# Presentation: 126081

##  b Production

** ****at the Tevatron**

**XXXV Rencontres de Moriond**
***QCD and Hadronic Interactions***
***Les Arcs, France (March 18-25, 2000)***

- Arthur Maciel
-  **Northern Illinois University**
- for the DØ and CDF collaborations

*Two New Results*

**Cross Section for**
** ****b-Jet Production**

**Cross Section for**
** ****B****+**** Production**

- CDF

- DØ

##  b Production Status at pp Colliders  

-  **UA1 (540 GeV)**
** ****DØ , CDF (1.8 TeV)**
** ****UA1 , CDF , D****Ø (630 GeV)**

**All experiments are in agreement with one another, and find significant data excess over theory**** **

**Recent report (G. Ridolfi at Fermilab b-Wshop, 10 ****/**** 99)**
-  resummation of log(PT/MQ) - no significant improvement
-  fragmentation treatment revisited  -  enhancement ~ 10%
-  intrinsic k**T****2** of incoming partons -  no significant changes,
-           and worsens (flattens) angular correlations Δφ**bb**

- B Meson Production Measurements

** ****b Production Status at pp Colliders  **

-  **CDF (1.8 TeV)   -  same pattern**

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

- b Production Theory

- note: photoproduction also same pattern
- Hera (e**+ **p)  γ p  b b X   (H1 & ZEUS)

***A. Maciel***
***(NIU)***

## 1.8TeV

- .63TeV

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

**b Quark Integrated Cross Section**
**( Data / Theory )**

***A. Maciel***
***(NIU)***

## Cross Section for  B+ Meson Production

***CDF****** Collaboration***
***( Preliminary )***

**XXXV Rencontres de Moriond**
***QCD and Hadronic Interactions***
***Les Arcs, France (March 18-25, 2000)***

-   an  updated  measurement  of

***A. Maciel***
***(NIU)***

- B +  J/ψ K+   ;    J/ψ  μ+μ–

## CDF:      B +  J/ψ K+       J/ψ  μ+μ–

**( both muons in SVX )**

- PT(K) > 1.25 GeV/c        PT(B) > 6.0 GeV/c

***A. Maciel***
***(NIU)***

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

## CDF:      B +  J/ψ K+ 

**P****T****(B****+****) > 6 GeV/c**
**|y (B****+****) | < 1**

**Integrated  ****σ****(B+)**** = 3.51 ± 0.42(stat) ± 0.53(sys) μb**
**Theory (central values μ , m****b**** , ε****P****)  is  1.54 μb**

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## Cross Section for b-Jet Production

***D******Ø Collaboration***
***( Preliminary )***

**XXXV Rencontres de Moriond**
***QCD and Hadronic Interactions***
***Les Arcs, France (March 18-25, 2000)***

-  introduction
-  inclusive spectrum
-  tagging acceptance

-  data selection
-  b component
-   results

***A. Maciel***
***(NIU)***

## Introduction

***Nucl.Phys. ***_***B483***_***,  321 (1997)***

-  **QCD production of jets containing heavy quarks**
** ****LO  bJets and  bQuarks  have identical spectra**
-  **NLO  amplitudes  have  3-parton  final  states**
-  **Loosely;  ‘MNR’(1992) + Snowmass Jet-Cone**
**      ****at partonic level;   d****σ =  dσ****(open)****  + dΔ (clustering)**

** ****Jets are more QCD-friendly** (than quarks)
-  Integrate away fragmentation details
-     (Jet Et is regardless of b-mom. fraction)
-  Jets  are  collinear-safe  objects
-   (  theory avoids resummation of large
-     logarithms from hard collinear gluons )

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

- (Theory)

***A. Maciel***
***(NIU)***

## Introduction

- (Experiment)

**  ****b-Jets are jets carrying  b-flavor**
**  ****A new D****Ø look into b-production**
-        complementary to open b-quark studies
-   **Jets are directly observable**
-  **Less model dependence in connecting**
**            ****observation with theory**
** ****Access to differential cross sections**
**  ****Jet counting  (muon tagged jets);**
-  **theory counts jets with b ( b-integrated)**
** ****D****Ø counts tagging muons (in jets)**
- 	         μ+ + μ–             b + b
- 	          2 B.R.            2

- =

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

- Δσ**bJet**  A**TAG**(ET)       FB(ET)         ΔN**μJet**
- ΔET      2(B.R.)    L ε(PT**μ**,ET**Jet**)  ΔET

- =

***A. Maciel***
***(NIU)***

**| ****η**** | < 1**

## Data Sample

- Run-1B (5.2±0.3) pb**–1  **muon **& **jet trigger
** **muon PT > 4GeV  Jet Tower > 3GeV

| Jets  | Muons |
| --- | --- |
| ET > 25 GeV | PT > 6 GeV |
| | η | < 0.6 | | η | < 0.8 |
| ΔR = 0.7 | ΔR < 0.7 |

*Offline Selection*

|  | Jet | Muon |
| --- | --- | --- |
| Trigger | ET (85 - 100%) | PT (50 - 60%)* |
| Reco | 100% | PT (90 - 95%) |
| Offline | (97±1)% | (83±3)% |

**(*) Includes geom. acceptance**

*Detection Efficiencies*

**30K events**

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## Inclusive Spectrum

**Muon-Tagged Jets**

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## b Component

**P****T****Rel**

**P****T****μ**

**Jet**

- P**T****Rel** template
- (b and non-b)
-  fits to data at
- four E**T **ranges

***A. Maciel***
***(NIU)***

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

## x E-3

**χ****2**[2]** **=** 0.96**

| 2.65 | 1.35 | 0.48 | -0.01 |
| --- | --- | --- | --- |
|  | 1.45 | 1.52 | 1.56 |
|  |  | 2.22 | 2.67 |
|  |  |  | 3.39 |

***Covariance Matrix***

**x** E-3

***b Component (jet E******T******)***

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

***Relative Uncertainty***

## b-Jets Spectrum

**b-Tagged Jets**

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## Tagging Acceptance

_*Corrections due to*__;_
-  **Muon  ****η-range , p****T****-threshold**
** ****Muon-Jet association; ****ΔR<0.7**
** ****Unseen Jet-E****T****;  ( μ + ν )**
** ****B. R.   b ******** μ X**
** ****Jet η-range **

- A(ET)–1 =

**Correct observed spectrum**
**with Monte Carlo ratio;**
- MC(bμ) parton jets, |η|<1
- MC(bμ)  analysis  image

***A. Maciel***
***(NIU)***

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

## b-Jets Cross Section

**(*)** **2 ****μ****O**** ...**** ****μ****O****/2  ,  ****μ****O**** = (E****T****2**** + M****b****2****)****1/2**

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## Systematic Uncertainties Summary

***( relative , percentual , mostly correlated )***

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## (Data-Theory) / Theory

***Systematic errors and their correlations confer ***
***~80% probability to theory upper edge***

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## b-Quark Integrated Cross Section

**b-Quark Integrated Cross Section**

**(*)** **2 ****μ****O**** ...**** ****μ****O****/2  ,  ****μ****O**** = (P****b****T****2**** + M****b****2****)****1/2**

**(*)**

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

***A. Maciel***
***(NIU)***

## Conclusion

- data-theory convergence at
- higher transverse momenta

***A. Maciel***
***(NIU)***

***XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000***

- Different experiments, and also
- different measurements within
- each experiment, all confirm a
- pattern for b production where
- data shows normalization excess
-  over theory  (NLO - pQCD)

-  Thanks !

- Tevatron Run-II (March 2001)
- should revisit /confirm this trend