Patterns of Flavour Violation in the Presence of a Fourth Generation of Quarks and Leptons

• Main Authors: Buras, Andrzej J, Duling, Björn, Feldmann, Thorsten, Heidsieck, Tillmann, Promberger, Christoph, Recksiegel, Stefan
• Format: Journal Article
• Language: English
• Published: 25-11-2010
• Subjects: Physics - High Energy Physics - Phenomenology
• DOI: 10.48550/arxiv.1002.2126

JHEP 1009:106,2010 We calculate a number of observables related to particle-antiparticle mixing
and the branching ratios for the most interesting rare and CP-violating K and B
decays in the Standard Model (SM3) extended by a fourth generation of quarks
and leptons (SM4). A model-independent parameterisation of these observables in
terms of gauge-independent functions is adopted, which is useful for studying
the breaking of the universality between K, Bd and Bs systems through
non-minimal flavour violating interactions. We calculate first the mass
differences Delta M_i in the neutral K and B system, the mixing-induced CP
asymmetries S_{psi K_S}, S_{psi phi}, S_{phi K_S}, S_{eta' K_S} and epsilon_K.
Subsequently, a detailed analysis of K^+ -> pi^+ nu nu, K_L -> pi^0 nu nu,
B_{s,d} -> mu^+ mu^-, B -> X_{s,d} nu nu, K_L -> pi^0 l^+ l^-, B -> X_s gamma
and B -> X_{s,d} l^+ l^- is presented, and also epsilon'/epsilon is considered.
For some of these observables the departures from SM3 predictions can still be
spectacular.
We discuss how the new mixing parameters (3 angles, 2 CP phases) can be
determined using the flavour observables in question. We identify the different
hierarchical structures in the SM4 flavour mixing matrix, allowed by
phenomenological and theoretical constraints, and define the corresponding
generalised Wolfenstein expansion. Most importantly, we show how the
characteristic patterns of correlations among the considered flavour
observables allow to distinguish this New Physics scenario from supersymmetric
flavour models, the Littlest Higgs model with T-parity and the Randall-Sundrum
model with custodial protection.