Upper limits for neutrino oscillations<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mover><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover><mml:mrow><mml:mi>μ</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo>→</mml:mo><mml:mrow><mml:msub><mml:mover><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover><mml:mrow><mml:mi>e</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>from m

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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.

Section: A Current Constraints On Sterile Neutrinosmentioning

confidence: 89%

Non-unitarity, sterile neutrinos, and non-standard neutrino interactions

Blennow

Coloma

Fernández‐Martínez

et al. 2017

202

310

“…The observation of an excess ofν e events at 3.8σ at the LSND experiment [2] could be explained by introducing one or more additional sterile neutrino states, with an additional mass squared difference of ∆m 2 41 ∼ O(eV 2 ) in order to allow for ν µ → ν e oscillations in the observed range of L/E. However, KARMEN did not observe any signal for similar values of L/E [3]. The dedicated MiniBooNE experiment [4][5][6] has to this day not confirmed or disproved the LSND anomaly.…”

Section: Introductionmentioning

confidence: 99%

Searching for sterile neutrinos at the ESSνSB

Blennow

Coloma

Fernández‐Martínez

2014

Abstract:The ESSνSB project is a proposed neutrino oscillation experiment based on the European Spallation Source with the search for leptonic CP violation as its main aim. In this letter we show that a near detector at around 1 km distance from the beamline is not only very desirable for keeping the systematic errors affecting the CP search under control, but would also provide a significant sensitivity probe for sterile neutrino oscillations in the region of the parameter space favored by the long-standing LSND anomaly. We find that the effective mixing angle θ µe can be probed down to sin 2 (2θ µe ) 2(8) · 10 −3 at 5σ assuming 15% bin-to-bin (un)correlated systematics.

“…The exclusion plot for the parameters of the non-standard ν µ → ν e oscillation, obtained from this analysis using the Bayesian method, is shown. The other limits shown, mostly using frequentist methods, are from KARMEN (ν µ → ν e [28]), BUGEY (ν e disappearance [29]), CHOOZ (ν e disappearance [30]), NOMAD (ν µ → ν e [31]) and ICARUS (ν µ → ν e [10]). The regions corresponding to the positive indications reported by LSND (ν µ → ν e [8]) and MiniBooNE (ν µ → ν e and ν µ → ν e [9]) are also shown.…”

Section: Non-standard Oscillationsmentioning

confidence: 99%

Search for ν μ → ν e oscillations with the OPERA experiment in the CNGS beam

Agafonova¹,

Aleksandrov²,

Anokhina³

et al. 2013

A first result of the search for ν µ → ν e oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of ν e in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters θ new and ∆m 2 new suggested by the LSND and MiniBooNE experiments. For large ∆m 2 new values (>0.1 eV 2 ), the OPERA 90% C.L. upper limit on sin 2 (2θ new ) based on a Bayesian statistical method reaches the value 7.2 × 10 −3 .