In extra-dimensional scenarios oscillations between active and sterile neutrinos can be governed by a new resonance in the oscillation amplitude. This resonance results when cancelation occurs between two phase differences, the usual kinematic one coming from the neutrino mass-squared difference, and a geometric one coming from the difference in travel times of the sterile neutrino through the bulk relative to the active neutrino confined to the brane. In this work we introduce a specific metric for the brane-bulk system, from which we explicitly derive extra-dimensional geodesics for the sterile neutrino, and ultimately the oscillation probability of the active-sterile two-state system. We find that for an asymmetrically-warped metric, the resonance condition involves both the neutrino energy E and the travel distance L on the brane. In other words, the resonant energy may be viewed as baseline-dependent. We show that to a good approximation, the resonance condition is not on E or on L, but rather on the product LE. The model is rich in implications, including the possibility of multiple solutions to the resonance condition, with ramifications for existing data sets, e.g., LSND and MiniBooNE. Some phenomenology with these brane-bulk resonances is discussed.
Light sterile neutrinos are a popular extension of the Standard Model and are being discussed as a possible explanation for various neutrino oscillation anomalies, including the LSND, MiniBooNE, Reactor and Gallium anomalies. In order to avoid inconsistencies with constraints derived from disappearance experiments and cosmology, altered dispersion relations - which may originate from extra dimensions - have been proposed as a possible solution, dubbed as "neutrino shortcuts in the extra dimension". In this paper we develop a neutrino mass model with an asymmetrically warped extra dimension and…
Existing bounds on the neutron-antineutron mass mixing, $ε_{n\bar n} < {\rm few} \times 10^{-24}$ eV, impose a severe upper limit on $n - \bar n$ transition probability, $P_{n\bar n}(t) < (t/0.1 ~{\rm s})^2 \times 10^{-18}$ or so, where $t$ is the neutron flight time. Here we propose a new mechanism of $n- \bar n$ transition which is not induced by direct mass mixing $ε_{n\bar n}$ but is mediated instead by the neutron mixings with the hypothetical states of mirror neutron $n'$ and mirror antineutron $\bar{n}'$. The latter can be as large as $ε_{nn'}, ε_{n\bar{n}'} \sim 10^{-15}$ eV or so, wit…
We study baryon-number-violating processes, including proton and bound neutron decays and $n-\bar n$ oscillations, in a left-right-symmetric (LRS) model in which quarks and leptons have localized wavefunctions in extra dimensions. In this model we show that, while one can easily suppress baryon-number-violating nucleon decays well below experimental bounds, this does not suppress $n-\bar n$ transitions, which may occur at levels comparable to current limits. This is qualitatively similar to what was found in an extra-dimensional model with a Standard-Model low-energy effective field theory (SM…
We examine the potential of the future medium-baseline reactor neutrino oscillation (MBRO) experiments in studying neutrino wave-packet impact. In our study, we treat neutrinos as wave packets and use the corresponding neutrino flavor transition probabilities. The delocalization, separation and spreading of the wave packets lead to decoherence and dispersion effects, which modify the plane-wave neutrino oscillation pattern, by amounts that depend on the energy uncertainties in the initial neutrino wave packets. We find that MBRO experiments could be sensitive to the wave-packet impact, since t…
Neutrino oscillations successfully explain the flavor transitions observed in neutrinos produced in natural sources like the center of the sun and the earth atmosphere, and also from man-made sources like reactors and accelerators. These oscillations are driven by two mass-squared differences, solar and atmospheric, at the sub-eV scale. However, longstanding anomalies at short-baselines might imply the existence of new oscillation frequencies at the eV-scale and the possibility of this sterile state(s) to mix with the three active neutrinos. One of the many future neutrino programs that are ex…
