# Presentation: 826016

## Physics with Jets & MET

**Shuichi Kunori**
**U. of Maryland**
**12-Dec-2000**
**.**
**Jet, MET performance**
**Some physics channels**
**Calibration**

## Pion Response: Linearlity

**96’H2 Teast Beam Data**

**CMS Simulation**

**ECAHL+HCAL: Non compensating calorimeter**

**0**

**200**

**400GeV**

**1.0**

**0.9**

**0.8**

**1.5 GeV**

**3.0 GeV**

**ET=3 GeV pion in 0<|********|<5**

**0**

**3**

**5**

**h****=**

**P=**

**E=EC + ******** x H1 + H2 +HO**

## Jet Response and  Correction( CMSIM/ORCA)

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

**=> Different corrections for  L1 jets,  tau-jets and b-jets**
**=>  Luminosity dependent.**

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

**No-pileup**

**(S.Aarcelli)**

## Correction and Pileup Energy@ 10E34

**Resolution after corrections is worse**
**because pileup fluctuations are not**
**removed by the ****average ****correction.**

**Event-by-event correction:**
**e.g.  algorithm developed for**
**heavy ion collision. (I.Vardanian)**

**<17.3> in-time min-bias events**

## Low Et Jets and Pile-up

**Reco with pile-up**

**Reco w/o pile-up**

**Generated**

**Fake jets < 40GeV**

**(R<0.7)**

**(A.Krokhotine)**

**=> core of jets**
**=> smaller cone**

## Seed Cut

**No cut**

**2 GeV / (0.087x0.087)**

**Et(reco)**

**> 10 GeV**

**> 20 GeV**

**> 30GeV**

**Suppression of fake jets!**
**    ****... ****but still many fakes remaining.**

## Low ET Jets and Threshold

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

**Lower threshold is better!**

**0.5GeV**

**1.0GeV**

**(A.Krokhotine)**

**(I.Vardanian)**

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

**E****T****(quark)=20GeV**

## MET Resolution

**QCD Jets with no neutrino/muon**

**Any way to improve this?**

**Ex = ******** (Ex-tower)**
**Ey = ******** (Ey-tower)**

**e.g.**
**Ex’=Ex+******** ( ********(Ex-jet))**
**Ey’=Ey+******** ( ********(Ey-jet))**

**(no pile-up)**

**Does this work?**

## Attempt to improve L1 METwith Jet Correction

**(S.Abdoulline)**

## Jet energy correction to MET

**Mass for A -> ******** -> j + j + MET**

**Ex’=Ex+******** ( ********(Ex-jet))**
**Ey’=Ey+******** ( ********(Ey-jet))**

**500GeV**

**200GeV**

**Need more work for MET!**

**(S.Abdoulline &A.Nikitenko)**

## HO and MET

**200GeV pions @ ******** 0.0**

**MET for QCD events**
**             ****with/without HO**

**1**

**10****-1**

**10****-2**

**10****-3**

**200**

**400**

**600**

**MET (GeV)**

**Result from**
**parametrized**
**simulation**

**E(reco)/E(gen)**

## Sample L1 Rates and Cutoffs@10E33

## Sample L1 Rates and Cutoff@ 10E34

## Single Top -> Wb -> lb

**Measurement of **
**   ****- V****tb**
**   ****- properties and decays of top**
**   ****- background process to new physics**

**250pb**

**10pb**

**50pb**

**Background:**
**   ****top+top    800pb**
**   ****W+2jets**
**   ****W+3jets**

**Event Selection:**
**    ****only one charged lepton**
**          ****PT > 20GeV in |********|<2.5**
**    ****only one cnetral jet**** **
**          ****ET > 20GeV in |********|<2.5**
**             ****(jet veto against tt)**
**          ****b-tagged**** (20<ET<100GeV)**
**    ****forward tagging jet**
**          ****ET>50GeV in 2.5<|********|<4.0**
**    ****MET**
**          ****> 20GeV**
**    ****W Mass (lepton + MET)**
**          ****50<MT<100GeV**
**    ****Di-jet mass outside M(Z****0****)  **
**    ****top mass cut**
**          ****140<M(Wb)<180GeV**

**CMS Note 1999/048**

## Single Top - Kinematics

**E****T****     (b-quark)      ******

**E****T****    (tagging jet)   ******

**0**

**200**

**0**

**200**

**-4**

**+4**

**0**

**200**

**-4**

**+4**

**-2**

**+2**

**P****T****     (lepton)        ******

**>20GeV**

**<2.5**

**20-100**

**<2.5**

**>50GeV**

**2.5-4.0**

**M****T**** (l+n)**

**0**

**0**

**200**

**>20GeV**

**50-100**

**200**

**MET**

## Top Mass

**S / N = 3.5 / 1.0**
**66 signal events / 100pb**
**30 housrs @ 10E33.**
**Efficiency: 1.2%**

**M(Wb)**

**b/c tagging efficiency**
**         ****and fake**
**                            ****.**
**   ****- very old parametrization**
**      ****used in this analysis-****  **

** **

**Charm rate and fake rate play **
**important role in background**
**rejection.**

**20-100GeV**

## H(170) -> WW -> ll

**Background:**
**  ****tt -> (Wb)(Wb)  ->(l********b)(l********b)  62.5pb**
**  ****WW(continum) -> l********l********            7.4pb**

**(CMS Note 1998/089)**

**Event Selection: **
**         ****(total 11 cuts)**
**    ****two opposite sign leptos**
**          ****- PT cuts (20GeV,10GeV)**
**          ****- angle between two leptons**
**    ****jet veto**
**          ****- ET>20GeV in |********|<2.4: removed**
**    ****Mass (WW)**
**          ****- M > 140GeV****       **

**1.24pb**

**Results:**
**   ****- number of events  (5fb****-1****)**
**        ****H / tt / WW = 54 / 35 / 28 **
**   ****- good channel for discovery**
**   ****- background: need good **
**                            ****understanding **
**   ****- jet veto: important.**

## ttH(~110) -> (lnb) (jjb) (bb)

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

**M(bb)**

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

**primary selection**
**    ****4 b-tags**
**    ****M(bb)**
**     ****+**
**    ****lepton**

## Higgs Couplings

## qqH(135), H -> 2 -> ej

**HF acceptance for tagging jets**
**     ****( 0 / 1 / 2 ) jets = (47%,46%, 7%)**
**--> need both HE and HF**** **

**(A.Nikitenko)**

**Cuts:**
**   ****E****t****(e) > 15GeV, |********e)|<2.4**
**   ****E****t****(******** > 30GeV, |********|<2.4**
**   ****E****t****(****q****) > 40GeV, |********q****)|<5.0**
**   ****|************q1q2)****|>4.4, M****(q1q2)**** >1TeV**
**   ****mini-jet veto**
**.**
**Result:**
**     ****H       / Zjj(QCD)**********/ Zjj(EW )**********/   Wjjj**
**6.7+-0.3 /    0.63       /    0.74       /  0.14**
**for 30fb****-1**
**               ****(**generated by S.Illyin, comphep)**

## H -> invisible 

**Black Hole @ low luminosity**

**CMS has studied**
**    ****H(500) -> ******** -> j+j, e+j**
**    ****H(200) -> ********  -> j+j, e+j**
**    ****qqH(135) -> ******** -> e+j**
**and look promising @ 10****34**
**More challenging channel is**
**    ****qqH(120-400) -> invisible**
**       ****E****T****(q)**** > 40GeV, |********(q)****|<5.0**
**       ********(qq)**** ****>4.4**
**       ****M****(qq)****>1TeV**
**       ****mini jet veto**
**       ****MET>100GeV**
**     ****Only forward jets are**
**     ****positive signal!**

**(O.J.Eboil and D.Zeppenfeld, MADPH-00-1191)**

**Need high luminosity to**
**close the hole (with Higgs **
**channels shown on right).**

## HCAL Calibration Tools(light -> ADC -> Jets/MET/tau) 

**A) Megatile scanner:**
**- Co****60**** gamma source**
**- each tile: light yield**
**- during construction**
**all tiles**
**B) Moving radio active source:**
**- Co****60**** gamma source**
**- full chain: gain**
**- during CMS-open (manual)**
**all tiles**
**- during off beam time (remote)**
**tiles in layer 0 & 9**
**C) UV Laser:**
**- full chain: timing, gain-change**
**- during off beam time**
**tiles in layer 0 & 9**
**all RBX**
**D) Blue LED:**
**- timing, gain change**
**- during the off beam time**
**all RBX**

**E) Test beam**
**- normalization between**
**GeV vs. ADC vs. A,B,C,D**
**- ratios: elec/pion, muon/pion**
**- before assembly**** **
**a few wedges**
**F) Physics events (in-situ)**
**- mip signal, link to HO**
**muon**
**- calo energy scale (e/pi)**
**charged hadron**
**- physics energy scale**
**photon+jet balancing**
**Z+jet balancing**
**di-jets balancing**
**di-jet mass**
**W->jj in top decay **
**>> non-linear response**
**>> pile-up effect**

## In Situ Calibration (1)

**E) 1 photon + 1 jet**
**-  E****T**** Scale over full ****h**** range **
**  ****by photon-jet balancing**
**Note:**
**- depend on ECAL Et scale**
**- sensitive to ISR (& FSR)**
**F) Z (-> ee, ******** ****) + 1 jet**
**- E****T**** Scale over full ****h**** range**
**  ****by  Z-jet balancing**
**Note:**
**- depend on Tracker and/or ECAL**
**- sensitive to ISR (& FSR)**

## Photon-Jet balancingfor HF Jets

**E.Dorshkevich,V.Gavrilov**
**CMS Note 1999/038**

**Using**
**Et( ******** ) > 40GeV, |******** ****(******** ****)| < 2.4**
**- minimize MET with 4000 ******** **
**   ****Et(calib) =**** C****(S)****(********) ****Et****(Short)**
**                    ****+****C****(L)****(********) ****Et****(Long)**
**- 2.3 days at 10E33**
**  ****with 1% efficiency**

**before**

**after**

**(tagging jets)**

**Accuracy < 1-5% for Et>40GeV**

## In Situ Calibration (2)

**F) Top trigger (1 lepton + jets + 2 b-tags)**
**- E****T****  scale by Mass(jj) for W in Top decay.**

**Freeman & Wu (Fermilab-TM-1984)**

**Mass(jj)**
**   ****R<0.4**

**Peak:  69.6 GeV**
**sigma: 7.2 GeV**

**Parameterized simulation**

**45000 events / month**
**at 10E33**
**with double ****b-tagging.**

**Top- good source for b-jet calibration!**

**0**

**100**

## Summary (1)

**Energy Resolution and Scale**
**Simple Jet energy correction is working in MC world.**** **
**Need to extend it to MET and tau.**
**We have been using very simple weighting method to sum energies in ECAL and HCAL.**
**look for better method(s), e.g. energy depend weights, use of fine segments in ECAL, use of Tracker, etc.**
**In-situ calibration will provide absolute scale.**
**Need plan to cover energy calibration up to the highest energy.**
**High Luminosity**
**Low E****T**** jets/MET (<100GeV)  at high luminosity is very challenging for both trigger and offline analyses.**** **
**Need good algorithms to remove fake jets and to subtract pile-up energy.**

## Summary (2)

**Physics with HCAL**
**Much of physics analyses depend on jets, MET and tau.**
**Forward tagging jet become more and more important, e.g. studies on property of  Higgs.**
**Many recent studies on Higgs. Need to extend to SUSY and other channels.**
**Calibration and Monitoring**
**Need to develop complete scenario.**
**ITEP/MSU group started working on it.**
**All the tools should be ready on day-1 of data taking and calibration has to be done in 1-3 months for quick publication of physics results.**