Launch09 Sascha Caron (Freiburg)

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Launch09 Sascha Caron (Freiburg)

Transcript Of Launch09 Sascha Caron (Freiburg)


Sascha Caron (Freiburg)

 Dark Matter (DM) production at LHC  LHC , ATLAS and CMS status  Search strategies and prospects  Measurement of DM properties  Summary and Outlook

Dark Matter and the LHC

Evidence from Astroparticle physics
• Dark Matter • Assumptions

Theoretical connections
• Supersymmetry • Extra Dimensions • … , ??

Consequences for LHC
• LHC phenomenology • Model testing

Dark Matter and the LHC : Astro
Evidence from Astroparticle physics mainly based on gravitational interactions Good candidate: - Non-relativistic (Cold Dark Matter) - Massive - Electrically and color neutral Furthermore mainly concentrate on: - Weakly interacting (WIMP) - The amount of WIMP DM suggests a new particle (in thermal equilibrium in early Universe) with a mass of O(100 GeV) at an electroweak annihilation cross section

Dark Matter and the LHC : Astro
O(100 GeV): This is the Electroweak scale According to some of the most interesting theories describing DARK MATTER it might be visible at LHC energies No particle in the Standard Model of particle physics has the right properties

Dark Matter and the LHC : Theory
Connection from Astrophysics and LHC physics via theoretical models:
Many theoretical models developed to solve other mysteries of the SM like the fine-tuning problem of EWSB turn out to deliver perfect candidates for cold dark matter
Huge amount of models on the market, the most popular classes of models are: -Supersymmetry -Extra Dimensions -Others (Little Higgs, etc.)

Dark Matter and the LHC : Theory
SUPERSYMMETRY (SUSY) is an extension of the Standard Model with a new symmetry between half-integer spin fermions and integer spin bosons.
Most studied new physics theory at LHC for several reasons : -Fermion and Boson loops protect the Higgs mass at large energies (solves “fine tuning”) -SUSY is a broken symmetry and thus offers (with R-parity conservation) perfect candidates for DM -Gauge couplings unification, “radiative” EWSB, …

SUSY Reminder
Models of SUSY breaking

MSSM particle Zoo

>100 parameters in MSSM
Sub-models with Less parameter: mSUGRA GMSB AMSB etc.

SUSY breaking mechanisms generate masses

Dark Matter and the LHC : Signal
SUSY leads to a huge increase in the number of particles and parameters which makes it a priori not so predictive for LHC phenomenology. Searches need to be quite general and model-parameter-independent

SUSY particles

Typically production of SUSY particles which cascade decay to Lightest SUSY particle (LSP)

DM candidates in Minimal Supersymmetric SM: - Lightest Neutralino (the WIMP candidate) - Gravitino (gravitational interacting spin 3/2)
LSP SM particles - Sneutrinos (largely excluded by direct DM searches)

Dark Matter and the LHC : Signal
If R-Parity is conserved then SUSY particles are pair produced.
LHC: Due to strong force dominant production of squarks and gluinos (if not too heavy) Cascade decay to lighter SUSY particles and finally the lightest SUSY particle (LSP)
The “Standard signals”:
Missing transverse energy (MET), maybe jets, maybe leptons, maybe photons
The “non-standard signals”:
New heavy particles with lifetime, non pointing photons , no MET, ….
Interesting: Similar conclusions for Universal Extra Dimension, ADD, Little Higgs, ….