C. C. Nishi

article

Solving the strong CP problem with non-conventional CP

A. L. Cherchiglia, C. C. Nishi

Journal of High Energy Physics > 2019 > 2019 > 3 > 1-19

Abstract A very simple model is presented where all CP violation in Nature is spontaneous in origin. The CKM phase is generated unsuppressed and the strong CP problem is solved with only moderately small couplings between the SM and the CP violation sector or mediator sector because corrections to θ ¯ $$ \overline{\theta} $$ arise only at two loops. The latter feature follows from an underlying...

article

Mu-tau reflection symmetry with a high scale texture-zero

C. C. Nishi, B. L. Sánchez-Vega, G. Souza Silva

Journal of High Energy Physics > 2018 > 2018 > 9 > 1-30

Abstract The μτ -reflection symmetric neutrino mass matrix can accommodate all known neutrino mixing angles, with maximal atmospheric angle fixed, and predicts all the unknown CP phases of the lepton sector but is unable to predict the absolute neutrino mass scale. Here we present a highly predictive scenario where μτ -reflection is combined with a discrete abelian symmetry to enforce a texture-zero...

article

One-loop considerations for coexisting vacua in the CP conserving 2HDM

A. L. Cherchiglia, C. C. Nishi

Journal of High Energy Physics > 2017 > 2017 > 11 > 1-35

Abstract The Two-Higgs-Doublet model (2HDM) is a simple and viable extension of the Standard Model with a scalar potential complex enough that two minima may coexist. In this work we investigate if the procedure to identify our vacuum as the global minimum by tree-level formulas carries over to the one-loop corrected potential. In the CP conserving case, we identify two distinct types of coexisting...

article

Mu-tau reflection symmetry with a texture-zero

C. C. Nishi, B. L. Sánchez-Vega

Journal of High Energy Physics > 2017 > 2017 > 1 > 1-13

Abstract The μτ-reflection symmetry is a simple symmetry capable of predicting all the unknown CP phases of the lepton sector and the atmospheric angle but too simple to predict the absolute neutrino mass scale or the mass ordering. We show that by combining it with a discrete abelian symmetry in a nontrivial way we can additionally enforce a texture-zero and obtain a highly predictive scenario where...

article

Erratum to: Axion like particles and the inverse seesaw mechanism

C. D. R. Carvajal, A. G. Dias, C. C. Nishi, B. L. Sánchez-Vega

Journal of High Energy Physics > 2015 > 2015 > 8 > 1-2

The two models containing two ALP_s in section 2.3 of ref. [1] lead to too light non-SM charged leptons E of only a few GeV. (The single ALP model of section 2.2 does not suffer from this problem.)

article

Compatible abelian symmetries in N-Higgs-doublet models

C. C. Nishi

Journal of High Energy Physics > 2015 > 2015 > 3 > 1-36

Abstract We analyze the compatibility between abelian symmetries acting in two different sectors of a theory using the Smith Normal Form method. We focus on N-Higgs-doublet models (NHDMs) and on the compatibility between symmetries in the Higgs potential and in the Yukawa interactions, which were separately analyzed in previous works. It is shown that two equal (isomorphic) symmetry groups that...

article

Symmetry breaking patterns in 3HDM

I. P. Ivanov, C. C. Nishi

Journal of High Energy Physics > 2015 > 2015 > 1 > 1-28

Abstract An attractive feature of New Physics models with multiple Higgs fields is that they are equipped with discrete symmetry groups in the Higgs and flavour sectors. These symmetry groups are often broken at the global minimum of the Higgs potential, either completely or to a proper subgroup, with certain phenomenological consequences. Here, we systematically explore these symmetry breaking patterns...

article

Axion like particles and the inverse seesaw mechanism

C. D. R. Carvajal, A. G. Dias, C. C. Nishi, B. L. Sánchez-Vega

Journal of High Energy Physics > 2015 > 2015 > 5 > 1-26

Abstract Light pseudoscalars known as axion like particles (ALPs) may be behind physical phenomena like the Universe transparency to ultra-energetic photons, the soft γ-ray excess from the Coma cluster, and the 3.5 keV line. We explore the connection of these particles with the inverse seesaw (ISS) mechanism for neutrino mass generation. We propose a very restrictive setting where the scalar field...

article

Constraining multi-Higgs flavour models

R. González Felipe, I. P. Ivanov, C. C. Nishi, Hugo Serôdio, more

The European Physical Journal C > 2014 > 74 > 7 > 1-12

To study a flavour model with a non-minimal Higgs sector one must first define the symmetries of the fields; then identify what types of vacua exist and how they may break the symmetries; and finally determine whether the remnant symmetries are compatible with the experimental data. Here we address all these issues in the context of flavour models with any number of Higgs doublets. We stress the importance...

article

The quest for an intermediate-scale accidental axion and further ALPs

A. G. Dias, A. C. B. Machado, C. C. Nishi, A. Ringwald, more

Journal of High Energy Physics > 2014 > 2014 > 6 > 1-62

Abstract The recent detection of the cosmic microwave background polarimeter experiment BICEP2 of tensor fluctuations in the B-mode power spectrum basically excludes all plausible axion models where its decay constant is above 10¹³ GeV. Moreover, there are strong theoretical, astrophysical, and cosmological motivations for models involving, in addition to the axion, also axion-like particles (ALPs),...

article

Abelian symmetries of the N-Higgs-doublet model with Yukawa interactions

I. P. Ivanov, C. C. Nishi

Journal of High Energy Physics > 2013 > 2013 > 11 > 1-32

Abstract We investigate finite abelian groups which can represent symmetries of the N-Higgs-doublet models with quarks. We build a general formalism based on the powerful method of the Smith normal form and obtain an analytic upper bound on the order of abelian symmetry groups for any N. We investigate in detail the case N = 2 and rederive known results in a more compact and intuitive fashion. We...

INFONA - science communication portal

Search results for: C. C. Nishi

Solving the strong CP problem with non-conventional CP

Mu-tau reflection symmetry with a high scale texture-zero

One-loop considerations for coexisting vacua in the CP conserving 2HDM

Mu-tau reflection symmetry with a texture-zero

Erratum to: Axion like particles and the inverse seesaw mechanism

Compatible abelian symmetries in N-Higgs-doublet models

Symmetry breaking patterns in 3HDM

Axion like particles and the inverse seesaw mechanism

Constraining multi-Higgs flavour models

The quest for an intermediate-scale accidental axion and further ALPs

Abelian symmetries of the N-Higgs-doublet model with Yukawa interactions

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