Speaker
Lorenzo Calibbi
(Universitat de Valencia)
Description
We will consider a SUSY-$SU(5)$ with one right-handed neutrino with
a large top like Yukawa coupling. Assuming universal soft masses at
high scale we compute the low-energy spectrum and subsequently
the neutralino LSP relic density taking also into consideration
$SU(5)$ as well as the see-saw running effects above the gauge coupling
unification scale. We found that there exists no viable region in
parameter space for $\tan\beta~\ler ~35$. The $\tilde{\tau}$
coannihilation process starts becoming efficient for $\tan\beta~\ger~35-40$.
However, unlike in mSUGRA, this process is significantly constrained
by the limited range in which the stau is lighter than the neutralino.
In fact, for a given $\tan\beta$ we find that there exists an
upper bound on the lightest neutralino mass ($M_{\chi_1^0}$) in this
region.
The A-pole funnel region appears at very large $\tan\beta~\sim 45-50$, while
the focus-point region does not make an appearance till large
($m_0,M_{1/2})\sim$ a few TeV. Large $A_0$ terms at high scale can
lead to extended regions consistent with WMAP constraints and remove
the upper bounds in the stau coannihilation regions.
Authors
Lorenzo Calibbi
(Universitat de Valencia)
Sudhir Vempati
(IIS Bangalore)
Yann Mambrini
(LPT Paris-Sud Orsay)
