Razmerje razpadov resonance $\Upsilon (4S)$ v nabite in nevtralne mezone $B$

Hrka, Saša (author), Zupanc, Anže (mentor)

Magistrsko delo predstavlja določitev vrednosti produkcijskega razmerja $R^{+/0}$, ki podaja razmerje verjetnosti za razpad mezona $\Upsilon(4S)$ v par $B^{+}B^{-}$ ali v par $B^{0}\bar{B}^{0}$. Izbrani razpadi za analizo so hadronski razpadi mezona $B$, natančneje $B^{+}\rightarrow J/\psi K^{+}$ in $B^{0}\rightarrow J/\psi K_{S}^{0}$. Uporabljeni podatki so pridobljeni z eksperimentom Belle in predstavljajo največjo količino podatkov doslej uporabljenih v ta namen. Rezultat meritve znaša $R^{+/0} = 1,142\pm0,015\pm0,011$, kar predstavlja najbolj natančno meritev te količine do sedaj.

• Language: Slovenian
• Keywords: fizika osnovnih delcev, mezon $\Upsilon(4S)$, mezon $B$, detektor Belle, simulacija Monte Carlo, elektronski razpadni kanal, mionski razpadni kanal
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Year: 2018
• PID: 20.500.12556/RUL-100705
• COBISS.SI-ID: 3196516
• Publication date in RUL: 07.04.2018

Secondary language

• Language: English
• Title: Production ratio of $\Upsilon (4S)$ resonance into charged and neutral $B$ mesons

Abstract

We present a measurement of production ratio $R^{+/0}$ which gives relative probability for meson $\Upsilon(4S)$ to decay either as $B^{+}B^{-}$ or $B^{0}\bar{B}^{0}$. Chosen decays for analysis are hadronic decays of meson $B$, $B^{+}\rightarrow J/\psi K^{+}$ and $B^{0}\rightarrow J/\psi K_{S}^{0}$. We use data obtained by Belle experiment which present the largest data sample ever used for such purpose. Result of measurement is $R^{+/0} = 1,142\pm0,015\pm0,011$ which represents the most precise measurement up to date.

• Keywords: elementary particle physics, meson $\Upsilon(4S)$, meson $B$, Belle detector, Monte Carlo simulation, electron decay channel, muon decay channel