# Presentation: 095792

## CMS Physics

**Status of CMS**
**Physics Studies**
**Dan Green**
**Fermilab**

## Outline

**CMS Detector**
**Trigger/DAQ - L1T, HLT**
**Higgs**
**gg Fusion**
**Associated Production**
**SUSY**
**Exotica (Composites, Z’, Extra Dimensions, ...)**

## The CMS Detector

**MUON BARREL**

**CALORIMETERS**

** **

**ECAL**

** **

**IRON YOKE**

**TRACKER**

**MUON**
**ENDCAPS**

**HCAL**

**Basic Choices:**
**Strong, large B field**
**All Si tracking**
**Best possible ECAL dE/E**
**Robust Muon - yoke**

## CMS Tracking - Crossing

## CMS Tracker – All Si

**5.4 m**

**Outer**** Barrel –TOB-**

**Inner Barrel –TIB-**

**End cap –TEC-**

**Pixel**

-  2,4 m

**Inner Disks –TID-**

**210 m****2**** of silicon sensors**
**6,136   Thin  detectors (1 sensor)**
**9,096   Thick detectors (2 sensors)**
**9,648,128 electronics channels**

**Notes:**
Changes Start of module production shows a delay of ~ 5 months w.r.t. v33.
Plans and milestones for 2003
Ramp-up mass-production of modules. Recover some of the delays incurred so far by exploiting high throughput of automated assembly gantries.
Submit 0.25 m version of pixel ROC chip.
Concerns Logistics of module production. 

## CMS Tracker Performance

**CMS Tracker Performance**

**Silicon strip : ********R******** = 10-60 ********m, cell size ~ 10 cm2**
**Pixel: ********R********, z = 10-20 ********m, cell size ~ 150 mm2**
**Occupancy ~ 10-4**
**        ****Pixel is used for seeding**
**Transverse IP resolution  ~ 20 mm for tracks with Pt ~ 10GeV**

**Notes:**
Dire perche’ e’ importante il pixel.. Ambiente clear etc...

Pixel utilizzato come seeding per il tracking
Normalmente come seeding vengono utilizzati gli strati esterni ma in CMS 8% -15% dei pioni da 1 GeV interagiscono nei primi 8 strati, pertanto si utilizzano gli strati di pixel con bassa occupancy e eccellente risoluzione in 3D.

## ECAL – PbWO Crystals

**Fully active detector – transverse size ~ Xo**

**Notes:**
Changes Redesign of the mechanical structure of ES
Plans and milestones for 2003
Improve the cutting process for large crystal boules
Place order for endcap crystals 
Choose the final electronics chain
Test of several hundred channels with final electronics by October 2003

Concerns Cutting process for large crystal boules 
Electronics Chain: schedule is aggressive
Assurance of funding – critical to place order for endcap crystals in 2003 

## ECAL Test Beam Module

##  CMS ECAL Calibration

**Lab measurements** of all modules; light yield, APD gain etc.  4.5 %
**Testbeam** precalibration transported  to CMS (for 25% of detector)  2.0 %
- Distributed within detector, as “standard candle”
**Min-bias** phi symmetry  2 %
- Fast calibration to reduce            number of  calibration constants
**Z ******** e****+****e****- **** ******** **0.5 % (design value)
- Needs tracking in Si-tracker
- Within ~2 months
- Laser **monitoring system** over time      to monitor crystal transparency

- Total ~85.000 channels

## HCAL : HB and HE

**Back-flange**
**18 Brackets**
**3 Layers of absorber**

## HCAL 2002 Test Beam

**HCAL 2002 Test Beam**

## HO in 2002 Test Beam

**HO in 2002 Test Beam**

## Check Monte Carlo – G4

- Resolution

- Linearity

**Check Monte Carlo – G4**

## Muon System – 4 Stations

**HO**

## Endcap Muon Chambers

## Muon Performance - Bs

| Lvl-1  | HLT  | Global  | Events/ 10fb-1 | Trigger Rate |
| --- | --- | --- | --- | --- |
| 15.2% | 33.5% | 5.1% | 47 | <1.7Hz |

**Offline analysis results (hep-ph/9907256), using SM BR=3.5x10****-9**
**(Lvl-1 trigger in |h|<2.4 instead of |h|< 2.1)**
**10 fb****-1  ****=> 7 signal events with <1 background **
**5s observation with 30 fb****-1**
**and analysis could be perfomed at high lumi too**

**s = 46 MeV**

**Notes:**
Background proviene dai processi di gluon splitting.

Allo scopo di aumentare
l’efficienza abbassare 
il taglio in Pt usando allo stesso
tempo la carica fornita dal lvl-1
Allo scopo di rendere accettabile il rate

Il rate di 1.7 viene dal fatto che la statistica e’ limitata....

Vecchia analisi 
Numero eventi di segnali 7 dopo un anno a 10^33.
Numero di eventi di fondo <1 at 90% CL.

## Level-1 Trigger

**Information from Calorimeters**
** ****and muon detectors**
**Electron/photon triggers**
**Jet and missing E****T**** triggers**
**Muon triggers**

## Level-1 Trigger Table (1034)

| Trigger | Threshold
(GeV or GeV/c) | Rate (kHz) | Cumulative Rate (kHz) |
| --- | --- | --- | --- |
| Isolated e/ | 34 | 6.5 | 6.5 |
| Di-e/ | 19 | 3.3 | 9.4 |
| Isolated muon | 20 | 6.2 | 15.6 |
| Di-muon | 5 | 1.7 | 17.3 |
| Single tau-jet | 101 | 5.3 | 22.6 |
| Di-tau-jet | 67 | 3.6 | 25.0 |
| 1-jet, 3-jet, 4-jet | 250, 110, 95 | 3.0 | 26.7 |
| Jet*ETmiss | 113*70 | 4.5 | 30.4 |
| Electron*jet | 25*52 | 1.3 | 31.7 |
| Muon*jet | 15*40 | 0.8 | 32.5 |
| Min-bias |  | 1.0 | 33.5 |
| TOTAL |  |  | 33.5 |

##  Minimum Bias Events

- _Idea: _fast calibration to reduce # of cal.constants
- _Method:_ use phi symmetry of deposited energy to intercalibrate crystals within rings of constant eta

- Barrel

- CMS Note 2003-031

- D.Futyan, C.Seez

## CMS DAQ and Trigger System

**CMS DAQ and Trigger System**

**Event size: 1MB from ~700 front-end electronics modules**
**Level-1 decision time: ~3********s ****— ****~1********s actual processing****(the rest in transmission delays)**
**DAQ designed to accept Level-1 rate of 100kHz**
**Modular DAQ: 8 x 12.5kHz units**
**HLT designed to output O(10****2****)Hz ****– rejection of 1000**
**~1000 processor units**

## HLT Selection - 

**HLT Selection - ******

******-leptons**
**Level-2: calorimetric reconstruction and isolation**
- Very narrow jet surrounded by isolation cone
**Level-3: tracker isolation**

## Electron Selection: Level-2

**“****Level-2” electron:**
**Search for match to Level-1 trigger**
**Use 1-tower margin around 4x4-tower trigger region**
**Bremsstrahlung recovery “super-clustering”**
**Select highest E****T**** cluster**
**Brem recovery:**
**Road along f ****— in narrow ********-window ****around seed**
**Collect all sub-clusters in road ******** “super-cluster”**

## Electron Selection: Level-2.5

**“****Level-2.5” selection: use pixel information**
**Very fast, large rejection with high efficiency (>15 for e=95%)**
**Before most material ******** before most bremsstrahlung, and before most conversions**
**Number of potential hits is 3: demanding ******** 2 hits quite efficient**

## HLT Summary: 2x1033 cm-2s-1

| Trigger | Threshold
(GeV or GeV/c) | Rate (Hz) | Cuml. rate (Hz) |
| --- | --- | --- | --- |
| Inclusive electron | 29 | 33 | 33 |
| Di-electron | 17 | 1 | 34 |
| Inclusive photon | 80 | 4 | 38 |
| Di-photon | 40, 25 | 5 | 43 |
| Inclusive muon | 19 | 25 | 68 |
| Di-muon | 7 | 4 | 72 |
| Inclusive tau-jet | 86 | 3 | 75 |
| Di-tau-jet | 59 | 1 | 76 |
| 1-jet * ETmiss | 180 * 123 | 5 | 81 |
| 1-jet OR 3-jet OR 4-jet | 657, 247, 113 | 9 | 89 |
| Electron * jet | 19 * 45 | 2 | 90 |
| Inclusive b-jet | 237 | 5 | 95 |
| Calibration etc |  | 10 | 105 |
| TOTAL |  |  | 105 |

## HLT and Physics Efficiency

## HLT Performance — Efficiency

| Channel | Efficiency 
(for fiducial objects) |
| --- | --- |
| H(115 GeV) | 77% |
| H(160 GeV)WW* 2  | 92% |
| H(150 GeV)ZZ4  | 98% |
| A/H(200 GeV)2  | 45% |
| SUSY (~0.5 TeV sparticles)  | ~60% |
| With RP-violation | ~20% |
| We  | 67% (fid: 60%) |
| W | 69% (fid: 50%) |
| TopX | 72% |

## B Tagging Efficiency

**The sctual light quark rejection and b quark acceptance as a function of ET will only be known when the actual environment and performance of the tracker is known.**

## Preparing for Physics

**To do the Physics well, we must – by 2007:**
**Commission – SX5, slice tests, trigger primitives, portable DAQ, pulsers, lasers, cosmics**
**Calibrate – test beam, sources, lasers, muons**
**Align – muons, photogrammetry, proximity sensors**
**Core Software – data challenges, calib samples (W, Z, JJ, J********, minbias)**

## Standard Model Physics

| Yields | Cross section(nb) | Acceptance   (1  in <2.1) | Eff. after HLT with  isolation | Yield for 10 fb-1 |
| --- | --- | --- | --- | --- |
| W   | 19.6 | 50 % | 69 % | 7 × 107 |
| Z    | 1.84 | 71 % | 92 % | 1.1 × 107 |
| tt  WbWb  +X | 0.126 | 86 % | 72 % | 7.8 × 105 |

-  **rare top decays**
** ****precision measurements of top couplings and properties**
** ****EW boson triple gauge couplings**

**An example: standard model physics using muons, CMS**

**Notes:**
Of course the LHC is not a two measurement machine.  We can also search for truly new “beyond the standard model physics” by using, for example, the high statistics samples of W’s, Z’s and tops that will be in our data.  For example, we can look for rare top decays, do previous measurements of to coulings and properties, or study EWK boson triple gauge couplings.  

## Higgs Production

**Higgs Production**

## Higgs Mass – Low?

**Current EW data indicates a low mass H. SUSY requires a low mass H. The mass width is then likely to be small < experimental resolution ******** ECAL**

## Higgs Decay Modes

**At low mass, several couplings are measurable. At higher masses WW and ZZ dominate.**

## Low Mass Higgs 

**H********: decay is rare (B~10****-3****)**
**But with good resolution, one gets a mass peak**
**Motivation for PbWO****4**** **
**     ****calorimeter**
**CMS: at 100 GeV, ******** 1GeV**
- S/B  1:20

## Intermediate mass Higgs

**H********ZZ************+********–********+********– **** (******** ****=e,********)**
**Very clean**
- Resolution: better than 1 GeV (around 100 GeV mass)
**Valid for the mass range 130<M****H****<600 GeV/c****2**

## Higgs Quantum Numbers

**If the 2 photon mode is observed then H is not a vector (Yangs’ theorem). **
**If the H is a SM then the leptons are ~ collinear in a WW decay.**
**If the ZZ decay is seen then a P = + state has decay planes aligned – P = - has planes orthogonal.**

## High mass Higgs

**H********ZZ******** ********+********–********jet jet**
**Need higher Branching fraction (also ********for the highest masses ~ 800 GeV/c****2****)**
**At the limit of statistics**

## Associated Production - Htt

**H made by radiation in a tt final state. At low H mass the cross section is sufficient to extract a clean signal. In addition, a “control” sample arises from the ttZ state with a leptonic Z decay.**

## Htt Associated Production

**Good b tagging is clearly essential.**
**ttZ can be used to measure the background in bb using leptonic Z decays.**

## H Production from W+W

**Use the EW radiation of a W by a quark. The “effective W approximation” analagous to the WW approximation. Need good jet coverage to low PT and small angles.**

## qqH, H -> W+W* -> 2l+2v

**H leads to ~ collinear and low mass lepton pairs. qqH is most useful at H masses > 150 GeV.**

## Higgs Summary in CMS

**For 10 fb-1, or 1 year at 1/10 of design luminosity almost all the allowed range for a SM Higgs is covered. **
**CMS must be ready to quickly and incisively analyze the early LHC data.**

## Higgs Self Coupling  

**Baur, Plehn, Rainwater**

**HH ******** W****+**** W****-**** W****+**** W****-**** ******** ************ ********jj  ****************jj**

**If the H mass is known, then the SM H potential is known ******** HH prediction. If H is found, measure mass, width, quantum numbers, branching ratios and self-couplings**

## No Higgs? VV Scattering?

** ****If no Higgs look at VV scattering? Individual diagrams diverge with C.M. energy. Total set of 3 EW diagrams approaches a constant. The ~ isotropic distribution of each diagram becomes a F/B peak in the sum of the 3 EW diagrams.**

## WW Fusion into ZZ

**Process depends only on VVV, VVVV couplings. Not viable at Tevatron. If no H then possibly large enhancement due to TT scattering.**

## W+W -> Z + Z Angular Distribution

**If there is a SM H then the distribution is very F/B peaked. If not, then the cross section may have a dramatic (~ 80 x) increase and the angular distribution may become isotropic – e.g. pure quartic.**

## SUSY ?

**Neutrino mass**
**GUT Mass scale, unification**
**P decay rate**
**Mass hierarchy – Planck/EW**
**String connections**

## Minimal SUSY

**2 vev (ratio tan******** sign ********) 2 masses (at GUT scale), soft SUSY breaking. Leads to 5 Higgs, sleptons, gauginos (LSP) and squarks and gluinos (higher mass0**

## WMAP and Other Constraints

**LEP2**
**g-2**
**WMAP**
**LSP is neutral**

## SUSY Cross Sections at LHC

**SUSY Cross Sections at LHC**

**Squarks and gluinos are most copious (strong production). Cascade decay to LSP (         ) ******** study jets and missing energy**

## SUSY - Disovery

- backgrounds

- SUSY
- 600 GeV
-  squark

**Dramatic event signatures and large cross section mean we will discover SUSY quickly, if it exists.**

**Notes:**
So, as I said in the introduction, the other question that the LHC was designed to adress about the standard model is whether supersymmetry is the reason the higgs can be light.  I for one hope it is, because not only is SUSY theoretically beautiful, but it provides the kind of dramatic event signatures that are a real pleasure for an experimentalist to analyze.  For example, even a simple variable such as the scalar sum of the PT of the neutrinos and jets gives good discrimination between signal and background.

##  SUSY – Mass Scale

- Effective mass “tracks”
- squark/gluino mass well

- 1 year of l/10th design luminosity

**Will immediately start to measure the SUSY parameters.**
**With 4 jets + missing energy the SUSY mass scale can be established to 20 %.**

**Notes:**
And once we have data, we can immediately start to measure the SUSY parameters.  For example, the average value of this simple variable correlates well with the squark or gluino mass.  

## SUSY – Mass “Reach”

**SUSY – Mass “Reach”**

**WMAP**

**1 year at 1/10 design luminosity**

## SUSY Higgs

**Mass of h = mass of Z. With top loops the h mass is increased. However, mass of h is < 130 GeV. Thus, SUSY predicts a light “Higgs” ~ the SM Higgs.**

## h Decays to b pairs

- Signature: B-jets + lepton + E**T****miss**
-  Requires b-tagging + jet counting + full calorimeter coverage for E**T****miss**

**CMS    1 fb****-1**

- Low tan  regime

**h Decays to b pairs**

## A to  + 

**Fast simulations of b an tau tags. Background from Z, tt, Wtb**

## A to  + 

**Even in the minimal model, there is a large parameter space. This study uses hadronic tau decays.**

## A, H to  + 

**A and H are ~ mass degenerate. B tag useful for backgrounds.**

## H+-> t + b

**Charged Higgs decay into quarks. Top decays to W+b with W decay to leptons supplying the trigger.**

## H+ -> + +  

##  Heavy SUSY Higgs - 10 fb-1

- A / H            tan =30, mA=130 GeV
- A / H              tan =40, mA=200 GeV
- Some parts of the parameter space are not covered.

## Sparticle Masses

**Sparticle Masses**

- 2-body decay:  edge in M*ll*

**10 fb****-1**

**An example of the kind of analysis done, from 1 year at 1/10****th**** design luminosity.**

**Notes:**
By a year, we’ll be doing sophisticated analyses to identify and measure the masses of the lighter sparticles.  Here is an example of an analysis that uses the mass distributions from di-lepton events to get a jacobian whose leading edge is related to the mass of the second lightest neutralino.  Events with two different types of leptons are used to estimate the background distribution, which is subtracted.  

## Sparticle Cascades

**Decay chain used is :**
**Then**
**And**

## Sparticle Reconstruction

## Full CMS Exposure – Heavy States

## Composites - Jets

**If  contact interactions **
**excess at low  ********, S **
**wave scattering a la **
**Rutherford**

**2-jet events:  expect  excess of high-E****T****  centrally produced  jets.**

**Composites - Jets**

## Composites - DY

## Extra Dimensions

**Number (D) of space-time dimensions ******** form of force observed**
**E+M: F~1/r****2**** because D=3+1**
**For “ants” living in D=2+1 dimensions, E+M is actually a F~1/r force**

**Inspired by “string theory” which naturally incorporates SUSY and which requires extra dimensions to be self consistent.**

## TeV Scale Extra Dimension 

**KK excitations of the ********, Z in D-Y**
**Direct: LHC/600 fb****-1       ****6  TeV**

**Democratic Hawking evaporation ******** copious Higgs production. Study with full CMS simulation.**

## Black Hole Production at CMS

-  **Black holes decay immediately (******** ~ 10****-26**** s) **
**by Hawking radiation (democratic evaporation) :**
**large multiplicity, small missing E, jets/leptons  ~ 5.**

**A  black hole  event with  M****BH**** ~ 8 TeV**
**Spectacular signature !**

## Summary and Conclusions

**CMS is designed for discovery**
**Trigger strategy is sound (e.g. no L2)**
**Higgs is ~ assured of discovery if it exists.**
**SUSY is ~ assured if it exists as a solution of the Hierarchy problem.**
**Discoveries will come early. CMS must be ready on day one.**
**With the SLHC the program at CMS will span decades.**

## Supersymmetry 

-        Impact of the SLHC
- Extending the discovery region
- by roughly 0.5 TeV i.e. from
-        ~2.5 TeV  3 TeV
- This extension involved high
- E**T** jets/leptons and missing E**T**
-  Not compromised by increased
-     pile-up at SLHC

## Sparticle Mass Measurements

**Proposed Post-LEP Benchmarks for Supersymmetry (hep-ph/0106204)**

##  Sparticle Reconstruction 

## Level-1 Trigger Table (2x1033)

| Trigger | Threshold
(GeV) | Rate (kHz) | Cumulative Rate (kHz) |
| --- | --- | --- | --- |
| Isolated e/ | 29 | 3.3 | 3.3 |
| Di-e/ | 17 | 1.3 | 4.3 |
| Isolated muon | 14 | 2.7 | 7.0 |
| Di-muon | 3 | 0.9 | 7.9 |
| Single tau-jet | 86 | 2.2 | 10.1 |
| Di-tau-jet | 59 | 1.0 | 10.9 |
| 1-jet, 3-jet, 4-jet | 177, 86, 70 | 3.0 | 12.5 |
| Jet*ETmiss | 88*46 | 2.3 | 14.3 |
| Electron*jet | 21*45 | 0.8 | 15.1 |
| Min-bias |  | 0.9 | 16.0 |
| TOTAL |  |  | 16.0 |