Garces, E. A., Miranda, O. G., Tortola, M., & Valle, J. W. F. (2012). Low-energy neutrino-electron scattering as a standard model probe: The potential of LENA as case study. Phys. Rev. D, 85(7), 073006–6pp.
Abstract: Several proposals for studying neutrinos with large detectors are currently under discussion. We suggest that they could provide a precise measurement of the electroweak mixing angle as well as a probe for new physics, such as nonstandard neutrino interactions, and the electroweak gauge structure. We illustrate this explicitly for the case of the LENA proposal, either with an artificial radioactive source or by using the solar neutrino flux.
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Miranda, O. G., Papoulias, D. K., Tortola, M., & Valle, J. W. F. (2020). Probing new neutral gauge bosons with CE nu NS and neutrino-electron scattering. Phys. Rev. D, 101(7), 073005–13pp.
Abstract: The potential for probing extra neutral gauge boson mediators (Z') from low-energy measurements is comprehensively explored. Our study mainly focuses on Z' mediators present in string-inspired E-6 models and left-right symmetry. We estimate the sensitivities of coherent-elastic neutrino-nucleus scattering (CE nu NS) and neutrino-electron scattering experiments. Our results indicate that such low-energy high-intensity measurements can provide a valuable probe, complementary to high-energy collider searches and electroweak precision measurements.
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Miranda, O. G., Tortola, M., & Valle, J. W. F. (2016). New Ambiguity in Probing CP Violation in Neutrino Oscillations. Phys. Rev. Lett., 117(6), 061804–5pp.
Abstract: If neutrinos get mass via the seesaw mechanism the mixing matrix describing neutrino oscillations can be effectively nonunitary. We show that in this case the neutrino appearance probabilities involve a new CP phase phi associated with nonunitarity. This leads to an ambiguity in extracting the “standard” three-neutrino phase delta(CP), which can survive even after neutrino and antineutrino channels are combined. Its existence should be taken into account in the planning of any oscillation experiment aiming at a robust measurement of delta(CP).
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Chatterjee, S. S., Lavignac, S., Miranda, O. G., & Sanchez Garcia, G. (2023). Constraining nonstandard interactions with coherent elastic neutrino-nucleus scattering at the European Spallation Source. Phys. Rev. D, 107(5), 055019–17pp.
Abstract: The European Spallation Source (ESS), currently under construction in Sweden, will provide an intense pulsed neutrino flux allowing for high-statistics measurements of coherent elastic neutrino-nucleus scattering (CEvNS) with advanced nuclear recoil detectors. In this paper, we investigate in detail the possibility of constraining nonstandard neutrino interactions (NSIs) through such precision CEvNS measurements at the ESS, considering the different proposed detection technologies, either alone or in combination. We first study the sensitivity to neutral-current NSI parameters that each detector can reach in 3 years of data taking. We then show that operating two detectors simultaneously can significantly improve the expected sensitivity on flavor-diagonal NSI parameters. Combining the results of two detectors turns out to be even more useful when two NSI parameters are assumed to be nonvanishing at a time. In this case, suitably chosen detector combinations can reduce the degeneracies between some pairs of NSI parameters to a small region of the parameter space.
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Escrihuela, F. J., Forero, D. V., Miranda, O. G., Tortola, M., & Valle, J. W. F. (2015). On the description of nonunitary neutrino mixing. Phys. Rev. D, 92(5), 053009–16pp.
Abstract: Neutrino oscillations are well established and the relevant parameters determined with good precision, except for the CP phase, in terms of a unitary lepton mixing matrix. Seesaw extensions of the Standard Model predict unitarity deviations due to the admixture of heavy isosinglet neutrinos. We provide a complete description of the unitarity and universality deviations in the light-neutrino sector. Neutrino oscillation experiments involving electron or muon neutrinos and antineutrinos are fully described in terms of just three new real parameters and a new CP phase, in addition to the ones describing oscillations with unitary mixing. Using this formalism we describe the implications of nonunitarity for neutrino oscillations and summarize the model-independent constraints on heavy-neutrino couplings that arise from current experiments.
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Kosmas, T. S., Miranda, O. G., Papoulias, D. K., Tortola, M., & Valle, J. W. F. (2015). Probing neutrino magnetic moments at the Spallation Neutron Source facility. Phys. Rev. D, 92(1), 013011–12pp.
Abstract: Majorana neutrino electromagnetic properties are studied through neutral current coherent neutrinonucleus scattering. We focus on the potential of the recently planned COHERENT experiment at the Spallation Neutron Source to probe muon-neutrino magnetic moments. The resulting sensitivities are determined on the basis of chi(2) analysis employing realistic nuclear structure calculations in the context of the quasiparticle random phase approximation. We find that they can improve existing limits by half an order of magnitude. In addition, we show that these facilities allow for standard model precision tests in the low energy regime, with a competitive determination of the weak mixing angle. Finally, they also offer the capability to probe other electromagnetic neutrino properties, such as the neutrino charge radius. We illustrate our results for various choices of experimental setup and target material.
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Celestino-Ramirez, J. M., Escrihuela, F. J., Flores, L. J., & Miranda, O. G. (2024). Testing the nonunitarity of the leptonic mixing matrix at FASERv and FASERv2. Phys. Rev. D, 109(1), L011705–6pp.
Abstract: The FASERv experiment has detected the first neutrino events coming from LHC. Near future highstatistic neutrino samples will allow us to search for new physics within the neutrino sector. Motivated by the forthcoming promising FASERv neutrino data, and its successor, FASERv2, we study its potential for testing the unitarity of the neutrino lepton mixing matrix. Although it would be challenging for FASERv and FASERv2 to have strong constraints on this kind of new physics, we discuss its role in contributing to a future improved global analysis.
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Kosmas, T. S., Miranda, O. G., Papoulias, D. K., Tortola, M., & Valle, J. W. F. (2015). Sensitivities to neutrino electromagnetic properties at the TEXONO experiment. Phys. Lett. B, 750, 459–465.
Abstract: The possibility of measuring neutral-current coherent elastic neutrino nucleus scattering (CENNS) at the TEXONO experiment has opened high expectations towards probing exotic neutrino properties. Focusing on low threshold Germanium-based targets with kg-scale mass, we find a remarkable efficiency not only for detecting CENNS events due to the weak interaction, but also for probing novel electromagnetic neutrino interactions. Specifically, we demonstrate that such experiments are complementary in performing precision Standard Model tests as well as in shedding light on sub-leading effects due to neutrino magnetic moment and neutrino charge radius. This work employs realistic nuclear structure calculations based on the quasi-particle random phase approximation (QRPA) and takes into consideration the crucial quenching effect corrections. Such a treatment, in conjunction with a simple statistical analysis, shows that the attainable sensitivities are improved by one order of magnitude as compared to previous studies.
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Cañas, B. C., Garces, E. A., Miranda, O. G., Tortola, M., & Valle, J. W. F. (2016). The weak mixing angle from low energy neutrino measurements: A global update. Phys. Lett. B, 761, 450–455.
Abstract: Taking into account recent theoretical and experimental inputs on reactor fluxes we reconsider the determination of the weak mixing angle from low energy experiments. We perform a global analysis to all available neutrino-electron scattering data from reactor antineutrino experiments, obtaining sin(2) theta(W) = 0.252 +/- 0.030. We discuss the impact of the new theoretical prediction for the neutrino spectrum, the new measurement of the reactor antineutrino spectrum by the Daya Bay collaboration, as well as the effect of radiative corrections. We also reanalyze the measurements of the nu(e) – e cross section at accelerator experiments including radiative corrections. By combining reactor and accelerator data we obtain an improved determination for the weak mixing angle, sin(2) theta(W) = 0.254 +/- 0.024.
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Miranda, O. G., & Valle, J. W. F. (2016). Neutrino oscillations and the seesaw origin of neutrino mass. Nucl. Phys. B, 908, 436–455.
Abstract: The historical discovery of neutrino oscillations using solar and atmospheric neutrinos, and subsequent accelerator and reactor studies, has brought neutrino physics to the precision era. We note that CP effects in oscillation phenomena could be difficult to extract in the presence of unitarity violation. As a result upcoming dedicated leptonic CP violation studies should take into account the non-unitarity of the lepton mixing matrix. Restricting non-unitarity will shed light on the seesaw scale, and thereby guide us towards the new physics responsible for neutrino mass generation.
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