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Register a new userImplications of hidden gauged $U(1)$ model for $B$ anomalies
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We propose a hidden gauged $U(1)_H$ $Z$ model to explain deviations from the Standard Model (SM) values in lepton flavor universality known as $R_K$ and $R_D$ anomalies. The $Z$ only interacts with the SM fermions via their mixing with vector-like doublet fermions after the $U(1)_H$ symmetry breaking, which leads to $b to s mumu$ transition through the $Z^{prime}$ at tree level. Moreover, introducing an additional mediator, inert-Higgs doublet, yields $bto c tau u$ process via charged scalar contribution at tree level. Using flavio package, we scrutinize adequate sizes of the relevant Wilson coefficients to these two processes by taking various flavor observables into account. It is found that significant mixing between the vector-like and the second generation leptons is needed for the $R_K$ anomaly. A possible explanation of the $R_D$ anomaly can also be simultaneously addressed in a motivated situation, where a single scalar operator plays a dominant role, by the successful model parameters for the $R_K$ anomaly.
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An additional $U(1)$ gauge interaction is one of promising extensions of the standard model of particle physics. Among others, the $U(1)_{B-L}$ gauge symmetry is particularly interesting because it addresses the origin of Majorana masses of right-handed neutrinos, which naturally leads to tiny light neutrino masses through the seesaw mechanism. We show that, based on the minimal $U(1)_{B-L}$ model, the symmetry breaking of the extra $U(1)$ gauge symmetry with its minimal Higgs sector in the early Universe can exhibit the first-order phase transition and hence generate a large enough amplitude of stochastic gravitational wave radiation which is detectable in future experiments.
We propose a one-loop induced neutrino mass model with hidden $U(1)$ gauge symmetry, in which we successfully involve a bosonic dark matter (DM) candidate propagating inside a loop diagram in neutrino mass generation to explain the $e^+e^-$ excess recently reported by the DArk Matter Particle Explorer (DAMPE) experiment. In our scenario dark matter annihilates into four leptons through $Z$ boson as DM DM $to Z Z (Z to ell^+ ell^-)$ and $Z$ decays into leptons via one-loop effect. We then investigate branching ratios of $Z$ taking into account lepton flavor violations and neutrino oscillation data.
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.
We consider a class of models with gauged U(1)_R symmetry in 4D N=1 supergravity that have, at the classical level, a metastable ground state, an infinitesimally small (tunable) positive cosmological constant and a TeV gravitino mass. We analyse if these properties are maintained under the addition of visible sector (MSSM-like) and hidden sector state(s), where the latter may be needed for quantum consistency. We then discuss the anomaly cancellation conditions in supergravity as derived by Freedman, Elvang and Kors and apply their results to the special case of a U(1)_R symmetry, in the presence of the Fayet-Iliopoulos term ($xi$) and Green-Schwarz mechanism(s). We investigate the relation of these anomaly cancellation conditions to the naive field theory approach in global SUSY, in which case U(1)_R cannot even be gauged. We show the two approaches give similar conditions. Their induced constraints at the phenomenological level, on the above models, remain strong even if one lifted the GUT-like conditions for the MSSM gauge couplings. In an anomaly-free model, a tunable, TeV-scale gravitino mass may remain possible provided that the U(1)_R charges of additional hidden sector fermions (constrained by the cubic anomaly alone) do not conflict with the related values of U(1)_R charges of their scalar superpartners, constrained by existence of a stable ground state. This issue may be bypassed by tuning instead the coefficients of the Kahler connection anomalies (b_K, b_{CK}).
We explore muon anomalous magnetic moment (muon $g-2$) in a scotogenic neutrino model with a gauged lepton numbers symmetry $U(1)_{mu-tau}$. In this model, a dominant muon $g-2$ contribution comes from not an additional gauge sector but the Yukawa sector. In our numerical $Delta chi^2$ analysis, we show that our model is in favor of normal hierarchy with some features. We also demonstrate two benchmark points, satisfying muon $g-2$ at the best fit value $25.1times10^{-10}$.
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