The CKM unitarity problem: a trace of new physics at the TeV scale? Benedetta Belfatto, Revaz Beradze and Zurab Berezhiani Eur. Phys. J. C, 80 2 (2020) 149 Published online: 19 February 2020 DOI: 10.1140/epjc/s10052-020-7691-6