We constrain general Dirac neutrino interactions based on the Standard Model Effective Field Theory framework extended with right-handed neutrinos $N$ (SMNEFT) using deep inelastic and coherent elastic neutrino scattering, nuclear beta decay, and meson decay data, and high energy electron-proton and proton-proton collider data. We compute the one-loop anomalous dimensions of the low-energy effective field theory (LEFT) below the electroweak scale and of SMNEFT above the electroweak scale. The tree-level matching between LEFT and SMNEFT is performed at the electroweak scale. Currently, the most stringent limits on scalar and tensor interactions arise from pseudoscalar meson decays and the LHC measurements at the per mille level. In the future, the upcoming High-Luminosity LHC (HL-LHC) has the potential to reach the $10^{-4}$ level and LHeC can play an important role under certain theoretical assumptions.
Neutrino-electron scattering is a purely leptonic fundamental interaction and therefore provides an important channel to test the Standard Model, especially at the low energy-momentum transfer regime. We derived constraints on neutrino nonstardard interaction couplings depending on model-independent approaches which are described by a four-Fermi pointlike interaction and unparticle physics model with tensorial components. Data on $\barν_{e}-e$ and $ν_{e}-e$ scattering from the TEXONO and LSND experiments, respectively, are used. The upper limits and the allowed regions of scalar, pseudoscalar,…
Large neutrino event numbers in future experiments measuring coherent elastic neutrino nucleus scattering allow precision measurements of standard and new physics. We analyze the current and prospective limits of a light scalar particle coupling to neutrinos and quarks, using COHERENT and CONUS as examples. Both lepton number conserving and violating interactions are considered. It is shown that current (future) experiments can probe for scalar masses of a few MeV couplings down to the level of $10^{-4}$ $(10^{-6})$. Scalars with masses around the neutrino energy allow to determine their mass …
The Neutrino oscillations have provided an excellent opportunity to study new-physics beyond the Standard Model, popularly known as BSM. The unknown couplings involving neutrinos, termed non-standard interactions (NSI), may appear as `new-physics' in different neutrino experiments. The neutrino NSI offers significant effects on neutrino oscillations and CP-sensitivity, which may be probed in various neutrino experiments. The idea of neutrinos coupling with a scalar has evolved recently and looks promising. The effects of scalar NSI may appear as a perturbation to the neutrino mass matrix in th…
The scalar nonstandard interactions (NSI) can also introduce matter effect for neutrino oscillation in a medium. Especially the recent Borexino data prefers nonzero scalar NSI, $η_{ee} = - 0.16$. In contrast to the conventional vector NSI, the scalar type contributes as a correction to the neutrino mass matrix rather than the matter potential. Consequently, the scalar matter effect is energy independent while the vector one scales linearly with neutrino energy. This leads to significantly different phenomenological consequences in reactor, solar, atmospheric, and accelerator neutrino oscillati…
We consider a class of models involving interactions between ultra-light scalar dark matter and Standard Model neutrinos. Such couplings modify the neutrino mass splittings and mixing angles to include additional components that vary in time periodically with a frequency and amplitude set by the mass and energy density of the dark matter. Null results from recent searches for anomalous periodicities in the solar neutrino flux strongly constrain the dark matter-neutrino coupling to be orders of magnitude below current and projected limits derived from observations of the cosmic microwave backgr…
In supersymmetric models with R-parity violation, scalar neutrinos may be produced as s-channel resonances in e^+e^- colliders. We note that within current constraints, the scalar neutrino may have a width of several GeV into b\bar{b} and be produced with large cross section, leading to a novel supersymmetry discovery signal at LEP II. In addition, if the scalar neutrino mass approximately equals m_Z, such a resonance necessarily increases R_b and reduces A_{FB}(b), significantly improving the fit to electroweak data. Bounds from B meson and top quark decays are leading constraints, and we str…
Experimentally, baryon number minus lepton number, $B-L$, appears to be a good global symmetry of nature. We explore the consequences of the existence of gauge-singlet scalar fields charged under $B-L$ -- dubbed lepton-number-charged scalars, LeNCS -- and postulate that these couple to the standard model degrees of freedom in such a way that $B-L$ is conserved even at the non-renormalizable level. In this framework, neutrinos are Dirac fermions. Including only the lowest mass-dimension effective operators, some of the LeNCS couple predominantly to neutrinos and may be produced in terrestrial n…
We search for scalar and tensor non-standard interactions using (anti)-electron neutrino disappearance in oscillation data. We found a slight preference for non-zero CP violation, coming from both tensor and scalar interactions. The preference for CP violation is lead by Daya Bay low-energy data with a significance that reaches $\sim1.7σ$ in the global analysis (and $\sim2.1σ$ when considering only medium baseline reactors data) compared to the standard neutrino oscillation scenario.
We study a radiative neutrino model with a SU(2) septet scalar with hypercharge $Y=2$ where active neutrino mass is induced at a one-loop level. Calculating a one-loop diagram, mass matrices for active neutrino is derived. We also analyze lepton flavor violations, anomalous magnetic moment of muon and the flavor violating Higgs decay $h \to μτ$. Then sizable muon $g-2$ and $\sim 1 \%$ of $BR(h \to μτ)$ could be obtained in our set up. Furthermore, the collider signature of the septet is discussed where we focus on quadratically charged scalar at the LHC 14 TeV. We find that it could be discove…
Scalar ultra-light dark matter (ULDM) interacting with neutrinos can induce, under certain conditions, time-dependent modifications to neutrino oscillation probabilities. The limit in which the ULDM perturbation can be treated as constant throughout the neutrino propagation time has been addressed by several previous works. We complement these by systematically analyzing the opposite limit -- accounting for the temporal-variations of the ULDM potential by solving time-dependent Schrödinger equations. In particular, we study a novel two-generations-like CP violating (CPV) signature unique to ra…
Recently more generalized four-fermion interactions of neutrinos such as tensor and scalar interactions (TSIs) have been extensively studied in response to forthcoming precision measurements of neutrino interactions. In this letter, we show that due to the chirality-flipping nature, at the 1-loop level TSIs typically generate much larger ($10^{7}\sim10^{10}$) neutrino magnetic moments ($ν$MMs) than the vector case. For some cases, the large $ν$MMs generated by TSIs may reach or exceed the known bounds, which implies potentially important interplay between probing TSIs and searching for $ν$MMs …
If ultra-light dark matter (ULDM) exists and couples to neutrinos, it can be discovered via time-periodic variations in the neutrino mass and mixing parameters. We analyze the current bounds on such a scenario and establish the sensitivity expected for both time-averaged and time-resolved modulations in future neutrino oscillation experiments. We place a special emphasis in our analysis on time modulations of the CP violating mixing phase. We illustrate with a toy model the case where the leading modulation effect can be CP violating while the effect on CP conserving parameters is suppressed. …
We classify new physics signals in coherent elastic neutrino-nucleus scattering (CE$ν$NS) processes induced by $^8$B solar neutrinos in multi-ton xenon dark matter (DM) detectors. Our analysis focuses on vector and scalar interactions in the effective and light mediator limits after considering the constraints emerging from the recent COHERENT data and neutrino masses. In both cases we identify a region where measurements of the event spectrum alone suffice to establish whether the new physics signal is related with vector or scalar couplings. We identify as well a region where measurements of…
One natural way to understand the excess of the measured $H\toγγ$ rate over the standard model (SM) expectation at the Large Hadron Collider (LHC) is to have charged scalar bosons, existing in most of the SM extensions. Motivated by this LHC result, we explore if it also sheds light on solving the small neutrino mass generation problem. We concentrate on a class of models with high dimensional representations of scalars to realize Majorana neutrino masses at two-loop level without imposing any new symmetry. In these models, multi scalars with the electric charges higher than two are naturally …
We discuss how the intensity and the energy frontiers provide complementary constraints within a minimal model of neutrino mass involving just one new field beyond the Standard Model at accessible energy, namely a doubly charged scalar $S^{++}$ and its antiparticle $S^{--}$. In particular we focus on the complementarity between high-energy LHC searches and low-energy probes such as lepton flavor violation. Our setting is a prime example of how high- and low-energy physics can cross-fertilize each other.
We discuss the Higgs inflation scenario with singlet scalar dark matter and a right-handed neutrino. The singlet scalar and the right-handed neutrino play crucial roles for realizing a suitable plateau of Higgs potential with the center value of the top mass of Tevatron and LHC measurements. This Higgs inflation scenario predicts about a 1 TeV scalar dark matter and an $\mathcal{O}(10^{14})$ GeV right-handed neutrino by use of 125.6 GeV Higgs mass, 173.34 GeV top mass, and a nonminimal gravity coupling $ξ\simeq10.1$. This inflation model is consistent with the recent result of the tensor-to-sc…
General neutrino-scalar couplings appear in many extensions of Standard Model. We can probe these neutrino-scalar couplings by leptonic decay of mesons and from heavy neutrino search. Our analysis improves the present limits to $|g_e|^2<1.9\times 10^{-6}$ and $|g_μ|^2<1.9\times 10^{-7}$ at 90\% C.L. for massless scalars. For massive scalars we found for the first time the constraints for $g^2_α$ couplings to be $10^{-6}-10^{-1}$ respectively for scalar masses between below 1 MeV and for 300 MeV.
If there exist only three light neutrinos below the weak scale, the neutrino masses can arise by breaking the lepton number L. One example is the Zee mechanism for the neutrino masses. We study phenomenological implications of neutrino masses arising from the L violation through introduction of SU(2) X U(1) singlet scalars with Q_{em}=1 and 2.
In the Minimal Supersymmetric Standard Model (MSSM), the scalar neutrino $\tildeν_L$ has odd R parity, yet it has long been eliminated as a dark-matter candidate because it scatters elastically off nuclei through the $Z$ boson, yielding a cross section many orders of magnitude above the experimental limit. We show how it can be reinstated as a dark-matter candidate by splitting the masses of its real and imaginary parts in an extension of the MSSM with scalar triplets. As a result, radiative Majorana neutrino masses are also generated. In addition, decays of the scalar triplets relate the abun…
Non-standard interactions (NSI) of neutrinos with matter mediated by a scalar field would induce medium-dependent neutrino masses which can modify oscillation probabilities. Generating observable effects requires an ultra-light scalar mediator. We derive general expressions for the scalar NSI using techniques of quantum field theory at finite density and temperature, including the long-range force effects, and discuss various limiting cases applicable to the neutrino propagation in different media, such as the Earth, Sun, supernovae and early Universe. We also analyze various terrestrial and s…
We study a model with Majorana neutrino masses generated through doubly charged scalars at two-loop level. We give explicit relationships between the neutrino masses and the same sign dilepton decays of the doubly charged scalars. In particular, we demonstrate that at the tribimaximal limit of the neutrino mixings, the absolute neutrino masses and Majorana phases can be extracted through the measurements of the dilepton modes at colliders.
An extremely light scalar weakly interacting with light neutrinos has interesting consequences in stellar evolution, neutrino oscillations and laboratory neutrino mass measurements. In this paper we construct realistic gauge models for such scalar-neutrino interactions.
We investigate the possibility of Higgs inflation with an extended standard model by right-handed neutrinos and scalar dark matter. We find that the masses of the dark matter and one of the right-handed neutrinos should stand around TeV and $10^{-14}$ GeV scale respectively even if the magnitude of tensor-to-scalar ratio indicates sufficiently small value.
Solar neutrinos with non-zero magnetic moments will contribute to the electron scattering rates in the Super-Kamiokande experiment. The magnetic moment scattering events in Super-K can be accommodated in the standard VO or MSW solutions by a change of the parameter space of mass square difference and mixing angle-but the shifted neutrino parameters obtained from Super-K will (for some values of neutrino magnetic moments) become incompatible with the fits from SNO, Gallium and Chlorine experiments. We compute the upper bounds on the Dirac and Majorana magnetic moments of solar neutrinos by simu…
We study the detection prospects of relatively light charged scalars in radiative Majorana neutrino mass models, such as the Zee model and its variants using scalar leptoquarks, at current and future neutrino telescopes. In particular, we show that these scalar mediators can give rise to Glashow-like resonance features in the ultra-high energy neutrino (UHE) event spectrum at the IceCube neutrino observatory and its high-energy upgrade IceCube-Gen2. The same scalars can also give rise to observable non-standard neutrino interactions (NSI), and we show that the UHE neutrinos provide a complemen…
One possible probe to physics beyond the standard model is to look for scalar bilinears, which couple to two fermions of the standard model. We point out that the scalar bilinears allow new diagrams contributing to the neutrinoless double beta decay. The upper bound on the neutrinoless double beta decay lifetime would then give new constraints on the ratio of the masses of these scalars to their couplings to the fermions.
Cold, ultralight ($\ll$ eV) bosonic dark matter with a misalignment abundance can induce temporal variation in the masses and couplings of Standard Model particles. We find that fast variations in neutrino oscillation parameters can lead to significantly distorted neutrino oscillations (DiNOs) and yield striking signatures at long baseline experiments. We study several representative observables to demonstrate this effect and find that current and future experiments including DUNE and JUNO are sensitive to a wide range of viable scalar parameters over many decades in mass reach.
Late-time entropy production from scalar decay arises in scenarios like thermal inflation, proposed to dilute long-lived, massive fields like the gravitino and the moduli. The scalar decay may continue into Mev-scale temperatures and affect BB nucleosynthesis. The effect of such entropy production on electron neutrino decoupling is studied. A lower bound of about 10^(-22) Gev is estimated for the scalar decay constant, such that, for higher values of the decay constant, standard electron neutrino decoupling is unaffected.
If high-energy neutrinos propagate in a background of ultralight scalar field particles of dark matter ($m_φ\sim 10^{-23}$eV), neutrino-dark matter interactions can play a role and affect the neutrino flux. In this work we analyse this effect using transport equations that account for the neutrino regeneration as well as absorption, and we consider the neutrino flux propagation in the extragalactic medium and also through the galactic halo of dark matter. We show the results for the final flux to arrive on Earth for different cases of point and diffuse neutrino fluxes. {We conclude that this t…
We study the effects of kination and scalar-tensor pre-Big Bang Nucleosynthesis cosmologies on the non-resonant production of sterile neutrinos. We show that if the peak of the production rate of sterile neutrinos occurs during the non-standard cosmological phase, the relic number density of sterile neutrinos could be reduced with respect to the number expected in the standard cosmology. Consequently, current bounds on active-sterile neutrino mixing derived from the relic energy density of sterile neutrinos could be greatly relaxed. In particular, we show that the sterile neutrinos which could…
We investigate a single scalar neutrino production at the upgraded HERA with high luminosity in the framework of an R-parityviolating supersymmetric model. We find that the scalar neutrino with mass around 100GeV could be observed through investigating the multilepton production process e- p -> mu- sneutrino(tau) X -> mu- (e- mu+) X. The signal would be characterized by mu+ and e- with high transverse momentum as well as a sharp peak in the invariant mass M(e-,mu+) distribution.
If the minimal standard model of particle interactions is extended to include a scalar triplet with lepton number $L=-2$ and a scalar doublet with $L=-1$, neutrino masses $m_ν\sim μ_{12}^4 v^2/M^5 \sim 10^{-2}$ eV is possible, where $v \sim 10^2$ GeV is the electroweak symmetry breaking scale, $M \sim 1$ TeV is the typical mass of the new scalars, and $μ_{12} \sim 1$ GeV is a soft lepton-number-violating parameter.
Extensions of the Standard Model (SM) with sterile neutrinos are well motivated from the observed oscillations of the light neutrinos and they have shown to successfully explain the Baryon Asymmetry of the Universe (BAU) through, for instance, the so-called ARS leptogenesis. Sterile neutrinos can be added in minimal ways to the SM, but many theories exist where sterile neutrinos are not the only new fields. Such theories often include scalar bosons, which brings about the possibility of further interactions between the sterile neutrinos and the SM. In this paper we consider an extension of the…
We consider an extension of the Standard Model involving two new scalar particles around the TeV scale: a singlet neutral scalar $ϕ$, to be eventually identified as the Dark Matter candidate, plus a doubly charged $SU(2)_L$ singlet scalar, $S^{++}$, that can be the source for the non-vanishing neutrino masses and mixings. Assuming an unbroken $Z_2$ symmetry in the scalar sector, under which only the additional neutral scalar $ϕ$ is odd, we write the most general (renormalizable) scalar potential. The model may be regarded as a possible extension of the conventional Higgs portal Dark Matter sce…
Couplings between light scalar dark matter (DM) and neutrinos induce a perturbation to the neutrino mass matrix. If the DM oscillation period is smaller than ten minutes (or equivalently, the DM particle is heavier than $0.69\times10^{-17}$ eV), the fast-averaging over an oscillation cycle leads to a modification of the measured oscillation parameters. We present a specific $μ-τ$ symmetric model in which the measured value of $θ_{13}$ is entirely generated by the DM interaction, and which reproduces the other measured oscillation parameters. For a scalar DM particle lighter than $10^{-15}$ eV,…
We study a one-loop induced radiative neutrino model with an inert isospin triplet scalar field, in which we discuss current neutrino oscillation data, lepton flavor violations, muon anomalous magnetic moment, and a dark matter candidate. We show global analysis combining all the constraints, and briefly mention another possibility.
We perform a phenomenological study of the scalar sector of two models that generate neutrino mass at the three-loop level and contain viable dark matter candidates. Both models contain a charged singlet scalar and a larger scalar multiplet (triplet or quintuplet). We investigate the effect of the extra scalars on the Higgs mass and analyze the modifications to the triple Higgs coupling. The new scalars can give observable changes to the Higgs decay channel $h\rightarrowγγ$ and, furthermore, we find that the electroweak phase transition becomes strongly first-order in large regions of paramete…
We investigate the stability of the scalar potential in a minimal $U(1)'$ extension of the Standard Model augmented by an extra complex scalar and three right handed neutrinos. We consider a type-I seesaw scenario for the generation of the small neutrino masses. Moreover, we focus our analysis on a class of models potentially accessible at the LHC experiment, in which the vacuum expectation value of the extra scalar is chosen in the TeV range. We show that the requirements of stability of the potential within the perturbative evolution under the renormalization group impose significant constra…
A new realization for radiative neutrino mass generation is presented. Based on the requirement of tree-level custodial symmetry and the introduction of higher (greater than two) dimensional representations for scalar fields, a specific scenario with a scalar septet is presented that generates neutrino Majorana masses radiatively. This is accomplished through an eleven dimensional operator that requires the addition of several scalar fields and a SU(2) 5-plet of new fermions, together with a Z2 that guarantees the preservation of custodial symmetry. The phenomenology of the setup is rather ric…
A Higgs sextet is introduced in order to generate Dirac and Majorana neutrino masses in the 331 model with right-handed neutrinos. As will be seen, the present sextet introduction leads to a rich neutrino mass structure. The smallness of neutrino masses can be achieved via, for example, a seesaw limit. The fact that the masses of the charged leptons are not effected by their new Yukawa couplings to the sextet is convenient for generating small neutrino masses.
We constrain generic nonstandard neutrino interactions with existing experimental data on neutrino transition magnetic moments and derive strong bounds on tensorial couplings of neutrinos to charged fermions. We also discuss how some of these tensorial couplings can be constrained by other experiments, e.g., on neutrino-electron and neutrino-nucleus scattering.
Supersymmetry with bilinear R-parity violation provides a predictive framework for neutrino masses and mixings in agreement with current neutrino oscillation data. The model leads to striking signals at future colliders through the R-parity violating decays of the lightest supersymmetric particle. Here we study charged scalar lepton decays and demonstrate that if the scalar tau is the LSP (i) it will decay within the detector, despite the smallness of the neutrino masses, (ii) the relative ratio of branching ratios Br({tilde tau}_1 --> e sum nu_i)/ Br({tilde tau}_1 --> mu sum nu_i) is predicte…
Leptogenesis appears to be a viable alternative to account for the baryon asymmetry of the universe through baryogenesis. In this context, we consider a scenario in which the standard model is extended with $S_3$ and $Z_2$ symmetry in addition to the two scalar triplets, two scalar doublets and three right handed neutrinos. Presence of scalar triplets and right-handed neutrinos in the scenarios of both type-I and type-II seesaw framework provide a different leptogenesis option and can help us to understand the matter-antimatter asymmetry with simple $S_3$ symmetry. We discuss the neutrino phen…
The LSND and MiniBooNE results as well as the reactor and Gallium anomalies seem to indicate the presence of a sterile neutrino with a mass of $\sim 1$ eV mixed with active neutrinos. Such sterile neutrino can be produced in the early universe before the neutrino decoupling, leading to a contribution to the effective number of neutrinos ($N_{eff}$) as well as to a contribution to the sum of neutrino masses which are in tension with cosmological observations. We propose a scenario to relax this tension by a Yukawa coupling of the sterile neutrinos to ultra-light scalar particles which contribut…
An extremely light ($m_ϕ \ll 10^{-33} {\rm eV}$), slowly-varying scalar field $ϕ$ (quintessence) with a potential energy density as large as 60% of the critical density has been proposed as the origin of the accelerated expansion of the Universe at present. The interaction of this smoothly distributed component with another predominately smooth component, the cosmic neutrino background, is studied. The slow-roll approximation for generic $ϕ$ potentials may then be used to obtain a limit on the scalar-neutrino coupling constant, found to be many orders of magnitude more stringent than the limit…
We consider an electroweak model based on the gauge symmetry SU(2)_L X U(1)_Y' X U(1)_B-L which has right-handed neutrinos with different exotic B-L quantum numbers. Because of this particular feature we are able to write Yukawa terms, and right-handed neutrino mass terms, with scalar fields that can develop vacuum expectation values belonging to different energy scales. We make a detailed study of the scalar and the Yukawa neutrino sectors to show that this model is compatible with the observed solar and atmospheric neutrino mass scales and the tribimaximal mixing matrix.We also show that the…
We investigate the possibility of using neutrino trident production to probe leptophilic charged scalars at future high intensity neutrino experiments. We show that under specific assumptions, this production process can provide competitive sensitivity for generic charged scalars as compared to common existing bounds. We also investigate how the recently proposed mixed-flavour production - where the two oppositely charged leptons in the final state need not be muon flavoured - can give a 20-50% increase in sensitivity for certain configurations of new physics couplings as compared to tradition…
