If there are new neutrino interactions with matter, and if they affect neutrinos of different flavor differently, then they could impact neutrino oscillations. Long-baseline neutrino experiments are well-suited to look for them, thanks to their use of intense, well-characterized neutrino beams.

If the new interactions have a long range—i.e., if they are mediated by a new, ultra-light mediator—then neutrinos on Earth may experience a matter potential sourced by the vast amount of faraway matter elsewhere inside the Earth, Moon, Sun, Milky Way, and in the cosmological matter distribution, as pointed out in 1808.02042 [Universe’s Worth of Electrons to Probe Long-Range Interactions of High-Energy Astrophysical Neutrinos, by MB & Sanjib Agarwalla, PRL 2019]. This boosts the chances of discovering the new interaction even if it is supremely feeble.

In a recent paper (2305.05184 [Flavor-dependent long-range neutrino interactions in DUNE & T2HK: alone they constrain, together they discover, by Masoom Singh, MB, and Sanjib Agarwalla, JHEP 2023]), we explored the prospects of constraining or discovering these new, long-range neutrino interactions in the upcoming long-baseline experiments DUNE and T2HK. We found promising prospects. However, we explored only three different possible forms of the interaction, introduced by gauging three of the accidental global lepton-number U(1) symmetries of the Standard Model.

In a new paper (2404.02775), led by PhD students Masoom Singh and Pragyanprasu Swain, we now extend this to many other symmetries—a plethora of them!—that introduce new neutrino interactions with electrons, neutrons, and protons. Each symmetry affects oscillations differently.

Our new results cement and extend our original findings: DUNE and T2HK should be able to probe the existence of new interactions—and possibly discover and distinguish between alternatives—regardless of which symmetry is responsible for inducing them. The reach of DUNE and T2HK to probe new neutrino interactions is not only deep, but also broad!

Read more at

A plethora of long-range neutrino interactions probed by DUNE and T2HK
Sanjib Kumar Agarwalla, Mauricio Bustamante, Masoom Singh, Pragyanprasu Swain
2404.02775 hep-ph

Download the digitized data from out plots from this GitHub repository.