Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMeasuring tau neutrino appearance probability via unitarity
68
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We propose a {em unitarity method} for determining $tau$ neutrino appearance probability $P( u_{mu} rightarrow u_{tau})$ in long-baseline (LBL) accelerator experiments and atmospheric neutrino observations. When simultaneous in situ measurements of $P( u_{mu} rightarrow u_{mu})$ and $P( u_{mu} rightarrow u_{e})$ proceed, as is typical in the LBL experiments, one can use unitarity to measure $P( u_{mu} rightarrow u_{tau})$. A theorists toy analysis for the model-independent determination of $P( u_{mu} rightarrow u_{mu})$ and $P( u_{mu} rightarrow u_{e})$ is presented by using the NOvA data. It is shown in our analysis that $lsim$5% (8%) measurement of $tau$ neutrino appearance probability in neutrino (antineutrino) mode is possible in the peak region $1.5 lesssim E_ u lesssim 2.5$ GeV. The $ u$SM-independent nature of determination of the probabilities is emphasized.
rate research
Read More
We explore the capabilities of the upcoming Deep Underground Neutrino Experiment (DUNE) to measure $ u_tau$ charged-current interactions and the associated oscillation probability $P( u_mu to u_tau)$ at its far detector, concentrating on how such results can be used to probe neutrino properties and interactions. DUNE has the potential to identify significantly more $ u_tau$ events than all existing experiments and can use this data sample to nontrivially test the three-massive-neutrinos paradigm by providing complementary measurements to those from the $ u_e$ appearance and $ u_mu$ disappearance channels. We further discuss the sensitivity of the $ u_tau$ appearance channel to several hypotheses for the physics that may lurk beyond the three-massive-neutrinos paradigm: a non-unitary lepton mixing matrix, the $3+1$ light neutrinos hypothesis, and the existence of non-standard neutral-current neutrino interactions. Throughout, we also consider the relative benefits of the proposed high-energy tune of the Long-Baseline Neutrino Facility (LBNF) beam-line.
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 normalizations of all rows and columns of the lepton mixing matrix will be constrained to $lesssim$10% precision, with the $e$-row best measured at $lesssim$1% and the $tau$-row worst measured at ${sim}10%$ precision. The measurements of the mixing matrix elements themselves will be improved on average by a factor of $3$. We highlight the complementarity of DUNE, T2HK, JUNO, and IceCube Upgrade for these improvements, as well as the importance of $ u_tau$ appearance measurements and sterile neutrino searches for tests of leptonic unitarity.
We present a measurement of atmospheric tau neutrino appearance from oscillations with three years of data from the DeepCore sub-array of the IceCube Neutrino Observatory. This analysis uses atmospheric neutrinos from the full sky with reconstructed energies between 5.6 GeV and 56 GeV to search for a statistical excess of cascade-like neutrino events which are the signature of nutau interactions. For CC+NC (CC-only) interactions, we measure the tau neutrino normalization to be 0.73 +0.30 -0.24 (0.57 +0.36 -0.30) and exclude the absence of tau neutrino oscillations at a significance of 3.2 sigma (2.0 sigma) These results are consistent with, and of similar precision to, a confirmatory IceCube analysis also presented, as well as measurements performed by other experiments.
We explore the hypothesis that the unexplained data from LSND and MiniBooNE are evidence for a new, heavy neutrino mass-eigenstate that mixes with the muon-type neutrino and decays into an electron-type neutrino and a new, very light scalar particle. We consider two different decay scenarios, one with Majorana neutrinos, one with Dirac neutrinos; both fit the data equally well. We find a reasonable, albeit not excellent, fit to the data of MiniBooNE and LSND. The decaying-sterile-neutrino hypothesis, however, cleanly evades constraints from disappearance searches and precision measurements of leptonic meson decays, as long as $1~{rm MeV}gtrsim m_4gtrsim 10$~keV. The SBN program at Fermilab should be able to definitively test the decaying-sterile-neutrino hypothesis.
If leptonic unitarity is violated by new physics at an energy scale much lower than the electroweak scale, which we call low-scale unitarity violation, it has different characteristic features from those expected in unitarity violation at high-energy scales. They include maintaining flavor universality and absence of zero-distance flavor transition. We present a framework for testing such unitarity violation at low energies by neutrino oscillation experiments. Starting from the unitary 3 active plus $N$ (arbitrary integer) sterile neutrino model we show that by restricting the active-sterile and sterile-sterile neutrino mass squared differences to $gtrsim$ 0.1 eV$^2$ the oscillation probability in the $(3+N)$ model becomes insensitive to details of the sterile sector, providing a nearly model-independent framework for testing low-scale unitarity violation. Yet, the presence of the sterile sector leaves trace as a constant probability leaking term, which distinguishes low-scale unitarity violation from the high-scale one. The non-unitary mixing matrix in the active neutrino subspace is common for the both cases. We analyze how severely the unitarity violation can be constrained in $ u_{e}$-row by taking a JUNO-like setting to simulate medium baseline reactor experiments. Possible modification of the features of the $(3+N)$ model due to matter effect is discussed to first order in the matter potential.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
