Weak Scale Supersymmetry Emergent from the String Landscape.

Superstring flux compactifications can stabilize all moduli while leading to an enormous number of vacua solutions, each leading to different 4-d laws of physics. While the string landscape provides at present the only plausible explanation for the size of the cosmological constant, it may also predict the form of weak scale supersymmetry which is expected to emerge. Rather general arguments suggest a power-law draw to large soft terms, but these are subject to an anthropic selection of a not-too-large value for the weak scale. The combined selection allows one to compute relative probabilities for the emergence of supersymmetric models from the landscape. Models with weak scale naturalness appear most likely to emerge since they have the largest parameter space on the landscape. For finetuned models such as high-scale SUSY or split SUSY, the required weak scale finetuning shrinks their parameter space to tiny volumes, making them much less likely to appear compared to natural models. Probability distributions for sparticle and Higgs masses from natural models show a preference for Higgs mass mh∼125 GeV, with sparticles typically beyond the present LHC limits, in accord with data. From these considerations, we briefly describe how natural SUSY is expected to be revealed at future LHC upgrades. This article is a contribution to the Special Edition of the journal Entropy, honoring Paul Frampton on his 80th birthday.

Same-sign diboson signature from supersymmetry models with light Higgsinos at the LHC.

In supersymmetric models with light Higgsinos (which are motivated by electroweak naturalness arguments), the direct production of Higgsino pairs may be difficult to search for at the LHC due to the low visible energy release from their decays. However, the wino pair production reaction W2(±)Z4→(W(±)Z1,2)+(W(±)W1(∓)) also occurs at substantial rates and leads to final states including equally opposite-sign and same-sign diboson production. We propose a novel search channel for LHC14 based on the same-sign diboson plus missing ET final state which contains only modest jet activity. Assuming gaugino mass unification, and an integrated luminosity ≳100 fb(-1), this search channel provides a reach for supersymmetry well beyond that from usual gluino pair production.

Radiative natural supersymmetry with a 125 GeV Higgs boson.

It has been argued that requiring low electroweak fine-tuning (EWFT) along with a (partial) decoupling solution to the supersymmetry (SUSY) flavor and CP problems leads to a sparticle mass spectra characterized by light Higgsinos at 100-300 GeV, sub-TeV third generation scalars, gluinos at a few TeV, and multi-TeV first or second generation scalars (natural SUSY). We show that by starting with multi-TeV first or second and third generation scalars and trilinear soft breaking terms, the natural SUSY spectrum can be generated radiatively via renormalization group running effects. Using the complete 1-loop effective potential to calculate EWFT, significantly heavier third generation squarks can be allowed even with low EWFT. The large negative trilinear term and heavier top squarks allow for a light Higgs scalar in the ~125 GeV regime.