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The precise determination of the CKM elements $V_{cb}$ and $V_{ub}$ iscrucial for any new physics analysis in the flavour sector. Their values can bedetermined from several tree-level decays: $V_{cb}$ can be extracted from $B\toD\ell\nu$ and $B\to D^*\ell\nu$ while $V_{ub}$ can be obtained from $B\to\pi\ell\nu$, $B\to \rho\ell\nu$ and $B\to\tau\nu$. In addition, for both $V_{cb}$ and $V_{ub}$ an inclusive determination is available. There is a longlasting discrepancy between the inclusive and exclusive determinations whichrecently even increased for $V_{cb}$ above the $3\;\sigma$ level. In thisarticle we study the possible effect of new physics on the inclusive andexclusive determination of $V_{cb}$ and $V_{ub}$ in a model independent way. Wefind that there is only one operator corresponding to a modified $W$ couplingwhich can achieve this. However, respecting $SU(2)$ gauge invariance at thehigh scale this would lead to very large violations of the $Z$ to $b\bar b$coupling not compatible with experiment. Therefore, we conclude that a newphysics explanation of the difference between the inclusive and exclusivedetermination of $V_{cb}$ and $V_{ub}$ is currently ruled out. Therefore, thediscrepancies must be due underestimated uncertainties in the theoreticaland/or the experimental analysis.

Can the differences in the determinations of $V_{ub}$ and $V_{cb}$ be explained by New Physics?