F. Duru, APS April Meeting 2006, Dallas

MSSM Higgs Tau Tau Tau Tau Leptonic LeptonicMissing Et and Mass Reconstruction

F. Duru, U. Akgun, S. Kunori, Y. OnelThe University of Iowa

Fermilab

F. Duru, APS April Meeting 2006, Dallas

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

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

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 zg1002tau2l

• All digitized events are processed with ORCA8_7_4 ExRoot.

F. Duru, APS April Meeting 2006, Dallas

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

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

B Quark Gen Pt and η Values

Low Pt, Central b-jets

F. Duru, APS April Meeting 2006, Dallas

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

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

Reconstructed Higgs Mass “Type 1” vs “Type 2”

MET GENYellow – “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

MET from Calorimeter Hits

MET CH (Gamma Jet Correction)

For Type1 corr, check CMS Note 2001/40

F. Duru, APS April Meeting 2006, Dallas

MET from Calorimeter Hits

MET CH (V1 Correction)

MET CH (MC Correction)

F. Duru, APS April Meeting 2006, Dallas

Reconstructed Mass with MET from CaloHits (with Gamma Jet Correction)

“Type 1”

“Type 2”

F. Duru, APS April Meeting 2006, Dallas

Reconstructed Higgs mass

Yellow – Before, Blue – WW Jet Corr., Green – τ+τ- Jet Corr

“Type 2”“Type 1”

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.

F. Duru, APS April Meeting 2006, Dallas

Total mass

Yellow – Zγ* 80-100GeV, solid line bbH/A (140 GeV)τ+τ-

F. Duru, APS April Meeting 2006, Dallas

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

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 qqHWW jet correction values for η regions

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

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

Cuts & Cross Sections

5085 68066 1515248

Leptons' Pt>20 2065.79651 6854.877 74393

Taus' Eta < 2.4 4926.01747 30718.818 638347

Leptons' Eta < 2.4 4932.20103 30760.0022 639821

cos angle leplep > -0.9 4490.89027 63158.2192 1371979

cos angle tautau > -0.9 4490.07664 63087.2909 1369450

sum of first 5 cuts 1780.86467 3507.51884 37400

+ MET is between 2 Taus on Trans. Plane 915.980191 1704.56721 18695

+ Type 2 Mass Term 0<X<1 483.456591 933.50795 9781

+ Type 1 Mass Term MET_Tau>0 915.980191 1704.56721 18643

Signal-140 zg100 zg80_100

So far we use the cuts related to the mass reconstruction techniques.No special attempt to get rid of backgrounds.

All values are (fb)