| 1. |
- Blennow, Mattias, et al.
(författare)
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Non-standard interactions using the OPERA experiment
- 2008
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Ingår i: European Physical Journal C. - : Springer-Verlag / Società Italiana di Fisica. - 1434-6044 .- 1434-6052. ; 56:4, s. 529-536
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the implications of non-standard interactions on neutrino oscillations in the OPERA experiment. In particular, we study the non-standard interaction parameter epsilon(mu tau) . We show that the OPERA experiment has a unique opportunity to reduce the allowed region for this parameter compared with other experiments such as the MINOS experiment, mostly due to the higher neutrino energies in the CNGS beam compared to the NuMI beam. We find that OPERA is mainly sensitive to a combination of standard and non-standard parameters and that a resulting anti-resonance effect could suppress the expected number of events. Furthermore, we show that running OPERA for five years each with neutrinos and anti-neutrinos would help in resolving the degeneracy between the standard parameters and epsilon(mu tau) . This scenario is significantly better than the scenario with a simple doubling of the statistics by running with neutrinos for ten years.
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| 2. |
- Akhmedov, Evgeny, et al.
(författare)
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Stability and leptogenesis in the left-right symmetric seesaw mechanism
- 2007
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; 4, s. 022-1-022-25
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the left-right symmetric type I+II seesaw mechanism, where an eight-fold degeneracy among the mass matrices of heavy right-handed neutrinos M-R is known to exist. Using the stability property of the solutions and their ability to lead to successful baryogenesis via leptogenesis as additional criteria, we discriminate among these eight solutions and partially lift their eight-fold degeneracy. In particular, we find that viable leptogenesis is generically possible for four out of the eight solutions.
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| 3. |
- Antusch, Stefan, et al.
(författare)
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Probing non-unitary mixing and CP-violation at a Neutrino Factory
- 2009
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 80:3, s. 033002-
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Tidskriftsartikel (refereegranskat)abstract
- A low-energy nonunitary leptonic mixing matrix is a generic feature of many extensions of the standard model. In such a case, the task of future precision neutrino oscillation experiments is more ambitious than measuring the three mixing angles and the leptonic (Dirac) CP phase, i.e., the accessible parameters of a unitary leptonic mixing matrix. A nonunitary mixing matrix has 13 parameters that affect neutrino oscillations, out of which four are CP violating. In the scheme of minimal unitarity violation we analyze the potential of a neutrino factory for determining or constraining the parameters of the nonunitary leptonic mixing matrix, thereby testing the origin of CP violation in the lepton sector.
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| 4. |
- Biggio, Carla, et al.
(författare)
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General bounds on non-standard neutrino interactions
- 2009
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- We derive model-independent bounds on production and detection nonstandard neutrino interactions (NSI). We find that the constraints for NSI parameters are around O (10(-2)) to O (10(-1)). Furthermore, we review and update the constraints on matter NSI. We conclude that the bounds on production and detection NSI are generally one order of magnitude stronger than their matter counterparts.
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| 5. |
- Biggio, Carla, et al.
(författare)
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Loop bounds on non-standard neutrino interactions
- 2009
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; :3
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Tidskriftsartikel (refereegranskat)abstract
- We reconsider the bounds on non-standard neutrino interactions with matter which can be derived by constraining the four-charged-lepton operators induced at the loop level. We find that these bounds are model dependent. Naturalness arguments can lead to much stronger constraints than those presented in previous studies, while no completely model-independent bounds can be derived. We will illustrate how large loop-contributions to four-charged-lepton operators are induced within a particular model that realizes gauge invariant non-standard interactions and discuss conditions to avoid these bounds. These considerations mainly affect the O(10(-4)) constraint on the non-standard coupling strength epsilon e(mu), which is lost. The only model-independent constraints that can be derived are O(10(-1)). However, significant cancellations are required in order to saturate this bound.
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| 6. |
- Blennow, Mattias, et al.
(författare)
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Approximative two-flavor framework for neutrino oscillations with nonstandard interactions
- 2008
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Ingår i: Physical Review D. - : The American Physical Society. - 1550-7998. ; 78:9, s. 093002-1-093002-9
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we develop approximative two-flavor neutrino oscillation formulas including subleading nonstandard interaction effects. Especially, the limit when the small mass-squared difference approaches zero is investigated. The approximate formulas are also tested against numerical simulations in order to determine their accuracy and they will probably be most useful in the GeV energy region, which is the energy region where most upcoming neutrino oscillation experiments will be operating. Naturally, it is important to have analytical formulas in order to interpret the physics behind the degeneracies between standard and nonstandard parameters.
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| 7. |
- Blennow, Mattias
(författare)
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Damping signatures in future neutrino oscillation experiments
- 2006
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Ingår i: Nuclear physics B, Proceedings supplements. - : Elsevier BV. - 0920-5632 .- 1873-3832. ; 155, s. 195-196
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Tidskriftsartikel (refereegranskat)abstract
- In precision measurements of neutrino oscillation parameters and in the search for theta(13), it becomes important to study small effects which may alter the precision measurements or mimic a theta(13) signal. Here, I give an introduction to a common framework in which many of the possible small effects - such as neutrino wave packet decoherence, neutrino quantum decoherence, and neutrino decay - can be studied. This framework is based on the introduction of damping factors on the probability level of the neutrino oscillation formulas.
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| 8. |
- Blennow, Mattias, et al.
(författare)
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Damping signatures in future neutrino oscillation experiments
- 2005
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Ingår i: Journal of High Energy Physics (JHEP). - : IOP Publishing. - 1126-6708 .- 1029-8479. ; 2005:06, s. 049-
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the phenomenology of damping signatures in the neutrino oscillation probabilities, where either the oscillating terms or the probabilities can be damped. This approach is a possibility for tests of damping effects in future neutrino oscillation experiments, where we mainly focus on reactor and long-baseline experiments. We extensively motivate different damping signatures due to small corrections by neutrino decoherence, neutrino decay, oscillations into sterile neutrinos, or other mechanisms, and classify these signatures according to their energy ( spectral) dependencies. We demonstrate, at the example of short baseline reactor experiments, that damping can severely alter the interpretation of results, e. g., it could fake a value of sin(2)(2 theta(13)) smaller than the one provided by Nature. In addition, we demonstrate how a neutrino factory could constrain different damping models with emphasis on how these different models could be distinguished, i.e., how easily the actual type of effect could be identified. We find that the damping models cluster in different categories, which can be much better distinguished from each other than models within the same cluster.
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| 9. |
- Blennow, Mattias, et al.
(författare)
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Effective neutrino mixing and oscillations in dense matter
- 2005
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Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 609:3-4, s. 330-338
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effective case of two-flavor neutrino oscillations in infinitely dense matter by using a perturbative approach. We begin by briefly summarizing the conditions for the three-flavor neutrino oscillation probabilities to take on the same form as the corresponding two-flavor probabilities. Then, we proceed with the infinitely dense matter calculations. Finally, we study the validity of the approximation of infinitely dense matter when the effective matter potential is large, but not infinite, this is done by using both analytic and numeric methods.
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| 10. |
- Blennow, Mattias, et al.
(författare)
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Effects of non-standard interactions in the MINOS experiment
- 2008
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Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 660:5, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effects of non-standard interactions on the determination of the neutrino oscillation parameters Delta m(31)(2), theta(23), and theta(13) in the MINOS experiment. We show that adding non-standard interactions to the analysis lead to an extension of the allowed parameter space to larger values of Delta m(31)(2) and smaller theta(23), and basically removes all predictability for theta(13). In addition, we discuss the sensitivities to the non-standard interaction parameters of the MINOS experiment alone. In particular, we examine the degeneracy between theta(13) and the non-standard interaction parameter epsilon(e tau). We find that this degeneracy is responsible for the removal of the theta(13) predictability and that the possible bound on vertical bar epsilon(e tau)vertical bar is competitive with direct bounds only if a more stringent external bound on theta(13) is applied.
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