We consider a minimal left-right model with a Peccei-Quinn symmetry, where generalised charge conjugation plays the role of the left-right symmetry. We show how the spontaneous breaking of the Peccei-Quinn symmetry by a scalar singlet can provide us with solutions not only to the strong CP and dark matter problems but can also help to generate naturally suppressed off-diagonal CKM elements and small neutrino masses via the inverse seesaw mechanism. For this, we make use of an economical scalar sector composed of a bi-doublet, two doublets and a singlet only. As a result of the new gauge bosons and neutrinos, the neutrinoless double beta decay, as well as lepton flavour violating processes, receives new contributions which can, in principle, become relevant due to the low-scale nature of the inverse seesaw mechanism. The model can easily accommodate all the current data on fermion masses and mixing even if the left-right scale is only high enough to evade the current experimental constraints.

Brazil

Alex Dias

Julio Leite

Natural quark mixing and inverse seesaw in a left-right model with an axion

General Two Higgs Doublet Models (2HDM) are popular Standard Model extensions but feature flavor changing interactions and lack neutrino masses. We discuss a 2HDM where neutrino masses are generated via type I seesaw and propose an extension where neutrino masses are generated via a type II seesaw mechanism with flavor changing interactions being absent via the presence of a U(1) gauge symmetry. After considering a variety of bounds such as those rising from collider and electroweak precision we show that our proposal stands as a UV complete 2HDM with a dark photon where neutrino masses and flavor changing interactions are addressed. A possible dark matter realization is also discussed.

Daniel Camargo

Téssio Melo

Farinaldo Queiroz

Neutrino masses in a two Higgs doublet model with a U(1) gauge symmetry

Motivated by the experimental measurements of D0 radiative decay modes, we have proposed a model to study the decay, by establishing a link with (V=ρ0, ω) decays through the vector meson dominance hypothesis. In order to do this properly, we have used the Lagrangians from the local hidden gauge symmetry approach to account for Vγ conversion. As a result, we have found the branching ratio , which is in fair agreement with the experimental values reported by the Belle and BaBar collaborations.

China

Spain

J.M. Dias

V.R. Debastiani

Ju-Jun Xie

E. Oset

The radiative decay with vector meson dominanceJ. M. Dias would like to thank the Brazilian funding agency FAPESP for the financial support (2016/22561-2), V. R. Debastiani wishes to acknowledge the support from the Programa Santiago Grisolia of Generalitat Valenciana (Exp. GRISOLIA/2015/005). This work is also partly supported by the Spanish Ministerio de Economia y Competitividad and European FEDER funds (FIS2014-57026- REDT, FIS2014-51948-C2-1-P, FIS2014-51948-C2-2-P), and the Generalitat Valenciana in the program Prometeo II-2014/068. This work is partly supported by the National Natural Science Foundation of China (11475227, 11735003) and the Youth Innovation Promotion Association CAS (2016367)

Weakly Interacting Massive Particles (WIMPs) and axions are arguably the most compelling dark matter candidates in the literature. Could they coexist as dark matter particles? More importantly, can they be incorporated in a well motivated framework in agreement with experimental data? In this work, we show that this two component dark matter can be realized in the Inert Doublet Model in an elegant and natural manner by virtue of the spontaneous breaking of a Peccei-Quinn U(1) P Q symmetry into a residual ℤ 2 $$ {\mathbb{Z}}_2 $$ symmetry. The WIMP stability is guaranteed by the ℤ 2 $$ {\mathbb{Z}}_2 $$ symmetry and a new dark matter component, the axion, arises. There are two interesting outcomes: (i) vector-like quarks needed to implement the Peccei-Quinn symmetry in the model may act as a portal between the dark sector and the SM fields with a supersymmetry-type phenomenology at colliders; (ii) two-component Inert Doublet Model re-opens the phenomenologically interesting 100-500 GeV mass region. We show that the model can successfully realize a two component dark matter framework and at the same time avoid low and high energy physics constraints such as monojet and dijet plus missing energy, as well as indirect and direct dark matter detection bounds.

Alexandre Alves

Colombia

Robinson Longas

Celso Nishi

Germany

Collider and dark matter searches in the inert doublet model from Peccei-Quinn symmetry

Models in which the 750 GeV resonance ( S ) decays to two light axion-like particles (ALPs a ), which in turn decay to collimated photons mimicking the observed signal, are motivated by Hidden Valley scenarios and could also provide a mechanism by which a S → γγ signal persists while S → Z γ , ZZ and W W remain subdued in the near future. We point out that these Hidden Valley like models invoking S → aa → 4γ must also contend with Z → a (→ γγ)γ constraints coming from CDF and ATLAS. Within an effective field theory framework, we work out the constraints on the couplings of S to a and gauge bosons coming from photonic Z decays and ensuring that the ALPs decay inside the electromagnetic calorimeter, in two regimes — where a decays primarily to photons, and where a also has hadronic branchings. The analysis is done for both when S has a large as well as a narrow width, and for different relative contributions to the signal coming from S → γγ and a → γγ. Results for the particular case where S and a belong to the same complex field are also presented. A γγ resonance at the Z -pole coming from Z → a γ is expected in this class of models. Taking benchmark ALP masses below around 0.4 GeV and, assuming reasonable values for the fake jet rate and the identification efficiency of the photon-jet, we find the prospects for the discovery of diphotons at the Z -pole.

United States

Kuver Sinha

Diphotons at the Z-pole in models of the 750 GeV resonance decaying to axion-like particles