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Stockholm, Sweden

Blennow M.,Albanova University Center
Journal of High Energy Physics | Year: 2014

We study the framework of Bayesian statistics for analyzing the capabilities and results of future experiments looking to solve the issue of the neutrino mass ordering. Starting from the general scenario, we then give examples of the procedure for experiments with Gaussian and non-Gaussian distributions for the indicator. We describe in detail what can and cannot be said about the neutrino mass ordering and a future experiment's capabilities to determine it. Finally, we briefly comment on the application to other binary measurements, such as the determination of the octant of θ 23. © 2014 The Author(s).

Ohlsson T.,Albanova University Center
Reports on Progress in Physics | Year: 2013

The phenomenon of neutrino oscillations has been established as the leading mechanism behind neutrino flavor transitions, providing solid experimental evidence that neutrinos are massive and lepton flavors are mixed. Here we review sub-leading effects in neutrino flavor transitions known as non-standard neutrino interactions (NSIs), which is currently the most explored description for effects beyond the standard paradigm of neutrino oscillations. In particular, we report on the phenomenology of NSIs and their experimental and phenomenological bounds as well as an outlook for future sensitivity and discovery reach. © 2013 IOP Publishing Ltd.

Grimvall G.,Albanova University Center | Magyari-Kope B.,Stanford University | OzolinENM,University of California at Los Angeles | Persson K.A.,Lawrence Berkeley National Laboratory
Reviews of Modern Physics | Year: 2012

Most metallic elements have a crystal structure that is either body-centered cubic (bcc), face-centered close packed, or hexagonal close packed. If the bcc lattice is the thermodynamically most stable structure, the close-packed structures usually are dynamically unstable, i.e., have elastic constants violating the Born stability conditions or, more generally, have phonons with imaginary frequencies. Conversely, the bcc lattice tends to be dynamically unstable if the equilibrium structure is close packed. This striking regularity essentially went unnoticed until ab initio total-energy calculations in the 1990s became accurate enough to model dynamical properties of solids in hypothetical lattice structures. After a review of stability criteria, thermodynamic functions in the vicinity of an instability, Bain paths, and how instabilities may arise or disappear when pressure, temperature, and/or chemical composition is varied are discussed. The role of dynamical instabilities in the ideal strength of solids and in metallurgical phase diagrams is then considered, and comments are made on amorphization, melting, and low-dimensional systems. The review concludes with extensive references to theoretical work on the stability properties of metallic elements. © 2012 American Physical Society.

Krasnov V.M.,Albanova University Center
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

I derive simple nonlocal dynamic boundary conditions, suitable for modeling of radiation emission from stacked Josephson junctions in an arbitrary dynamic state. Coherent flux-flow emission from intrinsic Josephson junctions in high- Tc superconductors is analyzed. It is shown that due to the lack of Lorentz contraction of fluxons in stacked junctions, high-quality geometrical resonances are prerequisite for high power flux-flow emission from the stack. This leads to a dual role of the radiative impedance: on one hand, small impedance increases the efficiency of emission from the stack, on the other hand, enhanced radiative losses reduce the quality factor of geometrical resonances, which may decrease the total emission power. Optimal conditions are achieved when radiative losses are comparable to resistive losses inside the stack. © 2010 The American Physical Society.

Krasnov V.M.,Albanova University Center
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

I propose a new mechanism of intense high-frequency electromagnetic wave generation by spatially uniform stacked Josephson junctions at zero magnetic field. The ac-Josephson effect converts the dc-bias voltage into ac supercurrent; however, in the absence of spatial variation of the Josephson phase difference it does not provide dc-to-ac power conversion, needed for emission of electromagnetic waves. Here I demonstrate that at geometrical resonance conditions, spatial homogeneity of the phase can be spontaneously broken by the appearance of breathers (bound fluxon-antifluxon pairs), facilitating effective dc-to-ac power conversion. This leads to self-oscillations at cavity-mode frequencies, accompanied by the emission of radiation. The proposed mechanism explains all major features of recently observed THz radiation from large-area Bi2Sr2CaCu 2O8+x mesa structures. © 2011 American Physical Society.

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