1. SUSY search prospects with 1 fb-1 data
Rasmus Mackeprang
Discovery, center for particle physics
On behalf of the CMS and ATLAS collaborations
Ann Arbor - Dec 14, 2010

2. SUSY search prospects with 1fb-1 data
You are aware that
Supersymmetry postulates “superpartners” to the SM particles
This regularises the higgs mass
R-parity is introduced to keep the proton stable:
R = (-1)2j+3B+L
Breaking R-parity “just a little” gives an even richer phenomenology
Cascade decays
Long-lived particles
Ann Arbor - Dec 14, 2010

3. You furthermore understand that
SUSY search prospects with 1fb-1 data
You furthermore understand that
Two general-purpose experiments are operating at the LHC
Differently sized physicists
silicon det. (pixel, strips)
4T solenoid magnet
crystal EM calorimeter
σ(E)/E~3%/√E+0.003
brass/scintillator had. Calorimeter
σ(E)/E~100%/√E+0.05
muon chambers
σ(p)/p<10% at 1TeV
silicon det. (pixel, strips) +TRT
2T solenoid + toroid magnets
LAr EM calorimeter
σ(E)/E~10%/√E+0.007
steel/scintillator had. calorimeter
σ(E)/E~50%/√E+0.03
muon chambers
σ(p)/p<10% at 1TeV
Ann Arbor - Dec 14, 2010

4. Taking a step back… LHC Tevatron
SUSY search prospects with 1fb-1 data
Taking a step back…
LHC
Tevatron
arXiv:
So, the SM seems best left to the Tevatron for the next year
Huge inroads exist into BSM physics, though
Orders of magnitude to be found in some production cross sections
Ann Arbor - Dec 14, 2010

5. SUSY is a broad concept…
SUSY search prospects with 1fb-1 data
SUSY is a broad concept…
The MSSM contains a mere 120 parameters
Not-so-minimal models even more
Parameterized classes of theories based on physics assumptions introduce dependencies between parameters
(e.g. mSUGRA, GMSB, AMSB…)
One can construct (theoretically well motivated) models that fall outside the phenomenologies spanned by these models
Do model-independent searches for generic signatures
that can be discerned from the SM
In preparation, scan parameter spaces
of the different theories
All these people… Looking for me?
Ann Arbor - Dec 14, 2010

6. A typical day at the LHC…
SUSY search prospects with 1fb-1 data
A typical day at the LHC…
2 b-jets
2 jets
1 lepton
Missing ET
LHS-2
SPS 1a
Lepton reconstruction and identification
Jet reconstruction (and energy scale)
Missing ET
Ann Arbor - Dec 14, 2010

7. Missing transverse energy is traditionally hard…
SUSY search prospects with 1fb-1 data
Missing transverse energy is traditionally hard…
Stick in non-minbias
ATLAS-CONF
CMS-PAS-JME
CMS-PAS-JME
Ann Arbor - Dec 14, 2010

8. Beating Back the Background
SUSY search prospects with 1fb-1 data
Beating Back the Background
= 0.5 for a well-reconstructed QCD event
One central jet (|η|<2)
Two jets over 100 GeV
10 TeV study
Cut on fraction of missing transverse jet momentum carried by soft jets
HT: Scalar sum of transverse jet momenta
MET cut is on Jet MET only
Ann Arbor - Dec 14, 2010
CMS PAS SUS

9. General strategies Look for 1, 2, 3, 4 lepton events (+ jets + MET)
SUSY search prospects with 1fb-1 data
General strategies
Look for 1, 2, 3, 4 lepton events (+ jets + MET)
Peaks
Edges
All-hadronic channels
Normalizations
Search for stable massive particles
Monojet signatures
Anomalous energy depositions
Out of time
Stopping in the detector and decaying later
Ann Arbor - Dec 14, 2010

10. Got to start somewhere SU4 (mSUGRA)
SUSY search prospects with 1fb-1 data
Got to start somewhere
SU4 (mSUGRA)
m0 = 200 GeV m1/2 = 160 GeV A0 = −400 GeV tanβ = 10
μ > GeV σ = 51 pb
Requiring leptons costs in yield
Reduces backgrounds too, though.
Ann Arbor - Dec 14, 2010
ATL-PHYS-PUB

11. Benchmarking in mSUGRA
SUSY search prospects with 1fb-1 data
Benchmarking in mSUGRA
0 and 1 lepton channels give largest significance
Gluino and squark masses up to ~700 GeV should be 1 fb-1
(if close)
ATL-PHYS-PUB
Significant improvement can be made on Tevatron limits during the next year.
CMS exclusion prospects for another mSUGRA scenario
CMS NOTE 2010/008
Ann Arbor - Dec 14, 2010

12. Two different samplings of parameter space
SUSY search prospects with 1fb-1 data
Two different samplings of parameter space
14 TeV study…
Can we detect the MSSM?
arXiv:
107 points defined in pMSSM
70k found to be allowed
Theoretical constraints
Precision measurements (g-2)μ
DM < WMAP measurement
Tevatron constraints
LEP constraints
ATLAS has 11 different “standard” searches defined
(CERN-OPEN )
Start counting…
Higgs potential bounded from below
EWSB
WIMP LSP thermal relic density …
There could be other sources of DM
Ann Arbor - Dec 14, 2010

13. How did we do? Call 1-800-CERN…
SUSY search prospects with 1fb-1 data
14 TeV study…
How did we do? Call CERN…
arXiv:
“Discovery yield:”
Systematic SM BG error
1 TeV
3 TeV
50 %
99.4 %
68.1 %
20 %
99.9 %
81.3 %
Caveat…
Prospino 2.1, NLO
CTEQ6
All other SUSY masses 10 TeV or higher…
Ann Arbor - Dec 14, 2010

14. A aside on long-lived particles
SUSY search prospects with 1fb-1 data
14 TeV study…
A aside on long-lived particles
Adopted from a table in…
arXiv:
Many models feature “CHAMPS”
R-hadrons remain an option
Mechanisms for LLP
Ann Arbor - Dec 14, 2010

15. Bottom-up Several candidates in the context of SUSY
SUSY search prospects with 1fb-1 data
Bottom-up
Several candidates in the context of SUSY
: Anomalous and late ionization
Cascade decays
Strong production  High cross section
Pair production
Hadronic interactions and theoretical uncertainties make life tricky…
hep-ph/ v2
Ann Arbor - Dec 14, 2010

16. MET? (jets, leptons, MET…) SUSY cascade Jet? Signatures of SMPs MU HAD
SUSY search prospects with 1fb-1 data
Signatures of SMPs
“Anomalously ionizing muon”
MET?
(jets, leptons, MET…)
SUSY cascade TR EM
HAD MU
Anomalous dE/dx or ToF
Monojet searches
Stopped sparticle decays
 All being actively pursued by both experiments
Out of time decays
Jet?
Ann Arbor - Dec 14, 2010

17. SMP prospects for the coming year
SUSY search prospects with 1fb-1 data
SMP prospects for the coming year
198 nb-1
284 GeV
Exclusion
One could hope to push coloured stable sparticle limits significantly towards 1 TeV within a year
No statement on staus as yet
Discovery potential:
Discovery
Assumptions:
High squark mass for the gluino result
Possible signal in muon system
Ann Arbor - Dec 14, 2010

18. Prospects for stopped gluinos
SUSY search prospects with 1fb-1 data
Prospects for stopped gluinos
Limiting life-time for one set of masses
CMS EXO
Gluino mass limit with fixed mass splitting to the neutralino
A 300 GeV gluino decaying to a 100 GeV neutralino is discoverable in 1032 Hz/cm2
CMS NOTE 2010/008
Significance falls off steeply with mass
Ann Arbor - Dec 14, 2010

19. Who said Nature would be “minimally” anything?
SUSY search prospects with 1fb-1 data
Who said Nature would be “minimally” anything?
Add a baryon-number violating term to the Soft SUSY breaking part of the Lagrangian
Presto:
kT jets with R=0.7:
Y1 is the last merging and so on…
4 jets in |η|<2.5
2 with PT > 275 GeV
y2 > y
2 jets with PT > 135 GeV
SPS 1a + RPV
ATL-PHYS-PUB
Lesson:
Not difficult to see, but you have to look…
1 fb-1
10 TeV
Ann Arbor - Dec 14, 2010

20. So, how’s the next year going to look?
SUSY search prospects with 1fb-1 data
So, how’s the next year going to look?
We’re going to be looking at plots like this:
Maybe you shouldn’t be expecting 70 k exclusion limits ;-)
A lot will be clearer though
CMS NOTE 2010/008
ATL-PHYS-PUB ? ?
Discovery?
Of what?
Ann Arbor - Dec 14, 2010

21. Backup slides SUSY search prospects with 1fb-1 data
Ann Arbor - Dec 14, 2010

22. CMS focus point definitions
SUSY search prospects with 1fb-1 data
CMS focus point definitions
Ann Arbor - Dec 14, 2010