Simply Unnatural Supersymmetry (1212.6971v1)

Abstract: The current measurement of the Higgs mass, the ubiquitous nature of loop-suppressed gaugino masses in gravity-mediated supersymmetry breaking, relic dark matter density from $\sim$ TeV mass gauginos, together with the success of supersymmetric gauge coupling unification, suggest that scalar superpartner masses are roughly $m_{sc} \sim$ 100-1000 TeV. Higgsino masses, if not at the Planck scale, should generically appear at the same scale. The gaugino mass contributions from anomaly mediation, with the heavy Higgsino threshold, generally leads to a more compressed spectrum than standard anomaly mediation, while the presence of extra vector-like matter near $m_{sc}$ typically leads to an even more compressed spectrum. Heavy Higgsinos improve gauge coupling unification relative to the MSSM. Heavy scalars suggest new possibilities for flavor physics -- large flavor violations in the soft masses are now allowed, yielding interesting levels for new FCNC's, and re-opening the attractive possibility of a radiatively generated fermion mass hierarchy. Gluinos and binos/winos must decay through higher dimension operators, giving a unique handle on the presence of new physics the scale $m_{sc}$. Gluino decays should be spectacular, for example yielding events with four tops -- at modestly displaced vertices -- and two Higgses plus missing energy. The high scale $m_{sc}$ can also be probed in flavor-violating gluino decays, as well as a specific pattern of gluino branching ratios to the third generation. Finally, with heavy Higgsinos, the dominant decay for neutral winos and binos proceeds via the Higgs $\tilde b \to \tilde w h$. The heaviness of the Higgsinos can be inferred from the branching ratio for the rare decay $\tilde b \to \tilde w Z$.

• The paper presents a supersymmetry model that intentionally abandons strict naturalness by elevating scalar masses to 100–1000 TeV.
• It utilizes heavy Higgsinos and compressed gaugino mass spectra, offering distinctive collider decay signatures and flavor physics implications.
• The analysis bridges theory with experiment, suggesting new avenues to test radiative corrections and high-scale FCNCs in particle physics.

Simply Unnatural Supersymmetry: An Analysis

The paper "Simply Unnatural Supersymmetry" presents an intriguing exploration into the nature of finely-tuned supersymmetric (SUSY) theories. The authors, Arkani-Hamed et al., focus on developing a model that subtly retracts from the naturalness principle—a guiding philosophy in particle physics which posits that fundamental parameters should not require precise adjustments to yield observed phenomena.

Theoretical Framework and Motivations

The authors delve into the conundrum raised by the Higgs boson mass measurements, the naturalness of loop-suppressed gaugino masses mediated by gravity, and dark matter relic densities stemming from TeV-scale gauginos. These phenomena collectively imply that scalar superpartners hold masses significantly higher, at around 100-1000 TeV. A central tenet of their analysis reveals that incorporating heavy Higgsinos into this framework closes the gap between theory and gauge coupling unification, surpassing the Minimal Supersymmetric Standard Model (MSSM) paradigms.

Scalar Mass Hierarchy: The proposed spectrum sees scalar masses positioned at considerably high scales, allowing leeway for incorporating large flavor violations. This versatility permits soft mass-induced flavor-changing neutral currents (FCNCs) and potentially reshapes the fermion mass hierarchy through radiative mechanisms. Consequently, these SU(3)\times SU(2) \times U(1) representations have their naturalness issues decoupled by pushing scalar masses upwards, a stance opposing the primordial MSSM conception where scalar masses are more closely allied to the weak scale.

Phenomenological Implications and Signals

A distinctive flavor of the research is the emphasis on ramifications across flavor physics and collider signals. A lingering question for particle physicists has been the nature of flavor violations at unprecedented scales within supersymmetric frameworks.

Collider Signatures: The decay patterns of the gluinos and winos/binos harbor the call for potential new physics at 100-1000 TeV scales, provided they decay via higher-dimensional operators. Such gluino decays, distinguished by events with multiple tops or displaced vertices, and assorted Higgs production mechanisms supersede standard anomaly mediation's reach and reveal the scalar mass scale.

Gaugino Spectrum Compression: The paper elucidates that contributions from anomaly mediation and Higgsino thresholds generally yield a compressed gaugino mass spectrum compared to typical anomaly mediation. The authors also speculate on the effects of new vector-like states near the scalar mass scale that may further compress this spectrum, potentially offering a window into novel prediction spaces at future colliders.

Conclusions and Future Directions

Conclusively, the authors impart their simply unnatural model as a minimal, non-epicyclic hypothesis, devoid of superfluous fittings, advocating its ability to forge coherent explanatory pathways for the Higgs sector's empirical intricacies. Such a model, reversing conventional SUSY motivation, could decidedly stand on wooden legs if signs such as flavored decays or unexpected radiative corrections are spotted in future experimental confirmations.

Future Developments in AI and Theoretical Physics: In a broader perspective, the insights gained from exploring such high-scale physics might invigorate computational paradigms afforded by AI developments. These investigations could bridge methodology gaps by optimizing data analytics and model simulations, leveraging AI for efficient processing and understanding of complex high-dimensional data. Further speculative ideations could interpret these results in string theory frameworks, potentially influencing quantum gravity discourse, and merging observational enigmas with theoretical projections.

Arkani-Hamed et al.'s treatise on supersymmetry acknowledges the elephant in the room—the naturalness problem—by presenting a model where blatant anthropic fine-tuning becomes not only tolerable but demarcated with empirical clews signaling higher dimensional physics. Their work mandates participative experimental validation to forge substantive paths in the fledgling corridors of theoretical physics.