Prospects for Hypercharged Anomaly Mediated SUSY Breaking at the LHC

We investigate the phenomenological consequences of string models wherein the MSSM resides on a D-brane, and the hypercharge gaugino mass is generated in a geometrically separated hidden sector. This hypercharged anomaly-mediated SUSY breaking (HCAMSB) model naturally solves the tachyonic slepton mass problem endemic to pure AMSB scenarios. In HCAMSB, one obtains a mass ordering M_1>\mu >M_2 with split left- and right- scalars, whereas in mAMSB models, one obtains \mu >M_1>M_2 with nearly degenerate left- and right-scalars. We compute the allowed parameter space and expected superparticle mass spectrum in the HCAMSB model. For low values of the HC and AMSB mixing parameter \alpha, the spectra is characterized by light left-sleptons, while the spectra for large \alpha is characterized by light top- and bottom- squarks. We map out the approximate reach of LHC for HCAMSB, and find that with 100 fb^{-1} of integrated luminosity, a gravitino mass of \sim 115 (105) TeV can be probed for low (high) values of \alpha, corresponding to a gluino mass reach of \sim 2.4 (2.2) TeV. Both cases contain-- as is typical in AMSB models-- long lived charginos that should yield visible highly ionizing tracks in the LHC detector. Also, in the lower \tan\beta range, HCAMSB models give rise to reconstructable Z\to \ell\bar{\ell} candidates in SUSY cascade decay events, while mAMSB models should do so only rarely.