Measurement of the form factor ratios in semileptonic decays of charm mesons

Thesis/Dissertation · Fri May 01 00:00:00 EDT 1998

DOI:https://doi.org/10.2172/3131· OSTI ID:3131

Zaliznyak, Renata ^[1]

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1. Stanford Univ., CA (United States)

I have measured the form factor ratios r₂ = A₂ (0)/A₁ (0) and r_V = V (0)/A₁ (0) in the semileptonic charm meson decay D⁺ → $$\bar{K}$$^*0 e⁺v_e from data collected by the Fermilab E791 collaboration. Form factors are introduced in the calculation of the hadronic current in semileptonic decays of strange, charm, or bottom mesons, such as D⁺ → $$\bar{K}$$^*0 e⁺ v_e . Semileptonic decays provide insight into quark coupling to the W boson since the leptonic and hadronic amplitudes in the Feynman diagram for the decay are completely separate. There are no strong interactions between the final state leptons and quarks. A number of theoretical models predict the values of the form factors for D⁺ → $$\bar{K}$$^*0 e⁺ v_e , though there is a large range of predictions. E791 is a hadroproduction experiment that recorded over 20 billion interactions with a 500 GeV π^- beam incident on five thin targets during the 1991-92 Fermilab fixed-target run. Approximately 3000 D⁺ → $$\bar{K}$$^*0 e⁺ v_e decays are fully reconstructed. In order to extract the form factor ratios from the data, I implement a multidimensional unbinned maximum likelihood fit with a large sample of simulated (Monte Carlo) D⁺ → $$\bar{K}$$^*0 e⁺v_e events. The large E791 data sample provides the most precise measurement of the form factor ratios to date. The measured values for the form factor ratios are r₂ = 0.71 ± 0.08 ± 0.09 and r_V = 1.84 ± 0.11 ±} 0.08. These results are in good agreement with some Lattice Gauge calculations. However the agreement with quark model predictions is not as good.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• OSTI ID: 3131
• Report Number(s): FERMILAB-THESIS-1998-34; ON: DE00003131; TRN: US0206363
• Resource Relation: Other Information: TH: Thesis (Ph.D.); Submitted to Stanford Univ., CA (US); Site address for thesis: http://www-lib.fnal.gov/archive/thesis/fermilab-thesis-1998-34.shtml; PBD: 26 Jan 1999
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BEAUTY MESONS
DECAY
FEYNMAN DIAGRAM
FORM FACTORS
LEPTONS
MAXIMUM-LIKELIHOOD FIT
MESONS
QUARK MODEL
SEMILEPTONIC DECAY
STRONG INTERACTIONS