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MSSM Higgs  Tau Tau  Leptonic Missing Et and Mass Reconstruction

MSSM Higgs  Tau Tau  Leptonic Missing Et and Mass Reconstruction. F. Duru, U. Akgun, S. Kunori, Y. Onel The University of Iowa Fermilab. The Motivation. The MSSM requires five Higgs members Three neutral: h, H, A Two charged: H ±

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MSSM Higgs  Tau Tau  Leptonic Missing Et and Mass Reconstruction

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  1. MSSM Higgs  Tau Tau  LeptonicMissing Et and Mass Reconstruction F. Duru, U. Akgun, S. Kunori, Y. Onel The University of Iowa Fermilab F. Duru, APS April Meeting 2006, Dallas

  2. The Motivation • The MSSM requires five Higgs members • Three neutral: h, H, A • Two charged: H± • bbH/A  τ+τ- production can be the sign of MSSM. σ(MSSM)/σ(SM) ~ 5000 (tanβ=30, mH/A=300 GeV) . • CMS Note 2004/027, Kinnunen et al. shows CMS discovery potential. • Our aim is to work on MET and jet reconstruction improvements. F. Duru, APS April Meeting 2006, Dallas

  3. MET Measurement and Jet Reconstruction Regarding MET • Complications: presence of pile-up collisions difference between photon and pion response in the calorimeters bending of tracks by the 4-T B-field • Advantages: excellent cell segmentation & hermeticity good forward coverage of CMS For Jet Reconstruction • Associating a jet measured in a calorimeter with the scattered parton or bending charge particles (due to B-field) is a problem. • The jet energy resolution and linearity play the key role in separating the signal and understanding its properties. F. Duru, APS April Meeting 2006, Dallas

  4. bbA/H  2tau  ll • We use DC04 sample. • Signal: • 140 GeV, 38k Events • 200 GeV, 20k Events • 250 GeV, 10k Events • Backgrounds (250k each): • Drell Yan zg80 100 2tau 2l • Drell Yan zg1002tau2l • All digitized events are processed with ORCA8_7_4 ExRoot. F. Duru, APS April Meeting 2006, Dallas

  5. Matching RecJets to GenJets • We used the iterated cone algorithm RecJet5 jets, ECAL plus HCAL tower. • Only 10% of the events have 2 matching RecJet5s. • 40% of events have at least 1 matching Jet. ~0.4 F. Duru, APS April Meeting 2006, Dallas

  6. Low Et and High Et B-Quark η The 2 b-jets are more likely to have opposite η signs F. Duru, APS April Meeting 2006, Dallas

  7. B Quark Gen Pt and ηValues Low Pt, Central b-jets F. Duru, APS April Meeting 2006, Dallas

  8. Leptons & Neutrinos • Leptons and Neutrinos are at central region • Neutrinos are very close to the “sister” lepton • Known direction of neutrinos allow us to reconstruct the Higgs mass. F. Duru, APS April Meeting 2006, Dallas

  9. Mass Reconstruction (Collinear Approximation) • Rainwater et al. MH ~ Mll/sqrt(X1X2) • “Type 1” approach: • On tranverse plane find the components of MET in the direction of Taus • Then assume that the same ratio will be valid for z-components • “Type 2” approach: • On tranverse plane add all MET to one of the Taus • Take the cross product with the other Tau. • Assume the ratio of the cross products before and after MET addition is X1 and X2 • Then MH ~ Mll/sqrt(X1X2) F. Duru, APS April Meeting 2006, Dallas

  10. Reconstructed Higgs Mass “Type 1” vs “Type 2” MET GEN Yellow – “type 1” Blue – “type 2” The reconstructed mass with collinear approximation, by using the generated MET, and generated lepton information. F. Duru, APS April Meeting 2006, Dallas

  11. MET from Calorimeter Hits MET CH (Gamma Jet Correction) For Type1 corr, check CMS Note 2001/40 F. Duru, APS April Meeting 2006, Dallas

  12. MET from Calorimeter Hits MET CH (MC Correction) MET CH (V1 Correction) F. Duru, APS April Meeting 2006, Dallas

  13. Reconstructed Mass with MET from CaloHits (with Gamma Jet Correction) “Type 1” “Type 2” F. Duru, APS April Meeting 2006, Dallas

  14. Reconstructed Higgs mass Standard CMS jet correction methods do not improve the mass resolution. We created jet corrections specific to this channel by comparing the generated jet Ets to reconstructed jet Ets in small η regions. “Type 1” “Type 2” Yellow – Before, Blue – WW Jet Corr., Green – τ+τ- Jet Corr F. Duru, APS April Meeting 2006, Dallas

  15. Total mass Yellow – Zγ* 80-100GeV, solid line bbH/A (140 GeV)τ+τ- F. Duru, APS April Meeting 2006, Dallas

  16. Status and Plans • We have two different collinear approximation techniques: • “Type 1” collinear approximation, has a tail on mass distribution, but yields almost 2 times more events than “type 2”. (For the signal and background.) • “Type 2” collinear approximation, yields a little sharper mass signal. • By using generator level lepton information, we focused on reconstructed Missing Et in ExRoot. F. Duru, APS April Meeting 2006, Dallas

  17. Status and Plans • There is room for improvement on MET with Jet Pt corrections: • the standard jet correction algorithms are not very helpful. • We used leptonic qqHWW jet correction values for ηregions of 0.2 increment. • Low statistics forces our jet corrections to be fit in bigger η regions. • We’ll try more sophisticated jet correction functions. • So far we have used Iterated Cone algorithm with R < 0.5. We will try other jet sizes and algorithms. • We will apply different calorimeter thresholds at ORCA level, try to eliminate the fake jets. F. Duru, APS April Meeting 2006, Dallas

  18. Applied Cuts • Daughter leptons have Pt > 20 GeV. • Daughter leptons have -2.4 < η < 2.4 • Cosine of the angle of τ’s > -0.9 • Cosine of the angle of daughter leptons > -0.9 • φ of the MET is between the φ of leptons (on the transverse plane) • 0 < X1 < 1, 0 < X2 < 1 • For Jet Corr; Jet Et > 10 GeV • For Muon Corr; -2.1 < Muon η < 2.1 F. Duru, APS April Meeting 2006, Dallas

  19. Cuts & Cross Sections So far we use the cuts related to the mass reconstruction techniques. No special attempt to get rid of backgrounds. zg80_100 Signal-140 zg100 All values are (fb) F. Duru, APS April Meeting 2006, Dallas

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