# Presentation: 193748

## MET35 trigger efficiency

## MET35 trigger

- The trigger used in ZHMet + b-jets analysis is MET35
- The trigger path is:
- L1_MET25
- L2_CJET10_JET10 (first ~450 pb-1 it was L2_TWO_JET10)
- L3_MET35
- The goals of study are:
- find the best way to parameterize the efficiency,
- identify the sources of inefficiencies trigger has (if any) and find ways to cure them,
- answer the question if we can lower the offline met cut used in analysis

- 02/15/2007

## Strategy 

- Look at two samples:
- HighPt Muon, which has high *real* MET
- Jet 50 sample, in which the MET is due to *jet mis-measurement*.
- Since the variables in the trigger are Jet Et’s and Met, we need to parameterize eff as a function of some combination of these.
- The trigger efficiency in the past was parameterized as a function of offline corrected MET.
- Check if we need a different efficiency for the new L2 trigger path (L2_TWO_JET10L2_CJET10_JET10)
- Check if that parameterization still applies, or we need a more sophisticated one.

- 02/15/2007

## Strategy

- The requirement of 1st jet Et>**35 **GeV and 2nd jet Et>**25** GeV makes 2-jet requirement fully efficient
- We split the sample into 4 cases:
- 1st jet: **Central**,** **2nd jet: **Central               ****(CC)**
- 1st jet: **Central**, 2nd jet: **NonCentral****        (CN)**
- 1st jet: **NonCentral**, 2nd jet: **Central****        (NC)**
- 1st jet: **NonCentral**, 2nd jet: **NonCentral ****(NN)**
- The analysis requires at least one central jet:
- find a set of cuts that makes 2-cluster requirement fully efficient in the 3 regions: CC, CN, NC
- does it matter which jet is central?

- 2-cluster efficiency in CJET10_JET10 trigger as a function of offline Leading and Second Jets: (top) CC, (middle) CN, (bottom) NC regions.

**35 GeV**

**25GeV**

- 02/15/2007

## Does it matter which jet is central?

- CJET10_JET10

|   | Higgs MC |  |   |   |
| --- | --- | --- | --- | --- |
|   | CC | CN | NC | NN |
| Acceptance*Efficiency | 0.641 | 0.2175 | 0.137 | 0.004 |

-   we lose only **0.4**% of the signal by discarding NN region

|   |               Muon Sample,  MET35_&_CJET_&_JET |  |  |  |
| --- | --- | --- | --- | --- |
|   | CC | CN | NC | NN |
| Efficiency | 0.915104 | 0.932135 | 0.90168 | 0.664865 |
| Acceptance*Efficiency | 0.605876 | 0.048772 | 0.252451 | 0.003733 |

|   |                Muon Sample, MET35_&_TWO_JETS |  |  |  |
| --- | --- | --- | --- | --- |
|   | CC | CN | NC | NN |
| Efficiency | 0.915013 | 0.936195 | 0.902005 | 0.908108 |
| Acceptance*Efficiency | 0.605815 | 0.048985 | 0.252542 | 0.005099 |

-   Efficiencies and distribution of events after centrality selection in Muon sample
-   TWO_JET

-   If there is a central jet, both triggers have **the same efficiency**
-   distribution of **Higgs** events

- 02/15/2007

## Identified sources of inefficiencies

- Efficiency losses come from Jet merging and trigger tower saturation in L1_MET calculation.
- Requiring the two leading jets to be at least 1.0 in R away from each other solves jet merging
- By rejecting events which have Leading tower Et>127, and collecting them from jet100 sample we can recover events lost due to tower saturation

- Efficiency plotted as a function of offline MET versus 2nd jet ET: (top) before applying jet separation and cut on  tower Et (bottom) after cutting on R(j1,j2)>1.0 and requiring leading tower below 127 GeV

- 02/15/2007

## Trigger efficiency as a function of offline MET

- Current trigger study uses the following offline cuts:
- MET>**50** GeV
- 1st jet Et>**35** GeV, 2nd jet Et>**25** GeV
- One central jet (|Eta|<1.1)
**DeltaR** between the two leading jets >**1.0**
- Efficiency is parameterized as a function of offline corrected MET
- All events pass goodrunlist with good Calorimeter

- 02/15/2007

## Met 35 trigger efficiency from muon sample

- Efficiency curves obtained from HighPt Muon sample
- The leftmost plot is the efficiency of **L1_MET25 **trigger
- The middle plot is the efficiency of  **L1_MET25 **trigger when **DPhi(MET,J2) > 0.4**
- shows efficiency in the signal region
- The rightmost plot is the efficiency of **L3_MET35** trigger

- 02/15/2007

## Met 35 trigger efficiency from muon sample

- Our cross-check of the turn-on curves (in the same order)

- 02/15/2007

## Systematic uncertainties

- Plot variables used in the analysis, before (*Incl*) and after passing trigger emulation (*MET35*)
- Scale events that pass offline cuts by *SF=(effL1**×effL3**)*
- Plot relative difference:
- To make comparison statistically independent we split the sample into two pieces:
- trigger selection applied on **odd** events
**even** events are scaled (down) by trigger efficiency

- 02/15/2007

## Convention used in the following slides

-              _If the background is __**blue**_
- The **Black** line is after passing trigger,
**Red** line is events passing offline cuts and being scaled by *SF=(effL1*effL3)*

-             _If the background is __**yellow**_
- To see how systematic uncertainty changes if the tower saturation effect is treated, for **Black **line we require:
- either L1_MET25 and **NO **tower above 127 GeV
**OR **the leading tower is above 127 GeV
- this would emulate taking events which are lost due to tower saturation from Jet100 sample

- 02/15/2007

## Muon sample, MET>50 GeV, odd-even split, 

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**Dijet Inv Mass**

**J1ET**

- 02/15/2007

## Muon sample, MET>50 GeV, odd-even split,

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**J2ET**

**J2Met_Phi**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Muon sample, MET>50 GeV, not split to odd-even

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**Dijet Inv Mass**

**J1ET**

- 02/15/2007

## Muon sample, MET>50 GeV, not split to odd-even

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**J2ET**

**J2Met_Phi**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Muon sample, MET>50 GeV, not split to odd-even, DPhi (J2,MET)>0.4 

-                                  Tower Saturation **NOT** eliminated

**Dijet Inv Mass**

**J1ET**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Jet50 sample, MET>50 GeV, odd-even split

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**Dijet Inv Mass**

**J1ET**

- 02/15/2007

## Jet50 sample, MET>50 GeV, odd-even split

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**J2ET**

**J2Met_Phi**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Jet50 sample, MET>50 GeV, not split to odd-even

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**Dijet Inv Mass**

**J1ET**

- 02/15/2007

## Jet50 sample, MET>50 GeV, not split to odd-even

- Tower Saturation **NOT** eliminated

- Tower Saturation eliminated

**J2ET**

**J2Met_Phi**

**J2ET**

**J2Met_Phi**

- 02/15/2007

##                   MET>70

- 02/15/2007

## Muon sample, MET>70 GeV, not split to odd-even

-                                    Tower Saturation **NOT** eliminated

**Dijet Inv Mass**

**J1ET**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Jet50 sample, MET>70 GeV, not split to odd-even

-                                      Tower Saturation **NOT** eliminated

**Dijet Inv Mass**

**J1ET**

**J2ET**

**J2Met_Phi**

- 02/15/2007

##                   MET>40

- 02/15/2007

## Muon sample, MET>40 GeV, odd-even split

*                                      *Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Muon sample, MET>40 GeV, not split to odd-even

*                                          *Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Jet50 sample, MET>40 GeV, odd-even split

*                                     *Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Jet50 sample, MET>40 GeV, not split to odd-even

*                                        *Tower Saturation eliminated

**Dijet Inv Mass**

**J1ET**

**J2ET**

**J2Met_Phi**

- 02/15/2007

## Zero track events

- The hardwired cut kills tracking during event reconstruction, if the number of hits is too big
- Events that potentially have good tracks are not correctly reconstructed.
- 0d and 0i data was ntuplized by us, so Viktor was able to skim through log files to find events where tracking was dropped

- The fraction of potentially interesting events is so tiny that the problem can be ignored

- 02/15/2007

## Conclusions

- Efficiency losses have been _identified_ and _understood_
- There is still some inefficiency in trigger due to incompatibility of L1_MET and offline MET
- events that have _high_ MET offline have _very low_ MET at trigger level...
- If we cut at MET>50 GeV, trigger efficiency can be parameterized as a function of offline MET only
- Lowering MET cut to 40 GeV would require more work:
- more sophisticated parameterization:
- 2-dimensional, e.g. *Eff(MET, J1Et)*
- split into regions of 2nd jet Et, obtain efficiency in each region from  fit to MET turn-on curve (Ming)
- obtain efficiency in each centrality region (CC,CN,NC)
- Maybe worthwhile to look at efficiency dependence on Inst Luminosity

- 02/15/2007

## Event distribution in 4 regions

- The central jet leading or no trigger efficiency is about the same

- Can use for both CJET10 and TWO_JET10

- 02/15/2007

- 02/15/2007