Non-standard interactions using the OPERA experiment

The European Physical Journal C, Aug 2008

We investigate the implications of non-standard interactions on neutrino oscillations in the OPERA experiment. In particular, we study the non-standard interaction parameter ε μ τ . We show that the OPERA experiment has a unique opportunity to reduce the allowed region for this parameter compared with other experiments such as the MINOS experiment, mostly due to the higher neutrino energies in the CNGS beam compared to the NuMI beam. We find that OPERA is mainly sensitive to a combination of standard and non-standard parameters and that a resulting anti-resonance effect could suppress the expected number of events. Furthermore, we show that running OPERA for five years each with neutrinos and anti-neutrinos would help in resolving the degeneracy between the standard parameters and ε μ τ . This scenario is significantly better than the scenario with a simple doubling of the statistics by running with neutrinos for ten years.

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Non-standard interactions using the OPERA experiment

Mattias Blennow 2 Davide Meloni 1 Tommy Ohlsson 0 Francesco Terranova 3 Mattias Westerberg 0 0 Department of Theoretical Physics, School of Engineering Sciences, Royal Institute of TechnologyAlbaNova University Center , Roslagstullsbacken 21, 106 91 Stockholm, Sweden 1 Dipartimento di Fisica, Universit di Roma Tre and INFN Sez. di Roma Tre , Via della Vasca Navale 84, 00146 Rome, Italy 2 Max-Planck-Institut fr Physik (Werner-Heisenberg-Institut) , Fhringer Ring 6, 80805 Munich, Germany 3 Laboratori Nazionali di Frascati dell'INFN, Via E. Fermi 40, 00044 Frascati, Italy We investigate the implications of non-standard interactions on neutrino oscillations in the OPERA experiment. In particular, we study the non-standard interaction parameter . We show that the OPERA experiment has a unique opportunity to reduce the allowed region for this parameter compared with other experiments such as the MINOS experiment, mostly due to the higher neutrino energies in the CNGS beam compared to the NuMI beam. We find that OPERA is mainly sensitive to a combination of standard and non-standard parameters and that a resulting anti-resonance effect could suppress the expected number of events. Furthermore, we show that running OPERA for five years each with neutrinos and anti-neutrinos would help in resolving the degeneracy between the standard parameters and . This scenario is significantly better than the scenario with a simple doubling of the statistics by running with neutrinos for ten years. 1 Introduction Neutrino oscillation physics has definitively entered the era of precision measurements of the fundamental neutrino parameters such as the neutrino mass squared differences (i.e., m 231 and m 221) and the leptonic mixing parameters (i.e., 12, 13, 23, and ). In particular, the Super-Kamiokande, SNO, KamLAND, K2K, and MINOS experiments have given valuable information on these parameters [16]. The precision measurements open up the possibility to investigate if neutrino flavor transitions are governed by neutrino oscillations only or if they are, in the next-to-leading order, a combination of neutrino oscillations and some other new physics mechanism. However, to leading order, there exists clear evidence that neutrino oscillations constitute the underlying physical model for neutrino flavor transitions. The next-to-leading order mechanism could e.g. be nonstandard interactions (NSIs), mass varying neutrinos, neutrino decay, neutrino decoherence etc., or some combination thereof. In this work, we will study NSI effects at the OPERA experiment [7], which is an experiment that consists of a massive lead/emulsion target (the OPERA detector) located at LNGS in Gran Sasso, Italy, receiving its neutrino beam, originally consisting almost exclusively of , from CERN in Geneva, Switzerland. The baseline length is approximately 732 km and the CNGS beam has an average neutrino energy of E 17 GeV. The OPERA experiment is especially designed to observe events from the neutrino oscillation channel. In fact, no previous experiment has investigated this channel or observed neutrinos of a different flavor than that originally produced at the source (although the neutral-current measurements at SNO imply that solar e have oscillated into a different flavor). Thus, the OPERA experiment presents a unique opportunity to study the direct appearance of [8]. In this work, we will not try to describe the origin of the NSIs but adopt a purely phenomenological point of view. In particular, NSIs may modify the production, the propagation in matter as well as the detection of the neutrinos. We will concentrate on the simplified scenario in which NSIs only affect the neutrino propagation. Previously, investigations of NSIs that are of importance for this work have been presented in the following papers. In [9], a two-flavor neutrino analysis of the so-called atmospheric neutrino anomaly has been performed, which effectively bounds the NSI parameters in the sector, and , to 0.03 0.02 and | | 0.05 at 99.73% confidence level. Although these bounds may seem quite restrictive, it has been shown that at least the bound on is severely weakened when considering the full three-flavor framework (allowing to be of O(1) or larger, depending on the values of ee and e [10]). As will be shown later in this work, the limit that could be put by the OPERA experiment would be insensitive to whether the two- or three-flavor scenario is studied, simply because of the relatively short baseline. In addition, in [11], the authors have come to the conclusion that it would be possible to observe NSI effects at the OPERA experiment (and the ICARUS experiment) if O(102). Next, in [12], the KamiokaKorea two detector setup has been investigated, which could also give restrictions on the NSI parameters and . Recently, in [13], a study of the OPERA experiment (in combination with the MINOS experiment) has been presented with the conclusion that it is (...truncated)


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Mattias Blennow, Davide Meloni, Tommy Ohlsson. Non-standard interactions using the OPERA experiment, The European Physical Journal C, 2008, pp. 529-536, Volume 56, Issue 4, DOI: 10.1140/epjc/s10052-008-0683-6