Quark flavour mixing with right-handed currents: An effective theory approach

The impact of right-handed currents in both charged- andand neutral-current flavour-violating processes is analysed by means of an effective theory approach. More explicitly, we analyse the structure of dimension-six operators assuming a left-right symmetric flavour group, commuting with an underlying SU(2)(L) x SU(2)(R) x U(1)(B-L) global symmetry, broken only by two Yukawa couplings. The model contains a new unitary matrix controlling flavour-mixing in the right-handed sector. We determine the structure of this matrix by charged-current data, where the tension between inclusive and exclusive determinations of vertical bar V-ub vertical bar can be solved. Having determined the size and the flavour structure of right-handed currents, we investigate how they would manifest themselves in neutral current processes, including particle-antiparticle mixing, Z -> b (b) over bar, B-s,B-d -> mu(+)mu(-), B -> {X-s, K, K*}nu(nu) over bar, and K -> pi nu(nu) over bar decays. The possibility to explain a non-standard CP-violating phase in B-s mixing in this context, and the comparison with other predictive new-physics frameworks addressing the same problem, is also discussed. While a large S-psi phi asymmetry can easily be accommodated, we point out a tension in this framework between vertical bar V-ub vertical bar and S-psi K. (C) 2010 Elsevier B.V. All rights reserved.