Search for Pair-Production of Scalar Top Quarks in R-Parity Violating Decay Modes in $$p \bar{p}$$ Collisions at $$\sqrt{s}$$ = 1.8 TeV

Thesis/Dissertation · Sun Sep 01 04:00:00 EDT 2002

DOI:https://doi.org/10.2172/1369297· OSTI ID:1369297

Miyazaki, Yoshiyuki

A search for the pair production of supersymmetric partner of the top quark in scenario with R-parity violation is presented. The quantum number called R-parity distinguishes particles in standard model from supersymmetric particles. A scalar top quark (stop) is assumed to decay only via $$R_p$$-violating supersymmetric coupling into tau lepton and $$b$$-quark. To collect events with multiple taus, a new special tau trigger (the lepton plus track trigger) is installed in Run II experiment of the Collider Detector at Fermilab (CDF). The goal of the lepton plus track trigger is to collect generic dilepton ($$\ell \ell, \ell \tau, \tau\tau$$) events with lower $$P_T$$ threshold (8 GeV /c) and without prescale even at high luminosity. The $$Z \to \tau\tau$$ event, where one $$\tau$$-lepton decays leptonically and the other hadronically, is a good benchmark to calibrate the the lepton plus track trigger and T identification. The data sample of 72 $$pb^{-1}$$ , collected using the electron plus track trigger, contains clear a $$\tau$$ signal from $$Z \to \tau\tau$$ events. The data used in stop search correspond to 200 $$pb^{-1}$$ . The lower stop mass bound of 134 GeV/c2 at a 95% confidence level is obtained. This limit is also directly applicable to the case of the third generation scalar leptoquark ($$LQ_3$$) assuming a 100% branching for the $$LQ_3 \to \tau b$$ decay mode.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 1369297
• Report Number(s): FERMILAB-THESIS--2002-43; 606588
• Country of Publication: United States
• Language: English

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