 2 Lecture 3 2

3 Detector Requirements Momentum resolution: σ(1/p) = GeV (1/10 LEP,LHC) Measurement of M H e + e - ZH ll X Impact parameter: σ d 5 μm + 10 μm/(p sin 3/2 Θ) (1/3xSLD) flavour tagging, Higgs branching fractions Jet energy: σ(e)/e = 0.3/ E (GeV) (< 1/2xLEP) ΔM Dijet <Γ Z/W separate e + e - ννww ννqqqq and e + e - ννzz ννqqqq Reconstruction of multijet final states e.g. e + e - H+H- tbtb bqqb bqqb Hermeticity to small angles θ = 5 mrad missing energy e.g. from SUSY 3

4 Example: The Large Detector Concept (LDC) Instrumented Instrumented Iron Iron Return Return Yoke Yoke 6.00m HCAL HCAL ECAL ECAL Coil Coil B=4T B=4T 5.60 m Large TPC Large TPC 5 layer layer Si Sipixel + intermediate intermediate Si Sistrips 4

5 Vertex Detector pixel size: µm low mass: 0.1 %Xo per layer close to IP, r = 15 mm (1st layer) 20 ns/row read out time 5 barrels stand alone tracking Background from Beamstrahlung pair background Competitors: - CCD - MAPS - DEPFET -. 5

6 DEPFET Pixels gate DEPFET- matrix reset off off on reset off off n x m pixel off off V GATE, OFF V GATE, ON I DRAIN drain 0 suppression V CLEAR, ON V CLEAR, OFF V CLEAR-Control output 6

7 DEPFET Modules Holes in frame can save material Chips are thinned to 50 μm, connection via bump bonding Thinned sensor (50 µm) in active area Thick support frame (~300 µm) Cross section of a module 1 st layer module: 100x13 mm 2 7

8 Main tracker - TPC Advantages: y z x B E drift 2 m many 3D points, efficient tracking Robust pattern recognition (Kinks) Little Material de/dx for particle ID Electrons drift to endplate Drift time ~ 50 μs integrate over many BX Pad readout with wires (ALEPH) 8

9 TPC for LDC Point resolution 100 μm Point resolution 100 μm Endplates with GEMs (Gas Electron Multipliers) or Micromegas (metalic micromesh) 9

10 TPC with Micro Pattern Gas Detectors (MPGD) GEMs Ø50-70 µm 2 mm HV Kapton Copper Avalanche in GEM foil

11 TPC with Micro Pattern Gas Detectors (MPGD) Micromegas Avalanche between mesh and pads

12 Calorimeters for LDC Optimize Jet energy resolution Particle Flow 12

13 Jet Energy Resolution Particle Flow Ideally would like to treat quarks as any fermion optimize jet energy res. Method: particle flow paradigm = most exclusive reconstruction of charged and neutral particles in a jet 65 % 25 % 10 % E jet 2 Ejet = E charged 2 Echarged + E photons 2 Ephotons neut. had. σ = σ + σ + σ + σ + E 2 Eneut.had. 2 confusion! 2 2 Ejet jet confusion jet 2 ( ) ( ) E GeV ( 0.3) ( E GeV) σ +σ dominated by HCAL! largest contribution! Granularity more important than energy resolution! 13

14 CALICE ECal 130T of tungsten An octagonal geometry A high level of density (20-40 layers, 24X 0 in ~170mm) Si-W 1 x 1 cm granularity layers! ECAL module 20 cm Alveolus Tungsten Carbone Fiber No large area of dead zone All modules are identical (Tungsten wrapped by Cfi) The detector slabs would be tested before assembling Detector slab 14

15 Calice HCAL Scintillator-Fe 5 x 5 cm (analog) 1 x 1 cm (digital) Silicon PhotoMultiplier (SiPM) MEPhI&PULSAR Si Photo-Multiplier SiPM Pixels of the SiPM Silicon photo-multiplier (SiPM): new detector concept, first test with beam sizes: 1x1mm 2, 1024 pixels/mm 2 gain ~ 1*10 6 No preamplifier needed quantum eff. ~ 15-20% single tile read out / mounted directly on tile 15

16 Testbeam 16

17 Physics at the ILC 17

18 Higgs discovery potential at LHC Higgs production pb Higgs decay fully hadronic final states dominate, but cannot be extracted from large QCD background 38. Herbstschule Maria Laach Ariane Frey, MPI München 18

19 Higgs discovery potential at LHC Guaranteed SM-like Higgs Higgs discovery over over the the full full allowed allowed mass mass range range with with fb fb -1-1 in in one one experiment Light Light Higgs Higgs most most challenging Whole Whole mass mass range range could could be be % CL CL after after ~ 1 month month of of running First First measurements of of Higgs Higgs properties possible: Mass: Mass: % 0.4% Production rates: rates: 10-20% Ratios Ratios of of couplings: W/Z, W/Z, W/t, W/t, W/t: W/t: 10-20% model-independent measurements of of absolute couplings impossible 19

20 Higgs - Task of a Linear Collider After the discovery of a Higgs boson, the key task of ILC is to establish the Higgs mechanism in all elements as being responsible for EW symmetry breaking Precision Measurements must comprise: Mass Total Width Quantum numbers J PC (Spin 0, CP-even?) Higgs-Fermion couplings (~ mass?) Higgs-Gauge-Boson couplings (W/Z masses) Higgs self coupling (spontaneous symmetry breaking) Measurements should be precise enough to distinguish between different models (e.g. SM/MSSM, effects from extra-dimensions, ) Aim at model-independence! 20

21 Higgs Production Dominant production processes at LC: σ ~1/s σ ~lns Higgs-strahlung WW fusion 21

22 Higgs-strahlung ee -> HZ Z -> l l H -> qq 22

23 Model-independent observation Anchor of LC Higgs physics: select di-lepton events consistent with Z ee/μμ calculate recoil mass: m = (p p ) 2 2 H ll initial model independent, decay-mode independent measurement! 23

24 Model-independent observation efficiency is ~independent of decay mode: works over the whole range of possible Higgs masses: small differences can be corrected with MC precision on σ(hz): 1-3% for m H <200 GeV 3-20% for m H <500 GeV 24

25 Measurement of the Higgs Mass Model-independent HZ analysis only uses a fraction of the events (Z ll) For a precise mass determination further statistics can be gained if hadronic Z-decays are used. For mass measurement, explicit Higgs final states (e.g. H bb) may be used Highest sensitivity to Higgs mass comes from purely hadronic events Kinematic fits improve the mass resolution 25

26 Higgs Mass M H = 120GeV M H 0 H Z bbqq 0 H Z = 120GeV + bbl l MH 0 H Z = 150GeV + W W qq MH 0 H Z = 150GeV + + W W l l sub-permille precision 500 fb s = 350 GeV 26

27 Total Width 27

28 Total Width 28

29 Total Width 29

30 Total Width Precision 30

31 Higgs Quantum Numbers Is it a Higgs boson? Rise of cross section near threshold is sensitive to Higgs Spin for J=0: rise ~ β for J>0: rise ~ β k,k>1 (some cases for J=2 are also ~β but can be distinguished from J=0 through angular distributions) also: m H =120 GeV 20 fb -1 /point observation of H γγ or γγ H rule out J=1 and require C = + 31

32 Quantum Numbers Method : CP from transverse polarization correlations in H ττ Needs exclusive reconstruction τ ρν and τ a 1 ν decay modes First estimate with detector simulation: > 8σ separation between CP+ and CPfor 120 GeV Higgs (350GeV/1 ab -1 ) 32

33 Higgs Branching Ratios Higgs Branching ratios best to study Higgs Yukawa couplings for a light H Crucial test: Γ(H ff) ~ m f? At ILC measurement of >absolute< BR s is possible, because of decay-mode independent g HZZ measurement: [ σ(hz) xbr(h X) ] meas BR(H X) = meas σ(hz) 33

34 Higgs Branching Ratios Most challenging: disentangle the hadronic Higgs decays H bb H cc H gg H bb 68.2% H cc 3.0 % H gg 6.7 % for m H =120 GeV Need sophisticated flavour tagging: Vertex reconstruction using ZVTOP algorithm (SLD) Tracks interpreted as 3D probability tubes Vertices = overlapping tubes After vertex reconstruction, use ANN s with vertex+track information to obtain b- and c-likeness for each jet 34

35 Higgs Branching Ratios ΔBR/BR bb 2.4% cc 8.3% gg 5.5% tt 6.0% gg 23.0% WW 5.4% For 500 fb-1 MH = 120 GeV 35

36 Higgs self-coupling ( the holy grail ): V =λv 2 H 2 + λvh 3 + 1/4λH 4 SM: g HHH = 6λv, fixed by M H essential test of the mechanism of spontaneous symmetry breaking Higgs Self Coupling 6 jet final states! 36

37 Measurement of Higgs self coupling Tiny cross section Complicated multi-jet final state detector design: energy flow Difficult backgrounds jet mass resolution: 60%/ E 30%/ E Need highest luminosity Precision for 1 ab -1 : Δλ λ 20% 37

38 Summary Mass Width Quantum Numbers Branching ratios Self Coupling 38