# Presentation: 794728

## Latest PRELIMINARY Results from Run 2 at DØ 

- Last updated – Jan. 11, 2002
**Boaz Klima**
-  (klima@fnal.gov)

## Z  e+e- Candidates

**2 EM objects, E****T**** > 20 GeV,**
**isolation and shower shape cuts**

- (uncalibrated energy scale)

- Leo Chan, Rochester

**e**

**e**

**L****~1.2pb****-1**

## W e Candidates

- W e Candidates

**EM cluster**
**with track**

**EM cluster**
**with track**

- Vishnu Zutshi, NIU
- Leo Chan, Rochester

**e**

**E****T**

**   ****m****T****(e,********)  ****L****~0.7pb****-1**
- (uncalibrated energy scale)

## Higgs Candidate (just kidding...)

**DØ W + 2 jet candidate**

**Electron**

**Jet 1**
**E****T****raw**** = 17 GeV***

**Jet 2**
**E****T****raw**** = 13 GeV***

**Jet 1**

**Jet 2**

**Electron**

*** Jet E****T**** corrections will be relatively large**

**E****T**

## Z  +- Candidate

- Two muons recoiling against a jet
- Dimuon invariant mass ~ 55 GeV (with large uncertainty)

- Onne Peters
- NIKHEF

## J/ +-

**Di-muons reconstructed in the forward region**

- Roger Moore and
- Adam Yurkewicz, MSU

## Muons in Jets

- Muon in jet (b candidate?)
- Hits in A,B,C layers

- Onne Peters, NIKHEF

- Back to back
- calorimeter jets

## bb (b   Candidate

**Two jets tagged with muons**
- Jet 1: ET ~ 18 GeV, pT ~ 7.4 GeV, pTrel ~ .30 GeV
- Jet 2: ET ~ 13 GeV, pT ~ 5.4 GeV, pTrel ~ .24 GeV
- ...and in case you wonder, M ~ 12 GeV and Mjj ~ 29 GeV

-      **3-D view**

-      **R-Z view**

**             ****X-Y view**

## Muons and Jets

- Onne Peters, NIKHEF

-    **Muon + Jet cross section**
-        (partially corrected)

-      **P****T****Rel**** Distribution**
-  (using Run 1 templates)

## Jetty Events

**Using R=0.7 Cone Algorithm with Run 1 corrections**

-     Alexander Kupco, Prague

**  ****2-jet event**
-  ETjet1~230GeV
-  ETjet2~190GeV

**  ****3-jet event**
-  ETjet1~310GeV
-  ETjet2~240GeV
-  ETjet3~110GeV
-  ET~8GeV

## Jet Distributions

- Alexander Kupco, Prague

**Using R=0.7 Cone Algorithm (energies partially corrected)**

-      **Single Jet P****T**

**Dijet Invariant Mass**

## Jet Energy Calibration

-    Ia Iashvili, Riverside

****

**jet**

**            **E' = ETxcosh(jet)

**Pre-shutdown Data**

**Post-shutdown Data**

**Calorimeter Response in CC+EC**

## J/ e+e-

**Di-electrons reconstructed in CFT and SMT**

- Sergey Burdin, LAL

- (uncalibrated EM energy scale)

## EM Energy Calibration

-   Marie-Claude Cousinou, Marseille

-  Data - before Correction

-     Monte Carlo
-  P3=0.959  corresponds to a mass of 87.5 GeV

-  Data - after Correction

## Ks +-

**Tracks reconstructed in the SMT detector**

**Black histogram – opposite-sign tracks**
**Red histogram – same-sign tracks**
**Dotted curve – fit to ****background**
**Full curve – fit to signal + background**

- Brad Abbott, Oklahoma

## Ks (+-) Lifetime

**Tracks reconstructed in the SMT detector**

- Ariel Schwartzman, Buenos Aires

************

## Hits in SMT and CFT

- Avto Kharchilava, Notre Dame

## Level 3 Calorimeter Trigger

**EM clusters, p****T**** > 10 GeV**
**Isolated, EM fraction > 0.9**
**|********| < 1.1 **

**Jets, p****T**** > 15 GeV**
**R = 0.7 cone**
**|********| < 1.1**

- fail (prescaled)

- pass

- fail (prescaled)

- pass

- Volker Buescher, Mainz