# Presentation: 902130

## Status of JetsMET

**Shuichi Kunori**
**U. of Maryland**
**18-May-2001**

**PRS: Physics Reconstruction and Selection**
**HCAL/JetsMET group**

## HCAL -  Jets/MET

**S.Eno / S.Kunori**** - Coordinator**
**http://home.fnal.gov/~sceno/jpg/Default.htm**
**Dates:**
**End 2002  DAQ TDR   (end 2001 for HLT section)**
**End 2004  Physics TDR**
**Organization: **
**HCAL simulation –                           ****Sunanda Banerjee (TIRF)**
**CMSIM/GEANT4/FAST **
**Verify shower model in G4.**
**Calibration & Monitoring –              ****Olga Kodolova (MSU)**** **
**       ****energy scale of jets, MET, tau**
**-> from detector construction/commission to in-situ calibration.**
**HCAL in ORCA –                              ****Salavat Abdoullin (Maryland)**
**readout simulation + ...**
**Physics objects with HCAL –         ****Sasha Niketenko (CERN/ITEP)**
**jets, MET & tau**

## DAQ TDR

**(P.Sphicas, Nov.20, 2000)**

**For both low and**
**high luminosity**

**We will cover all of these!  **

## Main Issues

**Many physics analyses require**
** ****- low E****T**** jets: **
**              ****from top, W, Higgs **
**              ****from WW fusion**
**          ****part of signal**
**          ****background rejection (e.g.  jet veto)**
** ****- High luminosity**
**          ****pile-up energy**
**          ****low ET jets from overlapping events**
**          ****fake jets due to pileup.**
** ****- ************jet**
** ****- b  jet (tag)**
** ****- Correct ****energy scale**** from low E****T**** to very high E****T**
** ****- Better ****resolution**** for Jet/MET**

**E****T**** range**
**20GeV-2TeV**

## Single Top - Kinematics

**Measurement of  **
**   ****- V****tb**** / top decay properties / background to new physics**

**250pb**

## Forward tagging jets &Higgs Couplings measurement

**Although ********(VBF)~********(GF)/3,  VBF process may play a big role in**
**measurement of higgs properties in addition to discovery potential.**

##  jet

**Branching ratios for H****+**

**M(H****+****)   200           500      1000**

**1**

**10****-4**

**10****-2**

**10****-2**

**10****-4**

**1**

****

****

**tb**

**tb**

**1 prong ********decay  (******** jet)**

##  jets

**tau jet:**
**narrow (one prong) jet**
**L1/L2:**
**use only calorimeter**
**    ****L1: 0.087x0.087**
**    ****L2: individual crystal**

## tau jets at L3

**1. Tracks are reconstructed with 3 pixel layers**
**    ****only within a cone given by L2.0 jet axis.**
**2. Isolation cuts: tracks in a big cone (0.3-0.4)**
**    ****vs. a small cone (~0,1), PT(tr)>1-2GeV**

**gg->bbA(500GeV)**

**(Nikitenko & Kotlinski : cms116 analysis)**

## Pion Response: Linearity

**96’H2 Teast Beam Data**

**CMS Simulation**

**ECAHL+HCAL: Non compensating calorimeter**

## Jet Response and Correction #1

**No pileup**

**With pileup**

**Et(corr)=a + b x E****T****(rec) + c x E****T****(rec)****2**

**Et-eta dependent correction for QCD jets**

**(S.Arcelli)**

## Dijet Mass Resolution

**Jet energy correction**
**    ****without:   ****19%**
**    ****with:         ****14%**
**CMSJET       ****15%**

**M(bb) in ttH**

**W(jj)**

**Top(jjj)**

**Before correction**

**15%**

**16%**

**21%**

**22%**

**After correction**

**With pileup**

**No pileup**

**(S.Arcelli & V.Drollinger)**

**(R.Kinunnen)**

## MET

**Corrections**
**     ****Type 1:   Jet corr. **
**     ****Type 2:   Jet corr. + out of cone corr.**

**Out of cone corr. uses weights**
**for jet(30GeV) corr****.**

## Corrected MET for mSUGURA Jets+MET at low lumi

**Mean offset**

****

## Higgs mass in bbA, A22j 

**before  correction**

**after correction**

**(A.Nikitenko)**

## Jet correction method #2

**Jet Corr. #1**
**   ******** ****x (EC+HC)**
**   ****- corr. for jet energy scale**
**   ****- ******** depends on jet(Et,********)**
**Jet Corr. #2**
**   ******** ****x EC + ******** x H1 + ********x H2**
**   ****- optimize jet resolution**
**     ****(and jet energy scale)**
**   ****- ********, ******** depends on jet(Et,********)**

**Optimized weights by #2**
**           ****0.0<********<0.4**

**(A.Oulianov)**

## Jet Correction method #2

## Correction method #3a(single pion)

**Correction method #3a****(single pion)**

**Method #1**

**resolution**

**linearity**

**1            10            100         1000  (GeV)**

**1              10            100          1000 (GeV)**

**30%**

**20%**

**10%**

**0%**

**0%**

**-5%**

**-10%**

**5%**

**10%**

**(E****REC****-****EIN****)/E****IN**

**Method #3**

**#1**

**#3 (open)**

**3%**

**(118+3)%**

**(127+3)%**

**Linearity is restored to 3% in 10-1000GeV for single pion!**

**i : longitudinal segmenation**

**(V.Genchev)**

## Correction Method #3b(single pion)

**Correction Method #3b****(single pion)**

**Linearity is restored to a few %.**** The resolution is Gaussian to a high level of accuracy with ~ NO constant term and a 120% stochastic coefficient**

**(e/h)****HCAL****~1.39****  ****(NIM paper)**
**To find e/h for ECAL, measure e/pi at different energies for showers where there is a substantial energy (> 30% of the beam energy) in ECAL.**
**(e/h)****ECAL****~1.60**

**Next: identify em cluster and had cluster in jet using transverse shower**
**          ****shape (in crystals) and reco-ed tracks and apply this to had cluster. **

**0           100          200           300 (GeV)**

**0**

**100**

**200**

**300**

**beam**

**reco**

******/E**

**linearity**

**resolution**

**10%**

**20%**

**5%**

**10                              100            300  (GeV)**

**(D.Green)**

## Effect of Thresholdon low ET jet and MET

**Electronics noise and occupancy define the threshold.**
**>> aim at ****0.5GeV/tower**** @ 10E34**** **

**Lower threshold is better!**

**(A.Krokhotine)**

**(S.Nikitenko)**

**Jets   35<E****T****(gen)<45geV**

**MET**

## Front end electronics simulation

**Updated**
**recently**

**E = ******** (Signal buckets)****i**** – ********(pre buckets)****j****/n**** **

**Electronics noise 200MeV/25nsec/ch ******** 500MeV/(3+3) buckets/ch**

****** ****Looking for better method for energy calculation**

**(S.Abdoullin)**

## Algorithm for L1 through Offline (1)

**L1 – calorimeter only (coarse segmentation)**
**Resolution improvement**
- Equalize calorimeter response with simple correction
**a x (EC+HC),      a depends on jet(ET,h)**
**a x EC + b x HC,    a,b depends on jet(ET,h)**
**Fake Jets/Pileup jets rejection**
- Threshold cut on a central tower in jets (seed cut)
**L2 – calorimeter only (fine segmentation)**
**Resolution improvement **
- Better energy extraction from ADC counts
- Em/had cluster separation using transverse shower shape in crystals
**Fake jet/Pileup jet rejection**
- Use of transverse shower shape

## Algorithm for L1 through Offline (2)

**L3 – calorimeter plus pixel**
**Resolution improvement**
- Pileup energy subtraction
**Estimation of energy flow from pileup events using pixel hits/tracks.**
**Fake jets/Pileup jets rejection**
**Vertex information and jet pointing using pixel hits/tracks.**
**Offline – calorimeter plus fully reco-ed tracks**
**Resolution improvement**
**Fake jets/Pileup jets rejection**
-  Jet and MET will be reconstructed with Tracks, EM clusters and HAD clusters.
-  All tracks down to ET~ 700MeV have to be reconstructed at 10E34!
**Physics correction – e.g. correction for IFR/FSR.**
-  In-situ calibration!

## Long way to go, but promising...