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BSM Searches:BSM Searches:From Tevatron to LHCFrom Tevatron to LHC
– LHC start-up
– Tevatron → LHC: examples & lessons?
– Plans for “Early Physics”
(mostly material collected from various recent talks)
Arnd Meyer
RWTH Aachen
22. February 2007
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 2
LHC: 22+ Years
1984: cms energy 10-18 TeV Luminosity 1031-1033cm-2s-1 1987: cms energy 16 TeV Luminosity 1033-1034cm-2s-1
Final: cms energy 14 TeV Luminosity 1033-1034cm-2s-1
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 3
LHC EndgameCrucial part: 1232 superconducting dipoles Can follow progress on the LHC dashboardhttp://lhc-new-homepage.web.cern.ch/lhc-new-homepage/
The LHC Schedule
• LHC will be closed and set up for beam on 1 September 2007
LHC commissioning will take time!• First collisions expected in November/December 2007
A short pilot runCollisions will be at injectionenergy i.e. cms of 0.9 TeV
• First physics run in 2008 ~ 0.1-1 fb-1? 14TeV! • Physics run in 2009 +… 10-20 fb-1/year ⇒ 100 fb-1/year
(Unofficial luminosity estimates)
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 4
LHC Endgame
Magnet Installation Progress
L. Evans: Presentation made to the Open Session of the LHC Machine Advisory Committee, 7 December 2006
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 5
LHC Endgame
November 2007First beam 450 GeV
Summer 2008First physics run 7 x 7 TeV
August 2007Machine closed
April 2007End installation
November 2006Last magnet delivered L. Evans: 20/2/07
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 6
LHC Start-up Schedule 2007M. Lamont
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 7
LHC Staged Commissioning for 2008
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 8
LHC Start-up
Obvious: considerable uncertainties in schedules
Dare to compare Tevatron Run II?
Summer 2000 engineering run (few stores with collisions)
April 2001 Run II started
February – April 2002 experiments collect “physics quality” data
Could it be done faster at the LHC? Maybe
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 9
General Purpose Detectors at the LHC
• Central tracker• EM calorimeter• HAD calorimeter• Muon Detectors
Trigger: Reduce 40 MHz collision rate to 100 Hz event rate to store for analysis
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 10
ATLAS and CMS Detectors
ATLAS cavern, 2006
CMS cavern, 2006
November 2006•ATLAS barrel toroid magnet reaches full current•ATLAS barrel tracker installed (TRT connected)•Endap muons being installed
All CMS tracker elements at CERN (integration ongoing!)CMS lowers first detector into cavern (forward calo) Lowering on weekly basis since then
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 11
Detectors at Start-Up in 2007Detectors progressing welland will be fairly completeat start-up
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 12
Expected Detector Performance
O(10 µm)20—200 µm in rφTracker alignment
1%<10%Jet energy scale
< 1%2—3% HCAL uniformity
0.1%0.5—2%Lepton energy scale
< 1%~ 1% ATLAS~ 4% CMS
ECAL uniformity
Goals for PhysicsExpected Day 0
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 13
Start-Up Physics: 2007
F. Gianotti/ICHEP06
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 14
Start-Up Physics: 2008
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 15
Trigger Menu (Later)
Typical LVL1menu forL= 2 ⋅ 1033cm-2s-1
– all thresholds are adjustable
– multiple objects allow lower thresholds
total rate ~20kHz
(allowing safetymargin and newideas)
21 and 45Electron and Jet
60 and 60Jet and ETmiss
+calibration, monitoring, etc…
-15*10Electron-Muon
177,86,70200,90,651-jet, 3-jets, 4-jets
-25 and 30τ-jet and ETmiss
59-Two τ-jet
86-Inclusive τ-jet
36Two muons
1420Inclusive isolated muon
1715Two electrons/Two photons
2925Inclusive isolated e/γ
CMS (GeV)Threshold
ATLAS (GeV)Threshold
Trigger type
D.Rousseau
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 16
New Phenomena is Approximately:
SupersymmetrySupersymmetry Bread and butter RPC MSSM
Jets + MET, 3rd Gen., lepton(s) from cascade decays, ...
R-Parity Violation
Long-Lived Particles (AMSB, split SUSY, RPV, ...)
Gauge Mediated SUSY Breaking
Extra DimensionsExtra Dimensions Monojets, di-leptons and di-photons
Extra Gauge BosonsExtra Gauge Bosons W´, Z´
LeptoquarksLeptoquarks 1st, 2nd, 3rd Generation
CompositenessCompositeness Lepton and Quark Substructure
AlternativesAlternatives Technicolor, Little Higgs, ...
UnknownUnknown Signature Based Searches
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 17
New Physics Reach at the LHC
100 GeV – 1 TeV (30 fb-1)covers full (mA, tanβ)
~ 3 TeV (300 fb-1)~ 5 TeV (100 fb-1)~ 25 / 40 TeV (30 / 300 fb-1)~ 6.5 / 3 TeV (100 fb-1)~ 9 / 6 TeV (100 fb-1)~ 6 TeV (100 fb-1)< 6 – 10 TeV
SM HiggsMSSM HiggsSUSY (squark, gluino)New gauge bosons (Z’)Quark substructure (ΛC)
q*, l*Large ED (MD for n=2,4)
Small ED (MC)
Black holes
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 18
CMS Physics TDR
650 pages308 figures 207 tables1.50 Kg
http://cmsdoc.cern.ch/cms/cpt/tdr/CERN/LHCC 2006-001 CERN/LHCC 2006-021 February 2006 June 2006 ATLAS Performance and
Physics TDR published in1999 – consistent set ofnew notes in Spring 2007
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 19
The SUSY Landscape at 1 fb-1
SUSY cross sections can be large. O(100 pb) for squarks / gluinos (105 sparticles in 1 fb-1).
First priority: discoverytools for 1 fb-1
SUSY manifests itself as:
Conventional jets+MET?
Leptons + jets + MET?
GMSB with photons?
Long lived R-hadrons?
SUSY signatures, however, are very diverse! Many different signatures could be “the one” we need to be ready for.
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 20
The Physics LandscapeBeyond SUSY, there are many other possible models of newphysics that could easily produce results in 1 fb-1. While SUSY may be popular, all that is certain is a high probability for some sort of new physics in the LHC range.
Need to be ready: Nature could be kind and give us new physics quickly.
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 21
Do we have the tools to properly model MET resolution (real zero bias overlay, etc.)
Do we have tools to “clean” MET, and remove contributions from hot channels, cosmics, beam-halo, etc.?
Do we know how to get the jet energy scale for the highest energy jets?
Can we trigger on massive, slow-moving particles?
Can we trigger on signatures that contain a very large number of low PT particles?
Can we trigger on... what we do not know yet?
– We have to confront these challenges before startup and in parallel: work within one physics group must not distract from work in the detector performance / trigger / simulation / ... groups.
BSM challenges the detector hardware, reconstruction algorithms, and trigger
Connect to Detector, Reconstruction, Trigger, ...
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 22
Benchmark analyses can be the guide towards extracting the physics from the first data. The documentation can be the “template” for the first papers, and the tools developed will be used with the first data.
To be useful, need to deliver them in time (by late 2007).
The Path to Benchmark Analyses (CMS)
Trigger path defined and studied, and trigger efficiencies measured and understood, with appropriate dataset definitionsDevelop and apply methods for extracting backgrounds and efficiencies, from data wherever possible. Definition of trigger paths and data sets needed for data-based efficiency and background measurementsFull systematics for startup luminositiesJustified selection criteriaMethods of demonstrating robustness of signal and correctness of background prediction
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 23
Based on physics prejudice and feasibility with 1 fb-1:
A. mu+jets+MET (mu based trigger paths)e+jets+MET (e based trigger paths)
B. Jet + MET (jetMET based trigger paths)
C. Di-object resonances (dielectron, dimuon, ditau, dijet, diphoton)
D. Photons / jets / MET
E. SUSY reconstruction methods – model parameter extraction and model discrimination (is it SUSY? UED? Little Higgs? etc.?)
Examples for Benchmark Analyses (CMS)
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 24
Map
Trigger / object path → benchmark physics → key experimental issues:
GeV muon-based samples → MSSM SUSY search Understand tails on MET
TeV muons → Zprime search Stress high pT lepton ID
GeV electron-based samples → MSSM SUSY search Understand difficult physics bgrds.
TeV electrons → Zprime search Stress high pT lepton ID
Tau-based samples → MSSM SUSY Instrumental backgrounds
GeV jet-based samples → MSSM SUSY search Trigger / “cleanup” problems
Tev jets → Zprime search High ET jet calibration
Photon-based samples → GMSB QCD fakes
Heavy stable particles → stable stau Relation to ID groups
SUSY-reconstruction → MSSM SUSY Prepare for success
Examples for Benchmark Analyses (CMS)
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 25
Example: DØ Run II NP Publications
17 publications on a wide variety of topics (CDF numbers similar)
8 x supersymmetry8 x supersymmetry
4 x leptoquarks4 x leptoquarks
2 x excited fermions2 x excited fermions
2 x extra dimensions2 x extra dimensions
1 x signature based1 x signature based
Time lag between “data taken” and publication: few months (“discoveries”) to ~3 years
Physics data taking since 2002 – first publication 2004 (“beat” Run I)
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 26
Constraints for “Early Physics”
Early physics results will be those that do not (strongly) depend on Monte Carlo
For searches, this implies
Something that “sticks out” (resonance, “bump-search”), or
Backgrounds can be modeled from data, or
Signal is so big that backgrounds become less important (unlikely, luminosity accumulates slowly!)
Keep it simple!
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 27
Constraints for “Early Physics”
Early physics results will be those that do not (strongly) depend on Monte Carlo
ComputingComputing(working, not perfect)
DetectorDetector(working, partially)
Monte CarloMonte Carlo(Physics, SM and
beyond)
Analysis(analysis tools)
ReconstructionReconstruction(also development detailed knowledge) Need all 5 shortcuts
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 28
Discoveries
Not always on day oneTop discovery: 7 years after turning on TevatronIn 2006, 18 years after “day one”:
Bs mixing
WZ production Single top
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 29
Example: Squarks and Gluinos
New “dijet” candidate with highest MET
Jet 2: (174.3 ,-0.37,0.12)
Jet 1: (282.4 ,-0.18,1.52)
MET = 369 GeV
LSP assumed stable(R
p conserved)
2 jets + MET
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 30
Example: Squarks and Gluinos / METMost of the time, a problem in online data taking will generate “fake” METExcellent detector operations are needed to trigger on META perfect understanding of the calorimeter is required to control the MET tailA huge amount of work, online and offline, prior (parallel?) to physics analysis
Patrice Verdier
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 31
Example: Squarks and Gluinos / MET
Choosing the wrong vertexis often the main sourceof QCD background inanalyses where MET is
important
Patrice Verdier
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 32
Example: Squarks and Gluinos / MET
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 33
Example: Squarks and Gluinos / MET
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 34
Squarks and Gluinos: Lessons?
Run II started in 2002, first publication in 2006...
Should have had experience from Run I
But: different people, different software, different detector, different ...
Had 6 years between end of Run I and beginning of Run II
Lack of competition cannot be an excuse
DØ vs. CDF. Still no CDF publication on the subject in Run II
Collaborations with > 600 people (still lack of people?!?)
Maybe SUSY did not have the priority
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 35
Squarks and Gluinos: Lessons?
Having triggers ready and understand them
Understanding jets and MET – same people who may commission the detector, work on trigger
Understanding SM background processes, in particular where predictions are uncertain (V + jets)
CMS / ATLAS (?): ask for people interested in measuring the water pressure in the restrooms, and you'll get 100 answers
But does the “important” work get done? Organization?
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 36
SUSY Expectations for early LHC
Inclusive channel leading
Others not far behind
Leptonic channels maybe there sooner
Need redundancy &confirmation
Low mass SUSY could be in the data early on – time to discovery
is then determined by understanding of SM processes:
W+jets, Z+jets, top, ...
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 37
Charginos / Neutralinos“Golden channel” at Tevatron: Cascade decays involving leptons three charged leptons + ME
T
But: small event rate ( x BF < 0.5pb), soft leptons
Selection (6 channels in DØ): Three leptons (ll + track), p
T > 3 GeV
(or higher depending on channel) Missing transverse energy Veto events with Z ll decays
Backgrounds
Multijet events with misidentified leptons
Drell-Yan, Z-production with Z ll
Di-boson
Still challenging – but first publication earlier than inclusive channels
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 38
Gauge Mediated SUSY BreakingGauge Mediated SUSY Breaking: Gravitino G is LSP
Possible scenario: neutralino NLSP, γG
Chargino / neutralino production leads to final state γγ + ET
Inclusive search for 2 photons plus ET (∫L dt = 760 pb-1)
~01
~
~
Limits for chargino and neutralino (N5=1, M
m=2, tan=15, >0):
m(m( ) > 120 GeV) > 120 GeV m(m(±±) > 220 GeV) > 220 GeV01
~ ~
Lifetime unknownAssume here:prompt decay
Selection: Two central photons with ET > 25 GeV
Optimized cut ET > 45 GeV
Data: 4 events, expect 2.1 ± 0.7 events background
Backgrounds estimated from data
→ little MC dependence
Predecessor of this analysis was the first
Run II DØ NP publication
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 39
Backgrounds in GMSB Search
Background without true MET: QCD multijet, direct photon, Z → ee
“Invert” suitable photon ID criterion (shower shape) → “QCD sample”
Verify that the resulting sample has characteristics similar to di-photon sample
Normalize the QCD sample at low MET, using the shape to extrapolate to high MET
Background with true MET (small): Wγ, ttbar, etc.
Start from eγ sample
Subtract QCD background, using low MET normalization
Apply e→gamma fake rate measured from Z → ee events
(GMSB can of course also lead to “delayed” photons, maybe not for day one)
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 40
Unusual signatures: Stopping GluinosGluinos hadronize into R-hadrons. Charged R-hadrons can lose all their kinetic energy through ionization and come to rest. See hep-ph/0506242 (“split SUSY” heavy squarks, light gauginos)
Lifetime between 10 ns and 100 sec, decay into jets + ET (LSP)
Tevatron: ~500 “stopped gluinos” in 2 fb-1 for m(gluino) = 300 GeV
DØ analysis: Exactly one central, “broad” jet with E
T > 90 GeV
“Rapidity gap” trigger, as veto against pp interaction No primary vertex, veto against muons
Signal MC
m(gluino)=400GeV m(LSP)=90GeV
– Backgrounds (beam halo, cosmics, detector, ...), trigger, readout challenging
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 41
Stopping Gluinos, R-Hadrons
A.Arvanitaki, S.Dimopoulos, A.Pierce, S.Rajendran, J.Wacker
O(106) stopped gluinos / 100 fb-1
LHC 100 fb-1
Tevatron 2 fb-1
GEANT simulation: energy loss of a 300 GeVR-hadron in the ATLAS calorimeter
For > 0.5, discovery potential forR-hadrons up to ~ 1.5 TeV
If the stopping gluinos aremissed, maybe those that sailthrough will be found...
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 42
More Unusual Signatures
Neutral long-lived particles, e.g. RPV SUSY → ability to reconstruct displaced vertices >> cm, and trigger on such topologies
Charged massive stable particles: staus, or charginos in AMSB → dE/dx or timing to identify slow-moving particles
“Late” photons (GMSB with long-lived Neutralino) → ability to recognize non-pointing photons
......
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 43
Special Signatures
In some models/phase space the gravitino is the LSPThen the NLSP (neutralino, Stau lepton) can live ‘long’Eg. χ→γ+ gravitino or heavy (slow) stau slepton
Signatures• Displaced vertices• Non-pointing showers• Long lived ‘heavy muons’ (time of flight)
Challenge to the experiments!
E.g. GMSB
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 44
Special Signatures
... and in fact some signatures may be more accessible (or only)at “low” luminosities
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 45
Signature Based Searches
The simplest example: di-lepton anomalies
Border between“model-dependent” and“model-independent”is fuzzy
First months of operation
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 46
Summary
Little time left before LHC starts up
Transition Tevatron → LHC without long lasting gap → synergies
For sure we don't want to miss anything exciting, and there are plenty of opportunities (apologies for only mentioning a small fraction today)
Arnd Meyer (RWTH Aachen) 22. February 2007 Page 47
Large Extra Dimensions
Main search streams:
Real graviton emission Apparent energy-momentum non-conservation in 3D-space
⇒ “Monojets” Direct sensitivity to the fundamental Planck scale MD
GKK
gq
q GKK
gg
g
V
V
GKKGKK
f
ff
fVirtual graviton exchange Modifies SM cross sections Sensitivity to the theory cutoff MS
(MS expected to be ∼ MD)
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