Proton Decay at MplM_{pl} and the Scale of SUSY-Breaking

It is sometimes argued that a virtue of pushing the supersymmetry breaking scale above 1 PeV is that no particular flavor structure is required in the soft sector in order to evade bounds on flavor-changing neutral currents. However, without flavor structure, suppressing generic Planck-suppressed contributions to proton decay requires even higher SUSY scales, of order $10^{11}$ ($10^9$) GeV for degenerate (mini-split) gauginos and scalars. With flavor structure, the question of whether proton decay or flavor symmetries are more constraining is model-dependent, but it straightforward to find simple models where both constraints are satisfied for much lower SUSY scales.Comment: 14 pages, 1 figure. v2: expanded discussion of alignment models in sec. 3. accepted for publication in JHE

Impact of LSP Character on Slepton Reach at the LHC

Searches for supersymmetry at the Large Hadron Collider (LHC) have significantly constrained the parameter space associated with colored superpartners, whereas the constraints on color-singlet superpartners are considerably less severe. In this study, we investigate the dependence of slepton decay branching fractions on the nature of the lightest supersymmetric particle (LSP). In particular, in the Higgsino-like LSP scenarios, both decay branching fractions of $\tilde\ell_L$ and $\tilde\nu_\ell$ depend strongly on the sign and value of $M_1/M_2$, which has strong implications for the reach of dilepton plus MET searches for slepton pair production. We extend the experimental results for same flavor, opposite sign dilepton plus MET searches at the 8 TeV LHC to various LSP scenarios. We find that the LHC bounds on sleptons are strongly enhanced for a non-Bino-like LSP: the 95% C.L. limit for $m_{\tilde\ell_L}$ extends from 300 GeV for a Bino-like LSP to about 370 GeV for a Wino-like LSP. The bound for $\tilde\ell_L$ with a Higgsino-like LSP is the strongest (~ 490 GeV) for $M_1/M_2$ ~ $-\tan^2\theta_W$ and is the weakest (~ 220 GeV) for $M_1/M_2$ ~ $\tan^2\theta_W$. We also calculate prospective slepton search reaches at the 14 TeV LHC. With 100 fb$^{-1}$ integrated luminosity, the projected 95% C.L. mass reach for the left-handed slepton varies from 550 (670) GeV for a Bino-like (Wino-like) LSP to 900 (390) GeV for a Higgsino-like LSP under the most optimistic (pessimistic) scenario. The reach for the right-handed slepton is about 440 GeV. The corresponding 5$\sigma$ discovery sensitivity is about 100 GeV smaller. For 300 fb$^{-1}$ integrated luminosity, the reach is about 50 - 100 GeV higher.Comment: 24 pages, 10 figure