| 1. |
- Abele, H., et al.
(författare)
-
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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| 2. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Asymmetric Dark Matter and Dark Radiation
- 2012
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; 7:022
-
Tidskriftsartikel (refereegranskat)abstract
- Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry, similar to the one observed in the Baryon sector, to account for the Dark Matter (DM) abundance. Both asymmetries are usually generated by the same mechanism and generally related, thus predicting DM masses around 5 GeV in order to obtain the correct density. The main challenge for successful models is to ensure efficient annihilation of the thermally produced symmetric component of such a light DM candidate without violating constraints from collider or direct searches. A common way to overcome this involves a light mediator, into which DM can efficiently annihilate and which subsequently decays into Standard Model particles. Here we explore the scenario where the light mediator decays instead into lighter degrees of freedom in the dark sector that act as radiation in the early Universe. While this assumption makes indirect DM searches challenging, it leads to signals of extra radiation at BBN and CMB. Under certain conditions, precise measurements of the number of relativistic species, such as those expected from the Planck satellite, can provide information on the structure of the dark sector. We also discuss the constraints of the interactions between DM and Dark Radiation from their imprint in the matter power spectrum.
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| 3. |
- Burgman, A., et al.
(författare)
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The ESSnuSB Design Study: Overview and Future Prospects
- 2023
-
Ingår i: Universe. - : MDPI. - 2218-1997. ; 9:8
-
Forskningsöversikt (refereegranskat)abstract
- ESSnuSB is a design study for an experiment to measure the CP violation in the leptonic sector at the second neutrino oscillation maximum using a neutrino beam driven by the uniquely powerful ESS linear accelerator. The reduced impact of systematic errors on sensitivity at the second maximum allows for a very precise measurement of the CP violating parameter. This review describes the fundamental advantages of measurement at the second maximum, the necessary upgrades to the ESS linac in order to produce a neutrino beam, the near and far detector complexes, and the expected physics reach of the proposed ESSnuSB experiment, concluding with the near future developments aimed at the project realization.
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| 4. |
- 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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| 5. |
- Agarwalla, Sanjib, et al.
(författare)
-
Neutrino Probes of the Nature of Light Dark Matter
- 2011
-
Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Dark matter particles gravitationally trapped inside the Sun may annihilate into Standard Model particles, producing a flux of neutrinos. The prospects of detecting these neutrinos in future multi-kt neutrino detectors designed for other physics searches are explored here. We study the capabilities of a 34/100 kt liquid argon detector and a 100 kt magnetized iron calorimeter detector. These detectors are expected to determine the energy and the direction of the incoming neutrino with unprecedented precision allowing for tests of the dark matter nature at very low dark matter masses, in the range of 10–25 GeV. By suppressing the atmospheric background with angular cuts, these techniques would be sensitive to dark matter-nucleon spin-dependent cross sections at the fb level, reaching down to a few ab for the most favorable annihilation channels and detector technology.
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| 6. |
- Aguilar, J., et al.
(författare)
-
Study of nonstandard interactions mediated by a scalar field at the ESSnuSB experiment
- 2024
-
Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 109:11
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study scalar mediator induced nonstandard interactions (SNSIs) in the context of the ESSnuSB experiment. In particular, we study the capability of ESSnuSB to put bounds on the SNSI parameters and also study the impact of SNSIs in the measurement of the leptonic ?? phase ???. Existence of SNSIs modifies the neutrino mass matrix and this modification can be expressed in terms of three diagonal real parameters (???, ???, and ???) and three off-diagonal complex parameters (???, ???, and ???). Our study shows that the upper bounds on the parameters ??? and ??? depend upon how Δ?231 is minimized in the theory. However, this is not the case when one tries to measure the impact of SNSIs on ???. Further, we show that the ?? sensitivity of ESSnuSB can be completely lost for certain values of ??? and ??? for which the appearance channel probability becomes independent of ???.
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| 7. |
- Antusch, Stefan, et al.
(författare)
-
New physics searches at near detectors of neutrino oscillation experiments
- 2010
-
Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- We systematically investigate the prospects of testing new physics with tau sensitive near detectors at neutrino oscillation facilities. For neutrino beams from pion decay, from the decay of radioactive ions, as well as from the decays of muons in a storage ring at a neutrino factory, we discuss which effective operators can lead to new physics effects. Furthermore, we discuss the present bounds on such operators set by other experimental data currently available. For operators with two leptons and two quarks we present the first complete analysis including all relevant operators simultaneously and performing a Markov Chain Monte Carlo fit to the data. We find that these effects can induce tau neutrino appearance probabilities as large as O(10(-4)), which are within reach of forthcoming experiments. We highlight to which kind of new physics a tau sensitive near detector would be most sensitive.
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| 8. |
- Antusch, Stefan, et al.
(författare)
-
Non-unitary Leptonic Mixing and Leptogenesis
- 2010
-
Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 1
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the relation between non-unitarity of the leptonic mixing matrix and leptogenesis. We discuss how all parameters of the canonical type-I seesaw mechanism can, in principle, be reconstructed from the neutrino mass matrix and the deviation of the effective low-energy leptonic mixing matrix from unitary. When the mass M' of the lightest right-handed neutrino is much lighter than the masses of the others, we show that its decay asymmetries within flavour-dependent leptogenesis can be expressed in terms of two contributions, one depending on the unique dimension five (d = 5) operator generating neutrino masses and one depending on the dimension six (d = 6) operator associated with non-unitarity. In low-energy seesaw scenarios where small lepton number violation explains the smallness of neutrino masses, the lepton number conserving d = 6 operator contribution generically dominates over the d = 5 operator contribution which results in a strong enhancement of the flavour-dependent decay asymmetries without any resonance effects. To calculate the produced final baryon asymmetry, the flavour equilibration effects directly related to non-unitarity have to be taken into account. In a simple realization of this non-unitarity driven leptogenesis, the lower bound on M' is found to be about 10(8) GeV at the onset of the strong washout regime, more than one order of magnitude below the bound in "standard" thermal leptogenesis.
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| 9. |
- Antusch, Stefan, et al.
(författare)
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Probing non-unitary mixing and CP-violation at a Neutrino Factory
- 2009
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 80:3, s. 033002-
-
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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| 10. |
- Biggio, Carla, et al.
(författare)
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General bounds on non-standard neutrino interactions
- 2009
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; 8
-
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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| 11. |
- Biggio, Carla, et al.
(författare)
-
Loop bounds on non-standard neutrino interactions
- 2009
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; :3
-
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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| 12. |
- Blaksley, Carl, et al.
(författare)
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Heavy neutrinos and lepton number violation in ℓp colliders
- 2011
-
Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 852:2, s. 353-365
-
Tidskriftsartikel (refereegranskat)abstract
- We discuss the prospects of studying lepton number violating processes in order to identify Majorana neutrinos from low scale seesaw mechanisms at lepton-proton colliders. In particular, we consider the scenarios of colliding electrons with LHC energy protons and, motivated by the efforts towards the construction of a muon collider, the prospects of muon-proton collisions. We find that present constraints on the mixing of the Majorana neutrinos still allow for a detectable signal at these kind of facilities given the smallness of the Standard Model background. We discuss possible cuts in order to further increase the signal over background ratio and the prospects of reconstructing the neutrino mass from the kinematics of the final state particles.
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| 13. |
- 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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| 14. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Aidnogenesis via Leptogenesis and Dark Sphalerons
- 2011
-
Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- We discuss aidnogenesis,(1) i.e. the generation of a dark matter asymmetry, via new sphaleron processes associated to an extra non-abelian gauge symmetry common to both the visible and the dark sectors. Such a theory can naturally produce an abundance of asymmetric dark matter which is of the same size as the lepton and baryon asymmetries, as suggested by the similar sizes of the observed baryonic and dark matter energy content, and provide a definite prediction for the mass of the dark matter particle. We discuss in detail a minimal realization in which the Standard Model is only extended by dark matter fermions which form "dark baryons" through an SU(3) interaction, and a (broken) horizontal symmetry that induces the new sphalerons. The dark matter mass is predicted to be similar to 6GeV, close to the region favored by DAMA and CoGeNT. Furthermore, a remnant of the horizontal symmetry should be broken at a lower scale and can also explain the Tevatron dimuon anomaly.
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| 15. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Bounds on lepton non-unitarity and heavy neutrino mixing
- 2023
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:8
-
Tidskriftsartikel (refereegranskat)abstract
- We present an updated and improved global fit analysis of current flavour and electroweak precision observables to derive bounds on unitarity deviations of the leptonic mixing matrix and on the mixing of heavy neutrinos with the active flavours. This new analysis is motivated by new and updated experimental results on key observables such as V-ud, the invisible decay width of the Z boson and the W boson mass. It also improves upon previous studies by considering the full correlations among the different observables and explicitly calibrating the test statistic, which may present significant deviations from a & chi;(2) distribution. The results are provided for three different Type-I seesaw scenarios: the minimal scenario with only two additional right-handed neutrinos, the next to minimal one with three extra neutrinos, and the most general one with an arbitrary number of heavy neutrinos that we parametrise via a generic deviation from a unitary leptonic mixing matrix. Additionally, we also analyze the case of generic deviations from unitarity of the leptonic mixing matrix, not necessarily induced by the presence of additional neutrinos. This last case relaxes some correlations among the parameters and is able to provide a better fit to the data. Nevertheless, inducing only leptonic unitarity deviations avoiding both the correlations implied by the right-handed neutrino extension as well as more strongly constrained operators is challenging and would imply significantly more complex UV completions.
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| 16. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
IceCube bounds on sterile neutrinos above 10 eV
- 2018
-
Ingår i: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 78:10
-
Tidskriftsartikel (refereegranskat)abstract
- We study the capabilities of IceCube to search for sterile neutrinos with masses above 10 eV by analyzing its nu(mu) disappearance atmospheric neutrino sample. We find that IceCube is not only sensitive to the mixing of sterile neutrinos to muon neutrinos, but also to the more elusive mixing with tau neutrinos through matter effects. The currently released 1-year data shows a mild preference, between 0.75 and 3 sigma depending on the binning and flux adopted, for non-zero sterile mixing. This hint overlaps with the favored region for the sterile neutrino interpretation of the ANITA upward shower although the null results from CHORUS and NOMAD on nu(mu) to nu(tau) oscillations in vacuum exclude this interpretation, while through a different channel and using a different energy range. At the 99% C.L. an upper bound is obtained that improves over the present Super-Kamiokande and DeepCore constraints in some parts of the parameter space. We also investigate the physics reach of the roughly 8 years of data that is already on tape as well as a forecast of 20 years data to probe the present hint or improve upon current constraints.
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| 17. |
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| 18. |
- Blennow, Mattias, 1980-
(författare)
-
MonteCUBES
- 2010
-
Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. ; 1222, s. 107-111
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce the software package MonteCUBES, which is designed to easily and effectively perform Markov Chain Monte Carlo simulations for analyzing neutrino oscillation experiments. We discuss the methods used in the software as well as why we believe that it is particularly useful for simulating new physics effects.
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| 19. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Neutrino oscillation parameter sampling with MonteCUBES
- 2010
-
Ingår i: Computer Physics Communications. - : Elsevier BV. - 0010-4655 .- 1879-2944. ; 181:1, s. 227-231
-
Tidskriftsartikel (refereegranskat)abstract
- We present MonteCUBES ("Monte Carlo Utility Based Experiment Simulator"), a software package designed to sample the neutrino oscillation parameter space through Markov Chain Monte Carlo algorithms. MonteCUBES makes use of the GLoBES software so that the existing experiment definitions for GLoBES, describing long baseline and reactor experiments. can be used with MonteCUBES. MonteCUBES consists of two main parts: The first is a C library, written as a plug-in for GLoBES, implementing the Markov Chain Monte Carlo algorithm to sample the parameter space. The second part is a user-friendly graphical Matlab interface to easily read, analyze, plot and export the results of the parameter space sampling.
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| 20. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Neutrino portals to dark matter
- 2019
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Ingår i: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 79:7
-
Tidskriftsartikel (refereegranskat)abstract
- We explore the possibility that dark matter interactions with Standard Model particles are dominated by interactions with neutrinos. We examine whether it is possible to construct such a scenario in a gauge invariant manner. We first study the coupling of dark matter to the full lepton doublet and confirm that this generally leads to the dark matter phenomenology being dominated by interactions with charged leptons. We then explore two different implementations of the neutrino portal in which neutrinos mix with a Standard Model singlet fermion that interacts directly with dark matter through either a scalar or vector mediator. In the latter cases we find that the neutrino interactions can dominate the dark matter phenomenology. Present neutrino detectors can probe dark matter annihilations into neutrinos and already set the strongest constraints on these realisations. Future experiments such as Hyper-Kamiokande, MEMPHYS, DUNE, or DARWIN could allow to probe dark matter-neutrino cross sections down to the value required to obtain the correct thermal relic abundance.
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| 21. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Neutrinoless double beta decay in seesaw models
- 2010
-
Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- We study the general phenomenology of neutrinoless double beta decay in seesaw models. In particular, we focus on the dependence of the neutrinoless double beta decay rate on the mass of the extra states introduced to account for the Majorana masses of light neutrinos. For this purpose, we compute the nuclear matrix elements as functions of the mass of the mediating fermions and estimate the associated uncertainties. We then discuss what can be inferred on the seesaw model parameters in the different mass regimes and clarify how the contribution of the light neutrinos should always be taken into account when deriving bounds on the extra parameters. Conversely, the extra states can also have a significant impact, canceling the Standard Model neutrino contribution for masses lighter than the nuclear scale and leading to unobservable neutrinoless double beta decay amplitudes even if neutrinos are Majorana particles. In particular, the decay rate is reduced by at least six orders of magnitude for masses of the extra states below 1MeV in absence of extra contributions. We also discuss how seesaw models could reconcile large rates of neutrinoless double beta decay with more stringent cosmological bounds on neutrino masses.
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| 22. |
- 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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| 23. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Non-standard interaction effects on astrophysical neutrino fluxes
- 2009
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 80:6, s. 065009-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate new physics effects in the production and detection of high-energy neutrinos at neutrino telescopes. Analyzing the flavor ratios ϕμ/ϕτ and ϕμ/(ϕτ+ϕe), we find that the standard model predictions for them can be sensibly altered by new physics effects in the case of pion sources. However, the experimental precision required to see the effects would be very difficult to obtain.
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| 24. |
- Blennow, Mattias, 1980-
(författare)
-
Non-standard interactions using the OPERA experiment
- 2008
-
Ingår i: Proceedings of Science. - 1824-8039. ; NUFACT08
-
Tidskriftsartikel (refereegranskat)abstract
- We discuss the interplay of non-standard interactions between neutrinos and charged fermions and their impact on the currently running OPERA experiment. We show that, due to the relatively short distance between CERN and the Gran Sasso laboratory, the neutrino oscillation probabilities can be expanded in the baseline length. This results in a rather simple understanding of numeric simulations, which we perform using the GLoBES software. © owned by the author.
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| 25. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Non-unitarity, sterile neutrinos, and non-standard neutrino interactions
- 2017
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :4
-
Tidskriftsartikel (refereegranskat)abstract
- The simplest Standard Model extension to explain neutrino masses involves the addition of right-handed neutrinos. At some level, this extension will impact neutrino oscillation searches. In this work we explore the differences and similarities between the case in which these neutrinos are kinematically accessible (sterile neutrinos) or not (mixing matrix non-unitarity). We clarify apparent inconsistencies in the present literature when using different parametrizations to describe these effects and recast both limits in the popular neutrino non-standard interaction (NSI) formalism. We find that, in the limit in which sterile oscillations are averaged out at the near detector, their effects at the far detector coincide with non-unitarity at leading order, even in presence of a matter potential. We also summarize the present bounds existing in both limits and compare them with the expected sensitivities of near-future facilities taking the DUNE proposal as a benchmark. We conclude that non-unitarity effects are too constrained to impact present or near future neutrino oscillation facilities but that sterile neutrinos can play an important role at long baseline experiments. The role of the near detector is also discussed in detail.
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| 26. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Nonstandard neutrino-neutrino refractive effects in dense neutrino gases
- 2008
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 78:11, s. 113004-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the effects of nonstandard four-fermion neutrino-neutrino interactions on the flavor evolution of dense neutrino gases. We find that in the regions where the neutrino-neutrino refractive index leads to collective flavor oscillations, the presence of new neutrino interactions can produce flavor equilibration in both normal and inverted neutrino mass hierarchy. In realistic supernova environments, these effects are significant if the nonstandard neutrino-neutrino interaction strength is comparable to the one expected in the standard case, dominating the ordinary matter potential. However, very small nonstandard neutrino-neutrino couplings are enough to trigger the usual collective neutrino flavor transformations in the inverted neutrino mass hierarchy, even if the mixing angle vanishes exactly.
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| 27. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Physics potential of the ESS nu SB
- 2020
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:3
-
Tidskriftsartikel (refereegranskat)abstract
- The ESS.SB project proposes to base a neutrino "Super Beam" of unprecedented luminosity at the European Spallation Source. The original proposal identified the second peak of the oscillation probability as the optimal to maximize the discovery potential to leptonic CP violation. However this choice reduces the statistics at the detector and penalizes other complementary searches such as the determination of the atmospheric oscillation parameters, particularly the octant of.23 as well as the neutrino mass ordering. We explore how these shortcomings can be alleviated by the combination of the beam data with the atmospheric neutrino sample that would also be collected at the detector. We find that the combination not only improves very significantly these drawbacks, but also enhances both the CP violation discovery potential and the precision in the measurement of the CP violating phase, forwhich the facilitywas originally optimized, by lifting parametric degeneracies. We then reassess the optimization of the ESS.SB setup when the atmospheric neutrino sample is considered, with an emphasis in performing a measurement of the CP violating phase as precise as possible. We find that for the presently preferred value of d - p/2, shorter baselines and longer running time in neutrino mode would be optimal. In these conditions, a measurement better than 14. would be achievable for any value of the.23 octant and the mass ordering. Conversely, if present and next generation facilities were not able to discover CP violation, longer baselines and more even splitting between neutrino and neutrino modes would be preferable. These choices would allow a 5s discovery of CP violation for around a 60% of the possible values of d and to determine its value with a precision around 6. if it is close to 0 or pi.
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| 28. |
- Blennow, Mattias, 1980-, et al.
(författare)
-
Physics potential of the ESSnuSB
- 2022
-
Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
-
Konferensbidrag (refereegranskat)abstract
- The ESSnuSB project proposes to base a neutrino “Super Beam” of unprecedented luminosity at the European Spallation Source. The original proposal identified the second peak of the oscillation probability as the optimal to maximize the discovery potential to leptonic CP violation. However this choice reduces the statistics at the detector and penalizes other complementary searches such as the determination of the atmospheric oscillation parameters, particularly the octant of θ23 as well as the neutrino mass ordering. We find that including the atmospheric sample, the combination not only improves very significantly these drawbacks, but also enhances both the CP violation discovery potential and the precision in the measurement of the CP violating phase, for which the facility was originally optimized. We then reassess the optimization of the ESSnuSB setup when the atmospheric neutrino sample is considered, with an emphasis in performing a measurement of the CP violating phase as precise as possible. We find that for values of δ near to maximal CP violation, shorter baselines like that with the Zinkgruvan detector site (360km) would be optimal. In these conditions, a measurement better than 8◦ would be achievable for any value of the θ23 octant and the mass ordering. Conversely, if present and next generation facilities were not able to discover CP violation, longer baselines like that with the Garpenberg detector site (540 km) and more even splitting between neutrino and neutrino modes would be preferable.
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| 29. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Probing lepton flavor models at future neutrino experiments
- 2020
-
Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 102:11
-
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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| 30. |
- Blennow, Mattias, 1980-
(författare)
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Prospects for cosmic neutrino detection in tritium experiments in the case of hierarchical neutrino masses
- 2008
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 77:11, s. 113014-
-
Tidskriftsartikel (refereegranskat)abstract
- We discuss the effects of neutrino mixing and the neutrino mass hierarchy when considering the capture of the cosmic neutrino background (CNB) on radioactive nuclei. The implications of mixing and hierarchy at future generations of tritium decay experiments are considered. We find that the CNB should be detectable at these experiments provided that the resolution for the kinetic energy of the outgoing electron can be pushed to a few 0.01 eV for the scenario with inverted neutrino mass hierarchy, about an order of magnitude better than that of the upcoming KATRIN experiment. Another order of magnitude improvement is needed in the case of normal neutrino mass hierarchy. We also note that mixing effects generally make the prospects for CNB detection worse due to an increased maximum energy of the normal beta decay background.
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| 31. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Right-handed neutrinos and the CDF II anomaly
- 2022
-
Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 106:7
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Tidskriftsartikel (refereegranskat)abstract
- We point out that right-handed neutrinos can resolve the tension between the latest CDF II measurement of MW and the SM. Integrating out the new states yields a single d 1/4 6 operator, which translates into a nonunitary leptonic mixing matrix. This alters the extraction of GF from muon decay and increases the prediction for MW, in line with the CDF II result. We find that this explanation worsens the so-called Cabibbo anomaly, which could still be explained through the same d 1/4 6 operator if it is not generated by right-handed neutrinos. Exploiting the flavor dependence, a common explanation of both anomalies would a priori be possible, but is ruled out by weak universality constraints.
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| 32. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Self-interacting inelastic dark matter : A viable solution to the small scale structure problems
- 2017
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : Institute of Physics Publishing (IOPP). - 1475-7516. ; 2017:3
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Tidskriftsartikel (refereegranskat)abstract
- Self-interacting dark matter has been proposed as a solution to the small-scale structure problems, such as the observed flat cores in dwarf and low surface brightness galaxies. If scattering takes place through light mediators, the scattering cross section relevant to solve these problems may fall into the non-perturbative regime leading to a non-trivial velocity dependence, which allows compatibility with limits stemming from cluster-size objects. However, these models are strongly constrained by different observations, in particular from the requirements that the decay of the light mediator is sufficiently rapid (before Big Bang Nucleosynthesis) and from direct detection. A natural solution to reconcile both requirements are inelastic endothermic interactions, such that scatterings in direct detection experiments are suppressed or even kinematically forbidden if the mass splitting between the two-states is sufficiently large. Using an exact solution when numerically solving the Schrödinger equation, we study such scenarios and find regions in the parameter space of dark matter and mediator masses, and the mass splitting of the states, where the small scale structure problems can be solved, the dark matter has the correct relic abundance and direct detection limits can be evaded.
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| 33. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Sensitivity of oscillation experiments to the neutrino mass hierarchy
- 2014
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Ingår i: Proceedings of the 49th Rencontres de Moriond - 2014 Electroweak Interactions and Unified Theories, EW 2014. - : ARISF. - 9782954640037 ; , s. 121-128
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Konferensbidrag (refereegranskat)abstract
- The large value of θ13 recently discovered at reactor neutrino experiments has opened the door to determine the ordering of their mass eigenstates in the near future. However, since the neutrino mass ordering is a discrete parameter it is not clear whether the median sensitivity of a given experiment would coincide with the usual values reported in the literature. In this talk we present a summary of the different possibilities to determine the neutrino mass ordering in the near future, and we briefly discuss the statistical issues related to the significance of the signal for this measurement.
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| 34. |
- 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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| 35. |
- Blennow, Mattias, 1980-, et al.
(författare)
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The distribution of inelastic dark matter in the Sun
- 2018
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Ingår i: European Physical Journal C. - : Springer-Verlag New York. - 1434-6044 .- 1434-6052. ; 78:5
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Tidskriftsartikel (refereegranskat)abstract
- If dark matter is composed of new particles, these may become captured after scattering with nuclei in the Sun, thermalize through additional scattering, and finally annihilate into neutrinos that can be detected on Earth. If dark matter scatters inelastically into a slightly heavier (O(10-100)keV) state it is unclear whether thermalization occurs. One issue is that up-scattering from the lower mass state may be kinematically forbidden, at which point the thermalization process effectively stops. A larger evaporation rate is also expected due to down-scattering. In this work, we perform a numerical simulation of the capture and thermalization process in order to study the evolution of the dark matter distribution. We then calculate and compare the annihilation rate with that of the often assumed Maxwell–Boltzmann distribution. We also check if equilibrium between capture and annihilation is reached. We find that, unless the mass splitting is very small (≲50keV) and/or the dark matter has a sub-dominant elastic cross section, the dark matter distribution does not reach a stationary state, it is not isothermal, annihilation is severely suppressed, and equilibrium is generally not reached. We also find that evaporation induced by down-scattering is not effective in reducing the total dark matter abundance.
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| 36. |
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| 37. |
- 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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| 38. |
- Blennow, Mattias, 1980-, et al.
(författare)
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Updated global bounds on non-unitarity and heavy neutrinos
- 2024
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Ingår i: European Physical Society Conference on High Energy Physics, EPS-HEP 2023. - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- We present an updated and improved global fit analysis of current flavor and electroweak precision observables to derive bounds on unitarity deviations of the leptonic mixing matrix and on the mixing of heavy neutrinos with the active flavours, which is motivated by the latest experimental updates on key observables such as Vud, the Z invisible width and the W mass.
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| 39. |
- Burgman, A., et al.
(författare)
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The European Spallation Source neutrino super-beam conceptual design report
- 2022
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Ingår i: The European Physical Journal Special Topics. - : Springer Nature. - 1951-6355 .- 1951-6401. ; 231:21, s. 3779-3955
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Forskningsöversikt (refereegranskat)abstract
- A design study, named ESSνSB for European Spallation Source neutrino Super Beam, has been carried out during the years 2018–2022 of how the 5 MW proton linear accelerator of the European Spallation Source under construction in Lund, Sweden, can be used to produce the world’s most intense long-baseline neutrino beam. The high beam intensity will allow for measuring the neutrino oscillations near the second oscillation maximum at which the CP violation signal is close to three times higher than at the first maximum, where other experiments measure. This will enable CP violation discovery in the leptonic sector for a wider range of values of the CP violating phase δCPδCP and, in particular, a higher precision measurement of δCPδCP. The present Conceptual Design Report describes the results of the design study of the required upgrade of the ESS linac, of the accumulator ring used to compress the linac pulses from 2.86 ms to 1.2 μs, and of the target station, where the 5 MW proton beam is used to produce the intense neutrino beam. It also presents the design of the near detector, which is used to monitor the neutrino beam as well as to measure neutrino cross sections, and of the large underground far detector located 360 km from ESS, where the magnitude of the oscillation appearance of νe from νμ is measured. The physics performance of the ESSνSB research facility has been evaluated demonstrating that after 10 years of data-taking, leptonic CP violation can be detected with more than 5 standard deviation significance over 70% of the range of values that the CP violation phase angle δCPδCP can take and that δCPδCP can be measured with a standard error less than 8° irrespective of the measured value of δCPδCP. These results demonstrate the uniquely high physics performance of the proposed ESSνSBESSνSB research facility.
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| 40. |
- Burgman, A., et al.
(författare)
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Updated physics performance of the ESSnuSB experiment
- 2021
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Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:12
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the physics performance of the ESSnuSB experiment in the standard three flavor scenario using the updated neutrino flux calculated specifically for the ESSnuSB configuration and updated migration matrices for the far detector. Taking conservative systematic uncertainties corresponding to a normalization error of 5% for signal and 10% for background, we find that there is 10 sigma (13 sigma) CP violation discovery sensitivity for the baseline option of 540 km (360 km) at delta(CP) = +/- 90 degrees. The corresponding fraction of delta(CP )for which CP violation can be discovered at more than 5 sigma is 70%. Regarding CP precision measurements, the 1 sigma error associated with delta(CP )= 0 degrees is around 5 degrees and with delta(CP )= -90 degrees is around 14 degrees (7 degrees) for the baseline option of 540 km (360 km). For hierarchy sensitivity, one can have 3 sigma sensitivity for 540 km baseline except delta(CP) = +/- 90 degrees and 5 sigma sensitivity for 360 km baseline for all values of delta(CP). The octant of theta(23) can be determined at 30 for the values of: theta(23) > 51 degrees (theta(23) < 42 degrees and theta(23) > 49 degrees) for baseline of 540 km (360 km). Regarding measurement precision of the atmospheric mixing parameters, the allowed values at 3 sigma are: 40 degrees < theta(23) < 52 degrees (42 degrees < theta(23) < 51.5 degrees) and 2.485 x 10(-3) eV(2) < Delta(2)(m31) < 2.545 x 10(-3) eV(2) (2.49x 10(-3 ) eV(2) < Delta(2)(m31) < 2.54 x 10(-3) eV(2)) for the baseline of 540 km (360 km).
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| 41. |
- Clementz, Stefan
(författare)
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Dark Matter Phenomenology in Astrophysical Systems
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is now a great deal of evidence in support of the existence of a large amount of unseen gravitational mass, commonly called dark matter, from observations in astrophysical systems of sizes ranging from that of dwarf galaxies to the scale of the entire Universe. One of the most promising explanations for this unseen mass is that it consists of a species of unobserved elementary particles. An expected feature of particle dark matter is that it should form halos in the early Universe that cannot collapse due to its weak interactions with itself and baryonic matter. It is within these halos that galaxies, including the Milky Way, which is the galaxy that we inhabit, are thought to be born.Different methods to detect dark matter that originates from the galactic halo have been devised and these generally fall into the categories of direct and indirect detection. On Earth, direct detection experiments are employed to detect the recoiling atoms that are generated through the occasional scattering between halo dark matter particles with the detector material. The indirect search for dark matter is conducted by attempting to detect the standard model particles that may be produced as dark matter annihilates or decays and by looking for the effects that dark matter may have on astrophysical bodies. The aim of this thesis is to study the effects that dark matter may have in different astrophysical systems and how its properties can be determined should an effect that is due to dark matter be detected.The Sun currently experiences the solar composition problem, which is a mismatch between simulated and observed helioseismological properties of the Sun. A large abundance of dark matter introduces a new heat transfer mechanism that has been shown to offer a viable solution. This problem is discussed here in a particular model of dark matter where the dark matter halo is made up of equal numbers of particles and antiparticles. It is shown that dark matter arising from the thermal freeze-out mechanism might alleviate the problem, whereas only asymmetric dark matter models have previously been considered.If a dark matter signal is seen in a direct detection experiment, the determination of the dark matter properties will be plagued by numerous uncertainties related to the halo. It has been shown that many of these uncertainties can be eliminated by comparing signals in different direct detection experiments in what is called ``halo-independent" methods. These methods can also be used to predict the neutrino signal from dark matter annihilating in the Sun, further constraining DM properties, if a direct detection experiment detects a signal. This framework is here generalized to inelastic dark matter and the information concerning dark matter properties in a direct detection signal is discussed.When the Sun captures dark matter, thermalization is a process where dark matter particles lose their remaining kinetic energy after being captured and sink into the solar core. Evaporation due to collisions with high-energy solar atoms is also possible. For inelastic dark matter, it is expected that the thermalization process stops prematurely, which will have an effect on the expected neutrino signal from its annihilation. Moreover, evaporation may also be significant due transitions from the heavier to the lighter state. Here, the thermalization problem is discussed, and results from numerical simulations are presented that show the extent to which inelastic dark matter thermalizes and if evaporation has to be taken into account.A number of issues have been observed in dark matter halos at smaller scales when compared to results from large simulations. Dark matter that interacts strongly with itself has been proposed as a solution. There are a number of problems associated with these models that are excluded by other means. A particular model of inelastic dark matter interacting via a light mediator is analyzed here and shown to possible alleviate at least some of the problems associated with models of this kind.
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| 42. |
- Rosauro-Alcaraz, S., et al.
(författare)
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Physics potential of the ESSνSB facility
- 2018
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
-
Konferensbidrag (refereegranskat)abstract
- The European Spallation Source Neutrino Super Beam (ESSνSB) is a proposed neutrino oscillation experiment to be held in Lund and which takes advantage of the ESS linac firstly designed to study spallation neutrons. Here we study the capability of this facility to discover the yet unknown parameters in the neutrino sector, such as the existence of CP violation. We optimize the physics performance as a function of the baseline and running time of the experiment in each polarity and make an in depth study of the impact of particular systematic errors.
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