Searches for New Physics (NP) beyond the Standard Model (SM) have been going on at various Particle Physics experiments in recent years. Tree-level decays of beauty mesons represent promising avenues in this quest. This is discussed in two parts as follows: Part 1: Lepton Flavour Universality and Semileptonic Decays Abstract: Measurements of Lepton Flavour Universality (LFU) are excellent tools for experimentally testing the SM. Any significant deviations from the SM expectations will indicate NP. This talk will focus on the measurement of the LFU ratio ๐ (๐ทโ) at the LHCb experiment and its implications. Proposed research plans on semileptonic decays at Belle II are also shown.