J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking with standalone SCT, dependencies on incidence angle, studies with LHC-like bunch structuring…

Light tight, thermally insulating box Telescopes 180 GeV pion Beam Telescopes Scintillator Trigger Modules inside the beam test box. Setup 2 SCT Beam test results Typical SCT beam test setup with different types of modules J. E. Garcia RTN – December 03

Variation of efficiency and noise occupancy with comparator threshold. Horizontal lines are the ATLAS specifications. After 10 years the SCT will receive up to 2·10 14 n eq /cm 2. Radiation causes damage on the module. – Radiation creates defects – Type inversion – Electronics noise and leakage current increase Resolution is measured. SCT modules are almost single-strip. The detector pitch is 80  m in order to avoid charge sharing and preserve a good resolution. Beam test studies 3 SCT Beam test results  ~ 23  m J. E. Garcia RTN – December 03

The Lorentz angle has been measured using a 1.56 T magnet and different incidence angles. The most sensitive parameter to these changes is the cluster size  L = 3.3 º  0.3 º (at 150 V) Beam test… (II) 4 SCT Beam test results Signal to noise ratio for the SCT modules is  14. The median charge observed on binary SCT prototypes is around 3.4  0.2 fC S-Curve J. E. Garcia RTN – December 03 The pulse shape can be reconstructed from beam test data and compared with the theoretical response of the shaper

For reconstructing tracks only the position measurements of the irradiated SCT modules are used. The beam telescope is only read out for comparison. Example of a reconstructed event SCT Modules Telescope Tracking study 5 SCT Beam test results J. E. Garcia RTN – December 03 efficiency The tracking efficiency depends on threshold. The maximum efficiency is 97 % obtained at a threshold of 1.2 fC for a bias over 450 V. Fake rate is kept below independent of the bias voltage on the detector.

J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking with standalone SCT, dependencies on incidence angle, studies with LHC-like bunch structuring… Little Higgs Searches: Capability of the ATLAS detector to find particles predicted by the Little Higgs Models. In particular new gauge bosons in the channels: W H  W H and Z H  Z H

Particle Spectrum Little Higgs Searches 7  0,  +,  ++ W H, Z H T AHAH 1 TeV Z,W h  t M scalar sector gauge sector top sector v’   ’ 1 new couplings J. E. Garcia RTN – December 03 Littlest Higgs model SU(5)  SO(5) Gauge sector  [SU 2  U 1 ] 2 Only 1 Higgs doublet Arkani-Hamed et al., JHEP 207 (2002) 34 Phenomenology Han et al., Phys. Rev. D67 (2003) Burdman, Perelstein, Pierce, hep-ph/

Strategies at LHC 8 q W b T q’ q1q1 W+W+ q2q2 W+W+ 1 2  ++ q q ZHZH T ZHZH VBF mechanism   ( v’) 2 v’ should be small W + W +  ++  W + W + large SM bkg Wb fusion   ( 1 ) 2 1  1 but suppressed by b- quark PDF. bW, t Z T  bW, t Z clear signal qq annihilation   ( cot) 2 Wide range in cot  possible. e + e - Z H  e + e - clear signal Little Higgs Searches J. E. Garcia RTN – December 03

Z H Zh with h bb 9 h ZHZH Z l + l - b b 2 TeV h bb ZHZH Z l + l - 1 TeV Cuts Background: Z + jets Cuts |  | < 2.5 (jets and leptons) P T (Z) > 250 GeV P T (h) > 250 GeV b-tagging |  | < 2.5 (jets and leptons) P T (Z) > 500 GeV P T (h) > 500 GeV b-tagging Little Higgs Searches J. E. Garcia RTN – December 03

Signal and background 10 b-tag:  b = 40%, R u = 100 Inside mass window: S = 15 S B = 8  B = 5 b-tag:  b = 50%, R u = 100 Inside mass window: S = 195 S B = 16  B = 50 M(Z H ) (GeV) M Z = 1 TeV H M(Z H ) (GeV) M Z = 2 TeV H L = 3·10 5 pb -1 cot  = 0.5 L = 3·10 5 pb -1 cot  = 0.5 Events Little Higgs Searches J. E. Garcia RTN – December 03

Discovery region Z H  Zh 11 L = 3·10 5 pb -1 S/  B > 5 N > 10 h(120)  bb Z H  Zh  l + l - bb W H  Wh  l bb Little Higgs Searches J. E. Garcia RTN – December 03

J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking with standalone SCT, dependencies on incidence angle, studies with LHC-like bunch structuring… Little Higgs Searches: Capability of the ATLAS detector to find particles predicted by the Little Higgs Models. In particular new gauge bosons in the channels: W H  W H and Z H  Z H b-tagging studies: b-tagging performance of the ATLAS detector for high p T jets applied to the Little searches and for the benchmark channels W H(120) and W H(400). Using the signed impact parameter b-tagging algorithms.

m h = 200 GeV BR(h W + W - ) = 74 % BR(hZZ) = 26 % Z H Zh 13 q q cot  cot 2    (cot  cot 2  ) 2  (cot  )  (cot  = 0.5) m h = 120 GeV BR(h bb) = 66 % BR(h) = 0.2 % ZHZH hZ Ratio 0.5 Little Higgs Searches J. E. Garcia RTN – December 03

b-tagging 14 = 220 GeV = 800 GeV M Z = 1 TeV H M Z = 2 TeV H ~ Little Higgs Searches J. E. Garcia RTN – December 03