# Presentation: 202738

## Beauty production cross section measurements at Ecm = 1.96 TeV  

- Monica D’Onofrio
*University of Geneva*
- On behalf of the D0 & CDF collaboration
*Rencontres de Moriond – QCD, 12-19 March 2005*

## Outline

- The Tevatron, CDF and D0 experiments
- Theory of beauty production
- Run II results on beauty production:
- b-hadron cross section with J/
- High pT b-jet cross section
- Bottomonium production
- Summary & Conclusions

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## The Tevatron in RunII

**2002**

**2004**

**2003**

**2005**

- Peak luminosity in 2005 above 1032 cm-2 s-1
- CDF and D0 collected > 500 pb-1 on tape
- Analyses shown here use 40-300 pb-1

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## CDF and D0 in RunII

**CDF**

**D0**

- L2 trigger on displaced vertices
-       Excellent tracking resolution

- Excellent muon ID and acceptance
- Excellent tracking acceptance || < 2-3

-         _Both detectors_
- Silicon microvertex tracker
- solenoid
- High rate trigger/DAQ
- Calorimeters and muons

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## Beauty production 

- Leading Order

- Next to Leading Order

- Gluon splitting

- Flavor excitation

- Flavor creation

- Full calculations
- have been done
- up to NLO and
- beyond ....

*Many developments in the theoretical approach in the past years*

-  To understand and probe perturbative QCD
-  at Ecm=1.96 TeV (bb) ~ 50 b  few kHz event rate

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## Recent developments 

-  Beyond NLO: resummation of
-    log(pT/m) terms  FONLL
-  Substantial change in fragmentation
-    function extraction (from LEP data)
-  new PDF functions 

- Good data/theory agreement
-   also due to improved treatment
-   of experimental inputs
-   (use b-jets and b-hadrons
-   rather than b-quark)

***... ******the past***

***... ******the present *********

-      Release date of PDF

- bNLO(|y|<1) (b)

** ****<****1994**

** **now

- CDF(1995)

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## B hadron production using J/CDF 

-   Exclusive decays of B-Hadrons used to
-   measure the b production cross section
-  Find J/ inclusive cross section
-  Extract fraction of J/ from decay of
-    long-lived b-hadrons
-  Find b-hadrons cross section for
-    pT(B) down to 0 considering |y(J/)|<0.6

- Subm. to PRD, FERMILAB-PUB-04-440-E

_***...***__***Counting J/***__******__*** (***__***p***__***T***__***= 0 to 20 GeV/c)***_

- Lum=39.7 pb-1

-  _muon trigger_:=0.9860.010
-   for p T>1.5 GeV/c (|y|<0.6)
-  use detector simulation
-   to model the shape as
-   expected for J/signal
-  Mass resolution ~ 14-15 MeV

- 1.25<pT()<1.5 GeV/c      12.0<pT()<14.0 GeV/c

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## Tagging b ...

- J/ inclusive cross-section contribution from
- Direct production of J/
- Decays of b-hadrons: B  J/ X
- Decays from excited charmonium: (2S)J/ +-, ...

-  ****** ****J/******** ****from ****B ******** J/******** X********will be displaced****  **

- In general b-tagging procedures take
- advantage of the long life-time of
- B hadrons  c ~ 450 m
-   use Lxy, distance primary-secondary
-     vertex in r- space to define sec.vtx
-     quality
-  If considering jets, selection also on
-     Lxy direction with respect to jet axis

- Primary vertex

- Secondary vertex

- Lxy

- Jet axis

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## Extract b fraction

- Maximum likelihood fit
- to extract b fraction
- as function of pT(J/)

- B  J/ X
- shape from
- MC templates

- fb = 9.4%

- fb = 33.7%

- To reduce dependence on J/ pT bin:
-        x = Lxy(J/) • M(J/) / pT(J/)
-         = flight path of J/ in r- plane

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## B hadron production cross section

- Total inclusive single b-hadron (Hb) cross section

- considering *Br*(HbJ/X) = 1.160.10% and *Br*(J/) = 5.880.10%

- Very good agreement
- with theory prediction

- comparison with RunI data
- |y(Hb)| < 1, RunII multiplied
- by B+ fragmentation=0.4
-           (Ecm rescaled)

- RunI

- RunII

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## High PT b-jet cross section (CDF)

- High PT b-jet cross section (CDF)

- b-jets include most of quark fragmentation remnants
-                    ********* ******small dependence on fragmentation***

-  MidPoint algorithm for jet reconstruction
-  _kinematics:_ jet PT and rapidity (y)
-  jet Rcone = 0.7,   |yjet|<0.7
-  PT range 30-360 GeV/c  38-400 GeV/c
-    (Energy scale corrected for detector effects)

-  Use displaced tracks inside jet to
-    reconstruct the secondary vertex
-    (b-tagging)

- Lum ~ 300 pb-1

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## b-jet cross section: b-fraction tagged jets

- b-jet cross section: b-fraction tagged jets

- Extract fraction of b-tagged jets from data using shape of mass of secondary vertex as discriminating quantity
-  bin-by-bin as a function of jet pT

- MonteCarlo
-  templates

- b

- non-b

**98 < p****T****jet ****< 106 GeV/c**

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## b-jet cross section: results

- b-jet cross section as
-    function of jet pT
- (Range 38-400 GeV/c)

- No comparison with NLO yet
- Data/Pythia Tune A ~ 1.4
-            in agreement
-         with expectations

- Error bar: stat. error from data

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## High PT b-jet cross section (D0)

-  Measurement performed also in RunI for ET bjet of 30-100 GeV using muon jets
-  Preliminary results for -tagged jets cross section shown here

- extraction of the b-jet cross section expected soon

-  - Lum ~ 300 pb-1
-  - R(-jet) < 0.5
-  - |yjet|<0.5
-  -  50<pTjet<400 GeV/c

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## Upsilon production (D0)

- Quarkonium production is a window on
- boundary region between perturbative and
- non-perturbative QCD.

- Bottomonium states production
-  Prompt
-  b (1S)

- Here: production of (1S) state
- (1S)  **              **

-  Function of  pT
-  3 rapidity range
- - 0.<|y|<0.6
-      - 0.6<|y|<1.2
-      - 1.2<|y|<1.8

- Fit components
- (1S),(2S),(3S)

- |y|<0.6

- 1.2<|y|<1.8

- pT [4,6] GeV/c

- Lum=159 pb-1 (dimuon trigger,
-                     >99% if pT>5 GeV/c)

- Subm. to PRD, FERMILAB-PUB-05/020-E

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## Upsilon production: results

*********(1S) cross section extracted***

- d/dy*Br()=
-  73219(stat)73(syst)48(lum) pb
- [CDF RunI: 68015(stat)18(syst)26(lum)
- Factor 1.11 between 1.96 and 1.8 TeV Ecm]

-  Assume (1S) production unpolarized
-  small effect due to rapidity range
-  good agreement with theory prediction

-      MC pred.

- D0 RunII
- CDF Run I

- E.L. Berger, J. Qiu, Y. Wang
- Phys Rev D 71 034007(2005)

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio

## Summary and Conclusion

- Studies of beauty production are precision tests of NLO pQCD
- New RunII measurements reported:
- Central b-hadron cross section extracted from J/production  very good agreement with recent theoretical prediction.
- New b-jets analyses considerably extend range in pT of cross section: for CDF, NLO (and beyond) comparison expected soon, LO comparison as expected.
- Improved measurement for Bottomonium production in a wider rapidity range: in agreement with earlier results and with theoretical expectation.
- Many further improvements are expected...:
- Extraction of b-jet cross section from -tagged jets (D0)
- bb cross section and correlations studies

- Jet Energy and Resolution Workshop, 10/21/2004

- Monica D'Onofrio