# Presentation: 273288

## b, c production

- Tara Shears, University of Liverpool

## Motivation

- Good testbed for quantitative QCD tests
-  +c events could be used to probe charm quark content of proton
- bb, cc events: imperfect NLO description
-  + heavy flavour sensitive to new physics (eg. chargino neutralino production)

## Production

**LO**

**NLO**

- Coupling  charge2  (c) ~ 4.(b)
- b quark ~ 60% c quark content of p  (**PRD 012003**)

- Dominates for c

- Diagrams equal for b

## Method / data

**Method:**
- Apply standard run 2  selection
- Estimate fakes from CPR info
- Use tagging algorithm for b/c id
- Run 1 used lepton pt
- We use sec. vtx  tag (SECVTX – will update with better)
- Divide data into Et bins, tag, take b,c frac. from MC => 

**Datasets:**
**CPH108** (25 Iso trigger)
- Good online run, clc, smx, cal, trigger, svx
- Good offline cal,cot
- L = 66.05 3.76 pb-1
**MC:** Pythia  + jet (LO)
- Will use madgraph for NLO

## Photon + jet sel. eff.

| Et bin | 25-28 | 28-32 | 32-38 | 38-46 | 46-60 |
| --- | --- | --- | --- | --- | --- |
| Central  | 118703 | 95499 | 75499 | 45487 | 28659 |
| +>=1 jet | 41514 | 39807 | 37410 | 25873 | 18327 |
| +fiducial | 38230 | 36675 | 34153 | 23789 | 16820 |
| +had/Em | 35742 | 34338 | 32085 | 22448 | 15910 |
| +chi2 | 34799 | 33340 | 30883 | 21366 | 14956 |
| +isolation | 32797 | 31559 | 29401 | 20445 | 14354 |
| +#tracks | 29242 | 28236 | 26680 | 18704 | 13287 |
| +Spt | 29197 | 28198 | 26640 | 18684 | 13275 |
| +2nd CES clus | 28748 | 27746 | 26192 | 18366 | 13077 |
| Eff ( jet) | 24.22±0.12 | 29.05±0.15 | 34.69±0.17 | 40.38±0.23 | 46.32±0.29 |

**Require at least 1 jet > 15 GeV, >=2 tracks, for tagging**

## Tagging eff. & composition

| Et bin | 25-28 | 28-32 | 32-38 | 38-46 | 46-60 |
| --- | --- | --- | --- | --- | --- |
| E(b tag) | 24.9±1.7 | 24.6±1.6 | 26.9±1.7 | 22.1±1.6 | 17.1±1.5 |
| E(c tag) | 4.3±0.3 | 4.8±0.3 | 5.1±0.3 | 3.7±0.3 | 2.7±0.3 |
| E(uds) | 0.13±0.02 | 0.13±0.02 | 0.18±0.02 | 0.18±0.02 | 0.18±0.03 |
| b. frac. | 0.42±0.02 | 0.41±0.02 | 0.41±0.02 | 0.46±0.03 | 0.52±0.04 |
| c. frac. | 0.50±0.03 | 0.52±0.02 | 0.49±0.02 | 0.42±0.03 | 0.34±0.03 |

**From Pythia MC..**

## Data 

| Et bin | 25-28 | 28-32 | 32-38 | 38-46 | 46-60 |
| --- | --- | --- | --- | --- | --- |
| No. +>=1 jet | 26415 | 28399 | 22736 | 13820 | 8680 |
| No. tags | 302 | 354 | 321 | 209 | 178 |
| Est. no.  tags | 147.8±50.4 | 168.8±50.4 | 204.0±52.4 | 216.1±48.0 | 113.9±35.6 |

******(********q) = N(********q)/(eff(********jet).eff(tag).eff(trg).********L)**

- Not known yet

- = no.tags * q fraction

## Systematic errors

**Photon + jet selection**: ±1.7% from  id (test on Z, loose cuts)
**Jet e scale**: not yet done
**Fake rate est**.: use standard procedure
**B/c fractions**: take arbitrary ±10%
**SECVTX systematics**: not yet done (small for top)
**Trigger systematics**: not yet done
**Luminosity**: use quoted ±5.8%

## Results 1. b

| Et bin | 25-28 | 28-32 | 32-38 | 38-46 | 46-60 |
| --- | --- | --- | --- | --- | --- |
| CPR | ± 5.3 | ± 4.5 | ± 3.6 | ± 3.8 | ± 3.5 |
| E(jet) | ± 0.1 | ± 0.1 | ± 0.1 | ± 0.1 | ± 0.1 |
| E(tag) | ± 1.1 | ± 1.0 | ± 0.9 | ± 1.2 | ± 1.0 |
| Total stat. error | ± 5.4 | ± 4.6 | ± 3.7 | ± 4.0 | ± 3.6 |
| CPR | ± 5.3 | ± 4.9 | ± 3.7 | ± 4.1 | ± 4.0 |
| E(jet) | ± 1.1 | ± 0.9 | ± 0.7 | ± 0.7 | ± 0.4 |
| lumi | ± 0.9 | ± 0.9 | ± 0.8 | ± 1.0 | ± 0.7 |
| Sys. err | ± 5.5 | ± 5.1 | ± 3.8 | ± 4.3 | ± 4.1 |
| (b) | 15.6 | 14.7 | 13.6 | 16.9 | 11.3 |
| Pythia | 21.6 | 17.6 | 13.4 | 7.7 | 5.2 |

**Nb. E(trg) = 1 here!**

## Results 2. c

| Et bin | 25-28 | 28-32 | 32-38 | 38-46 | 46-60 |
| --- | --- | --- | --- | --- | --- |
| CPR | ± 30.8 | ± 28.9 | ± 22.3 | ± 20.5 | ± 14.6 |
| E(jet) | ± 0.5 | ± 0.5 | ± 0.4 | ± 0.5 | ± 0.3 |
| E(tag) | ± 6.3 | ± 6.0 | ± 5.0 | ± 7.5 | ± 5.2 |
| Total stat. Err. | ± 31.4 | ± 29.5 | ± 22.9 | ± 21.8 | ± 15.5 |
| CPR | ± 30.3 | ± 31.7 | ± 23.5 | ± 22.4 | ± 16.6 |
| E(jet) | ± 5.2 | ± 5.6 | ± 4.2 | ± 3.9 | ± 1.7 |
| lumi | ± 5.2 | ± 5.5 | ± 5.0 | ± 5.3 | ± 2.7 |
| Sys. error | ± 31.2 | ± 32.7 | ± 24.4 | ± 23.3 | ± 16.9 |
| (c) | 107.4 | 95.3 | 85.6 | 92.0 | 46.8 |
| Pythia | 123.9 | 96.6 | 72.4 | 41.5 | 22.6 |

**Nb. E(trg) = 1 here!**

## Points: data (stat. Error and sysstat shown by notches)

**Points: data (stat. Error and sys********stat shown by notches)**
**Histogram: Pythia ********+jet (LO)**

## Points: data (stat. Error and sysstat shown by notches)

**Points: data (stat. Error and sys********stat shown by notches)**
**Histogram: Pythia ********+jet (LO)**

## Work plan

**Immediately:**
- Trigger efficiency (+sys.)
- SECVTX tagging sys., jet selection sys.
- Other photon backgrounds (eg. e->) (small)
- Add more data
**Next:**
- Tighten photon cuts to reduce fake, use CES
- Derive b/c fraction from data
- Use improved b/c tag
- Compare to NLO (Madgraph?)
**Longer term:**
- Extend to lower photon Et