No Arabic abstract
We show that neutral current (NC) measurements at neutrino detectors can play a valuable role in the search for new physics. Such measurements have certain intrinsic features and advantages that can fruitfully be combined with the usual well-studied charged lepton detection channels in order to probe the presence of new interactions or new light states. In addition to the fact that NC events are immune to uncertainties in standard model neutrino mixing and mass parameters, they can have small matter effects and superior rates since all three flavours participate. We also show, as a general feature, that NC measurements provide access to different combinations of CP phases and mixing parameters compared to CC measurements at both long and short baseline experiments. Using the Deep Underground Neutrino Experiment (DUNE) as an illustrative setting, we demonstrate the capability of NC measurements to break degeneracies arising in CC measurements, allowing us, in principle, to distinguish between new physics that violates three flavour unitarity and that which does not. Finally, we show that NC measurements can enable us to restrict new physics parameters that are not easily constrained by CC measurements.
The treatment of nuclear effects in neutrino-nucleus interactions is one of the main sources of systematic uncertainty for the analysis and interpretation of data of neutrino oscillation experiments. Neutrinos interact with nuclei via charged or neutral currents and both cases must be studied to obtain a complete information. We give an overview of the theoretical work that has been done to describe nuclear effects in neutral-current neutrin onucleus scattering in the kinematic region ranging between beam energies of a few hundreds MeV to a few GeV, which is typical of most ongoing and future accelerator-based neutrino experiments, and where quasielastic scattering is the main interaction mechanism. We review the current status and challenges of the theoretical models, the role and relevance of the contributions of different nuclear effects, and the present status of the comparison between the numerical predictions of the models as well as the available experimental data. We discuss also the sensitivity to the strange form factors of the nucleon and the methods and observables that can allow one to obtain evidence for a possible strange quark contribution from measurements of neutrino and antineutrino-nucleus scattering.
In detecting neutrinos from the Large Hadron Collider, FASER$ u$ will record the most energetic laboratory neutrinos ever studied. While charged current neutrino scattering events can be cleanly identified by an energetic lepton exiting the interaction vertex, neutral current interactions are more difficult to detect. We explore the potential of FASER$ u$ to observe neutrino neutral current scattering $ u N to u N$, demonstrating techniques to discriminate neutrino scattering events from neutral hadron backgrounds as well as to estimate the incoming neutrino energy given the deep inelastic scattering final state. We find that deep neural networks trained on kinematic observables allow for the measurement of the neutral current scattering cross section over neutrino energies from 100 GeV to several TeV. Such a measurement can be interpreted as a probe of neutrino non-standard interactions that is complementary to limits from other tests such as oscillations and coherent neutrino-nucleus scattering.
We study generalized neutrino interactions (GNI) for several neutrino processes, including neutrinos from electron-positron collisions, neutrino-electron scattering, and neutrino deep inelastic scattering. We constrain scalar, pseudoscalar, and tensor new physics effective couplings, based on the standard model effective field theory at low energies. We have performed a global analysis for the different effective couplings. We also present the different individual constraints for each effective parameter (scalar, pseudoscalar, and tensor). Being a global analysis, we show robust results for the restrictions on the different GNI parameters and improve some of these bounds.
By means of a Monte Carlo cascade method, to account for the rescattering of the outgoing nucleon, we study the charged and neutral current inclusive one nucleon knockout reactions off nuclei induced by neutrinos. The nucleon emission process studied here is a clear signal for neutral--current neutrino driven reactions, and can be used in the analysis of future neutrino experiments.
Light sterile neutrinos have been introduced as an explanation for a number of oscillation signals at $Delta m^2 sim 1$ eV$^2$. Neutrino oscillations at relatively short baselines provide a probe of these possible new states. This paper describes an accelerator-based experiment using neutral current coherent neutrino-nucleus scattering to strictly search for active-to-sterile neutrino oscillations. This experiment could, thus, definitively establish the existence of sterile neutrinos and provide constraints on their mixing parameters. A cyclotron-based proton beam can be directed to multiple targets, producing a low energy pion and muon decay-at-rest neutrino source with variable distance to a single detector. Two types of detectors are considered: a germanium-based detector inspired by the CDMS design and a liquid argon detector inspired by the proposed CLEAR experiment.