# Presentation: 087939

## 5.3.2pre1 Validation Studies

**Picture of CDF at small radii**
**Material effects on SecVtx tag rates**
**Validation of beampipe/L00 location in 5.3.2pre1**
**Beamline bug in 5.3.2pre1**

**Chris Neu**
- High pT Btag Meeting
- 3 June 2004

**5.3.2pre1 Validation Studies**

## Picture of CDF Out to 2cm

**- Center of COT**

**- Center of Beampipe:**

- x = ~ -0.11cm
- y = ~  0.15cm

**- Beampipe:**

- r = 1.26cm
- Thickness = 0.05cm

**- Layer00: **

- Inner: r = 1.35 cm
-        0.85x7.84 cm2
-        0.0300 cm  thick
- Outer: r = 1.62 cm
-        1.48x7.84 cm2
-           0.0300 cm  thick

**- Beam spot:  **

- x = ~ -0.15 cm
- y = ~  0.4 cm

***Sources****: Roser, Culbertson, CDF 5781, Gen4 jet50 data*

- 0.5 cm

**r = 1.26cm**

## Picture of CDF Out to 2cm

*R**xy* is the  distance of vertex wrt SVX-II center.

- 0.5 cm

- It has been known for some time that there is an asymmetry in the light quark SecVtx tag *L**xy* distribution; **the positive light quark tag rate is not equivalent to the negative**.  But it is assumed that these rates are the same in mistag estimates.
- Part of the problem is **positive tags with secondary vertices located in the material** surrounding the collision point.
*x,y,z* of each fitted secondary vertex is available to us in TopNtuple wrt the COT center ().
- Calculate *R**xy**corr*  and *φ**corr *instead:

## Secondary Vertices in the Material

**0**

**1 **

**2 **

**3 **

**4**

**5**

**6**

**7**

**8**

**9**

**10**

**11**

- These Rxy dists are from  the “odd” numbered regions of CDF.
- Positive tags only, this is 5.3.1 jet50 data (gjt20d).
- One can see features like beampipe (1.2cm) and inner L0 (2.5cm).

**Reg 1**

**Reg 3**

**Reg 5**

**Reg 11**

**Reg 9**

**Reg 7**

## Secondary Vertices in the Material

- These Rxy dists are from  the “even” numbered regions of CDF.
- Again positive tags only, this is 5.3.1 jet50 data (gjt20d).
- Features still evident (including “thicker” material near beampipe from inner L00).

## Recent History of Treatment of Beampipe and L00

**Gen4:**
- Pipe/L00/SVX are concentric
- However they are taken to also be concentric with the COT (unlike reality)
**5.3.1:**
- SVX now properly offset wrt COT
- But pipe/L00 still set concentric with COT
**5.3.2pre1:**
- Pipe/L00/SVX now concentric
- Pipe/L00/SVX properly offset as in reality

## 5.3.1: Jet50 Data V. MC

- The difference in the 5.3.1 simulation wrt reality is seen above.
- These are comparisons of 5.3.1 **jet50** **data** and **jet50 MC**. Positive tags  only.
- Left is all even regions, middle is verts from even regions AWAY from the beam spot.
- Right plot is phi wrt SVX center for verts in even regions (sanity check...but alos check on beam position.)
- Beampipe and L00 appear to be at a larger radius in the away even regions than in data...as one would expect if

## 5.3.1: Jet50 Data V. MC

- Even and Odd regions - Positive tags

## Validation of 5.3.2pre1 pipe/L00 Treatment

**In 5.3.2pre1 the beampipe/L00 were moved** to their more appropriate positions.  Some jet50 MC was made by Reda for us to check the changes.
- Do we see the tag rate excess in the MC where we expect to find it?
- Here: each even region pos tags.

## Validation of 5.3.2pre1 pipe/L00 Treatment

- This jet50 MC was TopNtuple -ized in 5.3.1 using same tagging version as previous studies
- (the su03 tagger: secVtxVersion set “4.7.1”)
- NB: Refit of tracks adding L00 by mistake in my jobs?  Important?

## Validation of 5.3.2pre1 pipe/L00 Treatment

- Positive tags Su03 tagger

- Above is for even regions only.  Middle plot (even away regions) indicates that the simulation appears to not be modelling the beampipe/inner L00 well.
- Looks like there is an excess tag rate at around Rxy~1.5cm instead of 1.2 < Rxy < 1.5cm.
- Summary for even and odd regions  on next page.

## Validation of 5.3.2pre1 pipe/L00 Treatment

- Positive tags Su03 tagger

## Validation of 5.3.2pre1 pipe/L00 Treatment

- 5.3.1 MC v 5.3.2pre1 MC

**How does the 5.3.2pre1 jet50 MC compare to the 5.3.1 jet50 MC?**
- Could the beampipe have been moved in the wrong direction?
- Even and odd summaries on the next page.

## Validation of 5.3.2pre1 pipe/L00 Treatment

- 5.3.1 MC v 5.3.2pre1 MC

## Validation of 5.3.2pre1 pipe/L00 Treatment

- Positive tags LF only in MC

- In jet50, some of the positive tags come from real b’s and some come from light quarks.
- In the MC we have the luxury of knowing which is which, thankfully.
- Do we see the effect more clearly if we only consider tagged jets matched to non-b’s?
- This is 5.3.2pre1 jet50 MC, even region summary, non-b-matched positively tagged jets:

- Not any better excluding real HF...

## Validation of 5.3.2pre1 pipe/L00 Treatment

- Positive tags LF only in MC

## b-Content of Gen5 Jet50 Samples?

|  | Gen4 | 5.3.1 | 5.3.2pre1 |
| --- | --- | --- | --- |
| # jets | 2118203 | 2481153 | 1420336 |
| # pos tags | 16606 | 32144 | 12212 |
| frac pos tags | 0.008 | 0.013 | 0.009 |
| frac b-matched | 0.583 | 0.566 | 0.477 |
| frac non-b-matched | 0.417 | 0.434 | 0.522 |

- This was a simple counting exercise to see if the HF content in the 5.3.2pre1
- Jet50 sample is consistent with previous incarnations.
- There appears to be higher light-quark content in the positively tagged sample.  Can these numbers be independently checked?
- Did anything really change?

- All counting done using Su03 SecVtx tagger

## Conclusions

- Took a look at the beampipe/L00 positioning in 5.3.2pre1 simulation
- From using SecVtx tag excess rates in data for comparison, it appears that the simulation is not reproducing the rate effect where one expects it to (for instance at the beampipe)
- Comparison between 5.3.1 jet50 MC and 5.3.2pre1 jet50 MC make it look as if the beampipe was moved in the wrong direction (?)
- This effect is expected to be much smaller when using the Su04 tight SecVtx tagger