We discuss short-baseline and very-short-baseline electron neutrino disappearance at a neutrino factory. We take into account geometric effects, such as from averaging over the decay straights, and the uncertainties of the cross sections. We follow an approach similar to reactor experiments with two detectors: we use two sets of near detectors at different distances to cancel systematics. We demonstrate that such a setup is very robust with respect to systematics, and can have excellent sensitivities to the effective mixing angle and squared-mass splitting. In addition, we allow for CPT invariance violation, which can be tested (depending on the parameters) up to a 0.1% level.
Recent measurements of large theta_{13} by Daya Bay and RENO reactor experiments have opened up the possibility of determining the neutrino mass hierarchy, i.e. the sign of the mass squared splitting Delta m_{31}^2, the CP-violating phase delta_{CP} and the octant of theta_{23}. In the light of this result, we study the performance of a low energy neutrino factory (LENF) for determination of the mass hierarchy. In particular, we explore the potential of the nu_e$ and barν_e disappearance channels at LENF to determine the neutrino mass hierarchy, that is free from the uncertainties arising from…
We study the $ν_μ$ disappearance channel at T2K-phase I and the SPL and analyse the achievable reduction of present uncertainties in $θ_{23}$ and $Δm^2_{23}$. We analyse the impact of discrete ambiguities in sign($Δm^2{23}$) and sign($2 \tan θ_{23}$). We show how the disappearance channel at the Neutrino Factory is complementary to the ``golden'' and ``silver'' appearance channels and can be used to reduce the eightfold-ambiguity problem in ($θ_{13}-δ$).
We discuss short-baseline electron and muon neutrino disappearance searches into sterile neutrinos at a Very Low Energy Neutrino Factory (VLENF) with a muon energy between about two and four GeV. A lesson learned from reactor experiments, such as Double Chooz and Daya Bay, is to use near and far detectors with identical technologies to reduce the systematical errors. We therefore derive the physics results from a combined near-far detector fit and illustrate that uncertainties on cross sections x efficiencies can be eliminated in a self-consistent way. We also include the geometry of the setup…
We discuss and quantify different possibilities to determine matter effects, the value and the sign of $Delta m^2_{31}$, as well as the magnitude of $\sin^2 2θ_{13}$ in very long baseline neutrino oscillation experiments. We study neutrino oscillation at a neutrino factory in the $ν_μ\toν_μ$ disappearance and $ν_e\toν_μ$ appearance channels with and without muon charge identification. One possibility is to analyze the $ν_e\toν_μ$ appearance channels leading to wrong sign muon events, which requires however very good muon charge identification. Without charge identification it is still possible…
We study the measurement of the atmospheric neutrino oscillation parameters, $θ_{23}$ and $Δm^2_{23}$, at the $ν_μ$ disappearance channel at three conventional beam facilities, the SPL, T2K-phase I and NO$ν$A. These two parameters have been shown to be of crucial importance in the measurement of two of the unknowns of the PMNS mixing matrix, $θ_{13}$ and the leptonic CP-violating phase $δ$. In our analyis, the effect of the two discrete ambiguities, ${\rm sign}(Δm^2_{23})$ and ${\rm sign}(\tan 2 θ_{23})$, is explicitly taken into account. We analyse also the $ν_μ$ disappearance channel at the …
The MINOS/MINOS+ experiment has recently reported stringent limits on $ν_μ$ disappearance that appear to rule out the 3+1 sterile neutrino model. However, in this paper we wish to point out problems associated with the MINOS/MINOS+ analysis. In particular, we find that MINOS/MINOS+ has either underestimated their systematic errors and/or has obtained evidence for physics beyond the 3-neutrino paradigm. Either case would invalidate the limits on $ν_μ$ disappearance.
A magnetized large-volume liquid scintillator might be used as a tracking detector with charge identification to measure high-energy neutrinos. I consider neutrino oscillations for a beam from a low-energy neutrino factory to such a detector for the baseline CERN-Pyhasalmi, with the length of 2288 km. The range to study the oscillation parameters extends to $\sin^2 2θ_{13}\sim 10^{-4}$ for reasonable assumptions for the detector and the beam.
We search for scalar and tensor non-standard interactions using (anti)-electron neutrino disappearance in oscillation data. We found a slight preference for non-zero CP violation, coming from both tensor and scalar interactions. The preference for CP violation is lead by Daya Bay low-energy data with a significance that reaches $\sim1.7σ$ in the global analysis (and $\sim2.1σ$ when considering only medium baseline reactors data) compared to the standard neutrino oscillation scenario.
This paper presents a combined analysis of the KARMEN and LSND nu_e-carbon cross section measurements within the context of a search for nu_e disappearance at high Delta m^2. KARMEN and LSND were located at 17.7 m and 29.8 m respectively from the neutrino source, so the consistency of the two measurements, as a function of antineutrino energy, sets strong limits on neutrino oscillations. Most of the allowed region from the nu_e disappearance analysis of the Gallium calibration data is excluded at >95% CL and the best fit point is excluded at 3.6$σ$. Assuming CPT conservation, comparisons are a…
We discuss the optimization of a neutrino factory for large \sin^2 2 θ_{13}, where we assume minimum effort on the accelerator side. This implies that we use low muon energies for the price of an optimized detection system. We demonstrate that such a neutrino factory performs excellent if combined with the electron neutrino appearance channel. Instead of the platinum channel operated with the muon neutrinos from the muon decays, we propose to use the initial superbeam from the decaying pions and kaons, which might be utilized at little extra effort. Since we assume out-of-phase bunches arrivin…
A neutrino factory is capable of answering basic questions in the physics of neutrino oscillations, which address fundamental issues in Grand Unified Theories and flavour physics. In addition, the front end of a neutrino factory offers exciting prospects using slow and stopped muons, such as the search for mu to e transitions and the muon electric dipole moment. There are also opportunities to study muonic atoms and in other areas of science. One should also keep in mind the long-term objective of building a muon collider, either for Higgs physics or at the high-energy frontier.
The results of LSND have yet to be confirmed at the $5 σ$-level. An experiment is proposed utilizing a 3 GeV muon storage ring that would allow for both disappearance and appearance channels to be explored at short-baselines. The appearance channel could provide well over $5 σ$ confirmation or rejection of the LSND result. Other physics could also be performed at such a facility such as the measurement of electron-neutrino cross sections. The sensitivity of experiments at a Very Low Energy Neutrino Factory (VLENF) to neutrinos at the eV-scale is presented.
We consider possible indications of Very-Short-BaseLine (VSBL) electron neutrino disappearance into sterile neutrinos in MiniBooNE neutrino data and Gallium radioactive source experiments. We discuss the compatibility of such a disappearance with reactor and MiniBooNE antineutrino data. We find a tension between neutrino and antineutrino data which could be due to: 1) statistical fluctuations; 2) underestimate of systematic uncertainties; 3) exclusion of our hypothesis of VSBL nu_e disappearance; 4) a violation of CPT symmetry. Considering the first possibility, we present the results of a com…
Data from atmospheric and solar neutrinos indicate that there are at least three neutrino types involved in oscillation phenomena. Even if the corresponding neutrino mass scales are very different, the inevitable reference to mixing between more than two neutrino types has profound consequences on the planning of the accelerator experiments suggested by these results. We discuss the measurement of mixing angles and CP phases in the context of the neutrino beam emanating from a {\it neutrino factory}: the straight sections of a muon storage ring. We emphasize the importance of charge identifica…
We show that a very precise neutrino/anti-neutrino event separation is not mandatory to cover the physics program of a low energy neutrino factory and thus non-magnetized detectors like water Cerenkov or liquid Argon detectors can be used. We point out, that oscillation itself strongly enhances the signal to noise ratio of a wrong sign muon search, provided there is sufficiently accurate neutrino energy reconstruction. Further, we argue that apart from a magnetic field, other means to distinguish neutrino from anti-neutrino events (at least statistically) can be explored. Combined with the fac…
We discuss neutrino oscillation physics with a neutrino factory in stages, including the possibility of upgrading the muon energy within the same program. We point out that a detector designed for the low energy neutrino factory may be used off-axis in a high energy neutrino factory beam. We include the re-optimization of the experiment depending on the value of theta_13 found. As upgrade options, we consider muon energy, additional baselines, a detector mass upgrade, an off-axis detector, and the platinum (muon to electron neutrino) channels. In addition, we test the impact of Daya Bay data o…
Most neutrino mass theories contain non-standard interactions (NSI) of neutrinos which can be either non-universal (NU) or flavor-changing (FC). We study the impact of such interactions on the determination of neutrino mixing parameters at a neutrino factory using the so-called ``golden channels'' \pnu{e}\to\pnuμ for the measurement of θ_{13}. We show that a certain combination of FC interactions in neutrino source and earth matter can give exactly the same signal as oscillations arising due to θ_{13}. This implies that information about θ_{13} can only be obtained if bounds on NSI are availab…
We discuss the impact of near detectors at a neutrino factory both on standard oscillation and non-standard interaction measurements. Our systematics treatment includes cross section errors, flux errors, and background uncertainties, and our near detector fluxes include the geometry of the neutrino source and the detector. Instead of a specific detector concept, we introduce qualitatively different classes of near detectors with different characteristics, such as near detectors catching the whole neutrino flux (near detector limit) versus near detectors observing a spectrum similar to that of …
We discuss the prospects of observing leptonic CP-violation at a neutrino factory in the context of the standard three neutrino scenario. If the large mixing angle MSW effect turned out to account for the solar neutrino deficit, we show that observing an asymmetry between the $\reu$ and $\reub$ oscillation probabilities would represent an exciting experimental challenge. We determine the portion of the parameter space where an evidence could be found as a function of the intensity of the muon source and of the detector size for different baselines. We discuss the consequent requirements on a n…
We study the optimization of a neutrino factory with respect to non-standard neutral current neutrino interactions, and compare the results to those obtained without non-standard interactions. We discuss the muon energy, baselines, and oscillation channels as degrees of freedom. Our conclusions are based on both analytical calculations and on a full numerical simulation of the neutrino factory setup proposed by the international design study (IDS-NF). We consider all possible non-standard parameters, and include their complex phases. We identify the impact of the different parameters on the go…
We discuss ways to explore non-standard interactions (NSI) which neutrinos may possess by expressing them as effective four Fermi operators with coefficient of the order of (M_{W} / M_{NP})^2 ~0.01 (0.0001) for energy scales of new physics as M_{NP} ~1 (10) TeV. Neutrino Factory is a prime candidate for such apparatus that can reach to the extreme precision. I describe a two detector setting, one at baseline L~3000 km and the other at L~7000 km, which is able to solve the notorious theta_{13}-NSI confusion, and possibly also the two-phase confusion. The resultant sensitivities to off-diagonal …
Neutrino factories, neutrino beams produced in the decay of a muon or antimuon beam inside a storage ring, yield cleaner, richer, and more flexible neutrino beams relative to super-beams. We explore the physics case for this type of beam both for standard oscillation as well as new physics searches and present some machine options. We argue that there is a rich program beyond what the current neutrino program can cover and a string synergy with the muon collider program.
With the 1998 announcement of new evidence for muon neutrino disappearance observed by the Super-Kamiokande experiment, the more than a decade old atmospheric neutrino anomaly moved from a possible indication for neutrino oscillations to an almost inescapable implication. The evidence from all experiments is reviewed, and indications are presented that the oscillations are probably between muon and tau neutrinos with nearly maximal mixing. Implications and future directions in neutrino oscillations research are discussed.
We derive the relation between the amplitudes of short-baseline appearance and disappearance oscillations in 3+$N_{s}$ neutrino mixing schemes which is the origin of the appearance-disappearance tension that is found from the analysis of the existing data in any 3+$N_{s}$ neutrino mixing scheme. We illustrate the power of the relation to reveal the appearance-disappearance tension in the cases of 3+1 and 3+2 mixing using the results of global fits of short-baseline neutrino oscillation data.
We discuss the optimization of a neutrino factory experiment for neutrino oscillation physics in terms of muon energy, baselines, and oscillation channels (gold, silver, platinum). In addition, we study the impact and requirements for detector technology improvements, and we compare the results to beta beams. We find that the optimized neutrino factory has two baselines, one at about 3000 to 5000km, the other at about 7500km (``magic'' baseline). The threshold and energy resolution of the golden channel detector have the most promising optimization potential. This, in turn, could be used to lo…
A Neutrino Factory, sending $>10^{20}$ decay neutrinos per year from a high-energy stored muon beam towards remote detectors, has been suggested as the ultimate tool for precision measurement of the neutrino mixing matrix. Following two rounds of design studies that focused primarily on feasibility, the latest such study has begun the process of cost optimization. New ideas include muon `phase rotation' using high-frequency rf cavities and rapid muon acceleration in non-scaling FFAG rings. The world-wide Neutrino Factory R&D effort is aimed at demonstrating the feasibility of the required tech…
We discuss the effects of one additional sterile neutrino at the Neutrino Factory. Compared to earlier analyses, which have been motivated by LSND results, we do not impose any constraint on the additional mass squared splitting. This means that the additional mass eigenstate could, with small mixings, be located among the known ones, as it is suggested by the recent analysis of cosmological data. We use a self-consistent framework at the Neutrino Factory without any constraints on the new parameters. We demonstrate for a combined short and long baseline setup that near detectors can provide t…
Within the framework of three-flavor neutrino oscillations, we consider the physics potential of ν_e --> ν_μappearance and ν_μ--> ν_μsurvival measurements at a neutrino factory for a leading oscillation scale δm^2 ~ 3.5 \times 10^{-3} eV^2. Event rates are evaluated versus baseline and stored muon energy, and optimal values discussed. Over a sizeable region of oscillation parameter space, matter effects would enable the sign of δm^2 to be determined from a comparison of ν_e --> ν_μwith \barν_e --> \barν_μevent rates and energy distributions. It is important, therefore, that both positive and n…
A sterile neutrino is a well motivated minimal new physics model that leaves an imprint in neutrino oscillations. Over the last two decades, a number of hints pointing to a sterile neutrino have emerged, many of which are pointing near $m_4\sim1$ eV. Here we show how MicroBooNE data can be used to search for electron neutrino disappearance using each of their four analysis channels. We find a hint for oscillations with the highest single channel significance of $2.4σ$ (using the Feldman-Cousins approach) coming from the Wire-Cell analysis and a simplified treatment of the experimental systemat…
In low energy neutrino factory ($E_μ< 10$GeV) using MIND detector, we have studied the optimization of $CP$ violation discovery reach in the leptonic sector for different baselines and different parent muon energy considering only Standard Model interactions of neutrinos with matter. Considering such optimized experimental set-up of baseline and energy we have addressed the question of how $CP$ violation discovery reach could get affected by the presence of non-standard interactions of neutrinos with matter during the propagation of neutrinos. For off diagonal NSI elements there could be compl…
We study the precision to which the sign of δm_{32}^2 can be determined at a neutrino factory, as a function of stored energies and baselines. This is done by simultaneously fitting the channels ν_μ\to ν_μ$, \barν_e \to \barν_μfrom μ^- decays and the channels \barν_μ\to \barν_μ, ν_e \to ν_μfrom μ^+ decays. We investigate the sensitivity reach in the parameter \sin^22θ_{13} to which one can determine the sign of δm_{32}^2 to 3 standard deviations as a function of the baseline length and magnitude of δm_{32}^2 with a 20 GeV muon storage ring. We find that for baselines longer than 2000 km, the s…
We analyzed the electron neutrino data of the Gallium radioactive source experiments and the electron antineutrino data of the reactor Bugey and Chooz experiments in terms of neutrino oscillations. We found a hint of a CPT-violating asymmetry of the effective neutrino and antineutrino mixing angles.
The precision and discovery potential of a neutrino factory based on muon storage rings is studied. For three-family neutrino oscillations, we analyse how to measure or severely constraint the angle $θ_{13}$, CP violation, MSW effects and the sign of the atmospheric mass difference $Δm^2_{23}$. We present a simple analytical formula for the oscillation probabilities in matter, with all neutrino mass differences non-vanishing, which clarifies the subtleties involved in disentangling the unknown parameters. The appearance of ``wrong-sign muons'' at three reference baselines is considered: 732 km…
I summarize the current understanding of the neutrino oscillation physics with a neutrino factory and a beta beam, where I emphasize more recent phenomenological developments.
The physics potential of an intense source of low-energy muons is studied. Such a source is a necessary stage towards building the neutrino factories and muon colliders which are being considered at present. The CERN Neutrino Factory could deliver muon beams with intensities 3-4 orders of magnitude higher than available now, with large freedom in the choice of the time structure. Low-energy muon physics contributes to many fields of basic research, including rare muon decays, i.e., decays that do not conserve muon number, measurements of fundamental constants, the muon anomalous magnetic momen…
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.
In response to the growing interest in building a Neutrino Factory to produce high intensity beams of electron- and muon-neutrinos and antineutrinos, in October 1999 the Fermilab Directorate initiated two six-month studies. The first study, organized by N. Holtkamp and D. Finley, was to investigate the technical feasibility of an intense neutrino source based on a muon storage ring. This design study has produced a report in which the basic conclusion is that a Neutrino Factory is technically feasible, although it requires an aggressive R&D program. The second study, which is the subject of th…
During the 1990s an international collaboration has been studying the possibility of constructing and operating a high-energy high-luminosity $μ^+μ^-$ collider. Such a machine could be the approach of choice to extend our discovery reach beyond that of the LHC. More recently, a growing collaboration is exploring the potential of a stored-muon-beam "neutrino factory" to elucidate neutrino oscillations. A neutrino factory could be an attractive stepping-stone to a muon collider. Its construction, possibly feasible within the coming decade, could have substantial impact on neutrino physics.
To be able to achieve their physics goals, future neutrino-oscillation experiments will need to reconstruct the neutrino energy with very high accuracy. In this work, we analyze how the energy reconstruction may be affected by realistic detection capabilities, such as energy resolutions, efficiencies, and thresholds. This allows us to estimate how well the detector performance needs to be determined a priori in order to avoid a sizable bias in the measurement of the relevant oscillation parameters. We compare the kinematic and calorimetric methods of energy reconstruction in the context of two…
The impact of heavy mediators on neutrino oscillations is typically described by non-standard four-fermion interactions (NSIs) or non-unitarity (NU). We focus on leptonic dimension-six effective operators which do not produce charged lepton flavor violation. These operators lead to particular correlations among neutrino production, propagation, and detection non-standard effects. We point out that these NSIs and NU phenomenologically lead, in fact, to very similar effects for a neutrino factory, for completely different fundamental reasons. We discuss how the parameters and probabilities are r…
Recently, three reactor neutrino experiments, Daya Bay, Double Chooz and RENO have directly measured the neutrino mixing angle $θ_{13}$. In this paper, another important oscillation parameter, effective $Δm_{31}^2$ (= $Δ\tilde{m}_{31}^2$) is measured using baseline dependence of the reactor neutrino disappearance. A global fit is applied to publicly available data and $Δ\tilde{m}_{31}^2 = 2.95^{+0.42}_{-0.61} \times 10^{-3}$ eV$^2$, $\sin^22θ_{13} = 0.099^{+0.016}_{-0.012}$ are obtained by setting both parameters free. This result is complementary to $Δtilde{m}_{31}^2$ to be measured by spectr…
The prospects of measuring CP violation in the leptonic sector using the intense neutrino beams arising from muon decay in the straight sections of a muon accumulator ring (the so-called neutrino factory) are discussed.
We explore the possibilities for measuring the quark content of the proton and neutron using neutrino beams produced at a muon storage ring. Because of the nature of the beams, small nuclear targets such as hydrogen and deuterium can be considered, as well as polarized targets. The statistics expected from these targets are calculated using nominal muon storage ring intensities, and the resulting statistical errors on the numerous structure functions available are given, for both polarized and unpolarized targets. It is shown that with a relatively small target, the structure functions F_2, xF…
The beams of Linear Collider after main collision can be utilized to build neutrino factory with exceptional parameters. We also discuss briefly possible applications of some elements of proposed scheme for standard fixed target experiments, new experiments with ν_μN interactions and in material sciences.
We discuss the possibility of constraining or discovering the non-standard neutrino physics beyond the standard model with future long baseline neutrino oscillation experiments. Among very many possible experimental set up we discuss neutrino factory and T2KK, in which two detector setting may be useful to achieve the goal. In particular, neutrino factory with two detectors at baselines of 3000 km and 7000 km have a great sensitivity to non-standard interaction (NSI) and solve the $θ_{13}$-NSI confusion problem.
It is shown in the three flavor framework that neutrino factories enable us to measure some of the oscillation parameters, such as the sign of $Δm_{32}^2$, $θ_{13}$, $δ$. Some efforts are made to determine the parameters (the muon energy and the neutrino path length) of a neutrino factory to optimize the signals.
We summarize what has been learned about the neutrino mass spectrum and neutrino mixing, identify interesting open questions that can be answered by accelerator neutrino facilities of the future, and discuss the importance and physics of answering them.
We present a complete update of the analysis of electron neutrino and antineutrino disappearance experiments in terms of neutrino oscillations in the framework of 3+1 neutrino mixing, taking into account the Gallium anomaly, the reactor anomaly, solar neutrino data and nu_e-C scattering data. We discuss the implications of a recent 71Ga(3He,3H)71Ge measurement which give information on the neutrino cross section in Gallium experiments. We discuss the solar bound on active-sterile mixing and present our numerical results. We discuss the connection between the results of the fit of neutrino osci…
A possibility to search for T-violation in neutrino oscillation with the use of muon polarization is studied. The sensitivity to T-violation is examined with different muon polarization as a function of muon energy and long-baseline distances.
We analyzed the electron neutrino data of the Gallium radioactive source experiments and the electron antineutrino data of the reactor Bugey and Chooz experiments in terms of neutrino oscillations allowing for a CPT-violating difference of the squared-masses and mixings of neutrinos and antineutrinos. We found that the discrepancy between the disappearance of electron neutrinos indicated by the data of the Gallium radioactive source experiments and the limits on the disappearance of electron antineutrinos given by the data of reactor experiments reveal a positive CPT-violating asymmetry of the…
A method for a direct measurement of the exclusive D_s branching ratios and of the decay constant f_{D_s} with a systematical error better than 5% is presented. The approach is based on the peculiar vertex topology of the anti-neutrino induced diffractive charm events. The statistical accuracy achievable with a neutrino factory is estimated.
Within the framework of three-neutrino and four-neutrino scenarios that can describe the results of the LSND experiment, we consider the capabilities of short baseline neutrino oscillation experiments at a neutrino factory. We find that, when short baseline ($L \alt 100$ km) neutrino factory measurements are used together with other accelerator-based oscillation results, the complete three-neutrino parameter space can best be determined by measuring the rate of $ν_e \to ν_τ$ oscillations, and measuring CP violation with either $ν_e \to ν_μ$ or $ν_μ\to ν_τ$ oscillations (including the correspon…
