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Register a new userSinglet Heavy Fermions as the Origin of B Anomalies in Flavour Changing Neutral Currents
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We show that a simple extension of the Standard Model involving the introduction of vector-like quarks and heavy neutrinos, provides an explanation of the so called B-anomalies in $bto sellbarell$ transitions. Vector-like quarks can explain, in the context of a discrete flavour symmetry, all the relevant characteristics of the Cabibbo-Kobayashi-Maskawa sector. It is in this framework that we study the requirements on the masses of the vector like quarks and the heavy neutrinos leading to viable models with sufficient deviations of lepton flavour universality and which simultaneously avoid too large Flavour Changing Neutral Current effects. Related predictions on $bto dellbarell$ and $sto dellbarell$ transitions are also analysed in detail.
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We construct a three-Higgs doublet model with a flavour non-universal ${rm U}(1)times mathbb{Z}_2$ symmetry. That symmetry induces suppressed flavour-changing interactions mediated by neutral scalars. New scalars with masses below the TeV scale can still successfully negotiate the constraints arising from flavour data. Such a model can thus encourage direct searches for extra Higgs bosons in the future collider experiments, and includes a non-trivial flavour structure.
We study the contraints on non-flavour-blind soft supersymmetry breaking terms coming from flavour and CP violating processes in the presence of hierarchical Yukawa couplings, and quantify how much these constraints are weakened in the regions of the MSSM parameter space characterized by heavy gauginos and multi-TeV sfermion masses, respectively. We also study the inverted sfermion mass hierarchy scenario in the context of D-term supersymmetry breaking, and show that generic hierarchical Yukawa couplings with arbitrary phases require first generation squarks in the few 10 TeV range.
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We investigate a speculative short-distance force, proposed to explain discrepancies observed between measurements of certain neutral current decays of $B$ hadrons and their Standard Model predictions. The force derives from a spontaneously broken, gauged $U(1)_{B_3-L_2}$ extension to the Standard Model, where the extra quantum numbers of Standard Model fields are given by third family baryon number minus second family lepton number. The only fields beyond those of the Standard Model are three right-handed neutrinos, a gauge field associated with $U(1)_{B_3-L_2}$ and a Standard Model singlet complex scalar which breaks $U(1)_{B_3-L_2}$, a `flavon. This simple model, via interactions involving a TeV scale force-carrying $Z^prime$ vector boson, can successfully explain the neutral current $B-$anomalies whilst accommodating other empirical constraints. In an ansatz for fermion mixing, a combination of up-to-date $B-$anomaly fits, LHC direct $Z^prime$ search limits and other bounds rule out the domain 0.15 TeV$< M_{Z^prime} <$ 1.9 TeV at the 95$%$ confidence level. For more massive $Z^prime$s, the model possesses a {em flavonstrahlung} signal, where $pp$ collisions produce a $Z^prime$ and a flavon, which subsequently decays into two Higgs bosons.
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