Delta F = 2 observables and B -> X_q gamma decays in the Left-Right Model: Higgs particles striking back

Abstract

We present a complete study of Delta S = 2 and Delta B = 2 processes in the left-right model (LRM) based on the weak gauge group SU(2)_L x SU(2)_R x U(1)_{B-L}. This includes epsilon_K, Delta M_K, Delta M_q, A_{SL}^q, Delta Gamma_q with q=d,s and the CP asymmetries S_{psi K_S} and S_{psi phi}. Compared to the Standard Model (SM) these observables are affected by tree level contributions from heavy neutral Higgs particles (H^0) as well as new box diagrams with W_R gauge boson and charged Higgs (H^\pm) exchanges. We also analyse the B -> X_{s,d} gamma decays that receive important new contributions from the W_L-W_R mixing and H^\pm exchanges. Compared to the existing literature the novel feature of our analysis is the search for correlations between various observables that could help us to distinguish this model from other extensions of the SM and to obtain an insight into the structure of the mixing matrix V^R that governs right-handed currents. We find that even for M_{H^0} ~ M_{H^\pm} ~ O(20)TeV, the tree level H^0 contributions to Delta F = 2 observables are by far dominant and the H^\pm contributions to B -> X_q gamma can be very important, even dominant for certain parameters of the model. While in a large fraction of the parameter space this model has to struggle with the experimental constraint from epsilon_K, we demonstrate that there exist regions in parameter space which satisfy all existing Delta F = 2, B -> X_{s,d} gamma, tree level decays and electroweak precision constraints for scales M_{W_R}\simeq2-3TeV in the reach of the LHC. We also show that the S_{psi K_S} - epsilon_K tension present in the SM can be removed in the LRM. However, we point out that the LRM cannot help in explaining the difference between the inclusive and exclusive determinations of |V_{ub}|, when all constraints are taken into account. Finally we present a rather complete list of Feynman rules.