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Neutrino Oscillations and Charged Higgs Bosons

Explore experimental projects for physics beyond the Standard Model, including neutrino oscillations and charged Higgs bosons. Discover the limitations of RICH counters for tau-neutrino detection and the Material Integration Service for particle reconstruction.

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Neutrino Oscillations and Charged Higgs Bosons

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  1. Neutrino Oscillations and Charged Higgs BosonsExperimental projects for physics beyond the Standard Model 3 May 2005, ISV Seminar

  2. Contents • Short about the Standard Model • Short about beyond the Standard Model • Tau RICH – Neutrino Oscillation • MIS – ALTAS Event Reconstruction • Charged Higgs Analysis – Exploring LHC physics beyond the Standard Model

  3. CERN Large Hadron Collider (LHC)

  4. The Standard Model Force Carriers Matter Particles

  5. e u e d γ Matter Particles Spin 1/2 g c μ μ Force Carriers Spin 1 Z0 W+   b t Spin 1/2 The Standard Model Spin 0,1 Force Carriers Matter Particles s

  6. e μ γ g g e u d Z0 W+ s c h0 μ e e u d H0 s c μ μ A0 χ01,2,3,4   b t b  t H±  χ±1,2 • Supersymmetry (SUSY) solves the “hierarchy problem” and predicts one partner to each SM-particle with spin ±1/2 • Minimal SUSY Model (MSSM) has a Higgs sector with 5 Higgs bosons • SUSY is broken  SUSY masses > SM masses and higgsinos and gauginos mix to charginos χ±1,2 and neutralinos χ01,2,3,4 The Minimal Supersymmetry Model The undiscovered particles (mass eigenstates) of MSSM:

  7. Tau RICH 1/13 Tau-RICHLimitations in the use of RICH counters to detect tau-neutrino appearance

  8. Tau RICH 2/13 μ  CERN to Gran Sasso Neutrino Beam (CNGS)

  9. Tau RICH 3/13 γ μ 100 cm    Tau-RICH: A new concept of appearance detection

  10. Tau RICH 4/13 The Cherenkov angles for each long track are decided from histograms of the reconstructed polar angles from each detected photon, assuming emision point in the middle of the track. Cut Algorithm C1 C2 a Rec  for track 1 Rec  for track 2

  11. Tau RICH 5/13 For each photon hit: • Reconstruct  for each point along a track to find min and max • Cut away this photon detection if min < C < max • Try all long tracks Cut Algorithm a

  12. Tau RICH 6/13 Cut Algorithm Also works for more complicated events a

  13. Tau RICH 7/13 Cut Algorithm And whith pixalization ↴ a

  14. Tau RICH 8/13 • Particles interaction with media is introduced by the GEANT4 toolkit. • Multiple scattering and delta electrons are added into the simulation. • Cherenkov photons from delta electrons are shown to be more numerous than those from the tau. Simulation – with GEANT4

  15. Tau RICH 9/13 Cut Algorithm – on G4 The Cut Algorithm unable to cut out Cherenkov photon hits from delta electrons. a

  16. Tau RICH 10/13 Cut Algorithm – on G4 Another example where all but the photon hits from delta electrons are cut. a

  17. Tau RICH 11/13 Cut Algorithm – on G4 Even though 13 tau photon hits remains after the cut it would be impossible to distinguish the tau ring from remaining delta electron background photons. a

  18. Tau RICH 12/13 Many more  photons but all in the  ring • With higher neutrino beam energy number photons from tau would increase more than number photons from the electrons. • But the kink angle between the tau and the muon would be smaller. Higher n beam energy

  19. Tau RICH 13/13 Conclusions for Tau-RICH • We have investigated the limitations to use RICH counters for tau-neutrino appearance detection • Delta electrons give a too disordered background and make the developed cut algorithm unfeasible • At higher energies than CNGS n beam energy the tau Cherenkov ring has more photon hits but aligns with a ring from a tau decay product • For more info, see Nuclear Instruments and Methods in Physics Research A502 (2003) 163-167

  20. MIS 1/7 MISMaterial Integration Service

  21. MIS 2/7 LHC, ATLAS and Inner Detector (ID) Particles going through the ID leave 46 detection points, these are reconstructed to helical tracks from which momenta and charge of particles are measured.

  22. MIS 3/7 SCT Geant4 Material Integration Service (MIS) In ATLAS 109 events per sec have to be reduced to 100 Particle tracks can be distorted by material Information about material in the detector should be provided to reconstruction programs MIS is a service program reading from Geant ID descriptions and providing reconstruction programs with material information fast and accurate Geantino Map MIS Reconstruction

  23. MIS 4/7 VolumeElements (VE) • ID is segmented into VEs that get their average RadiationLength (X0j) from intersecting geantinos • Each VE gets the length (xj) that the user specified line intersects it with • The xj / X0j , for each intersected VE are summed together

  24. MIS 5/7 fine granularity 5400 VE 20.6 MB course granularity 580 VE 1.1 MB Performance GeantinoMap examples: 2 different granularities lxplus087, PIII, 1 GHz ≈ 0.14 sec per MIS call ≈ 0.012 sec per MIS call RadiationLengthFraction RadiationLengthFraction RadiationLength RadiationLength F(PolarAngle) F(PolarAngle) RadiationLength RadiationLength

  25. MIS 6/7 fine granularity 5400 VE 20.6 MB course granularity 580 VE 1.1 MB Relative Errors and Performance of 500 MeV electrons with Random Distances lengths [10, 30] cm, B = 2 tesla MC test results of 2 GeantinoMaps RMS 0.25 0.01 s tfine / tcourse = 104 RMS 0.34 0.88 s Time per event (HLT) LVL1: 2 s LVL2: 10ms EF: ~few secs

  26. MIS 7/7 Conclusions for MIS • We have developed and tested a new method for providing material information to reconstruction programs • The new concept was shown, for TRT, to be accurate and have good performance • The functionality for other detector systems is yet to be proven • For more info, see ATLAS Notes: ATL-SOFT-2003-006, ATL-INDET-2003-006

  27. HIGGS 1/10 Set A HIGGS±Discovery potential for H+ decaying to SUSY particles

  28. HIGGS 2/10 Discovery Potentials for H± in ATLAS tan The H±, a charged scalar, would show physics beyond the SM One of ATLAS’ most important task will be to find H± In MSSM the Higgs sector is determined by mA and tan Simulations show discovery regions of H±in mA- tan plane These H±→ SM decays cannot cover intermediate tanβregion Try H±→χ±1,2χ01,2,3,4 Intermediate tan region ATLAS 300 fb-1 mA (GeV)

  29. Our channel: H± to SUSY HIGGS 3/10 The Signal We have investigated gb → tH± t → qqb H±→χ±1,2χ01,2,3,4 →3l+N Examples of H±→ 3l+N

  30. HIGGS 4/10 Signal SM Bkg SUSY Bkg Event Production • One point in the MSSM parameter space was chosen, called Parameter Set A • Used HERWIG for event production and ATLFAST for fast detector simulation • Have MC data for tanβ = 3, 5, 8, 10, 15, 20, 25, 30, 35, 40 and mA = 200, 220, 230 250, 300, 350, 400, 450, 500 GeV, in the Parameter Set A

  31. HIGGS 5/10 Cross Section and Branching Ratio Signal Cross Section, : NLO from Signal Branching Ratio, BR: H+ is forced to decay, via χχ, to 3l + N Expected Signal Rate,  x BR:→ SM-Bkg: CS(tt) = 737 pb (NLO), CS(ttZ) = 431 fb (LO) SUSY-Bkg: (LO)

  32. HIGGS 6/10 3 years of LHC operation at high luminosity give integrated luminosity L = 300 fb-1 Total expected events of a certain process is Ntot = ·BR·L Number selected events is given from the selection efficiency N = sel·Ntot ATLAS uses the significance: When N  ∞ then Binomial  Poisson where  = √, so the significance is a measure of how much bigger the signal is over the standard deviation of the bkg Event Selections Three Lepton Cut: Three isolated leptons with energy > 7, 7, 20 GeV Two Lepton Cut: Two leptons must come from the neutralino, χ01,2,3,4 Top Cut: Three jets with energy > 20 GeV, two of those from W Jet Cut: All other jets should not be too energetic.

  33. HIGGS 7/10 Cut Results Since Nsignal» Nbkg and since there is no discriminating signature for the signal this is a counting experiment  sensitive to systematic uncertainties L = 300 fb-1

  34. HIGGS 8/10 5- Discovery Contour for H+ Set A

  35. HIGGS 9/10 5- Discovery Contour for H+

  36. HIGGS 10/10 Conclusions for HIGGS± • ATLAS’ discovery region is about same size as that obtained for CMS. Different shapes, due to • Different cuts • Different used cross sections • Different detector descriptions • The 5- significance contour for H+ through H+ → χχ encloses major part of intermediate tanβ region • More MSSM parameter sets need to be analysed for a more general conclusion • Since this is a counting experiment the discovery potential is very sensitive to systematic uncertainties, e.g. rely upon exact measurements of bkg cross sections • For more info: ATLAS Scientific Note: SN-ATLAS-2005-050

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