Transcript Searches for SUSY with the ATLAS detector

LHC status and plan
Osamu Jinnouchi
(Tokyo Institute of Technology)
Annual meeting for ILC detectors
2011/03/09-11
contents
• Brief overview of the ATLAS and 2010 LHC run
• Skip the SM measurements (sorry!)
• Higgs searches in 2010 and future
• SUSY searches in 2010 and future
• Upgrade plan of LHC/ATLAS
N.B. my talk is heavily biased to ATLAS results
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Very short introduction
Short history of LHC pp runs:
• 2009.11.23 the first collision @ 900GeV
• 2009.12.14 collision at 2.36TeV (energy frontier)
• 2010.03.30 started 7.0TeV run
it lasted until the end of 2010 Oct.
• integrated L=45 pb-1 recorded by ATLAS
• established peak L=2x1032cm-2s-1 (2x 2010 target
luminosity)
ATLAS status
• all systems >97% channels operational
•
(LAr: due to the noise bursts and HV trips partially recovered offline)
initial target
good quality data > 94%
Immediate future plan:
• re-start up the 7.0TeV run in March 2011 (last week)
• in 2012, continue the operation and
possibility of 8.0TeV run
• long planned shutdown after 2013
preparing for the higher energy (13-14TeV)
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% of good quality data
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ATLAS detector performance in 2010
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Inner detector
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momentum scale known to 1% level (<100GeV)
reconstruction eff > 99% (muons > 20GeV)
material distribution known better than 10% (goal is 5%)
EM Calorimeter
• scale uniformity ~2% in eta, <0.7% in phi (goal is < 1%)
• energy scale known to < 1% (goal is 0.1%)
• electron
efficiency
known with ~1%toward
precision ultimate precision
still
roomIDfor
improvements
HAD Calorimeter
but
pretty
good for a first year performance
• Jet
energy scale uncertainty 4~5% (goal is 1%)
• missing Et : good MC/data agreement
no tail from instrumental origin after calibration with 15M minbias
MUONS
• momentum scale known to 1%
• momentum resolution known to rel. 10%
Rate (2010/ design)
Bunch crossing: 1MHz/40MHz
• reconstruction eff known to 1-2% (goal is 1%)
Level-1: 20kHz / 75kHz
Trigger / Data GRID transfer
Level-2: 3.5kHz / 2kHz
Luminosity 2010 (Van der Meer scan)
EF: 300Hz / 200Hz
• final uncertainty 3.2% (most of the papers used GRID: 1-4GB/s / 2GB/s
the previous estimation 11%)
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Higgs Searches and Prospects
(SM/MSSM)
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Higgs search channels at LHC
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Two main production processes
• Gluon fusion (GGF)
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dominates by a factor of 10
Vector boson fusion (VBF)
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characteristic signature
(two forward tagging jets & rapidity)
Main decay channels
• HWW
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dominant at intermediate region and in high
mass region
HZZ
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clean signal in 4-lep final state
Hgg
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low BR, important in low mass region
Hbb
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high BR, large QCD background
Htt
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important in low mass region, important
channel for MSSM higgs
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Higgs search in 2010 ATLAS data
The analyses and approval processes on going for 36pb-1
H ®WW (*) ® n n : highest/fastest sensitivity, exclusion result
approved in ATLAS and shown today
H ® gg
: background estimation approved shown today
rest of the channels under the approval processes
(please wait for the JPS or other meetings)
H ® gg
: exclusion result, coming soon
H ® ZZ ® nn + qq : coming soon
H ® ZZ ® 4 leptons : a bit later
H ®WW ® n qq
: a bit later
•H ® tt ®
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+ h decay : coming soon
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H ®WW
(*)
® n n
Jet multiplicity
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0-jet  1-jet  2jet
common requirements
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two opposite charge leptons (ee/mm/em)
1st > 20GeV, 2nd >15GeV
Mll > 15GeV, |Mll-MZ|>10GeV (ee/mm)
missing ET> 30GeV
separate search into 0,1,2 jet bins (>25GeV)
(different productions, bkgs differ)
channel specific selections
• 0-jet
• pT(ll)>30GeV (Drell-Yan suppression)
• 1-jet, 2-jet
• b-jet veto (top suppression)
• vector PT sum< 30GeV (soft gluon
radiation suppression)
• |mtt-mZ|>25GeV(Ztt veto)
• 2-jet
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[ATLAS-CONF-2011-005]
H+0j
H+1j
VBF cuts
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H ®WW
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(*)
® n n
[ATLAS-CONF-2011-005]
exclusion limits from this channel
• 95% CL exclusion limit in
multiples of the SM cross
section, using Profile
Likelihood method with a
Power Constrained Limit
(PCL) for the 35pb-1 2010 data
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ATLAS excludes at 95% CL
SM-like Higgs boson with a
production cross section of
1.2 x SM (observed), 2.4 x SM
(expected) at MH=160GeV
This is the only higgs exclusion limit plot with data, I can show you today
with the first year of 35pb-1data, we already got very close to
the Tevatron limit
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H ® gg
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[ATLAS-CONF-2011-004]
Backgrounds
• Irreducible (qq,qqgg, qgqgg)
• reducible
• di-jet, g-jet : jet g fake
• DY Zee: eg fake
Data driven bkg estimation
• signal region: two photons pass isolation
+ tight photon selection
• double sideband method to extract the
compositions of the bkg samples
• data-driven estimate of gg, gj, jj events in
the signal region
• Drell-Yan: eg fake rate estimate
net samples: event with two
objects passed loose photon ID
photon ID
fail
photon ID
pass
ETisol[GeV]
Isolation for 1st g
photon ID
fail
photon ID
pass
ETisol[GeV]
mgg distribution for
the signal region
Isolation for 2nd g
yellow band = gg (NLO) norm + (gj+jj) data driven
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H ® gg
new projected sensitivity at 1fb-1
[ATLAS-PUB-2010-009]
[ATLAS-CONF-2011-004]
7TeV 1fb-1
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uses observed diphoton distribution, rescaled to 2011 luminosity (1fb-1)
this channel can exclude 3.2-4.2 x SM for range MH=110-140GeV
dashed line : degraded photon energy resolution (pessimistic
assumption)
similar results to previous estimation (pure simulation)
exclusion sensitivity with 37pb-1 is about to be released
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SM Higgs sensitivity in 2011 and beyond
[ATLAS-PUB-2011-001]
expected limit in 2011
with basic scenario (1fb-1)
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discovery reach
with 1fb-1 of data at 7TeV, ATLAS expects median 95% CL exclusion
over the range 130-460GeV
challenge is at low mass (require 4(3)fb-1with 7(8)TeV to cover down to
LEP limit, which might be possible by the end of 2012)
with integrated luminosity 5-10 fb-1, ATLAS will move towards discovery
over a wide mass range
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SUSY Searches and Prospects
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Expected SUSY signatures at LHC
• R-parity conserving models
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high cross sections for gluinos/squarks production
• high-pT multi jets (and leptons) from cascade decays
stable LSP
• large missing Et
• no mass peak excess in the tail of the Meff distribution
accurate understanding of detector and bkg essential
other varieties of models are also under exploit (not shown today)
• R-parity violation models (kink inside ID)
• more exotic signatures (NLSP decay in detector, slow heavy ionizing particles, Rhadrons, sparticle stop in the calorimeter, etc)
Two 2010 results “OUT” from ATLAS
• 0 lepton + multi(2,3,more)-jets + MET (arXiv:1102.5290)
• squark→q+LSP, gluino→q+squark+LSP
• QCD bkg control is critical
• 1 lepton + multi(2,3,more)-jets + MET(arXive:1102.2357)
• cascade includes electroweak decays
• dominant bkg: ttbar, W, MC shape + normalization from data
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0 lepton analysis
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4 signal regions
require exactly 0 lepton (pT>10GeV)
need to suppress QCD bkg: tight cut
adopted
• 1st jet > 120GeV
• 2nd (+3rd ) jets >40GeV
• missing ET>100GeV
dominant bkg’s: W+jets, Z(nn)+jets
4 signal regions defined (target heavy/light
qq, gg, gq) to achieve maximum reach in
msq-mgl plane
optimized the cut to general MSSM
assumption (massless neutralino)
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1 lepton analysis
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require exactly
1 electron or 1 muon (pT>20GeV)
1st jet >60GeV
2nd & 3rd jets >30GeV
after lepton+jets cut
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further requirements
• Missing ET>125GeV
• MT(lep,EtMiss) > 100GeV
• Meff > 500GeV
Backgrounds
• easier handle on QCD
• top(single, pair), W +jets dominant
• MC based estimate with
normalization to a control region
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results in table
0 lepton
No excess observed
profile likelihood method to compute 95% CL upper limit
non-SM cross sections [pb] A: 1.3 B: 0.35 C: 1.1 D: 0.11
1 lepton
No excess observed
profile likelihood method to compute 95% CL upper limit
electron: 0.065 [pb] (2.2 events) muon: 0.073 [pb] (2.5 events)
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interpretation in mSUGRA/CMSSM framework
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not believing in mSUGRA, but it serves as the common ground for
comparison across (current/previous) experiments and theories
equal squak and gluino masses, below 775/700 GeV are
excluded with 95% CL for 0/1-lepton mode
exceed results from the previous (and CMS) experiments
0-lepton analysis
1-lepton analysis
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SUSY discovery reach in 2011 and beyond
• baseline scenario is 7TeV 1fb-1 in 2011, but 2-3 fb-1 is possible reach
(Chamonix 2011)
???
???
ATLAS/CMS excluded
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empirical rough estimate of the SUSY 5s
discovery reach in different
and
follows
(
)
3
0.9
??
possible choice in 2012
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Other Exotics Searches
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quick glance for search comparisons
ATLAS
TEVATRON
CMS
excited Q
M>1.26TeV (PRL 105, 16180 (2010))
dijet mass resonance search (315nb-1)
36pb-1 result coming soon
M>0.87TeV
M>1.58TeV
2.9pb-1
Contact
Interaction
L>3.4TeV (PLB694(2011)327)
dijet angular distribution (3.1pb-1)
36pb-1 result coming soon
L>2.84-3.06TeV
L>5.6TeV
36pb-1
NONE
various limits
(35pb-1)
quantum
36pb-1 result coming soon
Black Holes
W’
36pb-1 result coming soon
M>1120GeV
M>1580GeV
(36pb-1)
Z’
36pb-1 result coming soon
M>1071GeV
M>1140GeV
(35pb-1)
UED
1/R> 728 GeV (arXiv:1012.4272)(3.1pb-1) 1/R> 477GeV
diphoton + MET
NONE
ATLAS updates (soon) will be better or similar results to CMS
exceeded Tevatron limit in the first year, no surprise yet so far
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LHC/ATLAS Upgrade Plan
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the 10 year technical plan(based on schedule @12.2010)
2011Jan Chamonix
7-8TeV: 4-8 fb-1
shutdown (fixed)
shutdown in 2016 most
likely to be delayed (no
decision yet) ???
13-14TeV:
subject to change by various conditions (physics, machine)
HL-LHC
13-14TeV: up to 300 fb-1
3000fb-1 by 2030
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General idea towards HL-LHC
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[2011-2012] 1st physics results (Higgs 3s coverage, SUSY < 1TeV)
will be accomplished with 7TeV, 5-10fb-1
[by 2020] will cover LHC design goal with 14TeV, a few 100 fb-1
[post 2020] further pursue: HL-LHC for 3000fb-1
• new physics search: further extension to higher mass scale
• high precision measurements (Higgs couplings, SUSY masses)
complementary to ILC
In any regards, the upgrade is inevitable in both LHC and Detectors
• development for more intense beams
• detectors have to survive the high lumi, and keep (or improve)
the performance
• minimize the impact to physics program & maximize the outcome
 preparation for upgrade is important whatever the run
schedule would be
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LHC upgrade for higher intensity
current LHC
[0] LHC injection chain (x2-3 lumi)
[1]
[1] new high gradient / large aperture quadruples
• Bpeak = 13-15T, b* =55cm  23cm (x2.4lumi w/ CC)
• Nb-Ti (current LHC) would not be safice
• US-LARP (LHC Accelerator Research Program) engaged to
demonstration prototype with Nb3Sn by 2013
• KEK-CERN
develops
Nb3Al 
technology choice
~2014
In both cases,
Japan’s
Accelerator
technologies
[2] RF Crab Cavities
plays crucial roles: Japan-EU-US design team
• kick beam sideway to bring
had
beenhead-on
established
the
collision
• not yet been validated for
LHC (KEKB is the only
working proof on earth)
[2]
CC
new quads
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ATLAS detector upgrade plan
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Major items towards HL-LHC
• ID: replace full ID with silicon only tracker (pixel + short strips + long
strips)
• CAL: Endcap electronics, Forward CAL may require upgrades
three upgrade scenarios/development on going
• MUON: replacement of forward tracking MDT
• TRIGGER: upgrade for L1Cal and L1Muon, and combination (e.g. nonIsolated muon)
Commitments/Contributions from ATLAS-JAPAN group
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Summary
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LHC 2010 run was successful
(not shown in detail though) SM measurements/ detector
performance were super and more than expected
with 36pb-1
• Higgs: the exclusion limits came close to Tevatron
• SUSY & Exotics : significantly exceeded Tevatron limits
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fruitful results (hopefully with surprises) are promising
in 2011-2012 run
we are getting maximum speed for an efficient genuine
collaboration works
upgrade works for HL-LHC (2020 onward) is under way
complementary and (good) competitive to ILC
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