An Investigation Into the Normalisation Channel for Measuring the Branching Fraction of B+c → τ+ντ at the LHCb

Wiegertjes, Max (2024) An Investigation Into the Normalisation Channel for Measuring the Branching Fraction of B+c → τ+ντ at the LHCb. Master's Thesis / Essay, Physics.

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Abstract

In the Standard Model all lepton flavours share the same coupling constants. Violation of this property of lepton flavour universality may point towards New Physics. Previously, measurements of the branching fraction of semileptonic decays of B mesons have hinted towards such lepton flavour universality violations. If lepton flavour universality is violated, a measurement of the branching fraction Bc→τν could provide evidence in favour of such phenomena. However, the measurement of this decay requires the use of a novel reconstruction method where direct hits in the Vertex Locator of the LHCb are used to gain information on the kinematics of the decay. To better understand this technique, called B-tracking, and to ultimately minimize uncertainty in the measurement values, the research in this thesis intends to investigate potential normalisation modes for the decay Bc→τν . By estimating factors such as the measurement yield, reconstruction efficiency, and several uncertainties associated to the candidate normalisation channels, the best normalisation channel can be determined. By analysing simulation samples for several candidate decays, a good normalisation channel for a measurement of Bc→τν at LHCb was determined to be B+→Dππ. Using this normalisation channel a first measurement of the branching fraction of B→τν can be performed, which may alleviate or strengthen tensions in the lepton flavour universality property of the Standard Model.

Item Type:	Thesis (Master's Thesis / Essay)
Supervisor name:	Mulder, M.
Degree programme:	Physics
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Jul 2024 08:01
Last Modified:	15 Jul 2024 08:01
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/33324

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