# Presentation: 660105

## Outline

**Trigger**
**L1, L2, L3**
**Offline Reconstruction**
**TauReco**
**H-Matrix**
**Neural Network**
**Analysis Tools and Results**
**tau_analyze package**
**Tracking studies**
**Efficiency studies**

**Tau ID**

**Leo Chan**
**University of Rochester**
**(for the Tau ID Group)**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Tau ID Group

**Andrew Askew**
**Gustaaf Brooijmans**
**Dhiman Chakraborty **
**Leo Chan**
**Silke Duensing**
**Yuri Gershtein**
**Qizhong Li**
**Paul Padley**
**Serban Protopopescu**
**Naresh Sen**
**Bryan Smith**
**Andre Turcot**
**Marek Zielinski**
**Vishnu Zutshi**

- Tau ID, NIU Workshop

- June 19-23, 2000

## The Tau Lepton

******-decay branching ratios:**
**Leptonic: ~ 35%**
**Hadronic: 1-prong ~ 50%**
-                            **3-prong ~ 15%          65%**
**                           ******** ****5-prong ~ 0.1%**
**Main goal: identifying hadronic taus**
**Typical response in our detector:**
**narrow calorimeter cluster**
**low track multiplicity, highly collimated tracks**
**Useful variables:**
**RMS (width of jet) = ******** ********width****2****+********width****2**
** ********width**** = ********(******** ****i****)****2 *****E******T******i***** / *****E******T***** **
** ********width**** = ********(******** ****i****)****2**** *****E******T******i***** / *****E******T***
**Profile = *****E******T***** in hottest two towers/*****E******T***

- Tau ID, NIU Workshop

- June 19-23, 2000

## Event Display

**Z ******** (MC)**
**(1-prong and 3-prong)**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Triggers

_**L1**_** **
**Tau related triggers in Trigger List 2.5**
**TAU_JETC_TTK, TAU_JETC_QT (****Tau Jet****)**
**TAU_MET (****Tau Missing Et****)**
**TAU_JET (****Tau + Jet****)**
**ELE_TAU_A (****Tau + Electron****)**
**MU_TAU (****Tau + Muon****)**
**GAM_TAU (****Tau + EM particle****)**
**Other di-tau triggers**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Triggers

_**L2**_
**Some of the L2 triggers for various tau physics channels have been looked at. Further studies required and ongoing**
_**L3**_
**L3TauTool exists for L3 hadronic tau trigger:**
**Select calorimeter clusters from calorimeter cluster tools, tracks from tracking tools**
**Match tracks to clusters**
**Studies:**
**Simple Cone(SC) vs Nearest Neighbor(NN)**
**Varying cone size (for SC)**
**Use of stiff track finder**
**effects of multiple min. bias events**

- Tau ID, NIU Workshop

- June 19-23, 2000

## With width < 0.08 and profile > 0.45 get rejection factor of 10 and 85% efficiency, and stay away from sharp turn on

- Tau ID, NIU Workshop

- June 19-23, 2000

## Increasing luminosity...

**Increasing tower *****E******T***** threshold...**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Tau Reconstruction

**Preselections:**
**starts from 0.7 cone calorimeter clusters (*****E******T***** > 8 GeV)**
**RMS < 0.25 (tower *****E******T***** threshold = 0.1 GeV)**
**EM fraction < 0.95**
**1 ******** no. of matched tracks ******** 5 (within 0.2x0.2 in ********-******** space, track *****P******T***** threshold = 0.05 GeV/c)**
**Output as Tau objects, which also carry *********** *****2**** from signal and background H-matrices, fisher variable, neural network output, charge, vertex, matched tracks and matched CPS cluster information**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Tau Candidates

- Tau ID, NIU Workshop

- June 19-23, 2000

## Tracking Studies

**Z******** (average 1.1 min. bias)**

**( ****98.1%**** )**

**( ****79%**** )**

- Tau ID, NIU Workshop

- June 19-23, 2000

- Tau ID, NIU Workshop

- June 19-23, 2000

- Tau ID, NIU Workshop

- June 19-23, 2000

## Tau Reconstruction Efficiencies

_**Definition**_
_**denominator**_**:**
**number of generated taus that have:**
**decayed hadronically**
***visible *****(************* E******T *****subtracted)***** E******T***** ****> 8 GeV**
**at least one charged pion with *****p******T***** ****> 0.5GeV/c**
**at least one associated (dR < 0.7) calorimeter cluster (here dR uses the ************* *****subtracted direction of the tau)**
_**numerator**_**:**
**number of generated taus in denominator**** ****that **
**have an associated tau candidate after a specific **
**set of cuts**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Tau Reconstruction Efficiencies

**-1 < ******** < 1**

**Z******** (average 1.1 min. bias)**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Effects of Min. Bias Events

**RMS (Z********)**

**tower threshold = 0.1 GeV**

**tower threshold = 0.3 GeV**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Tau H-Matrix

**14 x 14 H-Matrix:**
**EM 1, 2, 3, 4, FH1 *****E******T***** fraction**
***E******T***** fraction in 5x5, 3x3 tower, profile**
**Log (total *****E******T*****) –1 ,***  ***z-vertex / ********z**
***p/E***** : *****p***** of seed track/*****E***** of cluster**
**Track RMS (0.4 cone around cluster)**
**# of tracks (0.4 cone around cluster)**
**(ntrk03 – ntrk01)/ntrk03 around seed**
**  ****track (isolation)**
**Training Samples:**
**signal:**** Z******** with avg. 1.1 min. bias**
**background:**** QCD (*****P******T***** > 20 GeV/c,**
**  ****avg. 1.1 min. bias)**
**Fisher**** ****=** (**2****bkgd**** - ****2****signal**)** / ****2**

- Tau ID, NIU Workshop

- June 19-23, 2000

## H-Matrix Elements

- Tau ID, NIU Workshop

- June 19-23, 2000

## H-Matrix Elements

- Tau ID, NIU Workshop

- June 19-23, 2000

## H-Matrix Efficiencies

- Tau ID, NIU Workshop

- June 19-23, 2000

## Neural Network

**MLPfit neural network**
**9 inputs used:**
**EM 3, 4, FH *****E******T***** fraction **
**RMS of cluster**
**Profile**
**Log(total *****E******T*****) -1 **
**# of tracks (0.4 cone around cluster)**
**Track Isolation fraction**
**Track RMS**
**1 hidden layer with 20 nodes, 1 output**
**training samples: same as the ones used for H-Matrix**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Neural Network Efficiencies

- Tau ID, NIU Workshop

- June 19-23, 2000

## Analysis Package

**tau_analyze package**
**creates ntuple of various tau related variables (from tau objects created by taureco)**
**can be used alone for tau study or used as part of reco_analyze for event root-tuples**
**also contains a MC utility class which provides utilities for easy access of tau related MC information**

- Tau ID, NIU Workshop

- June 19-23, 2000

## Current and Future Plans

**Further study of  H-Matrix (reduce no. of variables, look at preshower quantities, train H-matrices for different ********-bins, and perhaps different decay channels)**
**Further development of Neural Network (Level 3 and offline)**
**PDE method in progress**
**development of tau quality and likelihood fit**
**Further study of effects of minbias and calorimeter effects**
**Areas where additional manpower are especially needed:**
**Study of low *****P******T***** taus**
**Study of forward taus**

- Tau ID, NIU Workshop

- June 19-23, 2000