CERN Accelerating science

Preprint
Report number	CERN-OPEN-99-330
Title	Searches for Scalar Top and Scalar Bottom Quarks at LEP2
Author(s)	Antonelli, M ; Cerutti, F ; Pepé-Altarelli, M ; Orejudos, W ; Zachariadou, K
Affiliation	(CERN)
Publication	1997
Collaboration	ALEPH Collaboration
Imprint	21 Jul 1997
Number of pages	16
Presented at	International Europhysics Conference on High-Energy Physics, Jerusalem, Israel, 19 - 25 Aug 1997
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LEP ; ALEPH
Abstract	Searches for scalar top and bottom quarks have been performed with data collected by the ALEPH detector at LEP. The data sample consists of 21.7 pb^-1 taken at sqrt{s} = 161, 170, and 172 GeV and 5.7 pb^-1 taken at sqrt{s} = 130 and 136 GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels stop --> c chi, stop --> b l snu, and sbottom --> b chi. For the channel stop --> c chi a limit of 67 GeV/c^2 has been set on the scalar top quark mass, independent of the mixing angle between the supersymmetric partners of the left and right-handed states of the top quark. This limit assumes a mass difference between the stop and the chi of at least 10 GeV/c^2. For the channel stop --> b l snu the mixing-angle independent scalar top limit is 70 GeV/c^2, assuming a mass difference between the stop and the snu of at least 10 GeV/c^2. For the channel sbottom --> b chi, a limit of 73 GeV/c^2 has been set on the mass of the supersymmetric partner of the left-handed state of the bottom quark. This limit is valid if the mass difference between the sbottom and the chi is at least 10 GeV/c^2.
Submitted by	catherine.cart@cern.ch