# Presentation: 803069

## Early Physics Prospects at CMS

- Jeffrey Berryhill/FNAL CMS Center
- Beyond the Standard Model: from the Tevatron to the LHC
- Sept. 17 2008

## What happened September 10th?

- CERN celebrates first complete
- proton beam circulation in LHC
- Both beam lines sustained for
- minutes at a time
- CMS, ATLAS, LHCb and ALICE
-  all report beam halo events

- Fermilab/USCMS celebrates with all-night
- “pajama party”
- CMS beam halo observed in the remote
- operations center
- Worldwide press and live BBC coverage

## Possible 2008 Run Plan

- Establish collisions at 900 GeV this month
- Establish 10 TeV collisions within 30 days
**~30 days of physics delivering ~10 pb****-1 ****to detectors**
- Coasting for one month in most advanced mode (1% of design lumi) delivers ~40 pb-1
- Retrain the quenching dipoles during winter shutdown to allow 14 TeV collisions in 2009

- Mid-
- Oct.

## 10 TeV vs. 14 TeV

- 10 TeV operations is a temporary measure
- to minimize dipole quenches seen at 14 TeV
- (limited to a specific manufacturer).
- Dipoles to  be “re-trained” to restore
- response “forgotten” from surface tests,
- in time for 2009 run
- Running at 10 TeV instead of 14 TeV
- degrades cross sections of processes
- far from the LHC kinematic limit by
**about a factor 2**
**Discovery potential is largely **
**maintained** even with a (unanticipated)
- prolonged running period at 10 TeV

- 2

- 10

- 14

## 2009 Run Plan and Beyond

- B

- C

- No beam

- Beam

**2009**

| Train to
7TeV | Machine checkout | Beam Setup | 75ns ops | 25ns ops I | Shutdown |
| --- | --- | --- | --- | --- | --- |

- Commission beams for 14 TeV collisions
- Plan for 150 days of pp physics running, w/efficiency for physics 40%
- Phase B:  1-10% of design lumi, ~few 100 pb-1
- Phase C: 10-20% of design lumi, minimum bunch spacing, ~few fb-1
- >=2010:  attain 1034 design lumi, collect up to 60 fb-1/year, collect 300 fb-1
- SuperLHC:  IR+detector upgrades, 1035 lumi, 600 fb-1/year, collect 3 ab-1

## CMS Status

**All subdetectors have been installed and have **
**recorded cosmic ray data with central trigger/DAQ**
- Growing pains:
- ECAL endcaps all made it in at the last minute, however trigger
- electronics there is arriving late (Nov.) for 2008 run*

- *No electron or photon trigger for |eta| > 1.5
- BUT readout is operational for
- otherwise-accepted events

- 3.8T solenoid cavern-tested
- only 10 days ago, understanding
- fringe field and mechanical(!)
- impact on rest of CMS
- Troubleshooting front-end
- electronics noise

## CMS Physics Program

- Characterized roughly by epochs of log10(Integrated luminosity):
- 2008:
**0-1 pb****-1**     **Channel-level detector calibration & alignment.**  Measurements of minimum bias pp and low PT leptons and jets.  Modest W and Z signals possibly observable.

- 2008?2009?
**1-10 pb****-1**     **Commissioning of high PT electrons, muons, and jets.**  Thousands of Z to dileptons, 10X more W to leptons
-      Plentiful high-PT jet sample, small top signal possible

- 2009:
**10-100 pb****-1**  **Re-discovery of the Standard Model.**   Precision W/Z/top cross sections, diboson production + discovery potential in some channels (jets, CMSSM SUSY, TeV Z’).  b-jet commissioning.  Usable missing ET resolution and jet energy scale.

## CMS Physics Program

- 2009?2010?
**0.1-1 fb****-1**          **“Gold rush” phase begins**: usable calibration and commissioning for all high PT physics objects (taus).  Tevatron sensitivity usurped over a broad range of channels.  SM Higgs evidence from 160 to 400 GeV.

- 2010 and beyond
**1-10 fb****-1**          **SM Higgs discovery**, high-mass BSM discovery
**10-100 fb****-1**   precision BSM, or evidence for stingier scenarios (VBF)

**It is a prerequisite to almost **_**any**_** search or discovery to successfully complete the 1/10/100 pb****-1**** commissioning and SM re-discovery program **

## CMS Physics Program

**0-1 pb****-1**     calibration, alignment.  Measurements of minimum bias pp and low PT leptons and jets.  Very low lumi, very open trigger.
- In-situ ECAL and HCAL response calibration (phi symmetry et al.)
- Tracking/muon chamber efficiency of muons w/ J/ and Upsilon
- Underlying event measurement at 10-14 TeV
- Low PT electron, photon, and conversion studies
- First look at jets

-     Track multiplicity in minbias @ 1pb-1

-     0 calibration of ECAL

## CMS Physics Program

- Z →ee  signal @10 pb-1

- W →signal @10 pb-1

**1-10 pb****-1**     **Commissioning of high PT electrons, muons, and jets.**
- thousands of electron and muon pairs from Z’s essential for optimizing lepton triggering, reconstruction, and ID
- Usability of missing ET diagnosed with large (10^5) W sample
- EWK xsecs and ratios are first precision tests of CMS analysis capability

## CMS Physics Program

**10-100 pb-1**  **Re-discovery of the Standard Model.**   Precision W/Z/top cross sections, diboson production + discovery potential in some channels (jets, CMSSM SUSY, TeV Z’). Usable missing ET resolution and jet energy scale.

- Multi-TeV q/g compositeness sensitivity once JES is known

- Top dilepton signal @100 pb-1  with commissioned MET, btagging, JES. Top lepton+jets can ultimately be a calibration sample for them!

## CMS Discovery Phase

- Light SM Higgs discovery @ 10 fb-1

- MSSM gluino/squark 5 discovery @ 1fb-1
- M(1/2) < 650 GeV, M(0) < 1.5 TeV
- LM1 discovery with < 10 pb-1
- (if you understand jets and MET...
- but that will take ~10-100 pb-1)

- Heavy SM Higgs discovery @ 5 fb-1

## CMS vs. ATLAS

- ATLAS has better:
- HAD calorimetry,
- ~6 months head start in commissioning
- CMS has better:
- ECAL E resolution
- Track/muon P res.

## CMS vs. CDF/D0

- Advantages for CMS:
- ECAL **granularity and resolution is excellent**
- Tracking, ECAL and muon acceptance lead to good lepton trigger and ID **out to eta of 2.5**
- 3.8T magnet plus 200 m^2 of silicon lead to **better IP and momentum resolution**
- Muons are **everywhere redundantly triggered and tracked** with RPCs

## CMS vs. CDF/D0 

- BUT
- Even at 1% design lumi, **CMS trigger is much more selective/less efficient**. No inner tracking in the low-level trigger (bad for b,).
- The high mass **tracker causes electron, photons, and pions to shower**!
**S/B often worse at 14 TeV**: “signal” xsecs are 10X but tt, bb, multijet, and V+jet background xsecs are typically >10X
- Biggest Tevatron edge by far is detector and analysis _experience, _
- they will have better sensitivity per/event produced, so they will have unique results for medium x searches (read: Higgs) some time after the “crossover point” of ~100pb-1@LHC
- Once the LHC enters the fb-1 epoch, brute force wins the day....and the experience gap will close in time as well

## Caveats for BSM

- Missing ET commissioning will be a rocky road as we
- characterize and eliminate all the unsimulated instrumental backgrounds
- Signatures resulting in only **b or tau particles will be difficult to **
**trigger on**.  Needs an e, mu, photon or something else to improve
- “level 1” efficiency.
**Lower ET and non-isolated object topologies** will be prescaled away
- as lumi grows

- D0 raw missing ET in Run II

**Run II**
**V. Shary CALOR04**

- Need to understand
- MET from collisions (pileup)
- MET from LHC (halo)
- MET from CMS (noise)
- Before MET for physics is usable

## Caveats for BSM

**Signatures somewhat out of time (<10 ns) will have some **
**sensitivity**: ECAL has ~ns time resolution with high granularity so “non-pointing” photons (from GMSB) can be reconstructed
- Signatures with **way out-of-time (> ~10ns) particles** will have
- triggering problems (25 ns bunch crossing timing requirements
- for the trigger, “trigger rules” prohibiting consecutive bunches to
- trigger, limited time sampling of readout)
- Very **non-prompt (many cm) or kinked track** signatures may also
- be difficult to distinguish from tracker conversions/interactions

## Caveats for BSM

- Non-”Vanilla”  physics objects will require a good deal of foresight to detect (reconstruction software and triggering).  **Ask experimenters to get started now!  **
- Even seemingly vanilla signatures may not survive trigger evolution to higher lumi.  **Talk to your experimenter friends often about the trigger menu.**
- Although on paper discovery should be “instantaneous” in some BSM scenarios, there will be a protracted period of debugging and commissioning through the first 100 pb-1 which must occur to make any discovery a sound one.
- These are exciting times!

## Backups

## MET Plans:From 1023 to 1027 /(cm2sec) – 14 TeV

| L for 1 month run (106 sec) | Integrated L | Trigger | Process | Comments |
| --- | --- | --- | --- | --- |
| 1023 | 100 mb-1 | None
I~ 50 mb | Inelastic
non-diff | Input to tweak Pythia |
| 1024 | 1 b-1 | Setup Jet | Inelastic
non-diff | Calib in azimuth |
| 1025 | 10 b-1 | Jet
(gg) ~ 90 b
(ggg) ~ 6 b | g+g -> g+g
g+g -> g+g+g | Establish JJ cross section |
| 1026 | 100 b-1 | Jet | g+g -> g+g
g+g -> g+g+g | Dijet balance for polar angle – Establish MET |
| 1027 | 1 nb-1 | Jet
Setup Photon
(q) ~ 20 nb | g+g -> g+g
g+g -> g+g+g
q+g -> q+  | Dijet masses – start jet balance
J+ calib |

- From Dan Green

## Rough Plan for Taus

- Establishing basic trigger functionality:
- Tuning initial L1 tau definition and veto bits
- Tau trigger efficiency measurement using offline electrons and jets:
- Trigger efficiency measurements without real taus:
- Measurement using offline electrons:
- Measurement with tight offline “taus” (fakes):
- Final validation will need clean tau samples
- Re-measure efficiencies using clean Z→e)
- Use inclusive (e) triggers
- Establishing basic functionality:
- Offline efficiency measurement using high quality electrons:
- Basic understanding of conversion finding:
- Further progress requires clean tau samples:
- Measure “other” ID efficiencies, energy calibration etc
- Use Z→e) using inclusive e) trigger
- Bottom Line:
- Taus will be the last object to commission

- 0-0.1 pb-1

- 1-10 pb-1

- 10-100 pb-1 ?

- 100-500 pb-1 ?

- 10-100 pb-1 ?

- 100-500 pb-1 ?