Parallel Session 2 Collider Phenomenology (SUSY) 

Title: 
Measurement of Dark Matter Relic Density in the mSUGRA Co-annihilation Region at the LHC

Abstract:
We examine the stau-neutralino co-annihilation (CA) mechanism of 
the early universe using the minimal supergravity (mSUGRA) model 
at the LHC. The CA region is one of four distinct regions picked
out by the cold dark matter constraints and where both m_0 and 
m_1/2 can be small after all experimental constraints such as
measurements of the b --> s gamma decay branching ratio and the 
muon g-2 are included. The sigral in the CA region is characterized
by a small mass difference (~5-15 GeV) between the lightest stau 
and the lightest neutralino. An accurate measurement of the small 
mass difference at a collider is crucial to confirm the CA mechanism.  
From measurements at the LHC we show one can predict the dark matter 
relic density with an uncertainty of 4% (6%) with 70 (30) fb-1 of 
data, which is comparable to the direct measurement by WMAP. This 
is done by measuring four mSUGRA parameters m0, m1/2, A0 and tanB 
in the CA region without requiring direct measurements of the stop 
and sbottom masses. We also provide precision measurements of the 
gaugino, squark, and lighter stau masses without the mSUGRA 
assumption. This allows us to test the gaugino universality condition
at the GUT scale in  this CA region. 

Comments:
This talk is based on the following papers: 
arXiv:0802.2968v1 [hep-ph]; 
Phys. Lett. B649 (2007) 73; 
Phys. Lett. B639 (2006) 46.

Co-authors:
Prof. ARNOWITT, Richard (Texas A&M University) 
Prof. DUTTA, Bhaskar (Texas A&M University) 
Prof. KAMON, Teruki(Texas A&M University) 
Prof. TOBACK, David (Texas A&M University) 
Mr. KRISLOCK, Abram (Texas A&M University) 
Mr. GURROLA, Alfredo (Texas A&M University)