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 root s = 161, 170, and 172 GeV and 5.7 pb(-1) taken at root s = 130 and 136 GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels (t) over tilde --> c chi, (t) over tilde --> bl<(nu)over tilde>, and (b) over tilde --> b chi. For the channel (t) over tilde --> 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 (t) over tilde and the chi of at least 10 GeV/c(2). For the channel (t) over tilde --> bl<(nu)over tilde> the mixing-angle independent scalar top limit is 70 GeV/c(2), assuming a mass difference between the (t) over tilde and the <(nu)over tilde> of at least 10 GeV/c(2). For the channel (b) over tilde --> 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 (b) over tilde and the chi is at least 10 GeV/c(2). (C) 1997 Elsevier Science B.V.
Searches for scalar top and scalar bottom quarks at LEP2
SELVAGGI, Giovanna;NUZZO, Salvatore Vitale;DE PALMA, Mauro
1997-01-01
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 root s = 161, 170, and 172 GeV and 5.7 pb(-1) taken at root s = 130 and 136 GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels (t) over tilde --> c chi, (t) over tilde --> bl<(nu)over tilde>, and (b) over tilde --> b chi. For the channel (t) over tilde --> 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 (t) over tilde and the chi of at least 10 GeV/c(2). For the channel (t) over tilde --> bl<(nu)over tilde> the mixing-angle independent scalar top limit is 70 GeV/c(2), assuming a mass difference between the (t) over tilde and the <(nu)over tilde> of at least 10 GeV/c(2). For the channel (b) over tilde --> 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 (b) over tilde and the chi is at least 10 GeV/c(2). (C) 1997 Elsevier Science B.V.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
