lab meeting -1/12/2004

Lab Meeting -1/12/2004

Update on the Photon + Dijet Analysis

Outline:Outline:

Old Photon + Dijet triggerOld Photon + Dijet trigger Photon Trigger EfficiencyPhoton Trigger Efficiency Jets Trigger EfficiencyJets Trigger Efficiency Monte Carlo eventsMonte Carlo events News from the new triggerNews from the new trigger

IntroductionGoal:Goal: Search for the W/Z Peak on Events with an

Associated Photon

Need 200-250 pb-1 with the new trigger (unprescaled)

Problem: NO TIME !!

Strategy 1: Sifting all the useful events we have now(taken with Photon Triggers)

Strategy 2: Make an attempt to ask for a little moreRate, just to get rid of the horrible DPS


The Old +jets Trigger

PHOTON_DIJET:PHOTON_DIJET:L1 - EM8L2 - EM18_ISO L3 - 2 Jets with Et>18 GeV 1 Jet with Et>10 GeV

Like25_ISO

One is the photon

Total ~ 180 pb-1

First Run: 143938 (May 02)Last Run : 167059 (Jul 03)

Before GoodRun: ~3.5MAfter GoodRun: ~1.7M

Found a bug on April 02 (Et>100) and Good data only from May


Event Selection

Step 1: Reproduce the Run I analysis 3 Sets of Cuts

A)A)Vertex and Met cutsVertex and Met cuts (only one good vtx, good z, and Met<0.8)

( Run I ~standard. Run II official cuts Different. No Run II tight cut for serious

Photon analysis )

C) Jets CutsC) Jets Cuts

B) Photon CutsB) Photon Cuts

( Run I used harder data, 25_ISO triggerWith no jets requirement at trigger level)

# Jets (0.7) > 2 3rd Jet Et_corr < 10 GeV 2nd Jet Et_corr > 10 GeV 1st Jet Et_corr > 15 GeV #trk > 1 on 1st and 2nd jet Delta R(jet1,jet2) > 2 ( Offline cuts very close to trigger cuts,

Efficiency will suffer… )

PHOTON_DIJET:PHOTON_DIJET:L1 - EM8L2 - EM18_ISO L3 - 2 Jets with Et>18 GeV 1 Jet with Et>10 GeV


Event Selection

AA CCBB

1615 K

900 K

25 K25 K

116 K

Only one vtx

Photon Central

PhotonIsolation


Trigger Efficiency

L1 : EM8 considered 100% efficient for Photon >18 GeV

L2 : 18_ISO feeds other triggers (25_ISO and DIPHOTON)Other people already did this study (but for higher pt gamma)

L2

Method I: Use an unbiased lower trigger(in this case a L3_EM8) and check howOften L2 is on for a good photon and make The ratio. For L3 they use a similar method(25_ISO / L3_18ISO )

Method II: Several discussions on photonGroup about pi0 contamination in method I.More sophisticated approach using electronFrom Z and check when they fire the photonTriggers.


L3 Trigger Efficiency

L3 requires some additional quality to the photon

Same of the 25_ISO but I have lower pt photon…… and also I have the jets to disentangle.

I need the efficiency for the photon part (phph ) and forThe jets (jetsjets). (not sure about that)

Jet1 Eta Jet2 Eta

Trigger and analysis cuts tooClose. Not only Et threshold But also eta is a problem.

Eta distribution after final selection


Trigger Efficiency: Photon

To calculate ph with method I I need a sample With only the L3 photon selection (jet unbiased) and Then make the ratio, but I don’t have such a sample.

I need to reproduce offline the L3 cuts. UnfortunatelyI can only apply the same cuts but it is different.

Events with L3_off

18_ISO

18_ISO +L3_25ISO

Tested on 25_ISO , a Trigger with ONLY Photon selection

I assume the events with L3_offAre good enough to be used in ratio.


Trigger Efficiency: Jets

The L3_off events are also the unbiased sample To study the jets efficiency (jetsjets).

Et ANDAND eta bias make the efficiency study very Complicated ( 2d plot or several sets of 1d)

My approach is don’t care about them and go Directly to what I want: the dijetmass distribution

The idea is have jets as a function of the dijet mass



I compared the unbiased dijet mass distribution with that one from

the PHOTON_DIJET trigger

Unbiased (L3_off)

Trigger

Why so inefficient ??Why so inefficient ??

(Jet1 Et>18 and Jet2 Et>10)

Jet1 Et Raw Jet2 Et Raw

Dijet Mass Distribution

Look at the unbiased eventsthat didn’t pass the trigger

(Blue – Red)



Actually that distribution was real, the unbiased sample isreasonable and really low Et jets make high Dijet distribution

Unbiased but not trigger

(Maybe useful for S/B separation)


Use the 25_ISO ??

A possible approach is to use the unbiased (for jets) 25_ISOTrigger for photon ET>26 and the DIJET trigger for 18< ET <26

DIJET All

DIJET And NO 25_ISODijet All : 25.193No 25_ISO: 14.075

(25 * 50% = 12.5)(15 * 50%+10=17.5)


Monte Carlo

MC under control now and started to produce Wg events

MC essential for acceptance study, almost done…

There is some room from improvement on the event Selection and S/B separation, but the idea was to

Reproduce the run I results first. I’m not so sure anymore…

MCFSR

Example: FSR effect can be reducedWith some merging or bigger cone.We have some experience on that…

Some tools already developed andReady to be exploited


EVDLab Meeting -1/12/2004

EVD DataLab Meeting -1/12/2004

News from the new trigger

New trigger replacing the PHO_DIJET in since Aug 03

Trigger rate higher than proposed (80 nb) because theyDidn’t implement all our cuts and for cosmic contamination

We didn’t take into account properly

Final number was around 230 nb and they put a DPS of5:1:1, the first number for HiLum (L2>300Hz)

Several other problems with L2 ISO hardware, veryHigh rate (but not clear at the beginning…)


New Trigger Rate

L2 rate L3 rate

Problem not really fixed till last week (see table) …… but now the HiLum (with L2 busy and L3 farm Problems) made things even worse.


Trigger Efficiency: PhotonLab Meeting -1/12/2004

Conclusion/Plan/Future

In a real analysis attention to details are more Important than I expected

On several of them I’m not an expert (L2, L3, photon Isolation algo,etc..)

Several open issues and work in progress, probably tooMuch. Maybe useful some middle term tasks/ deadlines

To focus on exclusively.

Or a “road map” to graduation to follow point by point…


lab meeting -1/12/2004

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