| 1. |
- Bengtsson, Tommy, et al.
(författare)
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The Demographic Transition Revised
- 1994
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Ingår i: Population, Economy, and Welfare in Sweden. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 3540584234 ; , s. 13-36
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Bokkapitel (refereegranskat)
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| 2. |
- Abele, H., et al.
(författare)
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Particle physics at the European Spallation Source
- 2023
-
Ingår i: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 1023, s. 1-84
-
Forskningsöversikt (refereegranskat)abstract
- Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world’s brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
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| 3. |
- Agarwalla, S.K., et al.
(författare)
-
EUROnu-WP6 2010 Report
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This is a summary of the work done by the Working Package 6 (Physics) of the EU project "EUROnu" during the second year of activity of the project.
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| 4. |
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| 5. |
- Akhmedov, Evgeny K., et al.
(författare)
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Series expansions for three-flavor neutrino oscillation probabilities in matter
- 2004
-
Ingår i: Journal of High Energy Physics (JHEP). - : IOP Publishing. - 1126-6708 .- 1029-8479. ; 2004:04, s. 078-
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Tidskriftsartikel (refereegranskat)abstract
- We present a number of complete sets of series expansion formulas for neutrino oscillation probabilities in matter of constant density for three flavors. In particular, we study expansions in the mass hierarchy parameter alpha = Deltam(21)(2)/Deltam(31)(2) and mixing parameter s(13) = sin theta(13) up to second order and expansions only in alpha and only in s(13) up to first order. For each type of expansion we also present the corresponding formulas for neutrino oscillations in vacuum. We perform a detailed analysis of the accuracy of the different sets of series expansion formulas and investigate which type of expansion is most accurate in different regions of the parameter space spanned by the neutrino energy E, the baseline length L, and the expansion parameters alpha and s(13). We also present the formulas for series expansions in alpha and in s(13) up to first order for the case of arbitrary matter density profiles. Furthermore, it is shown that in general all the 18 neutrino and antineutrino oscillation probabilities can be expressed through just two independent probabilities.
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| 6. |
- Akhmedov, Evgeny, et al.
(författare)
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Stability and leptogenesis in the left-right symmetric seesaw mechanism
- 2007
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; 4, s. 022-1-022-25
-
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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| 7. |
- Akhmedov, Evgeny, et al.
(författare)
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T violation in neutrino oscillations in matter
- 2001
-
Ingår i: Nuclear Physics B. - : Elsevier Science B.V.. - 0550-3213 .- 1873-1562. ; 608:02-jan, s. 394-422
-
Tidskriftsartikel (refereegranskat)abstract
- We consider the interplay of fundamental and matter-induced T violation effects in neutrino oscillations in matter. After discussing the general features of these effects we derive a simple approximate analytic expression for the T-violating probability asymmetry DeltaP(ab)(T) for three-flavour neutrino oscillations in a matter with an arbitrary density profile in terms of the two-flavour neutrino amplitudes. Explicit examples are given for the cases of a two-layer medium and for the adiabatic Emit in the general case. We then discuss implications of the obtained results for long baseline experiments. We show, in particular, that asymmetric matter effects cannot hinder the determination of the fundamental CP- and T-violating phase delta (CP) in the long baseline experiments as far as the error in this determination is larger than 1% at 99% CL. Since there are no T-violating effects in the two-flavour case, and in the limits of vanishing theta (13) or Deltam(21)(2) the three-flavour neutrino oscillations effectively reduce to the two-flavour ones, studying the T-violating asymmetries ApT ab can in principle provide us with a complementary means of measuring theta (13) and Deltam(21)(2).
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| 8. |
- Baussan, E., et al.
(författare)
-
A very intense neutrino super beam experiment for leptonic CP violation discovery based on the European spallation source linac
- 2014
-
Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 885, s. 127-149
-
Tidskriftsartikel (refereegranskat)abstract
- Very intense neutrino beams and large neutrino detectors will be needed in order to enable the discovery of CP violation in the leptonic sector. We propose to use the proton linac of the European Spoliation Source currently under construction in Lund, Sweden, to deliver, in parallel with the spoliation neutron production, a very intense, cost effective and high performance neutrino beam. The baseline program for the European Spoliation Source linac is that it will be fully operational at 5 MW average power by 2022, producing 2 GeV 2.86 ms long proton pulses at a rate of 14 Hz. Our proposal is to upgrade the linac to 10 MW average power and 28 Hz, producing 14 pulses/s for neutron production and 14 pulses/s for neutrino production. Furthermore, because of the high current required in the pulsed neutrino horn, the length of the pulses used for neutrino production needs to be compressed to a few mu s with the aid of an accumulator ring. A long baseline experiment using this Super Beam and a megaton underground Water Cherenkov detector located in existing mines 300-600 km from Lund will make it possible to discover leptonic CP violation at 5 sigma significance level in up to 50% of the leptonic Dirac CP-violating phase range. This experiment could also determine the neutrino mass hierarchy at a significance level of more than 3 sigma if this issue will not already have been settled by other experiments by then. The mass hierarchy performance could be increased by combining the neutrino beam results with those obtained from atmospheric neutrinos detected by the same large volume detector. This detector will also be used to measure the proton lifetime, detect cosmological neutrinos and neutrinos from supernova explosions. Results on the sensitivity to leptonic CP violation and the neutrino mass hierarchy are presented.
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| 9. |
- Beiming, Christoffer, et al.
(författare)
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Phenomenological mass model for exotic hadrons and predictions for masses of non-strange dibaryons as hexaquarks
- 2022
-
Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 974, s. 115616-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the mass spectra of exotic hadrons known as hexaquarks in the form of dibaryons. We use a phenomenological model based on an extended version of the Giirsey-Radicati mass formula for hadrons to include non-charmed baryons, charmed baryons, and non-strange dibaryons to be able to predict masses of potential dibaryon states. We perform six numerical fits of this model to input data for three different sets of masses of baryons and dibaryons. We find that the model can fit some of the data sets well, especially the sets including charmed baryons and non-strange dibaryons, and observe that the predicted mass of one of the dibaryons is close to the measured mass of the observed hexaquark candidate d * (2380) reported by the WASA-at-COSY experiment. The predicted mass of the deuteron is slightly larger than its measured mass. Finally, for the data sets including charmed baryon and non-strange dibaryon masses, we find that the predicted masses of potential dibaryon states are all in the range from 1900 MeV to 3700 MeV.
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| 10. |
- Bengtsson, Tommy, et al.
(författare)
-
Age-specific mortality and short-term changes in the standard of living : Sweden, 1751-1859
- 1985
-
Ingår i: European Journal of Population. - 0168-6577. ; 1:4, s. 309-326
-
Tidskriftsartikel (refereegranskat)abstract
- The response of mortality to short-term changes in real wages is analyzed here not just in its own right but more particularly as an indicator of long-term shifts in the general standard of living. It is hypothesized that the response would have been stronger the lower the standard of living. The relationship between age-specific mortality levels and real-wage series for Sweden 1751–1860 is analyzed using a distributed-lag model and spectral analysis. The results suggest a real shift in the material standard of living during the period.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Bengtsson, Tommy, et al.
(författare)
-
Population and Economic Fluctuations in Sweden 1949-1914
- 1984
-
Ingår i: Pre-Industrial Population Change : The Mortality Decline and Short-Term Population Movements - The Mortality Decline and Short-Term Population Movements. - 9122007415 ; , s. 277-298
-
Bokkapitel (refereegranskat)
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| 15. |
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| 16. |
- Bengtsson, Tommy, et al.
(författare)
-
Sveriges befolkning - myter och verklighet
- 1993
-
Ingår i: Äventyret Sverige : En ekonomisk och social historia - En ekonomisk och social historia. - 9126933004 ; , s. 113-132
-
Bokkapitel (populärvet., debatt m.m.)
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| 17. |
- Bergström, Johannes, et al.
(författare)
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Constraining new physics with a positive or negative signal of neutrino-less double beta decay
- 2011
-
Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 2011:05, s. 122-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate numerically how accurately one could constrain the strengths of different short-range contributions to neutrino-less double beta decay in effective field theory. Depending on the outcome of near-future experiments yielding information on the neutrino masses, the corresponding bounds or estimates can be stronger or weaker. A particularly interesting case, resulting in strong bounds, would be a positive signal of neutrino-less double beta decay that is consistent with complementary information from neutrino oscillation experiments, kinematical determinations of the neutrino mass, and measurements of the sum of light neutrino masses from cosmological observations. The keys to more robust bounds are improvements of the knowledge of the nuclear physics involved and a better experimental accuracy.
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| 18. |
- Bergström, Johannes, 1985-
(författare)
-
Models in Neutrino Physics : Numerical and Statistical Studies
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The standard model of particle physics can excellently describe the vast majorityof data of particle physics experiments. However, in its simplest form, it cannot account for the fact that the neutrinos are massive particles and lepton flavorsmixed, as required by the observation of neutrino oscillations. Hence, the standardmodel must be extended in order to account for these observations, opening up thepossibility to explore new and interesting physical phenomena.There are numerous models proposed to accommodate massive neutrinos. Thesimplest of these are able to describe the observations using only a small numberof effective parameters. Furthermore, neutrinos are the only known existing particleswhich have the potential of being their own antiparticles, a possibility that isactively being investigated through experiments on neutrinoless double beta decay.In this thesis, we analyse these simple models using Bayesian inference and constraintsfrom neutrino-related experiments, and we also investigate the potential offuture experiments on neutrinoless double beta decay to probe other kinds of newphysics.In addition, more elaborate theoretical models of neutrino masses have beenproposed, with the seesaw models being a particularly popular group of models inwhich new heavy particles generate neutrino masses. We study low-scale seesawmodels, in particular the resulting energy-scale dependence of the neutrino parameters,which incorporate new particles with masses within the reach of current andfuture experiments, such as the LHC.
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| 19. |
- Bergström, Johannes, 1985-
(författare)
-
Predictions of Effective Models in Neutrino Physics
- 2011
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Experiments on neutrino oscillations have confirmed that neutrinos have small, but non-zero masses, and that the interacting neutrino states do not have definite masses, but are mixtures of such states.The seesaw models make up a group of popular models describing the small neutrino masses and the corresponding mixing.In these models, new, heavy fields are introduced and the neutrino masses are suppressed by the ratio between the electroweak scale and the large masses of the new fields. Usually, the new fields introduced have masses far above the electroweak scale, outside the reach of any foreseeable experiments, making these versions of seesaw models essentially untestable. However, there are also so-called low-scale seesaw models, where the new particles have masses above the electroweak scale, but within the reach of future experiments, such as the LHC.In quantum field theories, quantum corrections generally introduce an energy-scale dependence on all their parameters, described by the renormalization group equations. In this thesis, the energy-scale dependence of the neutrino parameters in two low-scale seesaw models, the low-scale type I and inverse seesaw models, are considered. Also, the question of whether the neutrinos are Majorana particles, \ie , their own antiparticles, has not been decided experimentally. Future experiments on neutrinoless double beta decay could confirm the Majorana nature of neutrinos. However, there could also be additional contributions to the decay, which are not directly related to neutrino masses. We have investigated the possible future bounds on the strength of such additional contributions to neutrinoless double beta decay, depending on the outcome of ongoing and planned experiments related to neutrino masses.
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| 20. |
- Bergström, Johannes, et al.
(författare)
-
Renormalization group running of neutrino parameters in the inverse seesaw model
- 2010
-
Ingår i: Physical Review D. - : The American Physical Society. - 1550-7998. ; 81:11, s. 116006-
-
Tidskriftsartikel (refereegranskat)abstract
- We perform a detailed study of the renormalization group equations in the inverse seesaw model. Especially, we derive compact analytical formulas for the running of the neutrino parameters in the standard model and the minimal supersymmetric standard model, and illustrate that, due to large Yukawa coupling corrections, significant running effects on the leptonic mixing angles can be naturally obtained in the proximity of the electroweak scale, perhaps even within the reach of the LHC. In general, if the mass spectrum of the light neutrinos is nearly degenerate, the running effects are enhanced to experimentally accessible levels, well suitable for the investigation of the underlying dynamics behind the neutrino mass generation and the lepton flavor structure. In addition, the effects of the seesaw thresholds are discussed, and a brief comparison to other seesaw models is carried out.
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| 21. |
- Bergström, Johannes, et al.
(författare)
-
Threshold effects on renormalization group running of neutrino parameters in the low-scale seesaw model
- 2011
-
Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 698:4, s. 297-305
-
Tidskriftsartikel (refereegranskat)abstract
- We show that, in the low-scale type-I seesaw model, renormalization group running of neutrino parameters may lead to significant modifications of the leptonic mixing angles in view of so-called seesaw threshold effects. Especially, we derive analytical formulas for radiative corrections to neutrino parameters in crossing the different seesaw thresholds, and show that there may exist enhancement factors efficiently boosting the renormalization group running of the leptonic mixing angles. We find that, as a result of the seesaw threshold corrections to the leptonic mixing angles, various flavor symmetric mixing patterns (e.g., bi-maximal and tri-bimaximal mixing patterns) can be easily accommodated at relatively low energy scales, which is well within the reach of running and forthcoming experiments (e.g., the LHC).
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| 22. |
- Bergström, Johannes, et al.
(författare)
-
Unparticle self-interactions at the Large Hadron Collider
- 2009
-
Ingår i: Physical Review D. Particles, fields, gravitation and cosmology. - : The American Physical Society. - 1550-7998. ; 80:11, s. 115014-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of unparticle self-interactions at the Large Hadron Collider (LHC). Especially, we discuss the three-point correlation function, which is determined by conformal symmetry up to a constant, and study its relation to processes with four-particle final states. These processes could be used as a favorable way to look for unparticle physics, and for weak enough couplings to the standard model, even the only way. We find updated upper bounds on the cross sections for unparticle-mediated 4 gamma final states at the LHC and novel upper bounds for the corresponding 2 gamma 2l and 4l final states. The size of the allowed cross sections obtained are comparably large for large values of the scaling dimension of the unparticle sector, but they decrease with decreasing values of this parameter. In addition, we present relevant distributions for the different final states, enabling the possible identification of the unparticle scaling dimension if there was to be a large number of events of such final states at the LHC.
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| 23. |
- Bilenky, Samoil M., et al.
(författare)
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Tests of CPT invariance at neutrino factories
- 2002
-
Ingår i: Physical Review D. Particles and fields. - : The American Physical Society. - 0556-2821 .- 1089-4918. ; 65:7, s. 073024-1-073024-6
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate possible tests of CPT invariance on the level of event rates at neutrino factories. We do not assume any specific model but phenomenological differences in the neutrino-antineutrino masses and mixing angles in a Lorentz invariance preserving context, such as could be induced by physics beyond the standard model. We especially focus on the muon neutrino and antineutrino disappearance channels in order to obtain constraints on the neutrino-antineutrino mass and mixing angle differences; we found, for example, that the sensitivity \m(3)-(m) over bar (3)\less than or similar to1.9x10(-4) eV could be achieved.
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| 24. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
A combined study of source, detector and matter non-standard neutrino interactions at DUNE
- 2016
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; 2016:8
-
Tidskriftsartikel (refereegranskat)abstract
- We simultaneously investigate source, detector and matter non-standard neutrino interactions at the proposed DUNE experiment. Our analysis is performed using a Markov Chain Monte Carlo exploring the full parameter space. We find that the sensitivity of DUNE to the standard oscillation parameters is worsened due to the presence of non-standard neutrino interactions. In particular, there are degenerate solutions in the leptonic mixing angle θ23 and the Dirac CP-violating phase δ. We also compute the expected sensitivities at DUNE to the non-standard interaction parameters. We find that the sensitivities to the matter non-standard interaction parameters are substantially stronger than the current bounds (up to a factor of about 15). Furthermore, we discuss correlations between the source/detector and matter non-standard interaction parameters and find a degenerate solution in θ23. Finally, we explore the effect of statistics on our results.
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| 25. |
- Blennow, Mattias, et al.
(författare)
-
Approximative two-flavor framework for neutrino oscillations with nonstandard interactions
- 2008
-
Ingår i: Physical Review D. - : The American Physical Society. - 1550-7998. ; 78:9, s. 093002-1-093002-9
-
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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| 26. |
- Blennow, Mattias, et al.
(författare)
-
Damping signatures in future neutrino oscillation experiments
- 2005
-
Ingår i: Journal of High Energy Physics (JHEP). - : IOP Publishing. - 1126-6708 .- 1029-8479. ; 2005:06, s. 049-
-
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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| 27. |
- Blennow, Mattias, et al.
(författare)
-
Day-night effect in solar neutrino oscillations with three flavors
- 2004
-
Ingår i: Physical Review D. Particles and fields. - : The American Physical Society. - 0556-2821 .- 1089-4918. ; 69:7, s. 073006-1-073006-9
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the effects of a nonzero leptonic mixing angle theta(13) on the solar neutrino day-night asymmetry. Using a constant matter density profile for the Earth and well-motivated approximations, we derive analytical expressions for the nu(e) survival probabilities for solar neutrinos arriving directly at the detector and for solar neutrinos which have passed through the Earth. Furthermore, we numerically study the effects of a nonzero theta(13) on the day-night asymmetry at detectors and find that they are small. Finally, we show that if the uncertainties in the parameters theta(12) and Deltam(2) as well as the uncertainty in the day-night asymmetry itself were much smaller than they are today, this effect could, in principle, be used to determine theta(13).
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| 28. |
- Blennow, Mattias, et al.
(författare)
-
Effective neutrino mixing and oscillations in dense matter
- 2005
-
Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 609:3-4, s. 330-338
-
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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| 29. |
- Blennow, Mattias, et al.
(författare)
-
Effects of non-standard interactions in the MINOS experiment
- 2008
-
Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 660:5, s. 522-528
-
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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| 30. |
- Blennow, Mattias, et al.
(författare)
-
Exact series solution to the two flavor neutrino oscillation problem in matter
- 2004
-
Ingår i: Journal of Mathematical Physics. - : American Institute of Physics. - 0022-2488 .- 1089-7658. ; 45:11, s. 4053-4063
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a real nonlinear differential equation for the two flavor neutrino oscillation problem in matter with an arbitrary density profile. We also present an exact series solution to this nonlinear differential equation. In addition, we investigate numerically the convergence of this solution for different matter density profiles such as constant and linear profiles as well as the Preliminary Reference Earth Model describing the Earth's matter density profile. Finally, we discuss other methods used for solving the neutrino flavor evolution problem.
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| 31. |
- Blennow, Mattias, et al.
(författare)
-
Exploring source and detector non-standard neutrino interactions at ESS nu SB
- 2015
-
Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :9
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate source and detector non-standard neutrino interactions at the proposed ESS nu SB experiment. We analyze the effect of non-standard physics at the probability level, the event-rate level and by a full computation of the ESS nu SB setup. We find that the precision measurement of the leptonic mixing angle theta(23) at ESS nu SB is robust in the presence of non-standard interactions, whereas that of the leptonic CP-violating phase delta is worsened at most by a factor of two. We compute sensitivities to all the relevant source and decector non-standard interaction parameters and find that the sensitivities to the parameters epsilon(s)(mu e) and epsilon(d)(mu e) are comparable to the existing limits in a realistic scenario, while they improve by a factor of two in an optimistic scenario. Finally, we show that the absence of a near detector compromises the sensitivity of ESS nu SB to non-standard interactions.
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| 32. |
- Blennow, Mattias
(författare)
-
Matter and damping effects in neutrino mixing and oscillations
- 2005
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is devoted to the study of neutrino physics in general and the study of neutrino mixing and oscillations in particular. In the standard model of particle physics, neutrinos are massless, and as a result, they do not mix or oscillate. However, many experimental results now seem to give evidence for neutrino oscillations, and thus, the standard model has to be extended in order to incorporate neutrino masses and mixing among different neutrino flavors. When neutrinos propagate through matter, the neutrino mixing, and thus, also the neutrino oscillations, may be significantly altered. While the matter effects may be easily studied in a framework with only two neutrino flavors and constant matter density, we know that there exists (at least) three neutrino flavors and that the matter density of the Universe is far from constant. This thesis includes studies of three-flavor effects and a solution to the two-flavor neutrino oscillation problem in matter with an arbitrary density profile. Furthermore, there have historically been attempts to describe the neutrino flavor transitions by other effects than neutrino oscillations. Even if these effects now seem to be disfavored as the leading mechanism, they may still give small corrections to the neutrino oscillation formulas. These effects may lead to erroneous determination of the fundamental neutrino oscillation parameters and are also studied in this thesis in form of damping factors.
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| 33. |
- Blennow, Mattias, et al.
(författare)
-
Neutrinos from Kaluza-Klein dark matter in the Sun
- 2010
-
Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing / SISSA. - 1475-7516. ; 2010:01, s. 018-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate indirect neutrino signals from annihilations of Kaluza-Klein dark matter in the Sun. Especially, we examine a five- as well as a six-dimensional model, and allow for the possibility that boundary localized terms could affect the spectrum to give different lightest Kaluza-Klein particles, which could constitute the dark matter. The dark matter candidates that are interesting for the purpose of indirect detection of neutrinos are the first Kaluza-Klein mode of the U(1) gauge boson and the neutral component of the SU(2) gauge bosons. Using the DarkSUSY and WimpSim packages, we calculate muon fluxes at an Earth-based neutrino telescope, such as IceCube. For the five-dimensional model, the results hat we obtained agree reasonably well with the results that have previously been presented in the literature, whereas for the six-dimensional model, we find that, at tree-level, the results are the same as for the five-dimensional model. Finally, if the first Kaluza-Klein mode of the U(1) gauge boson constitutes the dark matter, IceCube can constrain the parameter space. However, in the case that the neutral component of the SU(2) gauge bosons is the LKP, the signal is too weak to be observed.
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| 34. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Neutrinos from WIMP annihilations in the Sun including neutrino oscillations
- 2011
-
Ingår i: The Proceedings of the 22nd International Conference on Neutrino Physics and Astrophysics. - : Elsevier. ; , s. 37-38
-
Konferensbidrag (refereegranskat)abstract
- The prospects to detect neutrinos from the Sun arising from dark matter annihilations in the core of the Sun are reviewed. Emphasis is placed on new work investigating the effects of neutrino oscillations on the expected neutrino fluxes.
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| 35. |
- Blennow, Mattias, et al.
(författare)
-
Neutrinos from WIMP annihilations in the Sun including neutrino oscillations
- 2006
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; T127, s. 19-21
-
Tidskriftsartikel (refereegranskat)abstract
- The prospects for detecting neutrinos from the Sun arising from dark matter annihilations in the core of the Sun are reviewed. Emphasis is placed on new work investigating the effects of neutrino oscillations on the expected neutrino fluxes.
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| 36. |
- Blennow, Mattias, et al.
(författare)
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Neutrinos from WIMP annihilations obtained using a full three-flavor Monte Carlo approach
- 2008
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :1, s. 21-
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Tidskriftsartikel (refereegranskat)abstract
- Weakly interacting massive particles (WIMPs) are one of the main candidates for making up the dark matter in the Universe. If these particles make up the dark matter, then they can be captured by the Sun or the Earth, sink to the respective cores, annihilate, and produce neutrinos. Thus, these neutrinos can be a striking dark matter signature at neutrino telescopes looking towards the Sun and/or the Earth. Here, we improve previous analyses on computing the neutrino yields from WIMP annihilations in several respects. We include neutrino oscillations in a full three-flavor framework as well as all effects from neutrino interactions on the way through the Sun (absorption, energy loss, and regeneration from tau decays). In addition, we study the effects of non-zero values of the mixing angle theta(13) as well as the normal and inverted neutrino mass hierarchies. Our study is performed in an event-based setting which makes these results very useful both for theoretical analyses and for building a neutrino telescope Monte Carlo code. All our results for the neutrino yields, as well as our Monte Carlo code, are publicly available. We find that the yield of muontype neutrinos from WIMP annihilations in the Sun is enhanced or suppressed, depending on the dominant WIMP annihilation channel. This effect is due to an effective favor mixing caused by neutrino oscillations. For WIMP annihilations inside the Earth, the distance from source to detector is too small to allow for any significant amount of oscillations at the neutrino energies relevant for neutrino telescopes.
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| 37. |
- Blennow, Mattias, et al.
(författare)
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Non-standard Hamiltonian effects on neutrino oscillations
- 2007
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Ingår i: The European Physical Journal C. - : Springer-Verlag / Società Italiana di Fisica. - 1434-6044 .- 1434-6052. ; 49:4, s. 1023-1039
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Tidskriftsartikel (refereegranskat)abstract
- We investigate non-standard Hamiltonian effects on neutrino oscillations, which are effective additional contributions to the vacuum or matter Hamiltonian. Since these effects can enter in either the flavor or mass basis, we develop an understanding of the difference between these bases representing the underlying theoretical model. In particular, the simplest of these effects are classified as "pure" flavor or mass effects, where the appearance of such a "pure" effect can be quite plausible as a leading non-standard contribution from theoretical models. Compared to earlier studies investigating particular effects, we aim for a top-down classification of a possible "new physics" signature at future long-baseline neutrino oscillation precision experiments. We develop a general framework for such effects with two neutrino flavors and discuss the extension to three neutrino flavors, and we demonstrate the challenges for a neutrino factory to distinguish the theoretical origin of these effects with a numerical example as well. We find how the precision measurements of neutrino oscillation parameters can be altered by non-standard effects alone (not including non-standard interactions in the creation and detection processes) and that the non-standard effects on Hamiltonian level can be distinguished from other non-standard effects (such as neutrino decoherence and decay) if we consider the specific imprint of the effects on the energy spectra of several different oscillation channels at a neutrino factory.
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| 38. |
- 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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| 39. |
- Blennow, Mattias, et al.
(författare)
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Non-unitary neutrino mixing from an extra-dimensional seesaw model
- 2010
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We study the generation of light neutrino masses in an extra-dimensional model, where right-handed neutrinos are allowed to propagate in the extra dimension, while the Standard model (SM) particles are confined to a brane. Motivated by the fact that extra-dimensional models are non-renormalizable, we truncate the Kaluza–Klein (KK) towers at a maximal KK index. The structure of the bulk Majorana mass term, motivated by the Sherk–Schwarz mechanism, implies that the right-handed KK neutrinos pair to form Dirac neutrinos, except for a number of unpaired Majorana neutrinos at the top of each tower. These heavy Majorana neutrinos are the only sources of lepton number breaking in the model, and similarly to the type-I seesaw mechanism, they naturally generate small masses for the left-handed neutrinos. The lower KK modes mix with the light neutrinos, and the mixing effects are not suppressed with respect to the light neutrino masses. Compared to conventional fermionic seesaw models, the non-unitary effects induced by such mixing are quite significant. We study the signals of this model at the Large Hadron Collider (LHC), and find that the current bounds on the non-unitarity parameters are strong enough to exclude an observation.
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| 40. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Probing lepton flavor models at future neutrino experiments
- 2020
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Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 102:11
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Tidskriftsartikel (refereegranskat)abstract
- Non-Abelian discrete symmetries provide an interesting opportunity to address the flavor puzzle in the lepton sector. However, the number of currently viable models based on such symmetries is rather large. High-precision measurements of the leptonic mixing parameters by future neutrino experiments, including ESSnuSB, T2HK, DUNE, and JUNO, will be crucial to test such models. We show that the complementarity among these experiments offers a powerful tool for narrowing down this broad class of lepton flavor models.
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| 41. |
- Blennow, Mattias, et al.
(författare)
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Renormalization group running of the neutrino mass operator in extra dimensions
- 2011
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer-Verlag. - 1126-6708 .- 1029-8479. ; 2011:04, s. 052-
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Tidskriftsartikel (refereegranskat)abstract
- We study the renormalization group (RG) running of the neutrino masses and the leptonic mixing parameters in two different extra-dimensional models, namely, the Universal Extra Dimensions (UED) model and a model, where the Standard Model (SM) bosons probe an extra dimension and the SM fermions are confined to a four-dimensional brane. In particular, we derive the beta function for the neutrino mass operator in the UED model. We also rederive the beta function for the charged-lepton Yukawa coupling, and confirm some of the existing results in the literature. The generic features of the RG running of the neutrino parameters within the two models are analyzed and, in particular, we observe a power-law behavior for the running. We note that the running of the leptonic mixing angle theta(12) can be sizable, while the running of theta(23) and theta(13) is always negligible. In addition, we show that the tri-bimaximal and the bimaximal mixing patterns at a high-energy scale are compatible with low-energy experimental data, while a tri-small mixing pattern is not. Finally, we perform a numerical scan over the low-energy parameter space to infer the high-energy distribution of the parameters. Using this scan, we also demonstrate how the high-energy theta(12) is correlated with the smallest neutrino mass and the Majorana phases.
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| 42. |
- Blennow, Mattias, et al.
(författare)
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RG running in a minimal UED model in light of recent LHC Higgs mass bounds
- 2012
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 712:4-5, s. 419-424
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Tidskriftsartikel (refereegranskat)abstract
- We study how the recent ATLAS and CMS Higgs mass bounds affect the renormalization group running of the physical parameters in universal extra dimensions. Using the running of the Higgs self-coupling constant, we derive bounds on the cutoff scale of the extra-dimensional theory itself. We show that the running of physical parameters, such as the fermion masses and the CKM mixing matrix, is significantly restricted by these bounds. In particular, we find that the running of the gauge couplings cannot be sufficient to allow gauge unification at the cutoff scale.
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| 43. |
- Blennow, Mattias, et al.
(författare)
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Signatures from an extra-dimensional seesaw model
- 2010
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Ingår i: Physical Review D. - : The American Physical Society. - 1550-7998. ; 82:4, s. 045023-
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Tidskriftsartikel (refereegranskat)abstract
- We study the generation of small neutrino masses in an extra-dimensional model, where singlet fermions are allowed to propagate in the extra dimension, while the standard model particles are confined to a brane. Motivated by the fact that extra-dimensional models are nonrenormalizable, we truncate the Kaluza-Klein towers at a maximal Kaluza-Klein number. This truncation, together with the structure of the bulk Majorana mass term, motivated by the Sherk-Schwarz mechanism, implies that the Kaluza-Klein modes of the singlet fermions pair to form Dirac fermions, except for a number of unpaired Majorana fermions at the top of each tower. These heavy Majorana fermions are the only sources of lepton number breaking in the model, and similarly to the type-I seesaw mechanism, they naturally generate small masses for the left-handed neutrinos. The lower Kaluza-Klein modes mix with the light neutrinos, and the mixing effects are not suppressed with respect to the light-neutrino masses. Compared to conventional fermionic seesaw models, such mixing can be more significant. We study the signals of this model at the Large Hadron Collider, and find that the current low-energy bounds on the nonunitarity of the leptonic mixing matrix are strong enough to exclude an observation.
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| 44. |
- Blennow, Mattias, et al.
(författare)
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Solar Neutrino Day-Night Effect
- 2005
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Ingår i: NEUTRINO 2004. - : Elsevier Science B.V.. ; , s. 578-578
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Konferensbidrag (refereegranskat)abstract
- We summarize the results of Ref. [M. Blennow, T. Ohlsson and H. Snellman, Phys. Rev. D 69 (2004) 073006, hep-ph/0311098] in which we determine the effects of three flavor mixing on the day-night asymmetry in the flux of solar neutrinos. Analytic methods are used to determine the difference in the day and night solar electron neutrino survival probabilites and numerical methods are used to determine the effect of three flavor mixing at detectors.
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| 45. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Testing lepton flavor models at ESSnuSB
- 2020
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We review and investigate lepton flavor models, stemming from discrete non- Abelian flavor symmetries, described by one or two free model parameters. First, we confront eleven one- and seven two-parameter models with current results on leptonic mixing angles from global fits to neutrino oscillation data. We find that five of the one- and five of the two-parameter models survive the confrontation test at 3 sigma. Second, we investigate how these ten one- and two-parameter lepton flavor models may be discriminated at the proposed ESSnuSB experiment in Sweden. We show that the three one-parameter models that predict sin delta(CP) = 0 can be distinguished from those two that predict vertical bar sin delta(CP)vertical bar = 1 by at least 7 sigma. Finally, we find that three of the five one-parameter models can be excluded by at least 5 sigma and two of the one-parameter as well as at most two of the five two-parameter models can be excluded by at least 3 sigma with ESSnuSB if the true values of the leptonic mixing parameters remain close to the present best-fit values.
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| 46. |
- Blennow, Mattias, 1980-
(författare)
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Theoretical and Phenomenological Studies of Neutrino Physics
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is devoted to the theory and phenomenology of neutrino physics. While the standard model of particle physics has been extremely successful, it fails to account for massive neutrinos, which are necessary to describe the observations of neutrino oscillations made by several different experiments. Thus, neutrino physics is a possible window for exploring the physics beyond the standard model, making it both interesting and important for our fundamental understanding of Nature. Throughout this thesis, we will discuss different aspects of neutrino physics, ranging from taking all three types of neutrinos into account in neutrino oscillation experiments to exploring the possibilities of neutrino mass models to produce a viable source of the baryon asymmetry of the Universe. The emphasis of the thesis is on neutrino oscillations which, given their implication of neutrino masses, is a phenomenon where other results that are not describable in the standard model could be found, such as new interactions between neutrinos and fermions.
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| 47. |
- Blennow, Mattias, et al.
(författare)
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WIMP neutrinos from the Sun and the Earth
- 2008
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Konferensbidrag (refereegranskat)abstract
- We discuss the propagation treatment of the indirect dark matter detection using WIMP annihilations in the Sun and the Earth. In particular, we focus on treating neutrino interactions and oscillations in a consistent framework, including tau neutrino regeneration and a full three-flavor neutrino oscillation framework. We also discuss the equivalence of using a Monte Carlo approach - suited for inclusion in neutrino telescope Monte Carlos - and the density matrix formalism.
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| 48. |
- Bonnevier, Johan, et al.
(författare)
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Monoenergetic gamma rays from nonminimal Kaluza-Klein dark matter annihilations
- 2012
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Ingår i: Physical Review D. - : The American Physical Society. - 1550-7998 .- 1550-2368. ; 85:4, s. 043524-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate monoenergetic gamma-ray signatures from annihilations of dark matter comprised of Z(1), the first Kaluza-Klein (KK) excitation of the Z boson in a nonminimal universal extra dimensions (UED) model. The self interactions of the non-Abelian Z(1) gauge boson give rise to a large number of contributing Feynman diagrams that do not exist for annihilations of the Abelian gauge boson B-1, which is the standard Kaluza-Klein dark matter (KKDM) candidate. We find that the annihilation rate is indeed considerably larger for the Z(1) than for the B-1. Even though relic density calculations indicate that the mass of the Z(1) should be larger than the mass of the B-1, the predicted monoenergetic gamma fluxes are of the same order of magnitude. We compare our results to existing experimental limits, as well as to future sensitivities, for image air Cherenkov telescopes, and we find that the limits are reached already with a moderately large boost factor. The realistic prospects for detection depend on the experimental energy resolution.
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| 49. |
- Boucenna, Sofiane M., et al.
(författare)
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A minimal non-supersymmetric SO(10) model with Peccei-Quinn symmetry
- 2019
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 792, s. 251-257
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Tidskriftsartikel (refereegranskat)abstract
- We present a minimal non-supersymmetric SO(10) GUT breaking directly to the Standard Model gauge group. Precise gauge coupling unification is achieved due to the presence of two color-octet scalars, one of which is accessible to LHC searches. Proton lifetime is predicted to be below 4.5 x 10(34) years, which is within the projected five-year sensitivity of the proposed Hyper-Kamiokande experiment. We find that the Standard Model observables are reproduced to a reasonable accuracy in a numerical fit, which also predicts the unknown neutrino parameters. Finally, the two scalar representations stabilize the electroweak vacuum and the dark matter is comprised of axions.
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| 50. |
- Boucenna, Sofiane M., et al.
(författare)
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Novel constraints on mixed dark-matter scenarios of primordial black holes and WIMPs
- 2018
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP PUBLISHING LTD. - 1475-7516. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We derive constraints on mixed dark-matter scenarios consisting of primordial black holes (PBHs) and weakly interacting massive particles (WIMPs). In these scenarios, we expect a density spike of the WIMPs that are gravitationally bound to the PBHs, which results in an enhanced annihilation rate and increased indirect detection prospects. We show that such scenarios provide strong constraints on the allowed fraction of PBHs that constitutes the dark matter, depending on the WIMP mass m(x) and the velocity-averaged annihilation cross-section . For the standard scenario with m(x) = 100 GeV and = 3 x 10(-26) cm(3)/s, we derive bounds that are stronger than all existing bounds for PBHs with masses 10(-12) M-circle dot less than or similar to M-BH less than or similar to 10(4) where M-circle dot, is the solar mass, and mostly so by several orders of magnitude.
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