De Romeri, V., Martin Lozano, V., & Sanchez Garcia, G. (2024). Neutrino window to scalar leptoquarks: From low energy to colliders. Phys. Rev. D, 109(5), 055014–21pp.
Abstract: Leptoquarks are theorized particles of either scalar or vector nature that couple simultaneously to quarks and leptons. Motivated by recent measurements of coherent elastic neutrino -nucleus scattering, we consider the impact of scalar leptoquarks coupling to neutrinos on a few complementary processes, from low energy to colliders. In particular, we set competitive constraints on the typical mass and coupling of scalar leptoquarks by analyzing recent COHERENT data. We compare these constraints with bounds from atomic parity violation experiments, deep inelastic neutrino -nucleon scattering and collider data. Our results highlight a strong complementarity between different facilities and demonstrate the power of coherent elastic neutrino -nucleus scattering experiments to probe leptoquark masses in the sub-TeV range. Finally, we also present prospects for improving current bounds with future upgrades of the COHERENT detectors and the planned European Spallation Source.
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De Romeri, V., Papoulias, D. K., & Sanchez Garcia, G. (2025). Implications of the first CONUS plus measurement of coherent elastic neutrino-nucleus scattering. Phys. Rev. D, 111(7), 075025–19pp.
Abstract: The CONUS & thorn; collaboration has reported their first observation of coherent elastic neutrino-nucleus scattering (CEvNS). The experiment uses reactor electron antineutrinos and germanium detectors with recoil thresholds as low as 160 eVee. With an exposure of 327 kg x d, the measurement was made with a statistical significance of 3.76. We explore several physics implications of this observation, both within the standard model and in the context of new physics. We focus on a determination of the weak mixing angle, nonstandard and generalized neutrino interactions both with heavy and light mediators, neutrino magnetic moments, and the up-scattering of neutrinos into sterile fermions through the sterile dipole portal and new mediators. Our results highlight the role of reactor-based CEvNS experiments in probing a vast array of neutrino properties and new physics models.
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Mandal, S., Miranda, O. G., Sanchez Garcia, G., Valle, J. W. F., & Xu, X. J. (2022). Toward deconstructing the simplest seesaw mechanism. Phys. Rev. D, 105(9), 095020–32pp.
Abstract: The triplet or type-II seesaw mechanism is the simplest way to endow neutrinos with mass in the Standard Model (SM). Here we review its associated theory and phenomenology, including restrictions from S, T, U parameters, neutrino experiments, charged lepton flavor violation as well as collider searches. We also examine restrictions coming from requiring consistency of electroweak symmetry breaking, i.e., perturbative unitarity and stability of the vacuum. Finally, we discuss novel effects associated to the scalar mediator of neutrino mass generation namely, (i) rare processes, e.g., l(alpha)-> l(beta)gamma decays, at the intensity frontier, and also (ii) four-lepton signatures in colliders at the high-energy frontier. These can be used to probe neutrino properties in an important way, providing a test of the absolute neutrino mass and mass ordering, as well as of the atmospheric octant. They may also provide the first evidence for charged lepton flavor violation in nature. In contrast, neutrino nonstandard interaction strengths are found to lie below current detectability.
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Rossi, R. R., Sanchez Garcia, G., & Tortola, M. (2024). Probing nuclear properties and neutrino physics with current and future CEνNS experiments. Phys. Rev. D, 109(9), 095044–17pp.
Abstract: The recent observation of coherent elastic neutrino-nucleus scattering (CEvNS) with neutrinos from pion decay at rest (N-DAR) sources by the COHERENT Collaboration has raised interest in this process in the search for new physics. Unfortunately, current uncertainties in the determination of nuclear parameters relevant to those processes can hide new physics effects. This is not the case for processes involving lower-energy neutrino sources such as nuclear reactors. Note, however, that a CEvNS measurement with reactor neutrinos depends largely on a (still-missing) precise determination of the quenching factor at very low energies, making its observation more challenging. In the upcoming years, once this signal is confirmed, a combined analysis of N-DAR and reactor CEvNS experiments will be very useful to probe particle and nuclear physics, with a reduced dependence on nuclear uncertainties. In this work, we explore this idea by simultaneously testing the sensitivity of current and future CEvNS experiments to neutrino nonstandard interactions (NSIs) and the neutron root mean square (rms) radius, considering different neutrino sources as well as several detection materials. We show how the interplay between future reactor and accelerator CEvNS experiments can help to get robust constraints on the neutron rms and to break degeneracies between the NSI parameters. Our forecast could be used as a guide to optimize the experimental sensitivity to the parameters under study.
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Chatterjee, S. S., Lavignac, S., Miranda, O. G., & Sanchez Garcia, G. (2024). Exploring the sensitivity to non-standard neutrino interactions of NaI and cryogenic CsI detectors at the Spallation Neutron Source. Phys. Rev. D, 110(9), 095027–18pp.
Abstract: After the first observation of coherent elastic neutrino-nucleus scattering (CEvNS) by the COHERENT Collaboration, many efforts are being made to improve the measurement of this process, making it possible to constrain new physics in the neutrino sector. In this paper, we study the sensitivity to non-standard interactions (NSIs) and generalized neutrino interactions of two experimental setups at the Spallation Neutron Source at Oak Ridge National Laboratory: a NaI detector with characteristics similar to the one that is currently being deployed there and a cryogenic CsI detector proposed at the same facility. We show that a combined analysis of the data from these detectors, whose target nuclei have significantly different proton-to-neutron ratios, could help to partially break the parameter degeneracies arising from the interference between the Standard Model and NSI contributions to the CEvNS cross section, as well as between different NSI parameters. By contrast, only a slight improvement over the current CsI constraints is expected for parameters that do not interfere with the SM contribution.
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