3 pages, 2 figures, and 1 table. To appear in the proceedings of the 10th International Workshop on Neutrino Factories, Super beams and Beta beams (NUFACT08), June 30 - July 5 2008, Valencia, Spain
We discuss the prospects of exploring the neutrino mass parameters with a CERN based Beta-beam experiment using two different detectors at two different baselines. The proposed set-up consists of a 50 kton iron calorimeter (ICAL) at a baseline of around 7150 km which is roughly the magic baseline, e.g., ICAL@INO, and a 50 kton Totally Active Scintillator Detector at a distance of 730 km, e.g., at Gran Sasso. We take 8B and 8Li source ions with a boost factor $γ$ of 650 for the magic baseline while for the closer detector we consider 18Ne and 6He ions with a range of Lorentz boosts. We find that the locations of the two detectors complement each other leading to an exceptional high sensitivity. With $γ=650$ for 8B/8Li and $γ=575$ for 18Ne/6He and total luminosity corresponding to $5\times (1.1\times 10^{19})$ and $5\times (2.9\times 10^{19})$ useful ion decays in neutrino and antineutrino modes respectively, we find that the two-detector set-up can probe maximal CP violation and establish the neutrino mass ordering if $\sin^22θ_{13}$ is $1.8 \times 10^{-5}$ and $4.6 \times 10^{-5}$, respectively, or more. The sensitivity reach for $\sin^22θ_{13}$ itself is $5.3 \times 10^{-5}$. CP violation can be discovered for 64% of the possible $δ_{CP}$ values for $\sin^22θ_{13} \geq 8\times 10^{-5}$.
Probing Dark Sector Particles Coupling to Neutrinos with Double Beta Decay
UCL（伦敦大学学院）；Instituto de Física Corpuscular, CSIC-Universitat de València（瓦伦西亚大学与西班牙国家研究委员会粒子物理联合研究所）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；University of Massachusetts（马萨诸塞大学）；Nanjing University of Science & Technology（南京理工大学）
A large experimental program is being mounted to search for neutrinoless double-beta decay over the next decade. Multiple experiments using different target isotopes are being prepared to explore the whole parameter space allowed for inverted-ordered light neutrinos, and have the potential to make discoveries in several other scenarios, including normal-ordered light neutrinos and other exotic mechanisms. We investigate to what extent long-range and exotic short-range contributions may be distinguished by combining measurements of the decay half-life across isotopes. We demonstrate how measure…
We consider the light $Z'$ explanation of the muon $g-2$ anomaly. Even if such a $Z'$ has no tree-level coupling to electrons, in general one will be induced at loop-level. We show that future beam dump experiments are powerful enough to place stringent constraints on$-$or discover$-$a $Z'$ with loop-suppressed couplings to electrons. Such bounds are avoided only if the $Z'$ has a large interaction with neutrinos, in which case the scenario will be bounded by ongoing neutrino scattering experiments. The complementarity between beam dump and neutrino scattering experiments therefore indicates t…
The physics impact of a staged approach for double-beta decay experiments based on Ge-76 is studied. The scenario considered relies on realistic time schedules envisioned by the GERDA and the MAJORANA collaborations, which are jointly working towards the realization of a future larger scale Ge-76 experiment. Intermediate stages of the experiments are conceived to perform quasi background-free measurements, and different data sets can be reliably combined to maximize the physics outcome. The sensitivity for such a global analysis is presented, with focus on how neutrino flavor models can be pro…
We show that the longitudinal beam polarization option at a future electron-positron collider provides an unambiguous distinction between low-scale seesaw models of neutrino mass. This is possible due to the fact that the pair production cross section of the heavy neutrinos in seesaw models is sensitive to the polarization of the initial lepton beams, and for a suitable choice of the polarization, shows a clear enhancement over the unpolarized cross section. More interestingly, the choice of the beam polarization for which the enhancement is maximum is governed by the size of the light-heavy n…
Medium-energy electron beam-dump experiments provide an intense sources of secondary muons. These particles can be used to search for muon-coupling light dark scalars that may explain the $(g-2)_μ$ anomaly. We applied this idea to SLAC E137 experiment deriving new exclusion limits and evaluated the expected sensitivity for the planned Jefferson Lab BDX experiment (in case of null result report). The calculation is based on numerical simulations that include a realistic description of secondary muons generation in the dump, dark scalar production, propagation, and decay, and, finally, the decay…
