Motivated by the experimentally observed deviations from standard model predictions, we calculate the anomalous magnetic moments $a_α= (g-2)_α$ for $α=e,μ$ in a neutrino mass model originally proposed by Babu-Nandi-Tavartkiladze (BNT). We discuss two variants of the model, the original model plus a minimally extended version with an additional hypercharge zero triplet scalar. While the original BNT model can explain $a_μ$, only the variant with the triplet scalar can explain both experimental anomalies. The heavy fermions of the model can be produced at the high-luminosity LHC and in the part of parameter space, where the model explains the experimental anomalies, it predicts certain specific decay patterns for the exotic fermions.
We review the status of the solutions to neutrino anomalies by flavor-changing as well as flavor-diagonal neutrino interactions. While it is difficult to explain the atmospheric neutrino data the solar neutrino data can be well accounted for by the massless neutrino oscillation induced by such non-standard neutrino interactions. We also discuss the possibility to test such kind of interactions by the future neutrino oscillation experiments at neutrino factories.
Neutrino mass spectrum is reanalyzed in supersymmetric models with explicit trilinear $R$ violation. Models in this category are argued to provide simultaneous solution to the solar and atmospheric neutrino anomalies. It is shown specifically that large mixing and hierarchical masses needed for the vacuum solution of neutrino anomalies arise naturally in these models without requiring any additional symmetries or hierarchies among the trilinear couplings.
Recently the MiniBooNE Collaboration has confirmed its anomalous excess in (anti)muon- to (anti)electron-neutrino oscillation data. Combined with long-standing results from the LSND experiment this amounts to a 6.1 sigma evidence for new physics beyond the Standard Model. In this paper we develop a framework with 3 active and 3 sterile neutrinos with altered dispersion relations that provides a mechanism to explain these anomalies without being in conflict with the absence of anomalous neutrino disappearance in other neutrino oscillation experiments.
The solar and atmospheric neutrino anomalies constitute the only solid and most remarkable evidence for physics beyond the Standard Model, indicating that the lepton mixing matrix is fundamentally distinct from that describing the quarks. Here I will report on how supersymmetry with spontaneously or bilinearly broken R Parity provides a predictive theory for neutrino mass and mixing which leads to a solution of neutrino anomalies which can be clearly tested at high energy accelerators.
Supersymmetric standard model with softly broken lepton symmetry provides a suitable framework to accommodate the solar and atmospheric neutrino anomalies. This model contains a natural explanation for large mixing and hierarchal masses without fine tuning of the parameters. Neutrino spectrum is particularly constrained in the minimal messenger model (MMM) of gauge mediated SUSY breaking, since all SUSY breaking effects are controlled in MMM by a single parameter. We study the structure of neutrino masses and mixing both in MMM and in simple extensions of it in the context of solar and atmosph…
The sterile neutrino solutions to different irregular results and observations in neutrino physics are studied. It is pointed out that introducing sterile neutrinos helps to solve simultaneously the observed anomalies. It is argued that sterile neutrinos can solve the conflict between dark matter neutrinos, LSND result and supernova nucleosynthesis. Other supernova constraints for sterile neutrinos are revised. Possibilities to avoid the big bang nucleosynthesis constraints for sterile neutrinos are explored. It is claimed that sterile neutrinos can solve the crisis in big bang nucleosynthesis…
Theories with large extra dimensions can generate small neutrino masses when the standard model neutrinos are coupled to singlet fermions propagating in higher dimensions. The couplings can also generate mass splittings and mixings among the flavour neutrinos in the brane. We systematically study the minimal scenario involving only one singlet bulk fermion coupling weakly to the flavour neutrinos. We explore the neutrino mass structures in the brane that can potentially account for the atmospheric, solar and LSND anomalies simultaneously in a natural way. We demonstrate that in the absence of …
We show how, in the $B-L$ extension of the SM (BLSM) with an Inverse Seesaw (IS) mechanism for neutrino mass generation, a light $Z'$ state with moderate couplings to SM objects, hence `dark' in its nature, can be associated, in conjunction with light sterile neutrinos, to some present day data anomalies, such as the anomalous magnetic moment of the muon as well as a possible signal indicating the existence of sterile neutrinos in neutrino beam experiments.
The formalism for neutrino flavor change induced by lepton family number violating interactions is developed for the three-neutrino case, and used to derive the corresponding flavor change probabilities in matter. Applied to the solar and atmospheric neutrino fluxes, it is argued that the observed anomalies, including the zenith dependence for the atmospheric case, could be due to such interactions.
We make a number of small changes, including correcting an error in our heavy-neutrino decay rate. None of our analysis is changed, either in substance or detail.
There is a unique $SU(4) \otimes SU(2)_L \otimes SU(2)_R$ gauge model which allows quarks and leptons to be unified at the TeV scale. It is already known that the neutrino masses arise radiatively in the model and are naturally light. We study the atmospheric, solar and LSND neutrino anomalies within the framework of this model.
Vector leptoquarks provide an elegant solution to a series of anomalies and at the same time generate naturally light neutrino masses through their mixing with the standard model Higgs boson. We present a simple Froggatt-Nielsen model to accommodate the B physics anomalies $R_K$ and $R_D$, neutrino masses, and the $750$ GeV diphoton excess in one cohesive framework adding only two vector leptoquarks and two singlet scalar fields to the standard model field content.
If the leptoquarks proposed to account for the intriguing anomalies observed in the $B$-meson decays, $R_{D^{(\ast)}}$ and $R_{K^{(\ast)}}$, as well as in the anomalous magnetic moment of the muon, $(g-2)_μ$, can be embedded into the scotogenic Dirac neutrino model, all these flavor anomalies, together with the origin of neutrino masses and the nature of dark matter, would be potentially addressed in a unified picture. Among the minimal seesaw, one-loop, and two-loop realizations of the dimension-4 effective operator $\mathcal{L}_{4}$ for the Dirac neutrino masses, we show that plenty of diagr…
Anomalies in semi-leptonic $B$ decays could indicate new physics beyond the standard model(SM). There is an older puzzle in non-leptonic $B \to πK$ decays. The new particles, leptoquarks and diquarks, required to solve the semi-leptonic and the non-leptonic puzzles can also generate neutrino masses and mixing at loop level. We show that a consistent framework to explain the $B$ anomalies and the neutrino masses is possible and we make predictions for certain rare nonleptonic $B$ decays.
We show that the neutrino mixing pattern with the large mixing required for the atmospheric neutrino problem and the small mixing angle MSW solution for the solar neutrino problem can be naturally generated through radiative magnification, even though all the mixing angles at the seesaw scale may be small. This can account for the neutrino anomalies as well as the CHOOZ constraints in the context of quark-lepton unified theories, where the quark and lepton mixing angles are expected to be similar in magnitude at the high scale. We also indicate the 4$ν$ mixing scenarios for which this mechanis…
We interpret the neutrino anomalies in neutrino oscillation experiments and the high energy neutrino events at IceCube in terms of neutrino oscillations in an extension of the standard model where three sterile neutrinos are introduced so as to make two light neutrinos to be Pseudo-Dirac particles and a light neutrino to be a Majorana particle. Our model is different from the so-called $3+n$ model with $n$ sterile neutrinos suggested to interpret short baseline anomalies in terms of neutrino oscillations. While the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix in $3+n$ model is simply extended…
We study two possible explanations for short baseline neutrino oscillation anomalies, such as the LSND and MiniBooNE anti-neutrino data, and for the reactor anomaly. The first scenario is the mini-seesaw mechanism with two eV-scale sterile neutrinos. We present both analytic formulas and numerical results showing that this scenario could account for the short baseline and reactor anomalies and is consistent with the observed masses and mixings of the three active neutrinos. We also show that this scenario could arise naturally from an effective theory containing a TeV-scale VEV, which could be…
We investigate resonance structures in CPT and Lorentz symmetry violating neutrino-antineutrino oscillations in a two generation framework. We work with four non-zero CPT-violating parameters that allow for resonant enhancements in neutrino-antineutrino oscillation phenomena in vacuo which are suitably described in terms of charge conjugation eigenstates of the system. We study the relation between the flavor, charge conjugation and mass eigenbasis of neutrino-antineutrino oscillations and examine the interplay between the available CPT-violating parameter space and possible resonance structur…
We examine current constraints on and the future sensitivity to the strength of couplings between quarks and neutrinos in the presence of a form factor generated from loop effects of hidden sector particles that interact with quarks via new interactions. We consider models associated with either vector or scalar interactions of quarks and leptons generated by hidden sector dynamics. We study constraints on these models using data from coherent elastic neutrino-nucleus scattering and solar neutrino experiments and demonstrate how these new interactions may be discovered by utilizing the recoil …
We discuss an extended $SU(2)\times U(1)$ model which naturally leads to mass scales and mixing angles relevant for understanding both the solar and atmospheric neutrino anomalies. No right-handed neutrinos are introduced in the model.The model uses a softly broken $L_e-L_μ-L_τ$ symmetry. Neutrino masses arise only at the loop level. The one-loop neutrino masses which arise as in the Zee model solve the atmospheric neutrino anomaly while breaking of $L_e-L_μ-L_τ$ generates at two-loop order a mass splitting needed for the vacuum solution of the solar neutrino problem. A somewhat different mode…
Experimental hints for lepton flavor universality violation in beauty-quark decay both in neutral- and charged-current transitions require an extension of the Standard Model for which scalar leptoquarks (LQs) are the prime candidates. Besides, these same LQs can resolve the long-standing tension in the muon and the recently reported deviation in the electron $g-2$ anomalies. These tantalizing flavor anomalies have discrepancies in the range of $2.5σ-4.2σ$, indicating that the Standard Model of particle physics may finally be cracking. In this Letter, we propose a resolution to all these anomal…
Results from the LSND and MiniBooNE experiments have been interpreted as evidence for a sterile neutrino with a mass near the electronvolt scale. Here we propose to test such a scenario by measuring the coherent elastic scattering rate of neutrinos from a pulsed spallation source. Coherent scattering is universal across all active neutrino flavors, and thus can provide a measurement of the total Standard Model neutrino flux. By performing measurements over different baselines and making use of timing information, it is possible to significantly reduce the systematic uncertainties and to indepe…
We compare the solutions to the short baseline neutrino anomaly based on oscillations to sterile neutrinos and the Stochastic Neutrino Mixing Mechanism (SNMM) through an analysis of the present neutrino data. The SNMM suggests worse fits than a 3 + 1 sterile neutrino model, although it cannot be discarded by present data. We propose an experiment to distinguish between both solutions, based on placing a $^8$Li source inside a 5kton-yr detector (like SNO). We studied the sensitivity of such an experiment, which makes it possible to discriminate within $2σ$ the SNMM from the 3+1 sterile hypothes…
Leptoquarks have been proposed as a possible explanation of anomalies in $\bar{B}\mapsto D^{*} τ\bar{ν} $ decays, the apparent anomalies in $(g-2)_μ$ experiments and a violation of lepton universality. Motivated by this, we examine other motivations of leptoquarks: radiatively induced neutrino masses in the presence of a discrete symmetry that prevents a tree level see-saw mechanism, gauge coupling unification, and vacuum stability at least up to the unification scale. We present a new model for radiatively generating a neutrino mass which can significantly improve gauge coupling unification a…
The lepton sector of the Standard Model is at present haunted by several intriguing anomalies, including an emerging pattern of deviations in $b \to s \ell \ell$ processes, with hints of lepton flavor universality violation, and a discrepancy in the muon anomalous magnetic moment. More importantly, it cannot explain neutrino oscillation data, which necessarily imply the existence of non-zero neutrino masses and lepton mixings. We propose a model that accommodates all the aforecited anomalies, induces neutrino masses and provides a testable dark matter candidate. This is achieved by introducing…
Quantum-mechanical calculations of transitions dynamics between the left- and right-handed helicity states of the atmospheric muon Dirac neutrino,which has a gravitoelectrical dipole moment (GEDM) interacting with the gravitational field of the Earth have been carried out. It is shown that the asymmetry of the zenith-angle distribution of an atmospheric muon neutrino can be explained by the interference of two mutually perpendicular plain-wave neutrino states having different velocites inside the Earth in the presence of its gravitation field. The deficit of the solar neutrino can also be expl…
We discuss an extended SU(2)XU(1) model which naturally leads to mass scales and mixing angles relevant for understanding both the solar and atmospheric neutrino anomalies in terms of the vacuum oscillations of the three known neutrinos. The model uses a softly broken L_e-L_μ-L_τ symmetry and contains a heavy scale M_H\sim 10^{15} GeV. The L_e-L_μ-L_τ symmetric neutrino masses solve the atmospheric neutrino anomaly while breaking of L_e-L_μ-L_τ generates highly suppressed radiative mass scale Δ_S\sim 10^{-10} eV^2 needed for the vacuum solution of the solar neutrino problem. All the neutrino m…
We investigate the three-neutrino mixing scheme for solving the atmospheric and LSND anomalies. We find the region in the parameter space that provides a good fit to the LSND and the SK atmospheric data, taking into account the CHOOZ constraint. We demonstrate that the goodness of this fit is comparable to that of the conventional fit to the solar and atmospheric data. Large values of the LSND angle are favoured and $\sin^2(2θ_{\rm LSND})$ can be as high as 0.1. This can have important effects on the atmospheric electron neutrino ratios as well as on down-going multi-GeV muon neutrino ratios. …
We propose a leptoquark model simultaneously to explain anomalies of muon anomalous magnetic dipole moment and $b\to s μ\barμ$ in light of experimental reports very recently. Here, we satisfy several stringent constraints such as $μ\to eγ$ and meson mixings. In addition, we find these leptoquarks also play an role in generating tiny neutrino masses at one-loop level without introducing any additional symmetries. We have numerical analysis and show how degrees our parameter space is restricted.
The existing anomalies appearing in decays of the form $b\to s \ell^+ \ell^-$ constitute a possible hint for new physics. We point out that modifications to the SM results due to heavy neutrinos could account for the observed deviations while satisfying existing constraints from lepton flavor violating processes. The required mixing angle, however, is an order of magnitude larger than suggested by recent global fits to lepton flavor conserving processes. We frame our discussion in terms of a Type-I seesaw model, but it can be made more general.
We extend the contents of the standard model (SM) by introducing TeV-scale scalar leptoquarks to generate neutrino masses and explain some current observed deviations from the SM predictions, including the anomalous magnetic moments of charged leptons (electron and muon) and $B$-physics anomalies ($R_{K^{(*)}}$ and $R_{D^{(*)}}$). The model consists of $\text{SU}(2)_L$ singlet leptoquark $S_1\sim (\bar{3}, 1, 1/3)$, doublet leptoquark $\tilde{R}_2\sim (3, 2, 1/6)$ and triplet leptoquark $S_3\sim (\bar{3}, 3, 1/3)$. We combine the constraints arising from the low-energy lepton flavor violation,…
The current searches for neutrino oscillations seem to suggest an approximate $L_e-L_\m-L_τ$ flavor symmetry. This symmetry implies a pair of degenerate neutrinos with mass $m_0$ and large leptonic mixing. We explore the possibility that gravitational interactions break this global symmetry. The Planck scale suppressed breaking of the $L_e-L_\m-L_τ$ symmetry is shown to lead to the right amount of splitting among the degenerate neutrinos needed in order to solve the solar neutrino problem. The common mass $m_0$ of the pair can be identified with the atmospheric neutrino scale. A concrete model…
We study the constraints imposed by neutrino oscillation experiments on the minimal extension of the Standard Model that can explain neutrino masses, which requires the addition of just two singlet Weyl fermions. The most general renormalizable couplings of this model imply generically four massive neutrino mass eigenstates while one remains massless: it is therefore a minimal 3+2 model. The possibility to account for the confirmed solar, atmospheric and long-baseline oscillations, together with the LSND/MiniBooNE and reactor anomalies is addressed. We find that the minimal model can fit oscil…
I review explanations for the three neutrino anomalies (solar, atmospheric and LSND) which go beyond the ``conventional'' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well.
We discuss possibility of describing solar, atmospheric and LSND results with four neutrinos forming two quasi-degenerate pairs. The simplest versions of this 2+2 scheme with either $ν_e$ or $ν_μ$ mixing exclusively with sterile neutrino is disfavored by the SNO and atmospheric neutrino results respectively. A generalized scheme with sterile state participating in both the solar and atmospheric oscillations is still allowed. We show thasolar and atmospheric oscillations is still allowed. We show that the complex pattern of mixing needed for this purpose follows from a simple L_e+L_μ-L_τ-L_s sy…
I review explanations for the three neutrino anomalies (solar, atmospheric and LSND) which go beyond the ``conventional'' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well.
We explore the connection of the leptoquark solution to the recently reported $B$-meson anomalies with a mechanism of neutrino mass generation and a viable dark matter candidate. We consider a model consisting of two scalar leptoquarks and three generations of triplet fermions: neutrino masses are radiatively generated at the 3-loop level and, by imposing a discrete $Z_2$ symmetry, one can obtain a viable dark matter candidate. We discuss the constraints on the flavour structure of this model arising from numerous flavour observables. The rare decay $K\to π^+ν\barν$ and charged lepton flavour …
The effect of nuclear recoil on neutrino oscillations: Toward understanding of short baseline anomalies
Università del Salento（萨伦托大学）；INFN Sezione di Lecce（意大利国家核物理研究所莱切分部）；Institute of Nanotechnology of the National Research Council of Italy, CNR-NANOTEC, Lecce Central Unit（意大利国家研究委员会纳米技术研究所莱切中央单元）
In this paper we provide a combined explanation of charged- and neutral-current $B$-physics anomalies assuming the presence of a light sterile neutrino $N_R$ which contributes to the $B \to D^{(*)} τν$ processes. We focus in particular on two simplified models, where the mediator of the flavour anomalies is either a vector leptoquark $U_1^μ\sim ({\bf 3}, {\bf 1}, 2/3)$ or a scalar leptoquark $S_1 \sim ({\bf \bar 3}, {\bf 1}, 1/3)$. We find that $U_1^μ$ can successfully reproduce the required deviations from the Standard Model while being at the same time compatible with all other flavour and p…
In this work, we present a solution to the persistent tensions in the decay observables $R_{D^{(\ast)}}$ and $R_{K^{(\ast)}}$ by introducing a $SU(2)_L$ doublet and a $SU(2)_L$ triplet scalar leptoquarks (LQs) that reside at the TeV energy scale. Neutrinos that remain massless in the Standard Model receive naturally small masses at one-loop level via the propagation of the same LQs inside the loop. Such a common origin of apparently disjoint phenomenological observations is appealing, and we perform a comprehensive analysis of this set-up. We identify the minimal Yukawa textures required to ac…
A generalized phenomenological (3 + 2 + 1)-model with three active and three sterile neutrinos is considered for the calculation of the neutrino oscillation characteristics at normal mass hierarchy of active neutrinos and significant splitting between the mass of one sterile neutrino and the masses of other two sterile neutrinos. A new parametrization and a certain form of the general neutrino mixing matrix for active and sterile neutrinos are suggested taking into account the possible violation of CP invariance in the lepton sector. The test values of the neutrino masses and the mixing parame…
We propose a simple extension of the MSSM based on extra compact dimensions which includes an $SU(2) \otimes U(1)$ singlet superfield. The fermion present in this superfield is the sterile neutrino, which combines with one linear combination of $ν_e-ν_μ-ν_τ$ to form a Dirac pair whose mass accounts for the LSND anomaly. Its small mass can be ascribed to a volume suppression factor associated with extra compact dimensions. On the other hand the sterile neutrino scalar partner can trigger the spontaneous violation of R-parity, thereby inducing the necessary mass splittings to fit also the solar …
We introduce two scalar leptoquarks, the SU$(2)_L$ isosinglet denoted $ϕ\sim(\mathbf{3}, \mathbf{1}, -1/3)$ and the isotriplet $φ\sim(\mathbf{3}, \mathbf{3}, -1/3)$, to explain observed deviations from the standard model in semi-leptonic $B$-meson decays. We explore the regions of parameter space in which this model accommodates the persistent tensions in the decay observables $R_{D^{(*)}}$, $R_{K^{(*)}}$, and angular observables in $b\to s μμ$ transitions. Additionally, we exploit the role of these exotics in existing models for one-loop neutrino mass generation derived from $ΔL=2$ effective …
Motivated by the long-standing tension in the muon anomalous magnetic moment (AMM) and persistent observations of B-physics anomalies in $R_{D^{(\ast)}}$ and $R_{K^{(\ast)}}$ ratios, we construct a simple two-loop radiative neutrino mass model, and propose a combined explanations of all these apparently disjoint phenomena within this framework. Our proposed model consists of two scalar leptoquarks (LQs), a $SU(2)_L$ singlet $S_1\sim (\overline{3},1,1/3)$ and a $SU(2)_L$ triplet $S_3\sim (\overline{3},3,1/3)$ to accommodate $R_{D^{(\ast)}}$ and $R_{K^{(\ast)}}$ anomalies, respectively. The muon…
This report has been prepared as part of the US Community Study on the Future of Particle Physics (Snowmass 2021) by the Snowmass Neutrino Frontier Topical Group NF02 Conveners, and it is based on the NF02 Topical Group-contributed White Paper on Light Sterile Neutrino Searches and Related Phenomenology.
We investigate Majorana dark matter in a new variant of $U(1)_{L_μ-L_τ}$ gauge extension of Standard Model, containing three additional neutral fermions $N_{e}, N_μ, N_τ$, along with a $(\bar{3},1,1/3)$ scalar Leptoquark (SLQ) and an inert doublet, to study the phenomenology of dark matter, neutrino mass generation and flavour anomalies on a single platform. The lightest mass eigenstate of the $N_μ, N_τ$ neutral fermions plays the role of dark matter. We compute the WIMP-nucleon cross section in leptoquark portal and the relic density mediated by inert doublet components, leptoquark and the ne…
Very recently, a substantial $7σ$ deviation of the $W$-boson mass from the Standard Model (SM) prediction has been reported by the CDF collaboration. Furthermore, the Muon g-2 Experiment recently confirmed the longstanding tension in $(g-2)_μ$. Besides, the updated result from the LHCb collaboration found evidence for the breaking of lepton universality in beauty-quark decays, which shows a $3.1σ$ discrepancy and is consistent with their previous measurements. Motivated by several of these drawbacks of the SM, in this work, we propose a model consisting of two scalar leptoquarks and a vectorli…
We propose a simple model to simultaneously explain four observed flavor anomalies while generating the neutrino mass at the one-loop level. Specifically, we address the measured anomalous magnetic dipole moments of the muon, $Δa_μ$ , and electron, $Δa_e$, the observed anomaly of $b\rightarrow s l^+ l^-$ in the $B$-meson decays, and the Cabibbo-angle anomaly. The model consists of four colorful new degrees of freedom: three scalar leptoquarks with the Standard Model quantum numbers $(3,3,-1/3),(3,2,1/6)$, and $(3,1,2/3)$, and one pair of down-quark-like vector fermion in $(3,1,-1/3)$. The bary…
In gauge theories like the standard model, the electric charges of the fermions can be heavily constrained from the classical structure of the theory and from the cancellation of anomalies. We argue that the anomaly conditions are not quite as well motivated as the classical constraints, since it is possible that new fermions could exist which cancel potential anomalies. For this reason we examine the classically allowed electric charges of the known fermions and we point out that the electric charge of the tau neutrino is classically allowed to be non-zero. The experimental bound on the elect…
Scalar theories can account for the current $R_{D^{(*)}}$ measurements through a vector operator $\bar{c}_L γ_μ b_L\,\barτ_L γ^μν_L$ induced at the loop level. Once the vector contribution is considered on top of a subdominant tree-level scalar component, the predicted value of $R_{D^{(*)}}$ falls within the $1σ$ region indicated by the experiments. We explicitly demonstrate this claim in the framework of a three Higgs doublet model extended with GeV scale right-handed neutrinos, by matching the anomalous signal for perturbative values of the involved couplings and respecting the bounds from c…
The structure of neutrino masses and mixing resulting from trilinear $R$ violating interactions is studied in the presence of the gauge mediated supersymmetry breaking. Neutrino masses arise in this model at tree level through the RG-induced vacuum expectation values of the sneutrinos and also through direct contribution at 1-loop. The relative importance of these contributions is determined by the values of the strong and weak coupling constants. In case of purely $λ'$ couplings, the tree contribution dominates over the 1-loop diagram. In this case, one simultaneously obtains atmospheric neut…
Motivated by an explanation of the $R_{K^{(*)}}$ anomalies, we propose a Standard Model extension via two scalar SU(2)$_L$ triplet leptoquarks and three generations of triplet Majorana fermions. The gauge group is reinforced by a $Z_2$ symmetry, ensuring the stability of the lightest $Z_2$-odd particle, which is a potentially viable dark matter candidate. Neutrino mass generation occurs radiatively (at the three-loop level), and leads to important constraints on the leptoquark couplings to leptons. We consider very generic textures for the flavour structure of the $h_1$ leptoquark Yukawa coupl…
We reconsider a model introducing a scalar leptoquark $ϕ\sim (\mathbf{3}, \mathbf{1}, -1/3)$ to explain recent deviations from the standard model in semileptonic $B$ decays. The leptoquark can accommodate the persistent tension in the decays $\bar{B}\rightarrow D^{(*)}τ\barν$ as long as its mass is lower than approximately $10 \text{ TeV}$, and we show that a sizeable Yukawa coupling to the right-chiral tau lepton is necessary for an acceptable explanation. Agreement with the measured $\bar{B}\rightarrow D^{(*)}τ\barν$ rates is mildly compromised for parameter choices addressing the tensions i…
Motivated by the persistent anomalies reported in the $b\to cτ\barν$ data, we perform a general model-independent analysis of these transitions, in the presence of light right-handed neutrinos. We adopt an effective field theory approach and write a low-energy effective Hamiltonian, including all possible dimension-six operators. The corresponding Wilson coefficients are determined through a numerical fit to all available experimental data. In order to work with a manageable set of free parameters, we define eleven well-motivated scenarios, characterized by the different types of new physics t…
We argue that the neutrino advance of time observed in MINOS and OPERA experiments can be explained in the framework of the standard relativistic quantum theory as a manifestation of the large effective transverse size of the eigenmass neutrino wavepackets.
New phenomenological models of Quantum Gravity have suggested that a Lorentz-Invariant discrete spacetime structure may become manifest through a nonstandard coupling of matter fields and spacetime curvature. On the other hand, there is strong experimental evidence suggesting that neutrino oscillations cannot be described by simply considering neutrinos as massive particles. In this manuscript we motivate and construct one particular phenomenological model of Quantum Gravity that could account for the so-called neutrino anomalies.
