When the Fog Lifts: Constraining Light Mediators with CEνNSSignals
Abstract
Parallel talk presented at the XXI International Workshop on Neutrino Telescopes - Padova 29 September - 3 October 2025 (https://agenda.infn.it/event/44606/) Abstract: The recent observation of Coherent Elastic Neutrino–Nucleus Scattering (CEνNS) from solar neutrinos by dark matter direct detection experiments marks the first detection of the so-called “neutrino floor”. Far from being a mere background for dark matter searches, this signal opens a novel window to probe light new physics. In this talk, I will present new constraints on light scalar and vector mediators coupling to neutrinos and quarks, derived from recent data from these experiments. I will show that they already provide competitive — and in some cases leading — bounds in the sub-GeV mass range. I will also discuss subdominant but non-negligible contributions from neutrino–electron scattering and the Migdal effect, which can noticeably impact the detected event rates. These results highlight the growing potential of dark matter detectors as precision neutrino observatories, capable of testing a wide class of light mediator scenarios.
Full text
Pablo Blanco Mas Institute of Theoretical Pysics CSIC/UAM XXI NeuTel - Padova When the Fog Lifts: Constraining Light Mediators with CEνNS Signals Based on: PBM, P. Coloma, G. Herrera, P. Huber, J. Kopp, I. M. Shoemaker, and Z. Tabrizi JHEP 08 (2025) 043, arXiv:2411.14206
Outline of the talk •Introduction: CEvNS and the neutrino fog •Observation of 8B neutrinos in XENON and Panda experiments •Analysis: expected Beyond Standard Model events •Results: novel bounds to CEvNS BSM from DM experiments •Conclusions 2Pablo Blanco Mas – IFT [email protected]
Dark Matter – what is it? •In 1933, F. Zwicky postulates the existence of "dunkel materie" 3Pablo Blanco Mas – IFT [email protected] X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al. •Today, many hints pointing to ~25% of the energy content of the Universe being cold Dark Matter "IAA: Información y Actualidad Astronómica", M. A. Pérez-Torres
DM Direct Detection experiments •DM detection has harnessed a huge experimental effort 4Pablo Blanco Mas – IFT [email protected] S. Giagu, Front. Phys. 7 (2019), 75. doi:10.3389/fphy. 2019.00075 M. Guida, Zenodo (2021). doi:10.5281/z enodo.634758 1
The neutrino floor fog •Neutrinos are an irreducible background once DM experiments get enough sensitivity •Floor or fog? 5Pablo Blanco Mas – IFT [email protected] ? O’Hare, Ciaran A. J., PRL, DOI: 10.1103/PhysRevLett.127.251802. ?
CEvNS – What is it? •Coherent Elastic neutrino-Nucleus scattering •Purely a Standard Model process: ν + A → ν + A •First proposed in 1974, discovered 43 years later! 6Pablo Blanco Mas – IFT [email protected] D.Z. Freedman, PRD (1974) Akimov et al., Science (2017), doi: 10.1126/science.aao0990
CEvNS – What is it? •Coherence condition implies •Maximum recoil energy •Tiny (O(keV)) recoil energies! •Coherent effect •Cross-section is "large" for neutrinos 7Pablo Blanco Mas – IFT [email protected] Scholz, B. (2018). Springer Theses. Springer
New mediators in CEvNS •No signals in collider experiments: window for light BSM •Models for different new light mediators studied (simplified models): Scalar: "Leptophilic" Vector Full models see eg.: 8Pablo Blanco Mas – IFT [email protected] ? S. Karadağ et al. (TEXONO Collaboration), Phys. Rev. D 112 (2025), doi: 10.1103/PhysRevD.112.035038 Y. Farzan, M. Lindner, W. Rodejohann, X.-J. Xu, JHEP doi: 10.1007/JHEP05(2018)06606 6) S. Abbaslu, Y. Farzan, NewPhysB, doi: 10.1016/j.nuclphys b.2025.117070. G.-J. Ding, F. Feruglio, JHEP, doi: 10.1007/JHEP06(20 20)134134)
Seeing the neutrino fog •Recently (July-August 2024), two DM experiments have given hints of the solar neutrino floor, XENONnT and PandaX-4T •Detection of CEvNS from Boron-8 solar neutrinos at 2.73 σ (PandaX-4T) and 2.64 σ (XENONnT) 9Pablo Blanco Mas – IFT [email protected] ? XENON Collaboration, PRL. DOI: 10.1103/PhysRevLett.133.191002. PandaX Collaboration, PRL, DOI: 10.1103/PhysRevLett.133.191001
Seeing beyond the fog – leptophilic scalar •PandaX S2 only (combined analysis extracts EvES) •We include other neutrino fluxes from the Sun 16Pablo Blanco Mas – IFT [email protected] ? PBM et al., JHEP, doi:10.1007/JHEP08(2025)043
Conclusions •We are starting to reach the neutrino fog (bad for DM experimentalists, good for neutrino physicists) •Bounds to light mediators can be derived using neutrino fog data •The bounds are relevant, sometimes better than dedicated experiments •TAKE HOME: Dark Matter direct detection experiments are becoming excellent at catching neutrinos!! 17Pablo Blanco Mas – IFT [email protected] ?
Conclusions •We are starting to reach the neutrino fog (bad for DM experimentalists, good for neutrino physicists) •Bounds to light mediators can be derived using neutrino fog data •The bounds are relevant, sometimes better than dedicated experiments •TAKE HOME: Dark Matter direct detection experiments are becoming excellent at catching neutrinos!! 18Pablo Blanco Mas – IFT [email protected] ?
Backup slides •Poisson likelihood ratio ~ distribution 19Pablo Blanco Mas – IFT [email protected] ?
Seeing beyond the fog – scalar case •The scalar coupling adds events to the total rate 20Pablo Blanco Mas – IFT [email protected] ? P. Blanco-Mas et al., JHEP 08 (2025) 043, arXiv:2411.14206, doi:10.1007/JHEP08(2025)043
Backup slides - plots 21Pablo Blanco Mas – IFT [email protected] ?
Backup slides – quenching factor •Quenching factor transforms NR into the detected rate (usually in terms of ER) •For Xe, uncertain at low E 22Pablo Blanco Mas – IFT [email protected] ? M Szydagis, N Barry, K Kazkaz, J Mock, D Stolp, M Sweany, M Tripathi, S Uvarov, N Walsh, and M Woods, Journal of Instrumentation 6, P10002–P10002 (2011)