Prospects of Discovery for Supersymmetry at the Tevatron

We summarize a discovery potential for supersymmetric particles at the \ppbar collider of Tevatron with center-of-mass energy \sqrt{s} = 2 TeV and integrated luminosity \intlum = 15-30 \invfb. Any direct search is kinematically limited to below 450 \mgev. We, however, have a unique opportunity to test various supersymmetric scenarios by a measurement of the branching ratio for the rare decay mode \bsmumu. Using the background estimate in the CDF analysis of \bsmumu in Run I, we investigate the prospects for studying this mode in Run II. CDF would be sensitive to this decay for a branching ratio > 1.2 \times 10^{-8} with 15 \invfb (or, if a similar analysis holds for \Dzero, >6.5\times 10^{-9} for the combined data). For \tanb > 30, the \bsmumu search can probe the SUSY parameter space that cannot be probed by direct production of SUSY particles at Run II. An observation of \bsmumu with a large branching ratio > 7(14) \times 10^{-8} (feasible with only 2 \invfb) would be sufficient to exclude the mSUGRA model for \tan\beta \leq 50 (55) including other experimental constraints. For some models, the branching ratio can be large enough to be detected even for small $\tan\beta$ and large \mhalf.Comment: 16 pages, latex, 4 figures, talk at 10th International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY02),June 17-23, 2002, DESY, Hamburg, German

Minimal SUGRA Model and Collider Signals

The SUSY signals in the dominant stau-neutralino coannihilation region at a 500(800) GeV linear collider are investigated. The region is consistent with the WMAP measurement of the cold dark matter relic density as well as all other current experimental bounds within the mSUGRA framework. The signals are characterized by an existence of very low-energy tau leptons in the final state due to small mass difference between stau_1 and chi_1 (5-15 GeV). We study the accuracy of the mass difference measurement with a 1^deg active mask to reduce a huge SM two-photon background.Comment: 4 pages, 3 figures, Talk presented at ICHEP04, Aug.16-22, Beijing, China, Numerical typos in Table 5 and 6 are corrected, no changes in figures and in other numerical result

Detection of SUSY Signals in Stau Neutralino Co-annihilation Region at the LHC

We study the prospects of detecting the signal in the stau neutralino co-annihilation region at the LHC using tau leptons. The co-annihilation signal is characterized by the stau and neutralino mass difference (dM) to be 5-15 GeV to be consistent with the WMAP measurement of the cold dark matter relic density as well as all other experimental bounds within the minimal supergravity model. Focusing on tau's from neutralino_2 --> tau stau --> tau tau neutralino_1 decays in gluino and squark production, we consider inclusive MET+jet+3tau production, with two tau's above a high E_T threshold and a third tau above a lower threshold. Two observables, the number of opposite-signed tau pairs minus the number of like-signed tau pairs and the peak position of the di-tau invariant mass distribution, allow for the simultaneous determination of dM and M_gluino. For dM = 9 GeV and M_gluino = 850 GeV with 30 fb^-1 of data, we can measure dM to 15% and M_gluino to 6%.Comment: 4 pages LaTex, 3 figures. To appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 2006. A typo in a reference is correcte