A comparative analysis on Lattice QCD determined decay properties in B+ → tau nu and Bc+ → tau nu

Sarkar, Prerna (2024) A comparative analysis on Lattice QCD determined decay properties in B+ → tau nu and Bc+ → tau nu. Bachelor's Thesis, Physics.

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Abstract

This comparative analysis considered the Lattice QCD determined decay properties of the leptonic decay modes B(c)+ → tau nu in the form of a literature review. Although the LQCD determined mass of B+ is expected to be more precise than that of Bc+, due to the latter having errors associated to it that are absent or smaller for B+, the results presented in ref. [1] and ref. [2], don’t reflect this. The decay constants presented in ref. [2], [3], [4] and [5] indicate a smaller uncertainty for B+ than for Bc+, matching expectations. The determination of the meson masses and decay constants primarily utilized techniques incorporating NRQCD valence b quarks in combination with HISQ u/c quarks and techniques incorporating only HISQ valence quarks. With these decay properties, as well as the relevant CKM matrix elements and experimentally determined parameters such as the mesons lifetimes (due to these not being determined through LQCD yet), the branching fractions of the subsequent decay modes were calculated to be: B(B+ → tau nu ) ≈ 0.99(6) · 10^(−4) and B(Bc+ → tau nu) ≈ 1.92(6) · 10^(−2). The largest contributions towards the branching fractions uncertainties are relevant the CKM matrix elements |Vub|, |Vcb| and the decay constants. This paper also gives insight into the less apparent classification of the Bc+ meson within the heavy-light and heavy-heavy meson families by evaluating the positioning of its decay constant ratio within those of the corresponding meson groups.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Bruyn, K.A.M. de and Jones, S.A.
Degree programme:	Physics
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	16 Jul 2024 11:29
Last Modified:	16 Jul 2024 11:29
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/33414

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