Snowmass white paper: beyond the standard model effects on neutrino flavor

Eur. Phys. J. C (2023) 83:15 https://doi.org/10.1140/epjc/s10052-022-11049-7 Review Snowmass white paper: beyond the standard model effects on neutrino flavor Submitted to the proceedings of the US community study on the future of particle physics (Snowmass 2021) C. A. Argüelles1, G. Barenboim2 , M. Bustamante3 , P. Coloma4,a , P. B. Denton5 , I. Esteban6,7 , Y. Farzan8 , E. Fernández Martínez4,9 , D. V. Forero10,b , A. M. Gago11 , T. Katori12,c , R. Lehnert13,14 , M. Ross-Lonergan15 , A. M. Suliga16,17 , Z. Tabrizi18 , L. Anchordoqui19 , K. Chakraborty20 , J. Conrad21 , A. Das22 , C. S. Fong23 , B. R. Littlejohn24 , M. Maltoni4 , D. Parno25 , J. Spitz26 , J. Tang27 , S. Wissel28 1 Department of Physics and Laboratory for Particle Physics and Cosmology, Harvard University, Cambridge, MA 02138, USA 2 Departament de Física Teòrica and IFIC, Universitat de València-CSIC, 46100 Burjassot, Spain 3 Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark 4 Instituto de Fisica Teórica UAM-CSIC, Universidad Autónoma de Madrid, 28049 Madrid, Spain 5 High Energy Theory Group, Physics Department, Brookhaven National Laboratory, Upton, NY 11973, USA 6 Center for Cosmology and AstroParticle Physics (CCAPP), Ohio State University, Columbus, OH 43210, USA 7 Department of Physics, Ohio State University, Columbus, OH 43210, USA 8 School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran 9 Departamento de Fisica Teórica, Universidad Autónoma de Madrid, 28049 Madrid, Spain 10 Universidad de Medellín, Carrera 87 No 30-65, Medellín, Colombia 11 Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Apartado 1761, Lima, Peru 12 Department of Physics, King’s College London, London WC2R 2LS, UK 13 Department of Physics, Indiana University, Bloomington, IN 47405, USA 14 Indiana University Center for Spacetime Symmetries, Bloomington, IN 47405, USA 15 Department of Physics, Columbia University, New York, NY 10027, USA 16 Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA 17 Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA 18 Department of Physics, Northwestern University, Evanston, IL 60208, USA 19 Lehman College, City University of New York, Bronx, NY 10468, USA 20 Physical Research Laboratory, University Area, Ahmedabad, Gujarat 380009, India 21 Massachusetts Institute of Technology, Cambridge, MA 02139, USA 22 Hokkaido University, Sapporo, Hokkaido 060-0808, Japan 23 Universidade Federal do ABC, Santo André, SP 09210-580, Brazil 24 Illinois Institute of Technology, Chicago, IL 60616, USA 25 Carnegie Mellon University, Pittsburgh, PA 15213, USA 26 University of Michigan, Ann Arbor, MI 48109, USA 27 Sun Yat-sen University, Guangzhou 510275, People’s Republic of China 28 Pennsylvania State University, University Park, State College, PA 16802, USA Received: 11 July 2022 / Accepted: 5 November 2022 © The Author(s) 2023 Abstract Neutrinos are one of the most promising messengers for signals of new physics Beyond the Standard Model (BSM). On the theoretical side, their elusive nature, combined with their unknown mass mechanism, seems to indicate that the neutrino sector is indeed opening a window to new physics. On the experimental side, several long-standing anomalies have been reported in the past decades, providing a strong motivation to thoroughly test the standard threeneutrino oscillation paradigm. In this Snowmass21 white paper, we explore the potential of current and future neutrino experiments to explore BSM effects on neutrino flavor during the next decade. a e-mail: b e-mail: (corresponding author) c e-mail: 0123456789().: V,-vol 123 15 Page 2 of 57 Contents Eur. Phys. J. C (2023) 83:15 4 Summary and outlook . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . Executive summary . . . . . . . . . . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . 2 Theoretical aspects . . . . . . . . . . . . . . . . . . . Executive summary 2.1 New physics from the existence of additional neutrino states . . . . . . . . . . . . . . . . . . . Neutrinos are one of the most promising messengers for sig2.1.1 Neutrino oscillations in presence of heavy nals of new physics Beyond the Standard Model (BSM). On sterile neutrinos . . . . . . . . . . . . . . . the theoretical side, their elusive nature, combined with their 2.1.2 Neutrino oscillations in presence of light unknown mass mechanism, seems to indicate that the neusterile neutrinos . . . . . . . . . . . . . . . trino sector is indeed opening a window to new physics. On 2.1.3 Normalization of the oscillation probability the experimental side, several long-standing anomalies have 2.1.4 Present constraints on non-unitarity parameters been reported in the past decades, providing a strong moti2.1.5 Neutrino oscillations in the presence of vation to thoroughly test the standard three-neutrino oscillalarge extra dimensions (LED) . . . . . . . tion paradigm. This can be done in three main ways. First, 2.2 New interactions in the neutrino sector . . . . . neutrino oscillation experiments are very precise interferom2.2.1 General effective interactions between eters, sensitive to subleading effects from new physics affectneutrinos: the charged-current case . . . . . ing neutrino flavor transitions. On a separate front, neutrino 2.2.2 Neutral-current non-standard neutrino intertelescopes provide a unique avenue to probe BSM effects, actions . . . . . . . . . . . . . . . . . . . given the very long distances traveled by the detected neu2.2.3 Model building aspects: heavy vs light trinos (which range from the Earth radius to several gigamediators . . . . . . . . . . . . . . . . . . parsecs), as well as their ultra-high energies. Finally, astro2.2.4 New neutrino interactions with light mediators physical observations (such as a nearby core-collapse super2.2.5 Effective operators involving extra neunovae) in the upcoming decade will provide invaluable infortrino states . . . . . . . . . . . . . . . . . mation and allow us to test neutrino propagation in extremely 2.2.6 Neutrino interactions with dark matter . . . dense environments. 2.3 Neutrino decay . . . . . . . . . . . . . . . . . . In the past, neutrino physics has been driven by data, from 2.3.1 Theoretical formalism: invisible and visithe postulation of the neutrino by Pauli to the discovery of ble decay . . . . . . . . . . . . . . . . . . neutrino oscillations, which were awarded the Nobel Prize in 2015. While the upcoming generation of oscillation experi2.3.2 Current bounds: invisible and visible decay ments aims to measure the leptonic CP phase and the neutrino 2.3.3 Future perspectives . . . . . . . . . . . . . mass ordering, it will also test the standard picture with an 2.4 Tests of fundamental physics principles . . . . . unprecedented level of precision. For the com (...truncated)