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 that could mediate these transitions, and analyse which options seem to be preferred by the current measurements. The data exhibit a clear preference for new-physics contributions, and good fits to the data are obtained in several cases. However, the current measurement of the longitudinal $D^*$ polarization in $B\to D^*τ\barν$ cannot be easily accommodated within its experimental $1σ$ range. A general analysis of the three-body $B\to D τ\barν$ and four-body $B\to D^*(\to Dπ)τ\barν$ angular distributions is also presented. The accessible angular observables are studied in order to assess their sensitivity to the different new physics scenarios. Experimental information on these distributions would help to disentangle the dynamical origin of the current anomalies.
The recent intriguing measurements of $R_{K}$ and $R_{K^*}$ are important hints of new physics that violates lepton universality. We analyze the semileptonic decays $b \to s \ell^+ \ell^-$ in the framework of the $B-L$ extension of Minimal Supersymmetric Standard Model (MSSM) with Inverse Seesaw (BLSSMIS). A salient feature of this model is that one of the right-handed sneutrino can be light and the neutrino Yukawa couplings are of order one. We show that the box diagram mediated by right-handed sneutrino, higgsino-like chargino, and light stop can account simultaneously for both $R_{K}$ and $…
The gauge invariant and anomaly-free 331 model is studied with $R_ξ$ gauges in order to see which of the right-handed singlet between the case (i), assigning the bosonic singlet to the counterpart of 3 and $\bar 3$ representations, and the case (ii), assigning fermionic siglet to the counterpart of the left-handed 3 representation and assigning the antifermionic singlet to that of the left-handed $\bar 3$ representaion, should be assigned in physics but not mathematics to the counterparts of the left-handed fundamental 3 representation and the left-handed complex conjugate $\bar 3$ representat…
It is pointed out that in the $331-$like model which uses both fundamental and complex conjugate representations for an assignment of the representations to the left-handed quarks and the scalar representation to their corresponding right-handed counterparts, the nature of the scalar should be taken into account in order to make the fermion triangle anomalies in the theory anomaly-free, i.e. renormalizable in a sense with no anomalies, even after the spontaneous symmetry breaking.
We consider the possibility to explain the recent $R_K$ and $R_{K ^*}$ anomalies in a 2-Higgs Doublet Model, known as Aligned, combined with a low scale seesaw mechanism generating light neutrino masses and mixings. In this class of models, a large Yukawa coupling allows for significant non-universal leptonic contributions, through box diagrams mediated by charged Higgs bosons and right-handed neutrinos, to the $b \to s \ell^+ \ell^-$ transition that can then account for both $R_K$ and $R_{K^*}$ anomalies.
We show that a single vector leptoquark can explain both the muon $g-2$ anomaly recently measured by the Muon g-2 experiment at Fermilab, and the various $B$ decay anomalies, including the $R_{D^{(*)}}$ and $R_{K^{(*)}}$ anomalies which have been recently reported by the LHCb experiment. In order to provide sizeable positive new physics contributions to the muon $g-2$, we assume that the vector leptoquark particle couples to both left-handed and right-handed fermions with equal strength. Our model is found to satisfy the experimental constraints from the large hadron collider.
The $R_{D^{(*)}}$ anomalies are among the longest-standing and most statistically significant hints of physics beyond the Standard Model. Many models have been proposed to explain these anomalies, including the interesting possibility that right-handed neutrinos could be involved in the $B$ decays. In this paper, we investigate future measurements at Belle II that can be used to tell apart the various new physics scenarios. Focusing on a number of $τ$ asymmetry observables (forward-backward asymmetry and polarization asymmetries) which can be reconstructed at Belle II, we calculate the contrib…
We explain anomalies currently present in various data samples used for the measurement of the anomalous magnetic moment of electron ($a_e$) and muon ($a_μ$) in terms of an Aligned 2-Higgs Doublet Model with right-handed neutrinos. The explanation is driven by one and two-loop topologies wherein a very light CP-odd neutral Higgs state ($A$) contributes significantly to $a_μ$ but negligibly to $a_e$, so as to revert the sign of the new physics corrections in the former case with respect to the latter, wherein the dominant contribution is due to a charged Higgs boson ($H^\pm$) and heavy neutrino…
$U(1)^\prime$ extensions of the standard model with generation-dependent couplings to quarks and leptons are investigated as an explanation of anomalies in rare $B$-decays, with an emphasis on stability and predictivity up to the Planck scale. To these ends, we introduce three generations of vector-like standard model singlet fermions, an enlarged, flavorful scalar sector, and, possibly, right-handed neutrinos, all suitably charged under the $U(1)^\prime$ gauge interaction. We identify several gauge-anomaly free benchmarks consistent with $B_s$-mixing constraints, with hints for electron-muon …
We provide a combined explanation of the increasingly tantalizing $B$-meson anomalies, both in $R_{K^{(*)}}$ and $R_{D^{(*)}}$, in the Pati-Salam model with minimal matter content. This well-known model, based on the gauge group $SU(4)_{LC} \times SU(2)_L \times SU(2)_R$, naturally contains a variety of scalar leptoquarks with related and restricted couplings. In particular we show that the seesaw-motivated scalar leptoquark within the representation $(\overline{10}, 3, 1)$ and its right-handed parity partner $(\overline{10}, 1, 3)$ can solve both anomalies while making testable predictions fo…
The standard model is extended with three right-handed, singlet neutrinos with general couplings permitted by the $SU(2)_{L}\times U(1)$ symmetry. The traditional oscillations are accounted for, as usually, by three left-handed neutrinos. The article investigates new structures that develop when the masses of the right-handed states are in the eV range. The new states interfere and oscillate with the standard light neutrinos. New structures appear when the detectors average over short wavelengths. I use these results to present and classify properties of the observed anomalies in the MiniBooNe…
We propose a chiral Pati-Salam theory based on the gauge group $SU(4)_C\times SU(2)_L\times SU(2)_R$. The left-handed quarks and leptons are unified into a fundamental representation of $SU(4)_C$, while right-handed quarks and leptons have a separate treatment. The deviations measured in the rare semi-leptonic decays $B\to D^{(*)} τ\barν$ are explained by a scalar leptoquark which couples to right-handed fields and is contained in the $SU(4)_C\times SU(2)_R$ breaking scalar multiplet. The measured deviation of lepton flavor universality in the rare decays $\bar B\to \bar K^{(*)}\ell^+\ell^-$, …
Status of G2HDM with right handed neutrino coupling in the light of $b\to c τν$ anomalies
Indian Institute of Technology Gandhinagar（印度理工学院古吉拉特分校）；Aix Marseille Univ, Université de Toulon, CNRS, CPT, IPhU（艾克斯-马赛大学，土伦大学，法国国家科学研究中心，CPT，IPhU）；National institute of Technology Silchar（锡尔卡尔国立技术学院）
We explore the constraints imposed by the cancellation of triangle anomalies on models in which the flavour anomalies reported by LHCb and other experiments are due to an extra U(1)' gauge boson Z'. We assume universal and rational U(1)' charges for the first two generations of left-handed quarks and of right-handed up-type quarks but allow different charges for their third-generation counterparts. If the right-handed charges vanish, cancellation of the triangle anomalies requires all the quark U(1)' charges to vanish, if there are either no exotic fermions or there is only one Standard Model …
We propose a variant of the Pati-Salam model, with gauge group $SU(4)_C\times SU(2)_L\times U(1)_{Y'}$, in which the chiral left-handed quarks and leptons are unified into a $\underline{4}$ of $SU(4)_C$, while the right-handed quarks and leptons have quite a distinct treatment. The $SU(4)_C$ leptoquark gauge bosons can explain the measured deviation of lepton flavour universality in the rare decays: $\bar B \to \bar K^{(*)}\bar\ell\ell, \ell=μ,e$ (taken as a hint of new physics). The model satisfies the relevant experimental constraints and makes predictions for the important $B$ and $τ$ decay…
The updated measurements from the LHCb and SH0ES collaborations have respectively strengthened the deviations of the ratio $R_{K}$ in rare semi-leptonic $B$-meson decays and the present-day Hubble parameter $H_0$ in the Universe, implying tantalizing hints of new physics beyond the Standard Model. In this paper, we consider a simple flavor-specific two-Higgs-doublet model, where the long-standing $R_{K^{(*)}}$ anomalies can be addressed by a one-flavor right-handed neutrino. One of the intriguing predictions resulting from the parameter space for the $R_{K^{(*)}}$ resolution under flavor- and …
Given the particle content of the standard model without and with a right-handed neutrino, the requirement that all anomalies cancel singles out a set of possible global symmetries which can be gauged. I review this topic and propose a new gauge symmetry B - 3L_tau in the context of the minimal standard model consisting of the usual three families of quarks and leptons plus just one nu_R. The many interesting phenomenological consequences of this hypothesis are briefly discussed.
The lepton number violating interactions generated by the light Majorana neutrinos can erase the primordial baryon asymmetry of the universe during the electroweak phase transition. The Majorana masses of the left-handed neutrinos are constrained to avoid this problem. These constraints do not depend on the $(B-L)$ symmetry breaking mechanism.
We show that the baryon asymmetry of the Universe can be generated by a strongly coupled right handed neutrino condensate which also drives inflation. The resulting model has only a small number of parameters, which completely determine not only the baryon asymmetry of the Universe and the mass of the right handed neutrino but also the inflationary phase. This feature allows us to make predictions that will be tested by current and planned experiments. As compared to the usual approach our dynamical framework is both economical and predictive.
In recent years, several deviations from the Standard Model predictions in semileptonic decays of $B$-meson might suggest the existence of new physics which would break the lepton-flavour universality. In this work, we have explored the possibility of using muon sneutrinos and right-handed sbottoms to solve these $B$-physics anomalies simultaneously in $R$-parity violating minimal supersymmetric standard model. We find that the photonic penguin induced by exchanging sneutrino can provide sizable lepton flavour universal contribution due to the existence of logarithmic enhancement for the first…
The effects of possible right-handed weak hadronic currents in rare exclusive semileptonic decays B -> (K, K*) nu bar{nu} are investigated using a lattice-constrained dispersion quark model for the calculation of the relevant mesonic form factors. The results obtained for the branching ratios and the missing energy spectra are presented and the sensitivity of various observables to long-distance physics is investigated. It is shown that the asymmetry of transversely polarized K*(T) mesons as well as the K / K*(T) production ratio are only slightly sensitive to long-distance contributions and m…
We present a thorough investigation of the vector leptoquark hypothesis for a combined explanation of the $B$-physics anomalies. We analyze this hypothesis from a twofold perspective, taking into account recent results from $B$-physics observables and high-$p_T$ searches. First, using a simplified model, we determine the general conditions for a successful low-energy fit in presence of right-handed leptoquark couplings (neglected in previous analyses). Second, we show how these conditions, in particular a sizable 2-3 family mixing, can be achieved in a motivated ultraviolet completion. Our ana…
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 measured $B$-meson semi-leptonic branching ratios $R_{D}$ and $R_{D^*}$ have long-standing deviations between theory and experiment. We introduce a model which explains both anomalies through a single interaction by introducing a right-handed neutrino as the missing energy particle. This interaction is mediated by a heavy charged vector boson ($W'$) which couples only to right-handed quarks and leptons of the Standard Model through the mixing of these particles with new vector-like fermions. Previous $W'$ models for the $R_{D^{(*)}}$ anomaly were strongly constrained from flavor changing n…
Given that the two-Higgs-doublet model of type III (2HDM-III) has the potential to address the $R_{D^{(\ast)}}$ anomalies while the resolution to the $R_{K^{(\ast)}}$ deficits requires new degrees of freedom within this framework, we consider in this paper a unified scenario where the low-scale type-I seesaw mechanism is embedded into the 2HDM-III, so as to accommodate the $R_{D^{(\ast)}}$ and $R_{K^{(\ast)}}$ anomalies as well as the neutrino mass. We first revisit the $R_{D^{(\ast)}}$ anomalies and find that the current world-averaged results can be addressed at $2σ$ level without violating …
During a large period of time, the anomalous baryon number violating interactions are in equilibrium, when the $(B+L)$ asymmetry is washed out. If there is any lepton number violation during this period, that will also erase the $(B-L)$ asymmetry. As a result, survival of the baryon asymmetry of the universe pose strong constraints on lepton number violating interactions. We review here the constraints on the left-handed Majorana neutrino masses arising from this survival requirement of the baryon asymmetry of the universe. We then briefly review models of leptogenesis, where lepton number vio…
We explore scenarios where the $R(D^{(*)})$ anomalies arise from semitauonic decays to a right-handed sterile neutrino. We perform an EFT study of all five simplified models capable of generating at tree-level the lowest dimension electroweak operators that give rise to this decay. We analyze their compatibility with current $R(D^{(*)})$ data and other relevant hadronic branching ratios, and show that one simplified model is excluded by this analysis. The remainder are compatible with collider constraints on the mediator semileptonic branching ratios, provided the mediator mass is of order TeV…
Two recent experimental developments, when combined, may have far reaching implications. $S_{ϕK_S} < 0$, if confirmed, would imply large $s$-$b$ mixing, a new CP phase, and right-handed dynamics. Large $Δm_{B_s}$ would be likely, making the $B_s$ program at hadron machines difficult. Reconstruction of $B$ vertex from $K_S$ at B factories, as shown by BaBar's first measurement of $S_{K_Sπ^0}$, makes $S_{K_Sπ^0γ}$ in $\bar B\to \bar K^{*0}γ$ accessible. This would be a boon for B factory upgrades. Supersymmetric Abelian flavor symmetry, independently motivated, can realize all of this with a lig…
Motivated by the recent LHCb announcement of a $3.1σ$ violation of lepton-flavor universality in the ratio $R_K=Γ(B\to Kμ^+μ^-)/Γ(B\to K e^+ e^-)$, we present an updated, comprehensive analysis of the flavor anomalies seen in both neutral-current ($b\to s\ell^+\ell^-$) and charged-current ($b\to cτ\barν$) decays of $B$ mesons. Our study starts from a model-independent effective field-theory approach and then considers both a simplified model and a UV-complete extension of the Standard Model featuring a vector leptoquark $U_1$ as the main mediator of the anomalies. We show that the new LHCb dat…
Motivated by $-2 σ$ deviation from the Standard Model prediction for the forward--backward asymmetry of $Z \to b \bar{b}$ decay in the LEP data, we explore the anomalous couplings of $Z b \bar{b}$ vertex through the electroweak precision test extended by including $A_{FB}^b$. We introduce a new variable $ε'_b$ to measure the anomalous right-handed coupling in $Z b \bar{b}$ vertex. Implications of our analysis on the nonuniversal contact interactions are studied and the left-right model is also considered as a possible origin of the anomalous right-handed couplings.
In this paper we investigate the phenomenology of the U(1) gauge symmetry for right-handed fermions, where three right-handed neutrinos are introduced for anomalies cancellation. Constraints on the new gauge boson $Z_{\mathbf{R}}$ arising from $Z-Z^\prime$ mixing as well as the upper bound of $Z^\prime$ production cross section in di-lepton channel at the LHC are presented. We further study the neutrino mass generation and the phenomenology of $Z_{\mathbf{R}}$-portal dark matter in this model. The lightest right-handed neutrino can be the cold dark matter candidate stabilized by a $Z_2$ flavor…
The $B$-physics experiments at LHCb, BaBar and Belle hint towards deviations from Lepton Flavor Universality in both the tree-level and loop-induced $B$ meson semileptonic decays. We propose a leptoquark model with light right-handed neutrinos which can accommodate both $R_K^\mathrm{exp}<R_K^\mathrm{SM}$ and $R_{D^{(\ast)}}^\mathrm{exp}>R_{D^{(\ast)}}^\mathrm{SM}$. We discuss several of its predictions which can be tested in modern day experiments. We also comment on the recent finding at LHCb, namely $R_{K^\ast}^{\mathrm{exp}}<R_{K^\ast}^\mathrm{SM}$.
We propose a gauged $U(1)_{B-L}$ extension of the standard model (SM) to explain simultaneously the light neutrino masses and dark matter (DM). The generation of neutrino masses occurs through a variant of type-II seesaw mechanism in which one of the scalar triplets lies at the TeV scale yet have a large dilepton coupling, which paves a path for probing this model at colliders. The gauging of $U(1)_{B-L}$ symmetry in a type-II seesaw framework introduces $B-L$ anomalies. Therefore we invoke three right handed neutrinos $ν_{R_{i}}$(i=1,2,3) with $B-L$ charges -4,-4,+5 to cancel the anomalies. W…
The standard model has for massless quarks and leptons "miraculously" no triangle anomalies due to the fact that the sum of all possible traces $Tr [τ^{Ai}$$ τ^{Bj}$$ τ^{Ck}]$ --- where $τ^{Ai}, τ^{Bi}$ and $τ^{Ck}$ are the generators of one, of two or of three of the groups $SU(3), SU(2)$ and $U(1)$ --- over the representations of one family of the left handed fermions and anti-fermions (and separately of the right handed fermions and anti-fermions), contributing to the triangle currents, is equal to zero. It is demonstrated in this paper that this cancellation of the standard model triangle …
We study violation of quark-hadron duality for $\bar{B}\to X_ulν$ and $D\to X_dlν$ decays in the presence of the right-handed current operator. For this case, we show that duality violation has some aspects different from the standard model due to the existence of an instanton. In particular, the fermionic zero mode of an intermediate light quark can give a nonvanishing contribution owing to its chirality structure. A duality-violating component that arises from a single instanton is then analytically extracted as a finite-distance singularity, leading to an oscillatory correction to the obser…
We propose and study a novel extension of the Standard Model based on the B-L gauge symmetry that can account for dark matter and neutrino masses. In this model, right-handed neutrinos are absent and the gauge anomalies are canceled instead by four chiral fermions with fractional B-L charges. After the breaking of $U(1)_{B-L}$, these fermions arrange themselves into two Dirac particles, the lightest of which is automatically stable and plays the role of the dark matter. We determine the regions of the parameter space consistent with the observed dark matter density and show that they can be pa…
We point out that right-handed neutrinos can resolve the tension between the latest CDF II measurement of the $W$-boson mass, $M_W$, and the standard model. Integrating out the new states yields a single $d=6$ operator, which induces a deviation from unitarity in the PMNS matrix. This alters the extraction of the Fermi constant from muon decay and increases the prediction for $M_W$, in line with the CDF II result. Non-unitarity of the PMNS matrix would also affect beta, meson, and tau decays. We find that the CDF II value for $M_W$ can be explained without conflicting with lepton flavour unive…
We provide an ultraviolet (UV) complete model for the $R(D^{(*)})$ anomalies, in which the additional contribution to semi-tauonic $b \to c$ transitions arises from decay to a right-handed sterile neutrino via exchange of a TeV-scale $SU(2)_L$ singlet $W'$. The model is based on an extension of the Standard Model (SM) hypercharge group, $U(1)_Y$, to the $SU(2)_V\times U(1)'$ gauge group, containing several pairs of heavy vector-like fermions. We present a comprehensive phenomenological survey of the model, ranging from the low-energy flavor physics, direct searches at the LHC, to neutrino phys…
We study the possibility of baryogenesis in the case of supersymmetry breaking with large mixing between the right-handed scalar charm and right-handed scalar top or right-handed scalar up and right-handed scalar top squarks resulting in one light right-handed up-type squark mass eigenstate. We argue that in this case the electroweak phase transition will be first order, and that large phases already present in the quark mass matrices can generate a baryon asymmetry of the correct magnitude without introducing any new phases specifically for this purpose. We study in detail a particular ansatz…
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…
The recent recomputation of the neutrino fluxes from nuclear reactors relaxes the tension between the LSND and MiniBooNE anomalies and disappearance data when interpreted in terms of sterile neutrino oscillations. The simplest extension of the Standard Model with such fermion singlets is the addition of right-handed sterile neutrinos with small Majorana masses. Even when introducing three right-handed neutrinos, this scenario has less free parameters than the 3+2 scenarios studied in the literature. This begs the question whether the best fit regions obtained can be reproduced by this simplest…
The most promising scenarios of baryogenesis seems to be the one through lepton number violation. Lepton number violation through a Majarana mass of the right-handed neutrinos can generate a lepton asymmetry of the universe when the right-handed neutrinos decay. The left-handed neutrinos get small Majorana masses through see-saw mechanism in these models. A triplet higgs scalar violating lepton number explicitly through its couplings to two leptons or two higgs doublets can also naturally give small Majorana masses to the left-handed neutrinos and also generate a lepton asymmetry of the univer…
In this paper, we present the differential decay distributions for $\bar B \to D^{(*)} \ell \bar{X}$ decays with a massive right-handed neutrino in the low-energy effective field theory framework and show how the massive effects of the RH neutrinos can explain the positive value of the difference in forward-backward asymmetries, $ΔA_{\text{FB}}\equiv A_{\text{FB}}^μ-A_{\text{FB}}^e$, tentatively inferred from Belle data. We also make predictions for $q^2$ dependent angular observables to motivate future measurements.
We explore the anomalous right-handed $\bar{t}sW$ and $\bar{t}bW$ couplings using $ B \to X_s γ$ and $B \to X_s l^+ l^-$ decays induced by the flavour-changing penguin diagrams. The anomalous $\bar{t}sW$ coupling can yield 10% enhancement of the $B \to X_s l^+ l^-$ decay rate under the constraint from the present $B \to X_s γ$ data, while it does not affect the forward-backward asymmetry of the charged lepton. The allowed region for anomalous $\bar{t}bW$ coupling by the $ B \to X_s γ$ constraint is two-fold, the small value region and the large value region. Though the effect of the small anom…
The LHCb has measured the ratios of $B\to K^\astμ^+μ^-$ to $B\to K^\ast e^+ e^-$ branching fractions in two dilepton invariant mass squared bins, which deviate from the Standard Model predictions by approximately $2.5σ$. These new measurements strengthen the hint of lepton flavor universality breaking which was observed earlier in $B\to K\ell^+\ell^-$ decays. In this work we explore the possibility of explaining these anomalies within the framework of $R$-parity violating interactions. In this framework, $b\to s\ell^+\ell^-$ transitions are generated through tree and one loop diagrams involvin…
We consider the interplay between dark matter and leptogenesis in a common framework, where three right-handed neutrinos, one fermionic dark matter and two singlet scalars are introduced into the Standard Model. The mixing of the two singlet scalars not only determine the dark matter relic density but also connect right-handed neutrino with dark matter. We consider that the baryon asymmetry is generated via the resonant leptogenesis and the right-handed neutrino masses are at TeV level. We present a viable parameter space satisfying relic density constraint, and the parameter space is more fle…
Many GUT models conserve the difference between the baryon and lepton number, $B-L$. These models can create baryon and lepton asymmetries from heavy Higgs or gauge boson decays with $B+L \neq 0$ but with $B-L=0$. Since the sphaleron processes violate $B+L$, such GUT-generated asymmetries will finally be washed out completely, making GUT baryogenesis scenarios incapable of reproducing the observed baryon asymmetry of the Universe. In this work, we revisit the idea to revive GUT baryogenesis, proposed by Fukugita and Yanagida, where right-handed neutrinos erase the lepton asymmetry before the s…
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…
Experimental measurements collected by the BABAR, Belle, and LHCb experiments on different observables associated with the semileptonic transition $b \to c τ\barν_τ$, indicate the existence of disagreement respect with the Standard Model predictions. We analyse the charged scalar boson contributions to these charged-current $B$ meson anomalies within the framework of two Higgs doublet model with the most general Yukawa couplings to quarks and leptons from the third generation, involving left-handed and right-handed (sterile) neutrinos. We perform a phenomenological study of the Yukawa coupling…
We explore the CP violation in $B \to ϕK$ decay processes in the presence of the anomalous right-handed $\bar{t}sW$ and $\bar{t}bW$ couplings. The complex anomalous top coupling can be a source of the new CP violation and lead to a deviation of the observed weak phase in $B \to ϕK$ decays, which takes account for the present disagreement of the observed $\sin 2 β$ between $B \to J/ψK$ and $B \to ϕK$ decays. The direct CP violation is also predicted.
Renormalization effects of large baryon-nonconserving Yukawa couplings $λ^{\prime\prime}_{ijk} \overline{U_i} \overline{D_j} \overline{D_k}$ lower the right handed squark masses keeping the left-handed squark masses virtually untouched at the lowest order. At low energy they enhance the mass-splitting between left and right handed squarks of the same generation as well as intergenerational mass splitting among squarks, potentially detectable in future colliders or in rare decays. The predicted mass of the lightest stop squark becomes lower than the experimental bound for larger ranges of param…
Light sterile neutrinos of mass about an eV with mixing $\tilde U_{ls}$ of a few percent to active neutrinos may solve some anomalies shown in experimental data related to neutrino oscillation. How to have light sterile neutrinos is one of the theoretical problems which have attracted a lot of attentions. In this article we show that such an eV scale light sterile neutrino candidate can be obtained in a seesaw model in which the right-handed neutrinos satisfy a softly-broken Friedberg-Lee (FL) symmetry. In this model a right-handed neutrino is guaranteed by the FL symmetry to be light comparin…
Freedom from global anomalies in the presence of a local SU(2)_H horizontal symmetry under which right handed charged leptons transform nontrivially requires that there be at least two right handed neutrinos with masses of order of the horizontal symmetry breaking scale. If a third right handed neutrino is introduced to satisfy quark lepton symmetry, it is unprotected by the horizontal symmetry, becomes superheavy with a Planck scale mass and decouples from lower energy physics. The resulting seesaw mechanism with two right handed neutrinos in combination with the horizontal symmetry leads nat…
