Speaker
Description
There has been persistent ($>3\sigma$) disagreement between the Standard Model prediction and experimental measurements of $R_{D^{(*)} }=\mathcal{B}(B \rightarrow D^{(*)} \tau \nu_\tau)/\mathcal{B}(B \rightarrow D^{(*)} l \nu_l)(l=e,\mu)$. This anomaly may be addressed by introducing interactions beyond the Standard Model involving new states, such as leptoquarks. In this talk, I look at the constraints on third generation scalar leptoquarks from electroweak precision measurements at LEP and SLC. Among the electroweak observables, the partial decay width of $Z \rightarrow \tau\bar{\tau}$ places the strongest constraints. If one assumes Minimal Flavor Violation (MFV) in the quark sector, the leptoquarks masses and couplings required to satisfy the $R_{D^{(*)}}$ anomaly are strongly disfavored by electroweak data. Without MFV, one may still avoid electroweak constraints and address the anomaly.
