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The fundamental nature of mass is one of the greatest mysteries in physics. The Higgs mechanism is a theoretically appealing way to account for the different masses of elementary particles and implies the existence of a new, yet unseen…
The discovery of the Higgs boson suggests that also neutrinos get their mass from spontaneous symmetry breaking. In the simplest ungauged lepton number scheme, the Standard Model (SM) Higgs has now two other partners: a massive CP-even, as…
The discovery of the Standard Model (SM) Higgs boson by ATLAS and CMS at the LHC in 2012 marked a major milestone in particle physics. However, many questions remain unanswered, which has led to an active research program to search for…
Dark photons $\bar \gamma$ mediating long-range forces in a dark sector are predicted by various new physics scenarios, and are being intensively searched for in experiments. We extend a previous study of a new discovery process for dark…
We reconsider observables for discovering and measuring the mass of a Higgs boson via its di-leptonic decays: H --> WW* --> l nu l nu. We define an observable generalizing the transverse mass that takes into account the fact that one of the…
We extend the Standard Model (SM) by introducing a $U(1)'$ gauge boson and a real pseudo-scalar field, both odd under a $\mathbb{Z}_2$ symmetry. The resulting low-energy spectrum consists of a stable vector as the dark matter candidate, and…
After the Higgs discovery, the LHC has been looking for new resonances, decaying into pairs of Standard Model (SM) particles. Recently, the CMS experiment observed an excess in the di-photon channel, with a di-photon invariant mass of about…
The recent ATLAS and CMS diphoton resonance excesses are explored in a simple $U(1)$ gauge theory extension of the Standard Model where the resonance is the Higgs boson of the $U(1)$ symmetry breaking, $\phi$. This particle couples to…
We point out that a soliton such as an oscillon or boson star inevitably decays into gravitons through gravitational interactions. These decay processes exist even if there are no apparent self-interactions of the constituent field, scalar…
A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS Collaboration at the LHC, using a data set corresponding…
We propose that the diphoton resonance signal indicated by the recent LHC data might also arise from the pair productions of vector-like heavy down-type quarks with mass around $750$ GeV and above. The vector-like quark decays into an…
The critical point in particle physics at high temperature is studied through the ideal gas of scalars, the dilatons, in the model that implies the spontaneous breaking of an approximate scale symmetry. We consider the dynamical system of…
Biophotons are an ultra-weak emission of photons in the visible energy range from living matter. In this work, we study the emission from germinating seeds using an experimental technique designed to detect light of extremely small…
This review is based on the talk presented at the SUSY 2012 (Beijing). The new particle around 125 GeV observed at the Large Hadron Collider (LHC) is almost consistent with the standard model Higgs boson, except that the diphoton decay mode…
In this paper we discuss decays of the Higgs boson to quarkonia in association with a photon. We identify a new mechanism for producing such final states in Higgs decays that leads to predictions for the decay rates that differ by an order…
The linear dilaton geometry in five dimensions, rediscovered recently in the continuum limit of the clockwork model, may offer a solution to the hierarchy problem which is qualitatively different from other extra-dimensional scenarios and…
A radion in a scenario with a warped extra dimension can be lighter than the Higgs boson, even if the Kaluza-Klein excitation modes of the graviton turn out to be in the multi-TeV region. The discovery of such a light radion would be…
As an interpretation of the 750 GeV diphoton excesses recently reported by both ATLAS and CMS collaborations, we consider a simple extension of the Standard Model with a Dirac fermion dark matter where a singlet complex scalar field…
Recently, conceptually new physics beyond the Standard Model has been proposed, where a hidden conformal sector provides ``unparticle'' which couples to the Standard Model sector through higher dimensional operators in low energy effective…
LHC has reported tantalizing hints for a Higgs boson of mass 125 GeV decaying into two photons. We focus on two-Higgs-doublet Models, and study the interesting possibility that the heavier scalar (H) has been seen, with the lightest scalar…