scholarly journals Decomposition of d = 9 short-range 0νββ decay operators at one-loop level

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Ping-Tao Chen ◽  
Gui-Jun Ding ◽  
Chang-Yuan Yao
Keyword(s):  
Parameter Space ◽  
Short Range ◽  
Majorana Neutrino ◽  
Tree Level ◽  
Neutrino Masses ◽  
Loop Model ◽  
Loop Level ◽  
Decay Model

Abstract We perform a systematical study of the dimension-9 short-range 0νββ decay operators at one-loop level. There are only six genuine topologies which generate eight diagrams, and the recipe to identify the possible one-loop realizations of the 0νββ decay operators is sketched. Certain hypercharge assignments are excluded by the absence of tree-level diagrams in a genuine one-loop model. The mediators of each decomposition can generate Majorana neutrino masses which are discussed up to two-loop level. We present an example of 0νββ decay model in which the neutrino masses are generated at two-loop level, and the short-range contribution can be comparable with the mass mechanism in some region of parameter space.

scholarly journals Probing loop effects in wrong-sign Yukawa coupling region of Type-II 2HDM

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Wei Su
Keyword(s):  
Parameter Space ◽  
Yukawa Coupling ◽  
Higgs Mass ◽  
Precision Measurements ◽  
Tree Level ◽  
Type Ii ◽  
Coupling Region ◽  
Loop Level ◽  
Wrong Sign

AbstractIn the framework of 2HDM, we explore the wrong-sign Yukawa region with direct and indirect searches up to one-loop level. The direct searches include the latest $$H/A \rightarrow f{\bar{f}}, VV, Vh, hh$$ H / A → f f ¯ , V V , V h , h h reports at current LHC, and the study of indirect Higgs precision measurements works with current LHC, future HL-LHC and CEPC. At tree level of Type-II 2HDM, for degenerate heavy Higgs mass $$m_A=m_H=m_{H^\pm }<800$$ m A = m H = m H ± < 800 GeV, the wrong-sign Yukawa regions are excluded largely except for the tiny allowed region around $$\cos (\beta -\alpha )\in (0.2,0.3)$$ cos ( β - α ) ∈ ( 0.2 , 0.3 ) under the combined Higgs constraints. The excluded region is also nearly independent of parameter $$m_{12}$$ m 12 or $$\lambda v^2=m_A^2-m_{12}^2/(\sin \beta \cos \beta )$$ λ v 2 = m A 2 - m 12 2 / ( sin β cos β ) . The situation changes a lot after including loop corrections to the indirect searches, for example $$m_A=1500 \text {~GeV}$$ m A = 1500 GeV , the region with $$\lambda v^2<0$$ λ v 2 < 0 will be stronger constrained to be totally excluded. Whilst parameter space with $$\lambda v^2>0$$ λ v 2 > 0 would get larger survived wrong-sign region for $$m_A=800 ~\text {~GeV}$$ m A = 800 GeV compared to it at tree level. We also conclude Higgs direct searches works better on constraining $$\lambda v^2 \approx 0$$ λ v 2 ≈ 0 GeV range than theoretical constraints. We also find that the loop-level wrong-sign Yukawa limit only occurs at mass decoupling scale.

scholarly journals SUPERSYMMETRIC HIGGS TRIPLETS AND BILINEAR R-PARITY NONCONSERVATION

2002 ◽  
Vol 17 (19) ◽  
pp. 1259-1261 ◽  
Author(s):  
ERNEST MA
Keyword(s):  
Standard Model ◽  
Supersymmetric Standard Model ◽  
Majorana Neutrino ◽  
Lepton Number ◽  
Tree Level ◽  
Neutrino Masses ◽  
Parity Nonconservation ◽  
Particle Interactions

The supersymmetric standard model of particle interactions is extended to include two Higgs triplet superfields at the TeV scale, carrying two units of lepton number. Realistic tree-level Majorana neutrino masses are obtained in the presence of soft, i.e. bilinear, R-parity nonconservation.

scholarly journals Lepton dark matter portal in the inert Zee model

2020 ◽  
Vol 35 (31) ◽  
pp. 2050190
Author(s):  
Alexandra Gaviria ◽  
Robinson Longas ◽  
Andrés Rivera
Keyword(s):  
Dark Matter ◽  
Parameter Space ◽  
Tree Level ◽  
Neutrino Masses ◽  
Dark Matter Annihilation ◽  
Annihilation Channel ◽  
Flavor Changing ◽  
Inert Doublet Model ◽  
Relic Abundance ◽  
The Impact

The inert Zee model is an extension of the Zee model for neutrino masses. This new model explains the dark matter relic abundance, generates a one-loop neutrino masses and forbids tree-level Higgs-mediated flavor changing neutral currents. Although the dark matter phenomenology of the model is similar to that of the inert doublet model, the presence of new vector-like fermions opens the lepton portal as a new dark matter annihilation channel. We study the impact of this new portal in the low-mass regime and show the parameter space allowed by direct and indirect searches of dark matter. Remarkably, the region for [Formula: see text] GeV is recovered for [Formula: see text]. We also show that future experiments like LZ and DARWIN could probe a large region of the parameter space of the model.

scholarly journals Loop effect in the coherent neutrino-nucleus scattering

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Tong Li ◽  
Jiajun Liao
Keyword(s):  
Parameter Space ◽  
Neutrino Interaction ◽  
Tree Level ◽  
Dirac Fermion ◽  
Neutrino Scattering ◽  
Maximal Energy ◽  
Quark Sector ◽  
Loop Level ◽  
Nucleus Scattering ◽  
Recoil Spectrum

Abstract A connection between the neutrino and an exotic fermion is described in the general neutrino model. In this model the neutrinos can convert into the new fermion and thus the interaction leads to novel recoil spectrum in the neutrino scattering experiments. We study the general neutrino interaction by evaluating both the tree-level and loop-level contributions to the coherent elastic neutrino-nucleus scattering. We illustrate the scattering by taking the framework of a simplified neutrino model with a Dirac fermion χ and a spin-0 mediator. For the CP phase in the quark sector being 0 and π/2, the detection processes are dominated by the tree-level and loop-level contribution, respectively. We investigate the constraints on the couplings between the mediator and the new particle χ or the quarks by fitting to the COHERENT data. The parameter space with mχ larger than the maximal energy of incoming neutrinos can be also constrained by including the loop-level contribution.

scholarly journals Gauged $$U(1)_{L_\mu -L_\tau }$$ scotogenic model in light of $$R_{K^{(*)}}$$ anomaly and AMS-02 positron excess

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
Zhi-Long Han ◽  
Ran Ding ◽  
Su-Jie Lin ◽  
Bin Zhu
Keyword(s):  
Parameter Space ◽  
Gauge Boson ◽  
Comprehensive Analysis ◽  
Majorana Fermion ◽  
Neutrino Masses ◽  
Combined Analysis ◽  
Model Parameter ◽  
Loop Level ◽  
Scalar Singlet

AbstractWe study the gauged $$U(1)_{L_\mu -L_\tau }$$U(1)Lμ-Lτ scotogenic model with emphasis on latest measurement of LHCb $$R_{K^{(*)}}$$RK(∗) anomaly and AMS-02 positron excess. In this model, neutrino masses are induced at one-loop level with $$Z_2$$Z2-odd particles, i.e., right-handed neutrinos $$N_\ell (\ell =e,\mu ,\tau )$$Nℓ(ℓ=e,μ,τ) and inert scalar doublet $$\eta $$η inside the loop. Meanwhile, the gauged $$U(1)_{L_\mu -L_\tau }$$U(1)Lμ-Lτ symmetry is broken spontaneously by the scalar singlet S, resulting to the massive gauge boson $$Z'$$Z′. Provided certain couplings to quarks induced by heavy vector-like quarks, the gauge boson $$Z'$$Z′ would contribute to the transition $$b\rightarrow s \mu ^+\mu ^-$$b→sμ+μ-, hence explain the $$R_{K^{(*)}}$$RK(∗) anomaly. As for the Majorana fermion DM N, the gauge boson $$Z'$$Z′ and the singlet Higgs $$H_0$$H0 will generate various annihilation channels, among which the $$NN\rightarrow Z'Z'$$NN→Z′Z′ and $$NN\rightarrow Z'H_0(\rightarrow Z'Z')$$NN→Z′H0(→Z′Z′) channel could be used to interpret the AMS-02 positron excess. We give a comprehensive analysis on model parameter space with consider various current constraints. The combined analysis shows that the $$R_{K^{(*)}}$$RK(∗) anomaly and AMS-02 positron excess can be explained simultaneously.

scholarly journals Simplicity of AdS supergravity at one loop

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Luis F. Alday ◽  
Xinan Zhou
Keyword(s):  
Closed Form ◽  
Conformal Symmetry ◽  
Flat Space ◽  
Tree Level ◽  
Loop Level ◽  
Level Data ◽  
Space Limit ◽  
Loop Amplitude

Abstract We demonstrate the simplicity of AdS5× S5 IIB supergravity at one loop level, by studying non-planar holographic four-point correlators in Mellin space. We develop a systematic algorithm for constructing one-loop Mellin amplitudes from the tree-level data, and obtain a simple closed form answer for the $$ \left\langle {\mathcal{O}}_2^{SG}{\mathcal{O}}_2^{SG}{\mathcal{O}}_p^{SG}{\mathcal{O}}_p^{SG}\right\rangle $$ O 2 SG O 2 SG O p SG O p SG correlators. The structure of this expression is remarkably simple, containing only simultaneous poles in the Mellin variables. We also study the flat space limit of the Mellin amplitudes, which reproduces precisely the IIB supergravity one-loop amplitude in ten dimensions. Our results provide nontrivial evidence for the persistence of the hidden conformal symmetry at one loop.

scholarly journals The ScotoSinglet Model: a scalar singlet extension of the Scotogenic Model

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Ankit Beniwal ◽  
Juan Herrero-García ◽  
Nicholas Leerdam ◽  
Martin White ◽  
Anthony G. Williams
Keyword(s):  
Parameter Space ◽  
Direct Detection ◽  
Neutrino Masses ◽  
Minimal Models ◽  
Flavour Violation ◽  
The One ◽  
Relic Abundance ◽  
Electroweak Precision ◽  
Scalar Singlet ◽  
Lepton Flavour

Abstract The Scotogenic Model is one of the most minimal models to account for both neutrino masses and dark matter (DM). In this model, neutrino masses are generated at the one-loop level, and in principle, both the lightest fermion singlet and the lightest neutral component of the scalar doublet can be viable DM candidates. However, the correct DM relic abundance can only be obtained in somewhat small regions of the parameter space, as there are strong constraints stemming from lepton flavour violation, neutrino masses, electroweak precision tests and direct detection. For the case of scalar DM, a sufficiently large lepton-number-violating coupling is required, whereas for fermionic DM, coannihilations are typically necessary. In this work, we study how the new scalar singlet modifies the phenomenology of the Scotogenic Model, particularly in the case of scalar DM. We find that the new singlet modifies both the phenomenology of neutrino masses and scalar DM, and opens up a large portion of the parameter space of the original model.

scholarly journals Structure of flavor changing Goldstone boson interactions

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Jin Sun ◽  
Yu Cheng ◽  
Xiao-Gang He
Keyword(s):  
Symmetry Breaking ◽  
Model Building ◽  
Neutral Current ◽  
Goldstone Boson ◽  
New Physics ◽  
Majorana Neutrino ◽  
Neutrino Masses ◽  
Type I ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current

Abstract General flavor changing Goldstone boson (GB) interactions with fermions from a spontaneous global U(1)G symmetry breaking are discussed. This GB may be the Axion, solving the strong QCD CP problem, if there is a QCD anomaly for the assignments of quarks U(1)G charge. Or it may be the Majoron, producing seesaw Majorana neutrino masses by lepton number violation, if the symmetry breaking scale is much higher than the electroweak scale. It may also, in principle, play the roles of Axion and Majoron simultaneously as far as providing solution for the strong CP problem and generating a small Majorana neutrino masses are concerned. Great attentions have been focused on flavor conserving GB interactions. Recently flavor changing Axion and Majoron models have been studied in the hope to find new physics from rare decays in the intensity frontier. In this work, we will provide a systematic model building aspect study for flavor changing neutral current (FCNC) GB interactions in the fermion sectors, or separately in the quark, charged lepton and neutrino sectors and will identify in detail the sources of FCNC interactions in a class of beyond standard model with a spontaneous global U(1)G symmetry breaking. We also provide a general proof of the equivalence of using physical GB components and GB broken generators for calculating GB couplings to two gluons and two photons, and discuss some issues related to spontaneous CP violation models. Besides, we will also provide some details for obtaining FCNC GB interactions in several popular models, such as the Type-I, -II, -III seesaw and Left-Right symmetric models, and point out some special features in these models.

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