The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Thomas Schwetz - One of the best experts on this subject based on the ideXlab platform.
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updated global analysis of Neutrino Oscillations in the presence of ev scale sterile Neutrinos
arXiv: High Energy Physics - Phenomenology, 2018Co-Authors: Mona Dentler, Michele Maltoni, Joachim Kopp, P. A. N. Machado, Alvaro Hernandezcabezudo, Ivan Martinezsoler, Thomas SchwetzAbstract:We discuss the possibility to explain the anomalies in short-baseline Neutrino oscillation experiments in terms of sterile Neutrinos. We work in a 3+1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile Neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the $\nu_e$ disappearance channel favour sterile Neutrino Oscillations at the $3\sigma$ level with $\Delta m^2_{41} \approx 1.3$ eV$^2$ and $|U_{e4}| \approx 0.1$, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the $\nu_e$ appearance channel (dominated by LSND) are in strong tension with improved bounds on $\nu_\mu$ disappearance, mostly driven by MINOS+ and IceCube. Under the sterile Neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than $2.6\times 10^{-6}$. Therefore, an explanation of the LSND anomaly in terms of sterile Neutrino Oscillations in the 3+1 scenario is excluded at the $4.7\sigma$ level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor Neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths $|U_{\alpha 4}|$ ($\alpha = e,\mu,\tau$) of active Neutrinos with a fourth Neutrino mass state in the eV range.
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updated global analysis of Neutrino Oscillations in the presence of ev scale sterile Neutrinos
Journal of High Energy Physics, 2018Co-Authors: Mona Dentler, Michele Maltoni, Joachim Kopp, P. A. N. Machado, Alvaro Hernandezcabezudo, Ivan Martinezsoler, Thomas SchwetzAbstract:We discuss the possibility to explain the anomalies in short-baseline Neutrino oscillation experiments in terms of sterile Neutrinos. We work in a 3 + 1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile Neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the νe disappearance channel favour sterile Neutrino Oscillations at the 3σ level with Δm 41 2 ≈ 1.3 eV2 and |Ue4| ≈ 0.1, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the νe appearance channel (dominated by LSND) are in strong tension with improved bounds on νμ disappearance, mostly driven by MINOS+ and IceCube. Under the sterile Neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than 2.6 × 10−6. Therefore, an explanation of the LSND anomaly in terms of sterile Neutrino Oscillations in the 3 + 1 scenario is excluded at the 4.7σ level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor Neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths |Uα4| (α = e, μ, τ ) of active Neutrinos with a fourth Neutrino mass state in the eV range.
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sterile Neutrino Oscillations the global picture
Journal of High Energy Physics, 2013Co-Authors: Joachim Kopp, Michele Maltoni, P. A. N. Machado, Thomas SchwetzAbstract:Neutrino Oscillations involving eV-scale Neutrino mass states are investigated in the context of global Neutrino oscillation data including short and long-baseline ac- celerator, reactor, and radioactive source experiments, as well as atmospheric and solar Neutrinos. We consider sterile Neutrino mass schemes involving one or two mass-squared dierences at the eV 2 scale denoted by 3+1, 3+2, and 1+3+1. We discuss the hints for
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sterile Neutrino Oscillations the global picture
arXiv: High Energy Physics - Phenomenology, 2013Co-Authors: Joachim Kopp, Michele Maltoni, P. A. N. Machado, Thomas SchwetzAbstract:Neutrino Oscillations involving eV-scale Neutrino mass states are investigated in the context of global Neutrino oscillation data including short and long-baseline accelerator, reactor, and radioactive source experiments, as well as atmospheric and solar Neutrinos. We consider sterile Neutrino mass schemes involving one or two mass-squared differences at the eV^2 scale denoted by 3+1, 3+2, and 1+3+1. We discuss the hints for eV-scale Neutrinos from nu_e disappearance (reactor and Gallium anomalies) and nu_mu->nu_e appearance (LSND and MiniBooNE) searches, and we present constraints on sterile Neutrino mixing from nu_mu and neutral-current disappearance data. An explanation of all hints in terms of Oscillations suffers from severe tension between appearance and disappearance data. The best compatibility is obtained in the 1+3+1 scheme with a p-value of 0.2% and exceedingly worse compatibilities in the 3+1 and 3+2 schemes.
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sterile Neutrino Oscillations after first miniboone results
Physical Review D, 2007Co-Authors: Michele Maltoni, Thomas SchwetzAbstract:In view of the recent results from the MiniBooNE experiment we revisit the global Neutrino oscillation fit to short-baseline Neutrino data by adding one or two sterile Neutrinos with eV-scale masses to the three standard model Neutrinos, and for the first time we consider also the global fit with three sterile Neutrinos. Four-Neutrino Oscillations of the (3+1) type have been only marginally allowed before the recent MiniBooNE results, and become even more disfavored with the new data (at the level of 4cr). In the framework of so-called (3 + 2) five-Neutrino mass schemes we find severe tension between appearance and disappearance experiments at the level of more than 3cr, and hence no satisfactory fit to the global data is possible in (3 + 2) schemes. This tension remains also when a third sterile Neutrino is added, and the quality of the global fit does not improve significantly in a (3 + 3) scheme. It should be noted, however, that in models with more than one sterile Neutrino the MiniBooNE results are in perfect agreement with the appearance evidence reported by the LSND Collaboration, thanks to the possibility of CP violation available in such oscillation schemes. Furthermore, if disappearance data are not taken into account (3 + 2) Oscillations provide an excellent fit to the full MiniBooNE spectrum including the event excess at low energies.
M Laveder - One of the best experts on this subject based on the ideXlab platform.
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reactor fuel fraction information on the antiNeutrino anomaly
Journal of High Energy Physics, 2017Co-Authors: C Giunti, M Laveder, B R LittlejohnAbstract:We analyzed the evolution data of the Daya Bay reactor Neutrino experiment in terms of short-baseline active-sterile Neutrino Oscillations taking into account the theoretical uncertainties of the reactor antiNeutrino fluxes. We found that Oscillations are disfavored at 2.6σ with respect to a suppression of the 235U reactor antiNeutrino flux and at 2.5σ with respect to variations of the 235U and 239Pu fluxes. On the other hand, the analysis of the rates of the short-baseline reactor Neutrino experiments favor active-sterile Neutrino Oscillations and disfavor the suppression of the 235U flux at 3.1σ and variations of the 235U and 239Pu fluxes at 2.8σ. We also found that both the Daya Bay evolution data and the global rate data are well-fitted with composite hypotheses including variations of the 235U or 239Pu fluxes in addition to active-sterile Neutrino Oscillations. A combined analysis of the Daya Bay evolution data and the global rate data shows a slight preference for Oscillations with respect to variations of the 235U and 239Pu fluxes. However, the best fits of the combined data are given by the composite models, with a preference for the model with an enhancement of the 239Pu flux and relatively large Oscillations.
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reactor fuel fraction information on the antiNeutrino anomaly
Journal of High Energy Physics, 2017Co-Authors: C Giunti, M Laveder, B R LittlejohnAbstract:We analyzed the evolution data of the Daya Bay reactor Neutrino experiment in terms of short-baseline active-sterile Neutrino Oscillations taking into account the theoretical uncertainties of the reactor antiNeutrino fluxes. We found that Oscillations are disfavored at $2.6\sigma$ with respect to a suppression of the $^{235}\text{U}$ reactor antiNeutrino flux and at $2.5\sigma$ with respect to variations of the $^{235}\text{U}$ and $^{239}\text{Pu}$ fluxes. On the other hand, the analysis of the rates of the short-baseline reactor Neutrino experiments favor active-sterile Neutrino Oscillations and disfavor the suppression of the $^{235}\text{U}$ flux at $3.1\sigma$ and variations of the $^{235}\text{U}$ and $^{239}\text{Pu}$ fluxes at $2.8\sigma$. We also found that both the Daya Bay evolution data and the global rate data are well-fitted with composite hypotheses including variations of the $^{235}\text{U}$ or $^{239}\text{Pu}$ fluxes in addition to active-sterile Neutrino Oscillations. A combined analysis of the Daya Bay evolution data and the global rate data shows a slight preference for Oscillations with respect to variations of the $^{235}\text{U}$ and $^{239}\text{Pu}$ fluxes. However, the best fits of the combined data are given by the composite models, with a preference for the model with an enhancement of the $^{239}\text{Pu}$ flux and relatively large Oscillations.
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updated global 3 1 analysis of short baseline Neutrino Oscillations
arXiv: High Energy Physics - Phenomenology, 2017Co-Authors: S Gariazzo, C Giunti, M LavederAbstract:We present the results of an updated fit of short-baseline Neutrino oscillation data in the framework of 3+1 active-sterile Neutrino mixing. We first consider $\nu_e$ and $\bar\nu_e$ disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactor $\bar\nu_e$ spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of $|U_{e4}|^2$. The beta-decay constraints allow us to limit the oscillation length between about 2 cm and 7 m at $3\sigma$ for Neutrinos with an energy of 1 MeV. We then consider the global fit of the data in the light of the LSND anomaly, taking into account the constraints from $\nu_e$ and $\nu_\mu$ disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on $|U_{e4}|^2$ and the MINOS and IceCube constraints on $|U_{\mu4}|^2$ lead to an unacceptable appearance-disappearance tension which becomes tolerable only in a pragmatic fit which neglects the MiniBooNE low-energy anomaly. The minimization of the global $\chi^2$ in the space of the four mixing parameters $\Delta{m}^2_{41}$, $|U_{e4}|^2$, $|U_{\mu4}|^2$, and $|U_{\tau4}|^2$ leads to three allowed regions with narrow $\Delta{m}^{2}_{41}$ widths at $ \Delta m^2_{41} \approx 1.7 $ (best-fit), 1.3 (at $2\sigma$), 2.4 (at $3\sigma$) eV$^2$. The restrictions of the allowed regions of the mixing parameters with respect to our previous global fits are mainly due to the NEOS constraints. We present a comparison of the allowed regions of the mixing parameters with the sensitivities of ongoing experiments, which show that it is likely that these experiments will determine in a definitive way if the reactor, Gallium and LSND anomalies are due to active-sterile Neutrino Oscillations or not.
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updated global 3 1 analysis of short baseline Neutrino Oscillations
Journal of High Energy Physics, 2017Co-Authors: S Gariazzo, C Giunti, M LavederAbstract:We present the results of an updated fit of short-baseline Neutrino oscillation data in the framework of 3+1 active-sterile Neutrino mixing. We first consider ν e and $$ {\overline{\nu}}_e $$ disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactor $$ {\overline{\nu}}_e $$ spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of |U e4|2. The β-decay constraints of the Mainz and Troitsk experiments allow us to limit the oscillation length between about 2 cm and 7 m at 3σ for Neutrinos with an energy of 1 MeV. The corresponding Oscillations can be discovered in a model-independent way in ongoing reactor and source experiments by measuring ν e and $$ {\overline{\nu}}_e $$ disappearance as a function of distance. We then consider the global fit of the data on short-baseline $$ {}_{\nu_{\mu}}^{\left(-\right)}{\to}_{\nu_e}^{\left(-\right)} $$ transitions in the light of the LSND anomaly, taking into account the constraints from $$ {}_{\nu_e}^{\left(-\right)} $$ and $$ {}_{\nu_{\mu}}^{\left(-\right)} $$ disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on |U e4|2 and the MINOS and IceCube constraints on |U μ4|2 lead to an unacceptable appearance-disappearance tension which becomes tolerable only in a pragmatic fit which neglects the MiniBooNE low-energy anomaly. The minimization of the global χ 2 in the space of the four mixing parameters Δm 41 2 , |U e4|2, |U μ4|2, and |U τ4|2 leads to three allowed regions with narrow Δm 41 2 widths at Δm 41 2 ≈ 1.7 (best-fit), 1.3 (at 2σ), 2.4 (at 3σ) eV2. The effective amplitude of short-baseline $$ {}_{\nu_{\mu}}^{\left(-\right)}{\to}_{\nu_e}^{\left(-\right)} $$ Oscillations is limited by 0.00048 ≲ sin2 2ϑ eμ ≲ 0.0020 at 3σ. The restrictions of the allowed regions of the mixing parameters with respect to our previous global fits are mainly due to the NEOS constraints. We present a comparison of the allowed regions of the mixing parameters with the sensitivities of ongoing experiments, which show that it is likely that these experiments will determine in a definitive way if the reactor, Gallium and LSND anomalies are due to active-sterile Neutrino Oscillations or not.
Michele Maltoni - One of the best experts on this subject based on the ideXlab platform.
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updated global analysis of Neutrino Oscillations in the presence of ev scale sterile Neutrinos
arXiv: High Energy Physics - Phenomenology, 2018Co-Authors: Mona Dentler, Michele Maltoni, Joachim Kopp, P. A. N. Machado, Alvaro Hernandezcabezudo, Ivan Martinezsoler, Thomas SchwetzAbstract:We discuss the possibility to explain the anomalies in short-baseline Neutrino oscillation experiments in terms of sterile Neutrinos. We work in a 3+1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile Neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the $\nu_e$ disappearance channel favour sterile Neutrino Oscillations at the $3\sigma$ level with $\Delta m^2_{41} \approx 1.3$ eV$^2$ and $|U_{e4}| \approx 0.1$, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the $\nu_e$ appearance channel (dominated by LSND) are in strong tension with improved bounds on $\nu_\mu$ disappearance, mostly driven by MINOS+ and IceCube. Under the sterile Neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than $2.6\times 10^{-6}$. Therefore, an explanation of the LSND anomaly in terms of sterile Neutrino Oscillations in the 3+1 scenario is excluded at the $4.7\sigma$ level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor Neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths $|U_{\alpha 4}|$ ($\alpha = e,\mu,\tau$) of active Neutrinos with a fourth Neutrino mass state in the eV range.
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updated global analysis of Neutrino Oscillations in the presence of ev scale sterile Neutrinos
Journal of High Energy Physics, 2018Co-Authors: Mona Dentler, Michele Maltoni, Joachim Kopp, P. A. N. Machado, Alvaro Hernandezcabezudo, Ivan Martinezsoler, Thomas SchwetzAbstract:We discuss the possibility to explain the anomalies in short-baseline Neutrino oscillation experiments in terms of sterile Neutrinos. We work in a 3 + 1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile Neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the νe disappearance channel favour sterile Neutrino Oscillations at the 3σ level with Δm 41 2 ≈ 1.3 eV2 and |Ue4| ≈ 0.1, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the νe appearance channel (dominated by LSND) are in strong tension with improved bounds on νμ disappearance, mostly driven by MINOS+ and IceCube. Under the sterile Neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than 2.6 × 10−6. Therefore, an explanation of the LSND anomaly in terms of sterile Neutrino Oscillations in the 3 + 1 scenario is excluded at the 4.7σ level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor Neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths |Uα4| (α = e, μ, τ ) of active Neutrinos with a fourth Neutrino mass state in the eV range.
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sterile Neutrino Oscillations the global picture
Journal of High Energy Physics, 2013Co-Authors: Joachim Kopp, Michele Maltoni, P. A. N. Machado, Thomas SchwetzAbstract:Neutrino Oscillations involving eV-scale Neutrino mass states are investigated in the context of global Neutrino oscillation data including short and long-baseline ac- celerator, reactor, and radioactive source experiments, as well as atmospheric and solar Neutrinos. We consider sterile Neutrino mass schemes involving one or two mass-squared dierences at the eV 2 scale denoted by 3+1, 3+2, and 1+3+1. We discuss the hints for
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sterile Neutrino Oscillations the global picture
arXiv: High Energy Physics - Phenomenology, 2013Co-Authors: Joachim Kopp, Michele Maltoni, P. A. N. Machado, Thomas SchwetzAbstract:Neutrino Oscillations involving eV-scale Neutrino mass states are investigated in the context of global Neutrino oscillation data including short and long-baseline accelerator, reactor, and radioactive source experiments, as well as atmospheric and solar Neutrinos. We consider sterile Neutrino mass schemes involving one or two mass-squared differences at the eV^2 scale denoted by 3+1, 3+2, and 1+3+1. We discuss the hints for eV-scale Neutrinos from nu_e disappearance (reactor and Gallium anomalies) and nu_mu->nu_e appearance (LSND and MiniBooNE) searches, and we present constraints on sterile Neutrino mixing from nu_mu and neutral-current disappearance data. An explanation of all hints in terms of Oscillations suffers from severe tension between appearance and disappearance data. The best compatibility is obtained in the 1+3+1 scheme with a p-value of 0.2% and exceedingly worse compatibilities in the 3+1 and 3+2 schemes.
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sterile Neutrino Oscillations after first miniboone results
Physical Review D, 2007Co-Authors: Michele Maltoni, Thomas SchwetzAbstract:In view of the recent results from the MiniBooNE experiment we revisit the global Neutrino oscillation fit to short-baseline Neutrino data by adding one or two sterile Neutrinos with eV-scale masses to the three standard model Neutrinos, and for the first time we consider also the global fit with three sterile Neutrinos. Four-Neutrino Oscillations of the (3+1) type have been only marginally allowed before the recent MiniBooNE results, and become even more disfavored with the new data (at the level of 4cr). In the framework of so-called (3 + 2) five-Neutrino mass schemes we find severe tension between appearance and disappearance experiments at the level of more than 3cr, and hence no satisfactory fit to the global data is possible in (3 + 2) schemes. This tension remains also when a third sterile Neutrino is added, and the quality of the global fit does not improve significantly in a (3 + 3) scheme. It should be noted, however, that in models with more than one sterile Neutrino the MiniBooNE results are in perfect agreement with the appearance evidence reported by the LSND Collaboration, thanks to the possibility of CP violation available in such oscillation schemes. Furthermore, if disappearance data are not taken into account (3 + 2) Oscillations provide an excellent fit to the full MiniBooNE spectrum including the event excess at low energies.
J W F Valle - One of the best experts on this subject based on the ideXlab platform.
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Neutrino Oscillations refitted
Physical Review D, 2014Co-Authors: D V Forero, Mariam Tortola, J W F ValleAbstract:Here we update our previous global fit of Neutrino Oscillations by including the recent results which have appeared since the Neutrino-2012 conference. These include the measurements of reactor anti-Neutrino disappearance reported by Daya Bay and RENO, together with latest T2K and MINOS data including both disappearance and appearance channels. We also include the revised results from the third solar phase of Super-Kamiokande, SK-III, as well as new solar results from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred global determination of the atmospheric angle $\theta_{23}$ is consistent with maximal mixing. We also determine the impact of the new data upon all the other Neutrino oscillation parameters with emphasis on the increasing sensitivity to the CP phase, thanks to the interplay between accelerator and reactor data. In the appendix we present the updated results obtained after the inclusion of new reactor data presented at the Neutrino 2014 conference. We discuss their impact on the global Neutrino analysis.
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Neutrino Oscillations refitted
Physical Review D, 2014Co-Authors: D V Forero, Mariam Tortola, J W F ValleAbstract:Here, we update our previous global fit of Neutrino Oscillations by including the recent results that have appeared since the Neutrino 2012 conference. These include the measurements of reactor antiNeutrino disappearance reported by Daya Bay and RENO, together with latest T2K and MINOS data including both disappearance and appearance channels. We also include the revised results from the third solar phase of Super-Kamiokande, SK-III, as well as new solar results from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred global determination of the atmospheric angle ${\ensuremath{\theta}}_{23}$ is consistent with maximal mixing. We also determine the impact of the new data upon all the other Neutrino oscillation parameters with an emphasis on the increasing sensitivity to the $CP$ phase, thanks to the interplay between accelerator and reactor data. In the Appendix, we present the updated results obtained after the inclusion of new reactor data presented at the Neutrino 2014 conference. We discuss their impact on the global Neutrino analysis.
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cp violation and Neutrino Oscillations
arXiv: High Energy Physics - Phenomenology, 2007Co-Authors: Hiroshi Nunokawa, Stephen J Parke, J W F ValleAbstract:We review the basic mechanisms of Neutrino mass generation and the corresponding structure of the lepton mixing matrix. We summarize the status of three-Neutrino oscillation parameters as determined from current observations, using state-of-the-art solar and atmospheric Neutrino fluxes, as well as latest experimental data as of September 2007. We also comment on recent attempts to account for these results and to understand flavour from first principles. We discuss extensively the prospects for probing the strength of CP violation in two near term accelerator Neutrino oscillation experiments, T2K and NOvA, as well as possible extensions such as T2KK and a second large off-axis detector near the NOvA detector. We also briefly discuss the possibility of probing the effect of Majorana phases in future Neutrinoless double beta decay searches and discuss other implications of leptonic CP violation such as leptogenesis. Finally we comment on the issue of robustness of the current oscillation interpretation and possible ways of probing for non-standard Neutrino interactions in precision oscillation studies.
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are solar Neutrino Oscillations robust
Journal of High Energy Physics, 2006Co-Authors: O G Miranda, Mariam Tortola, J W F ValleAbstract:The robustness of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar Neutrino data is considered in a more general framework where non-standard Neutrino interactions (NSI) are present. Such interactions may be regarded as a generic feature of models of Neutrino mass. The 766.3 ton-yr data sample of the KamLAND collaboration are included in the analysis, paying attention to the background from the reaction 13C(?,n)16O. Similarly, the latest solar Neutrino fluxes from the SNO collaboration are included. In addition to the solution which holds in the absence of NSI (LMA-I) there is a ``dark-side'' solution (LMA-D) with sin 2?? = 0.70, essentially degenerate with the former, and another light-side solution (LMA-0) allowed only at 97% CL. More precise KamLAND reactor measurements will not resolve the ambiguity in the determination of the solar Neutrino mixing angle ??, as they are expected to constrain mainly ?m2sol. We comment on the complementary role of atmospheric, laboratory (e.g. CHARM) and future solar Neutrino experiments in lifting the degeneracy between the LMA-I and LMA-D solutions. In particular, we show how the LMA-D solution induced by the simplest NSI between Neutrinos and down-type-quarks-only is in conflict with the combination of current atmospheric data and data of the CHARM experiment. We also mention that establishing the issue of robustness of the oscillation picture in the most general case will require further experiments, such as those involving low energy solar Neutrinos.
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status of global fits to Neutrino Oscillations
Nuclear Physics B - Proceedings Supplements, 2005Co-Authors: Michele Maltoni, Thomas Schwetz, Mariam Tortola, J W F ValleAbstract:We review the present status of global analyses of Neutrino Oscillations, taking into account the most recent Neutrino data including the latest KamLAND and K2K updates presented at Neutrino 2004, as well as state-of-the- art solar and atmospheric Neutrino flux calculations. We give the two-Neutrino solar + KamLAND results, and the two-Neutrino atmospheric + K2K oscillation regions, discussing in each case the robustness of the oscillation interpretation against departures from the Standard Solar Model and the possible existence of non-standard Neutrino physics. Furthermore, we give the best-fit values and allowed ranges of the three-flavour oscillation parameters from the current worlds' global Neutrino data sample and discuss in detail the status of the small parameters α ≡ �m 2 /�m 2M as well as sin 2 θ13, which characterize the strength of CP violating effects in Neutrino Oscillations. We also update the degree of rejection of four-Neutrino interpretations of the LSND evidence in view of the most recent developments.
Joachim Kopp - One of the best experts on this subject based on the ideXlab platform.
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updated global analysis of Neutrino Oscillations in the presence of ev scale sterile Neutrinos
Journal of High Energy Physics, 2018Co-Authors: Mona Dentler, Michele Maltoni, Joachim Kopp, P. A. N. Machado, Alvaro Hernandezcabezudo, Ivan Martinezsoler, Thomas SchwetzAbstract:We discuss the possibility to explain the anomalies in short-baseline Neutrino oscillation experiments in terms of sterile Neutrinos. We work in a 3 + 1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile Neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the νe disappearance channel favour sterile Neutrino Oscillations at the 3σ level with Δm 41 2 ≈ 1.3 eV2 and |Ue4| ≈ 0.1, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the νe appearance channel (dominated by LSND) are in strong tension with improved bounds on νμ disappearance, mostly driven by MINOS+ and IceCube. Under the sterile Neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than 2.6 × 10−6. Therefore, an explanation of the LSND anomaly in terms of sterile Neutrino Oscillations in the 3 + 1 scenario is excluded at the 4.7σ level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor Neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths |Uα4| (α = e, μ, τ ) of active Neutrinos with a fourth Neutrino mass state in the eV range.
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updated global analysis of Neutrino Oscillations in the presence of ev scale sterile Neutrinos
arXiv: High Energy Physics - Phenomenology, 2018Co-Authors: Mona Dentler, Michele Maltoni, Joachim Kopp, P. A. N. Machado, Alvaro Hernandezcabezudo, Ivan Martinezsoler, Thomas SchwetzAbstract:We discuss the possibility to explain the anomalies in short-baseline Neutrino oscillation experiments in terms of sterile Neutrinos. We work in a 3+1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile Neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the $\nu_e$ disappearance channel favour sterile Neutrino Oscillations at the $3\sigma$ level with $\Delta m^2_{41} \approx 1.3$ eV$^2$ and $|U_{e4}| \approx 0.1$, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies in the $\nu_e$ appearance channel (dominated by LSND) are in strong tension with improved bounds on $\nu_\mu$ disappearance, mostly driven by MINOS+ and IceCube. Under the sterile Neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than $2.6\times 10^{-6}$. Therefore, an explanation of the LSND anomaly in terms of sterile Neutrino Oscillations in the 3+1 scenario is excluded at the $4.7\sigma$ level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor Neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths $|U_{\alpha 4}|$ ($\alpha = e,\mu,\tau$) of active Neutrinos with a fourth Neutrino mass state in the eV range.
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Collective Neutrino Oscillations and Neutrino wave packets
arXiv: High Energy Physics - Phenomenology, 2017Co-Authors: Evgeny Kh Akhmedov, Joachim Kopp, Manfred LindnerAbstract:Effects of decoherence by wave packet separation on collective Neutrino Oscillations in dense Neutrino gases are considered. We estimate the length of the wave packets of Neutrinos produced in core collapse supernovae and the expected Neutrino coherence length, and then proceed to consider the decoherence effects within the density matrix formalism of Neutrino flavour transitions. First, we demonstrate that for Neutrino Oscillations in vacuum the decoherence effects are described by a damping term in the equation of motion of the density matrix of a Neutrino as a whole (as contrasted to that of the fixed-momentum components of the Neutrino density matrix). Next, we consider Neutrino Oscillations in ordinary matter and dense Neutrino backgrounds, both in the adiabatic and non-adiabatic regimes. In the latter case we study two specific models of adiabaticity violation -- one with short-term and another with extended non-adiabaticity. It is demonstrated that, while in the adiabatic case a damping term is present in the equation of motion of the Neutrino density matrix (just like in the vacuum oscillation case), no such term in general appears in the non-adiabatic regime.
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sterile Neutrino Oscillations the global picture
Journal of High Energy Physics, 2013Co-Authors: Joachim Kopp, Michele Maltoni, P. A. N. Machado, Thomas SchwetzAbstract:Neutrino Oscillations involving eV-scale Neutrino mass states are investigated in the context of global Neutrino oscillation data including short and long-baseline ac- celerator, reactor, and radioactive source experiments, as well as atmospheric and solar Neutrinos. We consider sterile Neutrino mass schemes involving one or two mass-squared dierences at the eV 2 scale denoted by 3+1, 3+2, and 1+3+1. We discuss the hints for
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sterile Neutrino Oscillations the global picture
arXiv: High Energy Physics - Phenomenology, 2013Co-Authors: Joachim Kopp, Michele Maltoni, P. A. N. Machado, Thomas SchwetzAbstract:Neutrino Oscillations involving eV-scale Neutrino mass states are investigated in the context of global Neutrino oscillation data including short and long-baseline accelerator, reactor, and radioactive source experiments, as well as atmospheric and solar Neutrinos. We consider sterile Neutrino mass schemes involving one or two mass-squared differences at the eV^2 scale denoted by 3+1, 3+2, and 1+3+1. We discuss the hints for eV-scale Neutrinos from nu_e disappearance (reactor and Gallium anomalies) and nu_mu->nu_e appearance (LSND and MiniBooNE) searches, and we present constraints on sterile Neutrino mixing from nu_mu and neutral-current disappearance data. An explanation of all hints in terms of Oscillations suffers from severe tension between appearance and disappearance data. The best compatibility is obtained in the 1+3+1 scheme with a p-value of 0.2% and exceedingly worse compatibilities in the 3+1 and 3+2 schemes.