Speaker
Description
The notion of stringy naturalness– that an observable O2 is more natural than O1 if
more (phenomenologically acceptable) vacua solutions lead to O2 rather than O1– is
examined within the context of the Standard Model (SM) and various SUSY extensions:
CMSSM/mSUGRA, high-scale SUSY and radiatively-driven natural SUSY (RNS). Rather
general arguments from string theory suggest a (possibly mild) statistical draw towards
vacua with large soft SUSY breaking terms. These vacua must be tempered by an anthropic veto of non-standard vacua or vacua with too large a value of the weak scale
mweak. We argue that the SM, the CMSSM and various high-scale SUSY models are all
expected to be relatively rare occurances within the string theory landscape of vacua. In
contrast, models with TeV-scale soft terms but with mweak ∼ 100 GeV and consequent
light higgsinos (SUSY with radiatively-driven naturalness) should be much more common
on the landscape. These latter models have a statistical preference for mh ' 125 GeV
and strongly interacting sparticles beyond current LHC reach. Thus, while conventional
naturalness favors sparticles close to the weak scale, stringy naturalness favors sparticles
so heavy that electroweak symmetry is barely broken and one is living dangerously close to
vacua with charge-or-color breaking minima, no electroweak breaking or pocket universe
weak scale values too far from our measured value. Expectations for how landscape SUSY
would manifest itself at collider and dark matter search experiments are then modified
compared to usual notions.
