M ar 2 00 9 Yukawa Unification and Neutralino Dark Matter in SU ( 4 ) c × SU ( 2 ) L × SU

We consider a left-right symmetric SU(4)c×SU(2)L×SU(2)R (4-2-2) model with gravity mediated supersymmetry breaking. We find that with 4-2-2 compatible non-universal gaugino masses, t−b−τ Yukawa coupling unification is consistent with neutralino dark matter abundance and with constraints from collider experiments (except (g − 2)μ). The gluino mass lies close to that of the lightest neutralino, so that the gluino co-annihilation channel plays an important role in determining the neutralino relic abundance. By relaxing the Yukawa unification constraint we find stau and stop masses as low as 200 − 220 GeV. We highlight some benchmark points for these cases with 40 ≤ tanβ ≤ 58. E-mail: [email protected] On leave of absence from: Andronikashvili Institute of Physics, GAS, 380077 Tbilisi, Georgia. E-mail: [email protected]