We have studied the prospects of measuring the CP violating phase with atmospheric neutrinos at a large magnetized iron calorimeter detector considering the muons (directly measurable) of the neutrino events generated by a MonteCarlo event generator Nuance. The effect of $θ_{13}$ and $δ_{CP}$ appears dominantly neither in atmospheric neutrino oscillation nor in solar neutrino oscillation, but appears as subleading in both cases. These are observable in range of $E \sim 1$ GeV for atmospheric neutrino, where solar and atmospheric oscillation couple. In this regime, the quasi-elastic events dominate and the energy resolution is very good, but the angular resolution is very poor. Unlike beam experiments this poor angular resolution acts against its measurements. However, we find that one can be able to distinguish $δ_{CP}\approx 0^\circ$ and $180^\circ$ at 90% confidence level. We find no significant sensitivity for $δ_{CP}\approx 90^\circ$ or $270^\circ$.
We review the prospects of measurements of the CKM matrix elements corresponding to the first two generations of quarks, as well as measurements of leptonic and semileptonic charm meson decays at LHCb. We review the status of searches for Lepton Non-Universality in the charm sector, and provide motivation to continue such searches.
Bi-large patterns for the leptonic mixing matrix are confronted with current neutrino oscillation data. We analyse the status of these patterns and determine, through realistic simulations, the potential of upcoming long-baseline experiment DUNE in testing bi-large \emph{ansatze} and discriminating amongst them.
We perform realistic simulations of the current and future long baseline experiments such as T2K, NO$ν$A, DUNE and T2HK in order to determine their ultimate potential in probing neutrino oscillation parameters. We quantify the potential of these experiments to underpin the octant of the atmospheric angle $θ_{23}$ as well as the value and sign of the CP phase $δ_{CP}$.
The measurement of a non-zero value of the 1-3 mixing angle has paved the way for the determination of leptonic CP violation. However the current generation long-baseline experiments T2K and NOvA have limited sensitivity to delta_{CP}. In this paper we show for the first time, the significance of that atmospheric neutrino experiments in providing the first hint of CP violation in conjunction with T2K and NOvA. In particular, we find that adding atmospheric neutrino data from the ICAL detector at the India-based Neutrino Observatory (INO) to T2K and NOvA results in a two-fold increase in the ra…
One of the main neutrino oscillation parameters whose value has not been determined very precisely is the leptonic $δ_{CP}$ phase. Since neutrinos have a tiny but finite mass they can undergo decay both visibly and invisibly. The effect of invisible decay of the third mass eigen state $ν_3$ on the sensitivity to $δ_{CP}$ is analysed here using atmospheric neutrino and anti-neutrino events. Effects of detector resolutions and systematic uncertainties are studied to identify the optimum resolutions and efficiencies required by a detector to obtain a significant sensitivity even in presence of de…
The Dirac leptonic CP phase δ_CP is one of the crucial unknown parameters in neutrino oscillation physics. In this paper we explore the possibility of using low energy atmospheric neutrino events to probe δ_CP . We show that at sub GeV energies, when the events are binned as a function of the energy and direction of the final state leptons, a consistent distinction between various true δ_CP values is obtained. We also show that at these energies there is no sensitivity to the mass ordering/hierarchy, so that δ_CP can be measured without hierarchy ambiguity. In addition a preliminary \c{hi}^2 a…
After the observation of non-zero $θ_{13}$ the goal has shifted to observe $CP$ violation in the leptonic sector. Neutrino oscillation experiments can, directly, probe the Dirac $CP$ phases. Alternatively, one can measure $CP$ violation in the leptonic sector using Leptonic Unitarity Quadrangle(LUQ). The existence of Standard Model (SM) gauge singlets - sterile neutrinos - will provide additional sources of $CP$ violation. We investigate the connection between neutrino survival probability and rephasing invariants of the $4\times4$ neutrino mixing matrix. In general, LUQ contain eight geometri…
Two types of pseudoscalar quarkonium electromagnetic decay processes, i.e. decay to a lepton pair, and to a lepton pair plus a photon (Dalitz decay), are analyzed at the leading order in NRQCD expansion. The former type of processes, highly suppressed in the Standard Model, have been hoped to act as the sensitive probes of the possible new physics. The latter type of processes generally possess much greater decay rates than the former, owing to several conspiring factors. The recently launched BES-III program, with $10^8$ $η_c$ samples to be anticipated in the coming years, may be able to obse…
We present an overview of the current status of neutrino oscillation studies at atmospheric neutrino experiments. While the current data gives some tentalising hints regarding the neutrino mass hierarchy, octant of $θ_{23}$ and $δ_{CP}$, the hints are not statistically significant. We summarise the sensitivity to these sub-dominant three-generation effects from the next-generation proposed atmospheric neutrino experiments. We next present the prospects of new physics searches such as non-standard interactions, sterile neutrinos and CPT violation studies at these experiments.
Prospects for toponium formation at the LHC in the single-lepton mode
Sorbonne Université et CNRS（索邦大学与法国国家科学研究中心）；KEK Theory Center（高能加速器研究机构理论中心）；Xi’an University of Architecture and Technology（西安建筑科技大学）；The University of Osaka（大阪大学）
I attempt to quantify how far from maximal one should expect the atmospheric mixing angle to be given a neutrino mass-matrix that leads, at zeroth order, to a nu_3 mass-eigenstate that is 0% nu_e, 50% nu_mu, and 50% nu_tau. This is done by assuming that the solar mass-squared difference is induced by an "anarchical" first order perturbation, an approach than can naturally lead to experimentally allowed values for all oscillation parameters. In particular, both |cos 2theta_atm| (the measure for the deviation of atmospheric mixing from maximal) and |U_e3| are of order sqrt(Delta m^2_sol/Delta m^…
We explore a possibility to measure the CP-violating phase $δ$ using multi-megaton scale ice or water Cherenkov detectors with low, $(0.2 - 1)$ GeV, energy threshold assuming that the neutrino mass hierarchy is identified. We elaborate the relevant theoretical and phenomenological aspects of this possibility. The distributions of the $ν_μ$ (track) and $ν_e$ (cascade) events in the neutrino energy and zenith angle $(E_ν- θ_z)$ plane have been computed for different values of $δ$. We study properties and distinguishability of the distributions before and after smearing over the neutrino energy a…
We present a model for leptonic mixing and the lepton masses based on flavor symmetries and higher-dimensional mass operators. The model predicts bilarge leptonic mixing (i.e., the mixing angles theta_{12} and theta_{23} are large and the mixing angle theta_{13} is small) and an inverted hierarchical neutrino mass spectrum. Furthermore, it approximately yields the experimental hierarchical mass spectrum of the charged leptons. The obtained values for the leptonic mixing parameters and the neutrino mass squared differences are all in agreement with atmospheric neutrino data, the Mikheyev--Smirn…
We compute the next-to-leading order QCD predictions for the vertical flux of atmospheric muons and neutrinos from decays of charmed particles, for different PDF's (MRS-R1, MRS-R2, CTEQ-4M and MRST) and different extrapolations of these at small partonic momentum fraction x. We find that the predicted fluxes vary up to almost two orders of magnitude at the largest energies studied, depending on the chosen extrapolation of the PDF's. We show that the spectral index of the atmospheric leptonic fluxes depends linearly on the slope of the gluon distribution function at very small x. This suggests …
The leptonic mixing angle theta_13 is currently a high-priority topic in the field of neutrino physics, with five experiments under way, searching for neutrino oscillations induced by this angle. We review the phenomenology of theta_13 and discuss the information from present global oscillation data. A description of the upcoming reactor and accelerator experiments searching for a non-zero value of theta_13 is given, and we evaluate the sensitivity reach within the next few years.
We calculate, for the first time, the NNLO QCD corrections to identified heavy hadron production at hadron colliders. The calculation is based on a flexible numeric framework which allows the calculation of any distribution of a single identified heavy hadron plus jets and non-QCD particles. As a first application we provide NNLO QCD predictions for several differential distributions of $B$ hadrons in $t\bar t$ events at the LHC. Among others, these predictions are needed for the precise determination of the top quark mass. The extension of our results to other processes, like open or associat…
In this talk we will discuss the physics reach of the atmospheric neutrino data collected by a future megaton-class neutrino detector. First we will discuss the potentialities of atmospheric neutrinos on general basis, presenting our results in the form of neutrino oscillograms of the Earth: contour plots in the neutrino energy--nadir angle plane. In this context we will analyze in detail the various signatures related to theta_13, to the neutrino mass hierarchy, to the octant of theta_23 and to the delta_CP phase which appear for different values of the neutrino energy and baseline. Then we w…
We propose to use the unique event topology and reconstruction capabilities of liquid argon time projection chambers to study sub-GeV atmospheric neutrinos. The detection of low energy recoiled protons in DUNE allows for a determination of the leptonic $CP$-violating phase independent from the accelerator neutrino measurement. Our findings indicate that this analysis can exclude several values of $δ_{CP}$ beyond the $3σ$ level. Moreover, the determination of the sub-GeV atmospheric neutrino flux will have important consequences in the detection of diffuse supernova neutrinos and in dark matter…
I discuss some theoretical aspects of how to observe leptonic CP violation. It is divided into two parts, one for CP violation due to Majorana, and the other more conventional leptonic Kobayashi-Maskawa (KM) phases. In the first part, I estimate the effect of Majorana phase to observable of neutrinoless double beta decay experiments by paying a careful attention to the definition of the atmospheric scale Delta m^2. In the second part, I discuss Tokai-to-Kamioka-Korea two detector complex which receives neutrino superbeam from J-PARC as a concrete setting for discovering CP violation due to the…
We study leptonic CKM mixing matrices when the neutrino Yukawa matrices are antisymmetric which gives rise to mass patterns suitable to explain solar, atmospheric and LSND neutrino oscillation experiments. Taking diagonal leptonic matrices which can give rise to hierarchical lepton masses, we compute the leptonic CKM matrix.
The discovery of leptonic CP violation is one of the primary goals of next-generation neutrino oscillation experiments, which is feasible due to the recent measurement of a relatively large leptonic mixing angle θ_{13}. We suggest two new working observables ΔA^{\rm m}_{αβ} \equiv \max[A^{\rm CP}_{αβ}(δ)] - \min[A^{\rm CP}_{αβ}(δ)] and ΔA^{\rm CP}_{αβ}(δ) \equiv A^{\rm CP}_{αβ}(δ) - A^{\rm CP}_{αβ}(0) to describe the CP-violating effects in long-baseline and atmospheric neutrino oscillation experiments. The former signifies the experimental sensitivity to the leptonic Dirac CP-violating phase …
The pattern of oscillation parameters emerging from current experimental data can be further elucidated by the observation of matter effects. In contrast to planned experiments with conventional neutrino beams, atmospheric neutrinos offer the possibility to search for Earth-induced matter effects with very long baselines. Resonant matter effects are asymmetric on neutrinos and anti-neutrinos, depending on the sign of $Δm^2$. In a three-generation oscillation scenario, this gives access to the mass hierarchy of neutrinos, while the size of the asymmetry would measure the admixture of electron n…
We construct and present a model for leptonic mixing based on higher-dimensional operators, using the Froggatt-Nielsen mechanism, and Abelian horizontal symmetries (flavor symmetries) of continuous and discrete type. Our model naturally yields bilarge leptonic mixing, coming from both the charged leptons and the neutrinos, and an inverted neutrino mass hierarchy spectrum. The obtained values of the parameters, i.e., the leptonic mixing parameters and the neutrino mass squared differences, are all consistent with the atmospheric neutrino data and the Mikheyev-Smirnov-Wolfenstein large mixing an…
It is shown that in SO(10) models where the large solar and atmospheric neutrino angles come from the charged-lepton mass being "lopsided", there is a characteristic relation between the 13 mixing angle of the neutrinos and the size of the Dirac CP- violating phase in the lepton sector. This is illustrated in a recently proposed realistic and predictive model.
We propose that leptonic CP violation arises from a breaking of the mu-tau exchange symmetry in the neutrino mass matrix which in turn is indicated by the near maximal atmospheric neutrino mixing and the near zero θ_{13}. We find that for the case of a normal hierarchy, present data already restricts the way CP violation may appear in the neutrino mass matrix and there is an interesting correlation between the mixing angle θ_{13}, the solar mixing angle θ_{12} and the Dirac CP phase. In the inverted hierarchy only θ_{13} and the Dirac phase are linked. We also discuss the impact of this kind o…
Differences in lepton number (i.e., $ L _e - L _μ$, $ L _e - L _τ$, $ L_μ- L _τ$, or combinations thereof) are not conserved charges in the Standard Model due to the observation of neutrino oscillations. We compute the divergence of the corresponding currents in the case of Majorana or Dirac-type neutrinos and show that, in the high energy limit, the vector interactions map onto those of a light scalar coupled to neutrinos with its coupling fixed by the observed neutrino masses and mixing. This leads to amplitudes with external light vectors that scale inversely with the vector mass. By studyi…
An extension of the neutrino sector with two right handed singlet neutrinos responsible for Dirac neutrino masses is discussed. We show that this setup with flavor symmetry can give large solar and atmospheric neutrino mixings and suppressed Theta_13. The flavor symmetry U(1) x S_4 is shown to lead to Theta_23 = π/4 and a new predictive formula for the Theta_13(\simeq 0.015).
We take up the point of view that Yukawa couplings can be either 0 or 1, and the mass patterns of fermions are generated purely from the structure of the Yukawa matrices. We utilize such neutrino as well as charged leptonic textures which lead to (maximal) mixing angles of $π/4$ in each sector for relevant transitions. The combined leptonic CKM mixing angles are $π/4 \pm π/4$ which lead to very small $\sin^2 2 Θ$ relevant to solar neutrino and LSND experiments. We propose that on the other hand the absence of the charged leptonic partner of the sterile neutrino maintains the angle $π/4$ from t…
The unitarity of the lepton mixing matrix is a critical assumption underlying the standard neutrino-mixing paradigm. However, many models seeking to explain the as-yet-unknown origin of neutrino masses predict deviations from unitarity in the mixing of the active neutrino states. Motivated by the prospect that future experiments may provide a precise measurement of the lepton mixing matrix, we revisit current constraints on unitarity violation from oscillation measurements and project how next-generation experiments will improve our current knowledge. With the next-generation data, the normali…
Models of leptonic flavour with discrete symmetries can provide an attractive explanation of the pattern of elements found in the leptonic mixing matrix. The next generation of neutrino oscillation experiments will allow the mixing parameters to be tested to a new level of precision, crucially measuring the CP violating phase δ for the first time. In this contribution, we present results of a systematic survey of the predictions of a class of models based on residual discrete symmetries and the prospects for excluding such models at medium- and long-term oscillation experiments. We place parti…
Neutrino oscillations as solutions of the solar neutrino problems and the atmospheric neutrino deficits may restrict neutrino mass squared differences and mixing angles in three-neutrino mixing scheme. Currently we have several solutions depending on the interpretations of the solar neutrino problems. Combining the neutrino oscillation solutions and a mass matrix ansatz, we investigated the neutrino mass bounds and found possible leptonic CP-violating rephasing-invariant quantity $J^{l}_{\tiny CP} \leq 0.012$ for large mixing angle MSW and just-so vacuum oscillations solutions, and $J^{l}_{\ti…
The octant of the atmospheric mixing angle $θ_{23}$ is still undetermined by neutrino oscillation experiments. Long-baseline experiments like NO$ν$A, T2K and DUNE offer good prospects for determining the octant of $θ_{23}$. However, their capability to do so may be compromised by the possible presence of non-unitarity in the leptonic mixing matrix. In this paper, we study in detail the octant degeneracy with and without non-unitarity at the level of oscillation probabilities and events for these experiments. We also analyze their octant sensitivity and discovery reach and show that they are ha…
Model-independent consequences of applying a generalized hidden horizontal Z_2 symmetry to the neutrino mass matrix are explored. The Dirac CP phase delta_D can be expressed in terms of the three mixing angles as 4 c_a s_a c_s s_s s_x cos delta_D = (s^2_s - c^2_s s^2_x) (c^2_a - s^2_a) where the s_i, c_i are sines and cosines of the atmospheric, solar, and reactor angles. This relation is independent of neutrino masses and whether neutrinos are Dirac- or Majorana-type. Given the present constraints on the angles, delta_D is constrained to be almost maximal, a result which can be explored in ex…
We present a global analysis of solar, atmospheric, reactor and accelerator neutrino data in the framework of three-neutrino oscillations based on data available in summer 2014. We provide the allowed ranges of the six oscillation parameters and show that their determination is stable with respect to uncertainties related to reactor neutrino and solar neutrino flux predictions. We find that the maximal possible value of the Jarlskog invariant in the lepton sector is $0.0329 \pm 0.0009$ ($\pm 0.0027$) at the $1σ$ ($3σ$) level and we use leptonic unitarity triangles to illustrate the ability of …
We explore the collider prospects of neutrino non-standard interaction with a Standard Model (SM) gauge-singlet leptonic scalar $ϕ$ carrying two units of lepton-number-charge. These leptonic scalars are forbidden from interacting with the SM fermions at the renormalizable level and, if one allows for higher-dimensional operators, couple predominantly to SM neutrinos. For masses at or below the electroweak scale, $ϕ$ decays exclusively into neutrinos. Its characteristic production signature at hadron collider experiments like the LHC would be via the vector boson fusion process and leads to sam…
We update and improve past efforts to predict the leptonic Dirac CP-violating phase with models that predict perturbatively modified tribimaximal or bimaximal mixing. Simple perturbations are applied to both mixing patterns in the form of rotations between two sectors. By translating these perturbed mixing matrices to the standard parameterization for the neutrino mixing matrix we derive relations between the Dirac CP-phase and the oscillation angles. We use these relations together with current experimental results to constrain the allowed range for the CP-phase and determine its probability …
We show that the simultaneous determination of the leptonic CP-odd phase $δ$ and the angle $θ_{13}$ from the subleading transitions $ν_e\toν_μ$ and ${\barν}_e\to{\barν}_μ$ results generically, at fixed neutrino energy and baseline, in two degenerate solutions. In light of this, we refine a previous analysis of the sensitivity to leptonic CP violation at a neutrino factory, in the LMA-MSW scenario, by exploring the full range of $δ$ and $θ_{13}$. Furthermore, we take into account the expected uncertainties on the solar and atmospheric oscillation parameters and in the average Earth matter densi…
We point out the opportunity of tau neutrino astronomy for neutrino energies of the order of 10 GeV to 10$^{3}$ GeV. In this energy range, it is demonstrated that the flavor dependence in the background atmospheric neutrino flux leads to drastically different prospects between the observation of astrophysical muon neutrinos and that of astrophysical tau neutrinos. Taking the galactic-plane neutrino flux as a targeted astrophysical source, we found that the galactic-plane tau neutrino flux dominates over the atmospheric tau neutrino flux for neutrino energies beyond 10 GeV. Hence the galactic-p…
The non-unitarity of the effective leptonic mixing matrix at low energies is a generic signal of extensions of the Standard Model (SM) with extra fermionic singlet particles, i.e. sterile or right-handed neutrinos, to account for the observed neutrino masses. The low energy effects of such extensions can be described in a model-independent way by the Minimal Unitarity Violation (MUV) scheme, an effective field theory extension of the SM. We perform a global fit of the MUV scheme parameters to the present experimental data, which yields the up-to-date constraints on leptonic non-unitarity. Furt…
The intensity of TeV atmospheric muons and neutrinos depends on the temperature in the stratosphere. We show that the energy-dependence in the 100 TeV range of the correlation with temperature is sensitive to the fraction of muons and neutrinos from decay of charmed hadrons. We discuss the prospects for using the temperature effect as observed in gigaton neutrino detectors to measure the charm contribution.
We present the prospects of ORCA searches for new physics phenomena using atmospheric neutrinos. Focus is given to exploiting the impact of strong matter effects on the oscillation of atmospheric neutrinos in light of expanded models, such as sterile neutrinos and non-standard interactions. In the presence of light sterile neutrinos that mix with active neutrinos, additional resonances and suppressions may occur at different energies. One may also use neutrino oscillations to probe the properties of the coherent forward scattering which may be altered by new interactions beyond the Standard Mo…
Precision measurement of the neutrino mixing parameters and the determination of mass hierarchy are the primary goals of the present and upcoming neutrino experiments. In this work, we study the sensitivity of T2K,NO$ν$A and LBNE experiments to discover leptonic CP violation and the determination of neutrino mass hierarchy. We obtain the correlation between the CP violating phase $δ_{CP}$ and the mixing angles $θ_{13}$, $θ_{23}$ and the sensitivity to determine the octant of atmospheric mixing angle $θ_{23}$. The entire analysis is done for a total 10 years (5$ν$+ 5$\bar ν$) of running of T2K,…
Fermion mixing is generally believed to be a low-energy manifestation of an underlying theory whose energy scale is much larger than the electroweak scale. In this paper we investigate the possibility that the parameters describing lepton mixing actually arise from the low-energy behavior of the neutrino interacting fields. In particular, we conjecture that the measured value of the mixing angles for a given process depends on the number of unobservable flavor states at the energy of the process. We provide a covariant implementation of such conjecture, draw its consequences in a two neutrino …
In this talk, based on the work \cite{cpviolation}, we refine our previous analysis \cite{golden} of the sensitivity to leptonic CP violation and $\tetaot$ at a neutrino factory in the LMA-MSW scenario, by exploring the full range of these two parameters. We have discovered that there exist, at fixed neutrino energy, $E_ν$, and baseline, $L$, degenerate solutions. Although the spectral analysis helps in disentangling fake from true solutions, a leftover product of this degeneracy remains for a realistic detector, which we analyse. Furthermore, we take into account the expected uncertainties on…
We propose that the observed large leptonic mixing may just reflect a quasidegeneracy of three Majorana neutrinos. The limit of exact degeneracy of Majorana neutrinos is not trivial, as leptonic mixing and even CP violation may occur. We conjecture that the smallness of $|U_{13}|$, when compared to the other elements of $U_{PMNS}$, may just reflect the fact that, in the limit of exact mass degeneracy, the leptonic mixing matrix necessarily has a vanishing element. We show that the lifting of the mass degeneracy can lead to the measured value of $|U_{13}|$ while at the same time accommodating t…
Tribimaximal leptonic mixing is a mass-independent mixing scheme consistent with the present solar and atmospheric neutrino data. By conveniently decomposing the effective neutrino mass matrix associated to it, we derive generic predictions in terms of the parameters governing the neutrino masses. We extend this phenomenological analysis to other mass-independent mixing schemes which are related to the tribimaximal form by a unitary transformation. We classify models that produce tribimaximal leptonic mixing through the group structure of their family symmetries in order to point out that ther…
The experimental prospects for precise measurements of the leptonic decays B_u -> tau nu / mu nu, B_s -> mu+ mu-, D -> mu nu and D_s -> mu nu / tau nu are very promising. Double ratios involving four of these decays can be defined in which the dependence on the values of the decay constants is essentially eliminated, thus enabling complementary measurements of the CKM matrix element V_ub with a small theoretical error. We quantify the experimental error in a possible future measurement of |V_ub| using this approach, and show that it is competitive with the anticipated precision from the conven…
We show the prospects of probing neutral-current non-standard interaction (NSI) in the propagation of atmospheric neutrinos in future large-volume neutrino experiments including DUNE, HK, KNO, and ORCA. For DUNE, we utilize its ability of identifying the tau neutrino event and combine the $ν_τ$ appearance with the $ν_μ$ disappearance. Based on our simulated results, the ten years of data taking of the atmospheric neutrinos can enormously improve the bounds on the NSI parameters $\varepsilon_{μτ}, | \varepsilon_{μμ} - \varepsilon_{ττ} |$, $\varepsilon_{e μ}$, $\varepsilon_{e τ}$ and $| \varepsi…
The high scale mixing unification hypothesis recently proposed by three of us (R. N. M., M. K. P. and G. R.) states that if at the seesaw scale, the quark and lepton mixing matrices are equal then for quasi-degenerate neutrinos, radiative corrections can lead to large solar and atmospheric mixings and small reactor angle at the weak scale in agreement with data. Evidence for quasi-degenerate neutrinos could, within this framework, be interpreted as a sign of quark-lepton unification at high scale. In the current work, we extend this model to show that the hypothesis works quite successfully in…
In this paper we quantify the trade-off between setups optimized to be ancillary to Phase II Superbeams or Neutrino Factories and experiments tuned for maximal sensitivity to the subdominant terms of the neutrino transition probability at the atmospheric scale (``maximum discovery potential''). In particular, the theta(13) sensitivity is computed for both Phase I superbeams (JHF-SK and NuMI Off-Axis) and next generation long baseline experiments (ICARUS, OPERA and MINOS). It is shown that Phase I experiments cannot reach a sensitivity able to ground (or discourage in a definitive manner) the b…
We consider a supersymmetric SU(4)$_c \times$SU(2)$_L \times$SU(2)$_R$ model with a minimal number of Higgs multiplets and Dirac and Majorana $CP$-violating phases in the neutrino flavor mixing matrix. The model incorporates the charged fermion masses and quark mixings, and uses type I seesaw to explain the solar and atmospheric neutrino oscillations. With the neutrino oscillation data of two mass squared differences and three flavor mixing angles, we employ thermal leptogenesis and the observed baryon asymmetry to find the allowed regions for the Dirac and Majorana phases. For a normal neutri…
We discuss general predictions for neutrino masses and mixing angles from R parity violation in the Minimal Supersymmetric Standard Model. If the soft supersymmetry breaking terms are flavor blind at short distance, then the leptonic analogue of the CKM matrix depends on only two real parameters, which are completely determined by fits to solar and atmospheric neutrino oscillations. Either the small angle MSW, large angle MSW, or ``just-so'' solutions to the solar neutrino problem are allowed, although the large angle MSW solution requires substantial fine-tuning. The latter two cases require …
We propose a generalized $μ-τ$ reflection symmetry to constrain the lepton flavor mixing parameters. We obtain a new correlation between the atmospheric mixing angle $θ_{23}$ and the "Dirac" CP violation phase $δ_{\rm CP}$. Only in a specific limit our proposed CP transformation reduces to standard $μ-τ$ reflection, for which $θ_{23}$ and $δ_{CP}$ are both maximal. The "Majorana" phases are predicted to lie at their CP-conserving values with important implications for the neutrinoless double beta decay rates. We also study the phenomenological implications of our scheme for present and future …
We extend a treatment of the causal structure of space-time to active-sterile neutrino transformation-based schemes for lepton number generation in the early universe. We find that these causality considerations necessarily lead to the creation of spatial domains of lepton number with opposite signs. Lepton number gradients at the domain boundaries can open a new channel for MSW resonant production of sterile neutrinos. The enhanced sterile neutrino production via this new channel allows considerable tightening of Big Bang Nucleosynthesis constraints on active-sterile neutrino mixing, includin…
We review the current status of neutrino oscillations after 1258 days of Super-Kamiokande, assess their future prospects over the next 10 years as the next generation of experiments come on-line, and discuss the longer-term opportunities presented by a Neutrino Factory. We also give an introduction to the see-saw mechanism and its application to atmospheric and solar neutrinos.
The importance of non-zero neutrino mass as a probe of particle physics, astrophysics, and cosmology is emphasized. The present status and future prospects for the solar and atmospheric neutrinos are reviewed, and the implications for neutrino mass and mixing in 2, 3, and 4-neutrino schemes are discussed. The possibilities for significant mixing between ordinary and light sterile neutrinos are described.
