Search for techniparticles at D0 Run II

Thesis/Dissertation · Sun Jan 01 00:00:00 EST 2006

DOI:https://doi.org/10.2172/907811· OSTI ID:907811

Feligioni, Lorenzo ^[1]

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1. Univ. of Perugia (Italy)

Technicolor theory (TC) accomplishes the necessary electroweak symmetry breaking responsible for the mass of the elementary particles. TC postulates the existence of a new SU(N_TC) gauge theory. Like QCD the exchange of gauge bosons causes the existence of a non-vanishing chiral condensate which dynamically breaks the SU(N_TC)_L x SU(N_TC)_R symmetry. This gives rise to N_TC²-1 Nambu-Goldstone Bosons. Three of these Goldstone Bosons become the longitudinal components of the W^± and Z which therefore acquire mass; the remaining ones are new particles (technihadrons) that can be produced at the high energy colliders and detected. The Technicolor Straw Man Model (TCSM) is a version of the dynamical symmetry breaking with a large number of technifermions and a relative low value of their masses. One of the processes predicted by the TCSM is q$$\bar{q}$$ → V_T {yields} W{pi}_T, where V_T is the Technicolor equivalent of the QCD vector meson and {pi}_T is the equivalent of the pion. W is the electroweak gauge boson of the Standard Model. This dissertation describes the search for Wπ_T with the D0 detector, a multi-purpose particle detector located at one of the collision points of the Tevatron accelerator situated in Batavia, IL. The final state considered for this thesis is a W boson that decays to electron and neutrino plus a π_T that decays into b$$\bar{c}$$ or b$$\bar{b}$$, depending on the charge of the initial technivector meson produced. In the D0 detector this process will appear as a narrow cluster of energy deposits in the electromagnetic calorimeter with an associated track reconstructed in the tracking detector. The undetected neutrino from the decay of the W boson will be seen as missing momentum. The fragmentation of the quarks from the decay of the π_T will produce two jets of collimated particles. Events where a b-quark is produced are selected by requesting at least one jet to be associated with a secondary vertex of interaction produced by the decay of B-meson (b-tagging). In the absence of an excess over the Standard Model prediction for the final state considered in this analysis, we compute a 95% Confidence Level upper limit on the techniparticle production cross section for the V_T mass range: 190 GeV/c² ≤ m(V_T ) ≤ 220 GeV/c².

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 907811
• Report Number(s): FERMILAB-THESIS-2006-32; TRN: US0703325
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCELERATORS
BOSONS
CALORIMETERS
CONDENSATES
CROSS SECTIONS
DECAY
ELECTRONS
ELEMENTARY PARTICLES
FERMILAB TEVATRON
FRAGMENTATION
GOLDSTONE BOSONS
INTERMEDIATE BOSONS
MESONS
NEUTRINOS
QUANTUM CHROMODYNAMICS
QUARKS
STANDARD MODEL
SYMMETRY
SYMMETRY BREAKING
VECTOR MESONS
Experiment-HEP