The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on high-statistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (60.7 \pm 6.9 (stat.) \pm 7.4 (sys.)) ns was measured. This anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.48 \pm 0.28 (stat.) \pm 0.30 (sys.)) \times 10-5.

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Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

http://at-web.physik.uni-wuppertal.de/~kampert/Publications-PDF/Achterberg-06b.pdf

First year performance of the IceCube neutrino telescope

We show that mass varying neutrinos (MaVaNs) can behave as a negative pressure fluid which could be the origin of the cosmic acceleration. We derive a model independent relation between the neutrino mass and the equation of state parameter of the neutrino dark energy, which is applicable for general theories of mass varying particles. The neutrino mass depends on the local neutrino density and the observed neutrino mass can exceed the cosmological bound on a constant neutrino mass. We discuss microscopic realizations of the MaVaN acceleration scenario, which involve a sterile neutrino. We consider naturalness constraints for mass varying particles, and find that both eV cut-offs and eV mass particles are needed to avoid fine-tuning. In microscopic realizations of this scenario with a sterile neutrino, these considerations give the sterile neutrino a maximum mass today of order an eV, which could be detectable at MiniBooNE. Because the sterile neutrino was much heavier at earlier times, constraints from big bang nucleosynthesis on additional states are not problematic. We consider regions of high neutrino density and find that the most likely place today to find neutrino masses which are significantly different from the neutrino masses in our solar system is in a supernova. The possibility of different neutrino mass in different regions of the galaxy and the local group could be significant for Z-burst models of ultra-high energy cosmic rays. We also consider the cosmology of and the constraints on the 'acceleron', the scalar field which is responsible for the varying neutrino mass, and briefly discuss neutrino density dependent variations in other constants, such as the fine structure constant.

https://iopscience.iop.org/article/10.1088/1475-7516/2004/10/005/pdf

Dark energy from mass varying neutrinos

This paper reviews recent experiments on tritium β-spectroscopy searching for the absolute value of the electron neutrino mass m(νe). By the use of dedicated electrostatic filters with high acceptance and resolution, the uncertainty on the observable m2(νe) has been pushed down to about 3 eV2. The new upper limit of the mass is m(νe) < 2 eV at 95% C.L. In view of erroneous and unphysical mass results obtained by some earlier experiments in β decay, particular attention is paid to systematic effects. The mass limit is discussed in the context of current neutrino research in particle- and astrophysics. A preview is given of the next generation of β-spectroscopy experiments currently under development and construction; they aim at lowering the m2(νe) uncertainty by another factor of 100, reaching a sensitivity limit m(νe) < 0.2 eV.

https://iopscience.iop.org/article/10.1088/0034-4885/71/8/086201/pdf

I. V. Krivosheina

Papers

Detection of the neutrino signal from SN 1987A in the LMC using the INR Baksan underground scintillation telescope

Detection of the neutrino signal from SN 1987A using the INR Baksan underground scintillation telescope.