A Light shed on Lepton Flavor Universality in B decays

At the back of succeeding measurements of anomalies in semileptonic decays at LHCb and several collider experiments hinting at the possible violation of lepton flavor universality, we undertake a concise review of theoretical foundations of the tree- and loop-level $b$-hadron decays, $b\to cl{\nu }_l$ and $b\to s{l}^{+}{l}^{-}$ along with experimental environments. We revisit the world averages for $R_{D(D^{\ast })}$, $R_{K(K^{\ast })}$, $R_{J\mathrm{/}\psi }$, and $R_{{\eta }_c}$, for the semileptonic transitions and provide results within the framework of the relativistic independent quark model in addition to the results from model-independent studies. If the ongoing evaluation of the data of LHC Run 2 confirms the measurements of Run 1, then the statistical significance of the effect in each decay channel is likely to reach 5~$\sigma$. A confirmation of these measurements would soon turn out to be the first remarkable observation of physics beyond the Standard Model providing a wider outlook on the understanding of New Physics.