The CKM Matrix and the Unitarity Triangle
M. Battaglia, A. J. Buras, P. Gambino, A. Stocchi, D. Abbaneo, A. Ali, P. Amaral, V. Andreev, M. Artuso, E. Barberio, C. Bauer, D. Becirevic, M. Beneke, I. Bigi, C. Bozzi, T. Brandt, G. Buchalla, M. Calvi, D. Cassel, V. Cirigliano, M. Ciuchini, G. Colangelo, A. Dighe, G. Dubois-Felsmann, G. Eigen, K. Ecklund, P. Faccioli, R. Fleischer, J. Flynn, R. Forty, E. Franco, P. Gagnon, R. Gupta, S. Hashimoto, R. Hawkings, D. Hitlin, A. Hoang, A. Hocker, T. Hurth, G. Isidori
TL;DR
This paper summarizes a CERN workshop (2002) on the CKM Unitarity Triangle, focusing on determining the CKM matrix from $K$, $D$, and $B$ physics via tree-level decays, meson mixing, and global unitarity-triangle fits. It discusses two parametrizations—the standard form and a generalized Wolfenstein expansion—and emphasizes the role of nonperturbative inputs, including lattice QCD, in constraining CKM parameters. It highlights experimentally clean observables (e.g., $a_{\psi K_S}$, rare kaon decays) and discusses the expected impact of future measurements from B factories, the Tevatron, and LHC on tightening the unitarity-triangle constraints and probing new physics. Overall, the work provides a coherent framework for CKM determination within the SM and gauges sensitivity to physics beyond the SM.
Abstract
This report contains the results of the Workshop on the CKM Unitarity Triangle, held at CERN on 13-16 February 2002 to study the determination of the CKM matrix from the available data of K, D, and B physics. This is a coherent document with chapters covering the determination of CKM elements from tree level decays and K and B meson mixing and the global fits of the unitarity triangle parameters. The impact of future measurements is also discussed.