Muon g-2 Anomaly and Dark Leptonic Gauge Boson

One of the major motivations to search for a dark gauge boson of MeV-GeV scale is the long-standing muon g-2 anomaly. Because of active searches such as fixed target experiments and rare meson decays, the muon g-2 favored parameter region has been rapidly reduced. With the most recent data, it is practically excluded now in the popular dark photon model. We overview the issue and investigate a potentially alternative model based on the gauged lepton number or U(1)_L. The muon g-2 favored parameter region of the U(1)_L survives all the constraints that were critical in the dark photon case, yet it is disfavored by the new constraints from the large flux neutrino experiments.Comment: Version to appear in PR

Muon g-2 anomaly and dark leptonic gauge boson

One of the major motivations to search for a dark gauge boson of MeV-GeV scale is the long-standing g(mu) - 2 anomaly. Because of active searches such as fixed target experiments and rare meson decays, the g(mu) - 2 favored parameter region has been rapidly reduced. With the most recent data, it is practically excluded now in the popular dark photon model. We overview the issue and investigate a potentially alternative model based on the gauged lepton number or U(1)(L). The g(mu) - 2 favored parameter region of the U(1)(L) survives all the constraints that were critical in the dark photon case, yet it is disfavored by the new constraints from the large flux neutrino experiments

Dileptons and four leptons at Z' resonance in the early stage of the LHC

The LHC era just began. The first discovery at the LHC experiment would be arguably a new resonance pole at TeV scale, if it exists. While the discovery of the Z' would be exciting by itself, it may also suggest what other new physics signals should be looked for while the LHC experiment is still at its early stage. We argue that the four lepton resonance at the Z' pole is a well-motivated and promising signal especially in supersymmetry framework, which can serve as a supersymmetry search scheme even in the early stage of the LHC experiment.Comment: Version to appear in PL

Long-range interaction effects on neutrino oscillation

Motivated by the recent anomaly in the muon neutrino and anti-muon neutrino disappearance experiments, we consider a long-range interaction with an extremely light gauge boson and extraordinarily weak coupling. A long-range interaction, consistent with current bounds, could have very pronounced effects on atmospheric neutrino disappearance that will be studied with the IceCube DeepCore array, currently in operation, and can have a significant effect on future high-precision long-baseline oscillation experiments.Comment: Talk given at NUFACT 11, XIIIth International Workshop on Neutrino Factories, Super beams and Beta beams, 1-6 August 2011, CERN and University of Genev

Fourth Generation Parity

We present a very simple fourth generation (4G) model with an Abelian gauge interaction under which only the 4G fermions have nonzero charge. The U(1) gauge symmetry can have a Z(2) residual discrete symmetry (4G parity), which can stabilize the lightest 4G particle (L4P). When the 4G neutrino is the L4P, it would be a neutral and stable particle and the other 4G fermions would decay into the L4P, leaving the trace of missing energy plus the standard model fermions. Because of the new symmetry, the 4G particle creation and decay modes are different from those of the sequential 4G model, and the 4G particles can be appreciably lighter than typical experimental bounds. DOI: 10.1103/PhysRevLett.110.02180

Implications of the dark axion portal for SHiP and FASER and the advantages of monophoton signals

We investigate the implications of the dark axion portal interaction, the axion-photon-dark photon vertex, for the future experiments SHiP and FASER. We also study the phenomenology of the combined vector portal (kinetic mixing of the photon and dark photon) and dark axion portal. The muon $g-2$ discrepancy is unfortunately not solved even with the two portals, but the low-energy beam dump experiments with monophoton detection capability can open new opportunities in light dark sector searches using the combined portals.Comment: 11 pages, 8 figures. v2 added an additional reference. v3 version published in Phys. Rev. D. Added discussion of MATHUSLA, REDTOP and NA6

Four-Lepton Resonance at the Large Hadron Collider

A spin-1 weakly interacting vector boson, Z', is predicted by many new physics theories. Searches at colliders for such a Z' resonance typically focus on lepton-antilepton or top-antitop events. Here we present a novel channel with a Z' resonance that decays to 4 leptons, but not to 2 leptons, and discuss its possible discovery at the Large Hadron Collider. This baryonic gauge boson is well motivated in a supersymmetry framework.Comment: Version to appear in PR