1. Inclusive Measurements as an mSUGRA Signal with ATLAS
David López Mateos, September 2, 2006
Approaches to Discovering SUSY
The ATLAS Detector
Data Analysis
Discovery Reach and Implications
Advisor: Emlyn W. Hughes, Columbia University
Contact:

2. Reducing the Parameter Space
Extend the Standard Model to include SUSY (MSSM)
MSSM has 105 extra parameters
Assume SUSY Breaking mechanism (higher-scale theory)
Gravity-Mediated (Supergravity, SUGRA)
Gauge-Mediated (GMSB)
Anomaly-Mediated (AMSB)
Even if the physical SUSY is not the MSSM,
MSSM should be a good first approximation
44th EMISSP 4/9/2006
David LOPEZ MATEOS

3. SUGRA Essentials
Promote SUSY to be a local symmetry (same as local invariance under full Poincaré algebra)
SUSY Breaking caused by gravitational strength interactions between hidden sector and the MSSM
Theoretical Framework for RGE evolution
Still not many simplifications with respect to MSSM
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David LOPEZ MATEOS

4. mSUGRA Essentials Flavor-blind interactions communicate SUSY breaking:
universality
At the SUSY
breaking scale: u d
sgn{}
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5. mSUGRA at the LHC Heavy LSP in all the allowed parameter space
Trigger on missing ET
Strong interactions dominate production
Gluino and squark production
Specific decay chains can be assumed for
reconstruction
Missing ET, jets and leptons
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David LOPEZ MATEOS

6. Overview of ATLAS Tile calorimeters LAr calorimeters Muon chambersy
,   z x
Superconducting
coil: B= 2 T
Inner tracker
Toroidal
magnets
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David LOPEZ MATEOS

7. Challenges of the Analyses
Understanding the detector
Understanding the background
Determination of the energy scale
Z+multijet, with Z  (or )
W+multijet, with W l
tt production and decay
QCD multijet processes
these can be simulated, but also calculated from
other measurements
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David LOPEZ MATEOS

8. Determination of the Energy Scale
Need an understanding of the whole detector
Hadronic jets limit the scale determination (~5-10%)
Calibration
Detector effects
For ||<3.2:
For ||>3.2:
~1%
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9. Updated ATLAS Studies Fast detector simulation
Online trigger: ETsum+Etmiss>60 GeV+60 GeV
Cuts were optimized
In the experiment:
No discovery: limits on SUSY cross-sections
Discovery: probably a signal consistent over
a region of parameter space (with different cuts)
D. R. Tovey, SN-ATLAS
44th EMISSP 4/9/2006
David LOPEZ MATEOS

10. No Discovery Scenario M1/2 (GeV) M1/2 (GeV) M0 (GeV) M0 (GeV)
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11. Discovery Scenario: the Scale of SUSY
If there is a discovery, missing ET spectrum
determines the scale of SUSY
Meffsusy (GeV)
Mest (GeV)
m0=100 GeV
m1/2=300 GeV
A0=300 GeV
>0
tan=2.1
Mest (GeV)
d/dMest (mb/400GeV)
~20% 10 fb-1
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12. mSUGRA Constraints and Checks
M1/2 (GeV)
Contours of
constant
M0 (GeV)
mSUGRA missing ET
vs GMSB missing ET
susy (mb)
Meffsusy (GeV)
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13. Summary and Implications
Mass scale of SUSY in the most favored models
can be determined very early on in the Physics program
Inclusive measurements will guide exclusive
measurements and will provide evidence of SUSY breaking
mechanism
mSUGRA can easily give Dark Matter
SUSY as a solution to the Hierarchy Problem
will be found or almost ruled out at the LHC
A very attractive theory, a wealth of Physics to unveil
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14. Discovery Reach and Luminosity
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15. Top Background T. Plehn, D. Rainwater and P. Skands. hep-ph/0510144
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