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Okada H.,National Center for Theoretical science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

We propose a four-loop induced radiative neutrino mass model inspired by the diphoton excess at 750 GeV recently reported by ATLAS and CMS, in which a sizable diphoton excess is obtained via photon fusion introducing multi doubly-charged scalar bosons. Also we discuss the muon anomalous magnetic moment, and a dark matter candidate. The main process to explain the observed relic density relies on the final state of the new particle at 750 GeV. Finally we show the numerical results and obtain allowed region of several physical values in our model. © 2016 The Authors. Source


Okada H.,National Center for Theoretical science | Yagyu K.,University of Southampton
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

We discuss a possibility to explain the 750 GeV diphoton excess observed at the LHC in a three-loop neutrino mass model which has a similar structure to the model by Krauss, Nasri and Trodden. Tiny neutrino masses are naturally generated by the loop effect of new particles with their couplings and masses to be of order 0.1-1 and TeV, respectively. The lightest right-handed neutrino, which runs in the three-loop diagram, can be a dark matter candidate. In addition, the deviation in the measured value of the muon anomalous magnetic moment from its prediction in the standard model can be compensated by one-loop diagrams with exotic multi-charged leptons and scalar bosons. For the diphoton event, an additional isospin singlet real scalar field plays the role to explain the excess by taking its mass of 750 GeV, where it is produced from the gluon fusion production via the mixing with the standard model like Higgs boson. We find that the cross section of the diphoton process can be obtained to be a few fb level by taking the masses of new charged particles to be about 375 GeV and related coupling constants to be order 1. © 2016 The Authors. Source


Chang W.-F.,National Tsing Hua University | Ng J.N.,TRIUMF Laboratory Particle and Nuclear Physics | Wu J.M.S.,National Center for Theoretical science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We study the implications the recent results from the LHC Higgs searches have on scalar new physics. We study the impact on both the Higgs production and decay from scalars with and without color, and in cases where decoupling does and does not happen. We investigate possible constraints on scalar parameters from the production rate in the diphoton channel, and also the two vector boson channels. Measurements from both channels can help disentangle new physics due to color from that due to charge, and thus reveal the nature of the new scalar states. © 2012 American Physical Society. Source


Tang Y.,National Center for Theoretical science
Journal of High Energy Physics | Year: 2012

With the latest LHC available results, we consider the generic constraints on massive graviton. Both dijet and dilepton resonance searches are used. The limits on parameter space can be applied to many models. As an illustration, we show the constraints for Randall-Sundrum (RS) model. Implications on massive graviton and the coupling strength are discussed. For k/M pl = 0.1, M G < 2.2 TeV region is excluded at 95% confidence level. We also present some interesting implications on the RS radion with respect to the 125 GeV excess at the LHC. For k/M pl = 0.1, Λ φ < 13.8TeV is excluded where Λ φ is the scale to charactarize the interaction strengh of radion. © 2012 SISSA. Source


Gu J.-A.,National Taiwan University | Lee C.-C.,National Tsing Hua University | Geng C.-Q.,National Tsing Hua University | Geng C.-Q.,National Center for Theoretical science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We propose the simplest model of teleparallel dark energy with purely a non-minimal coupling to gravity but no self-potential, a single model possessing various interesting features: simplicity, self-potential-free, the guaranteed late-time cosmic acceleration driven by the non-minimal coupling to gravity, tracker behavior of the dark energy equation of state at earlier times, a crossing of the phantom divide at a late time, and the existence of a finite-time future singularity. We find the analytic solutions of the dark-energy scalar field respectively in the radiation, matter, and dark energy dominated eras, thereby revealing the above features. We further illustrate possible cosmic evolution patterns and present the observational constraint of this model obtained by numerical analysis and data fitting. © 2012 Elsevier B.V. Source

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