Combining dark matter detectors and electron-capture sources to hunt for new physics in the neutrino sector

In this letter we point out the possibility to study new physics in the neutrino sector using dark matter detectors based on liquid xenon. These are characterized by very good spatial resolution and extremely low thresholds for electron recoil energies. When combined with a radioactive $\nu_e$ source, both features in combination allow for a very competitive sensitivity to neutrino magnetic moments and sterile neutrino oscillations. We find that, for realistic values of detector size and source strength, the bound on the neutrino magnetic moment can be improved by an order of magnitude with respect to the present value. Regarding sterile neutrino searches, we find that most of the gallium anomaly could be explored at the 95% confidence level just using shape information.Comment: 5 pages, 2 figures. Minor modifications, references added. Version accepted for publication in JHE

Missing energy and the measurement of the CP-violating phase in neutrino oscillations

In the next generation of long-baseline neutrino oscillation experiments, aiming to determine the charge-parity violating phase $\delta_{CP}$ in the appearance channel, fine-grained time-projection chambers are expected to play an important role. In this Letter, we analyze an influence of realistic detector capabilities on the $\delta_{CP}$ sensitivity for a setup similar to that of the Deep Underground Neutrino Experiment. We find that the effect of the missing energy, carried out by undetected particles, is sizable. Although the reconstructed neutrino energy can be corrected for the missing energy, the accuracy of such procedure has to exceed 20\%, to avoid a sizable bias in the extracted $\delta_{CP}$ value.Comment: 6 pages, 2 figures. v2 matches the version published in PR

Curtailing the Dark Side in Non-Standard Neutrino Interactions

In presence of non-standard neutrino interactions the neutrino flavor evolution equation is affected by a degeneracy which leads to the so-called LMA-Dark solution. It requires a solar mixing angle in the second octant and implies an ambiguity in the neutrino mass ordering. Non-oscillation experiments are required to break this degeneracy. We perform a combined analysis of data from oscillation experiments with the neutrino scattering experiments CHARM and NuTeV. We find that the degeneracy can be lifted if the non-standard neutrino interactions take place with down quarks, but it remains for up quarks. However, CHARM and NuTeV constraints apply only if the new interactions take place through mediators not much lighter than the electroweak scale. For light mediators we consider the possibility to resolve the degeneracy by using data from future coherent neutrino-nucleus scattering experiments. We find that, for an experiment using a stopped-pion neutrino source, the LMA-Dark degeneracy will either be resolved, or the presence of new interactions in the neutrino sector will be established with high significance.Comment: 33 pages, 9 figures. Minor modifications. Version accepted for publication in JHE

Comparison of the calorimetric and kinematic methods of neutrino energy reconstruction in disappearance experiments

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 muon-neutrino disappearance experiments operating in different energy regimes. For the calorimetric reconstruction method, we find that the detector performance has to be estimated with a ~10% accuracy to avoid a significant bias in the extracted oscillation parameters. On the other hand, in the case of kinematic energy reconstruction, we observe that the results exhibit less sensitivity to an overestimation of the detector capabilities.Comment: 16 pages, 14 figures, matches the version published in Phys. Rev.

Detection theory approach to multichannel pattern location

We propose and assess new algorithms for detecting and locating an object in multichannel images. These algorithms are optimal for additive Gaussian noise and maximize the likelihood of the observed images. We consider two cases, in which the illumination of the target and the variance of the noise in each channel are either known or unknown. We show that in the latter case the algorithm provides accurate estimates of variance and luminance. These algorithms can be viewed as postprocessed versions of the correlation of a reference with the scene image in each channel

New constraints on Heavy Neutral Leptons from Super-Kamiokande data

Heavy neutral leptons are predicted in many extensions of the Standard Model with massive neutrinos. If kinematically accessible, they can be copiously produced from kaon and pion decays in atmospheric showers, and subsequently decay inside large neutrino detectors. We perform a search for these long-lived particles using Super-Kamiokande multi-GeV neutrino data and derive stringent limits on the mixing with electron, muon and tau neutrinos as a function of the long-lived particle mass. We also present the limits on the branching ratio versus lifetime plane, which are helpful in determining the constraints in non-minimal models where the heavy neutral leptons have new interactions with the Standard Model.Comment: 6 pages, 4 figures. v2: Minor changes, references added. Version accepted for publication in EPJ

Description of the tadpole of Cochranella resplendens and redescription of the tadpole of Hyalinobatrachium aureoguttatum (Anura, Centrolenidae)

Se describe el renacuajo de Cochranella resplendens y se redescribe el de Hyalinobatrachium aureoguttatum, incluyendo información sobre su variación ontogénica. Cochranella resplendens se caracteriza por tener un aparato oral sin inflexión intramarginal y un supraquerostoma casi recto, aunque ligeramente arqueado en la mitad. Por otro lado, H. aureoguttatum tiene un aparato oral con inflexión intramarginal; presenta un característico supraquerostoma en forma de "M" y pocas papilas intramarginales (1-5) en el labio superior. Ninguna de las dos especies mostró una variación significativa en el aparato oral durante su desarrollo (excepto en los estadios Gosner 24 y 42 en C. resplendens y 23-24 en H. aureoguttatum). Los cambios ontogénicos más evidentes fueron en el tamaño y la coloración.Descrevemos o girino de Cochranella resplendens e redescrevemos o girino de Hyalinobatrachium aureoguttatum, incluindo informação sobre sua variação ontogenética. Cochranella resplendens caracteriza-se por apresentar um aparato oral sem inflexão intramarginal e a porção superior do bico córneo quase reta, ainda que ligeiramente arqueado na porção mediana. Por outro lado, H. aureoguttatum possui aparato oral com inflexão intramarginal e apresenta a porção superior do bico córneo característica, em forma de "M", e poucas papilas intramarginais (1-5) no lábio superior. Nenhuma das duas espécies mostrou uma variação significativa no aparato oral durante o desenvolvimento (exceto nos estágios 24 e 42 de Gosner em C. resplendens e 23-24 em H. aureoguttatum). As mudanças ontogenéticas mais evidentes estão relacionadas com o tamanho e a coloração.The tadpole of Cochranella resplendens is described and that of Hyalinobatrachium aureoguttatum is redescribed; information on their ontogenetic variation also is included. Cochranella resplendens is characterized by having a non-emarginated oral apparatus and an upper jaw sheath nearly straight with a smooth arch in the middle. Hyalinobatrachium aureoguttatum has an emarginated oral apparatus with a characteristic M-shaped upper jaw sheath and bears few (1-5) submarginal papillae on the upper labium. Although the two species show few changes in the oral apparatus during their development (except for changes in Gosner Stages 24 and 42 in C. resplendens and 23-24 in H. aureoguttatum), there are major ontogenetic changes in size and coloration