| 1. |
- Ohlsson, Tommy, 1973-, et al.
(författare)
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Neutrino oscillations with three flavors in matter : Applications to neutrinos traversing the earth
- 2000
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Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 474:1-2, s. 153-162
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Tidskriftsartikel (refereegranskat)abstract
- Analytic formulas are presented for three flavor neutrino oscillations in matter in the plane wave approximation. We calculate in particular the time evolution operator in both mass and flavor bases. We also find the transition probabilities expressed as functions of the vacuum mass squared differences, the vacuum mixing angles, and the matter density parameter. The application of this to neutrino oscillations for both atmospheric and long baseline neutrinos in a mantle-core-mantle step function model of the Earth's matter density profile is discussed.
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| 2. |
- Jacobsson, Björn, et al.
(författare)
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Effects of random matter density fluctuations on the neutrino oscillation transition probabilities in the Earth
- 2002
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Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 532:04-mar, s. 259-266
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we investigate the effects of random fluctuations of the Earth matter density for long baselines on the neutrino oscillation transition probabilities. We especially identify relevant parameters characterizing the matter density noise and calculate their effects by averaging over statistical ensembles of a large number of matter density profiles. For energies and baselines appropriate to neutrino factories, absolute errors on the relevant appearance probabilities are at the level of \DeltaP(alphabeta)\ similar to 10(-4) (with perhaps \P-mue similar to 1% for neutrinos), whereby a modest improvement in understanding of the geophysical data should render such effects unimportant.
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| 3. |
- Ohlsson, Tommy, 1973-, et al.
(författare)
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Bilarge leptonic mixing from Abelian horizontal symmetries
- 2002
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Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 537:02-jan, s. 95-102
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Tidskriftsartikel (refereegranskat)abstract
- We construct and present a model for leptonic mixing based on higher-dimensional operators, using the Froggatt-Nielsen mechanism. and Abelian horizontal symmetries (flavor symmetries) of continuous and discrete type. Our model naturally yields bilarge leptonic mixing. coming from both the charged leptons and the neutrinos, and an inverted neutrino mass hierarchy spectrum. The obtained values of the parameters, i.e.. the leptonic mixing parameters and the neutrino mass squared differences, are all consistent with the atmospheric neutrino data and the Mikheyev-Smirnov-Wolfenstein large mixing angle solution for the solar neutrino problem.
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| 4. |
- Ohlsson, Tommy, 1973-
(författare)
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Effects and influences on neutrino oscillations due to a thin density layer perturbation added to a matter density profile
- 2001
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Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 522:04-mar, s. 280-286
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we show the effects on the transition probabilities for neutrino oscillations due to a thin constant density layer perturbation added to an arbitrary matter density profile, In the case of two neutrino flavors, we calculate the effects both analytically and numerically, whereas in the case of three neutrino flavors, we perform the studies purely numerically. As an realistic example we consider the effects of the Earth's atmosphere when added to the Earth's matter density profile on the neutrino oscillation transition probabilities for atmospheric neutrinos.
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| 5. |
- Ohlsson, Tommy, 1973-
(författare)
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Equivalence between Gaussian averaged neutrino oscillations and neutrino decoherence
- 2001
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Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 502:04-jan, s. 159-166
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we show that a Gaussian averaged neutrino oscillation model is equivalent to a neutrino decoherence model. Without loss of generality, the analysis is performed with two neutrino flavors. We also estimate the damping (or decoherence) parameter for atmospheric neutrinos and compare it to earlier obtained results.
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| 6. |
- Ohlsson, Tommy, 1973-, et al.
(författare)
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Reconstruction of the Earth's matter density profile using a single neutrino baseline
- 2001
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Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 512:04-mar, s. 357-364
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we show numerically that a symmetric Earth matter density profile can, in principle, be reconstructed from a single baseline energy spectrum up to a certain precision. For the numerical evaluations in the high-dimensional parameter space we use a genetic algorithm.
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| 7. |
- Ambrosio, M, et al.
(författare)
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Atmospheric neutrino oscillations from upward throughgoing muon multiple scattering in MACRO
- 2003
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Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 566:1-2, s. 35-44
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Tidskriftsartikel (refereegranskat)abstract
- The energy of atmospheric neutrinos detected by MACRO was estimated using multiple Coulomb scattering of upward throughgoing muons. This analysis allows a test of atmospheric neutrino oscillations, relying on the distortion of the muon energy distribution. These results have been combined with those coming from the upward throughgoing muon angular distribution only. Both analyses are independent of the neutrino flux normalization and provide strong evidence, above the for level, in favour of neutrino oscillations. (C) 2003 Published by Elsevier B.V.
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| 8. |
- Ambrosio, M, et al.
(författare)
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Matter effects in upward-going muons and sterile neutrino oscillations
- 2001
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 517:1-2, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- The angular distribution of upward-going muons produced by atmospheric neutrinos in the rock below the MACRO detector shows anomalies in good agreement with two flavor nu (mu) --> nu (tau) oscillations with maximum mixing and Deltam(2) around 0.0024 eV(2). Exploiting the dependence of magnitude of the matter effect on oscillation channel, and using a set of 809 upward-going muons observed in MACRO, we show that the two flavor nu (mu) --> nu (s) oscillation is disfavored with 99% C.L. with respect to nu (mu) --> nu (tau). (C) 2001 Elsevier Science B.V. All rights reserved.
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| 9. |
- Apostolakis, A., et al.
(författare)
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Measurement of the energy dependence of the form factor f+ in K 0 e3 decay
- 2000
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 473:1, s. 186-192
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Tidskriftsartikel (refereegranskat)abstract
- Neutral-kaon decays to πeν were analysed to determine the q2 dependence of the K0e3 electroweak form factor f+. Based on 365612 events, this form factor was found to have a linear dependence on q2 with a slope λ+=0.0245±0.0012stat±0.0022syst.
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| 10. |
- Babaev, Egor
(författare)
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Mass generation without symmetry breakdown in the chiral Gross-Neveu model at finite temperature and finite N in 2+1 dimensions
- 2001
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Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 497:04-mar, s. 323-327
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Tidskriftsartikel (refereegranskat)abstract
- The chiral Gross-Neveu model is one of the most popular toy models for QCD being a generic testing field for many ideas in particle physics. It has been studied in the past in detail in the limit of infinite number of flavors of fermions. Quite astonishingly, the study of this model was not carried through in all its facets. The most important omission is the study of the onset of quasi-long-range order in the decoupled massless phase field. The present work eliminates this deficiency. In this paper we derive behavior of the Kosterlitz-Thouless transition in this model at finite temperature in 2 + 1 dimensions in the regime when the number N of field components is large but finite. We also prove the anticipated before key feature of the model, namely, that in the regime of infinite N the temperature of the Kosterlitz-Thouless transition merges with the critical temperature T*, given by a mean-field equation for the gap modulus, thus recovering the BCS-like scenario [(T* - T-KT)/T* --> 0] of the phase transition at N --> infinity.
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