Abstract:
In this thesis, we studied B → Dτ ¯ ντ decay in Standard Model and a few New
Physics(NP) models, such as the W′-model, the Vector-leptoquark model, and then
the aligned-two-Higgs-doublet model(A2HDM). We calculated the branching fraction
B(B → Dτ ¯ν), Lepton Flavor Universality(LFU) ratio(RD), Diferential branching
fraction and LFU ratio dB
dq2 and RD(q2) the Lepton-side forward-backward asymmetry
AFB(q2), the convexity parameter CτF
(q2) and the τ -polarization fraction PτL
(q2),
using the parameter spaces generated from various avor restrictions. We found that:
The branching fraction B(B → Dτ ¯ν) shows a signi cant divergence from SM,
and the LFU ratio RD only shows a noticeable divergence from SM in the case
of A2HDM.
The di erential branching fraction and LFU ratio both show noticeable divergence
from SM in the case of above mentioned NP models.
The AFB(q2), CτF
(q2) and PτL
(q2) are only sensitive to A2HDM, Due to scalar-type
interaction which can be generated in such model.
