2023/02/27 by Belfatto, Benedetta, Trifinopoulos, Sokratis
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2302.14097
The combination of precise determinations of Vus and Vud hints towards a violation of the CKM first row unitarity at about 3σ level. Conversely, the recent measurement of the W-boson mass by the CDF Collaboration exhibits significant tension with the SM prediction, intensifying the conflict that may arise in models addressing the unitarity violation. We demonstrate that one vector-like SU(2)L doublet with mass of a few TeV mixing with light quarks and the top quark can simultaneously account for the two anomalies, without conflicting with flavour-changing phenomena and electroweak observables. Moreover, another tension in the value of the Cabibbo angle is reported also at 3σ level, between two determinations of Vus obtained from semi-leptonic Kℓ3 and leptonic Kμ2 kaon decays. We show that the vector-like doublet can be at the origin of this discrepancy and the substantial positive shift in the W-boson mass. This unique feature of the vector-like quark doublet may render it a crucial puzzle piece in new physics scenarios addressing the CKM unitarity problem. The model can be potentially probed in future colliders.