The Rencontres de Moriond Electroweak Interactions session at La Thuile, Italy, ran from 22–29 March 2025. About 150 physicists gathered for a week of presentations on the latest results in precision electroweak measurements, flavor physics, and neutrino physics. This is our recap of the neutrino-specific content.
Background — what Moriond is
The Moriond conferences have been running since 1966 as a series of smaller, intense gatherings in the French/Italian Alps. The Electroweak Interactions session — held every March — is one of the two largest. It combines collider electroweak results (LHC, Belle II) with neutrino, dark matter, and precision physics. Each speaker typically gets 20–25 minutes, leaving substantial time for discussion. The “post-Moriond review” by experimentalists is widely watched in the community.
In neutrino physics, Moriond often gives the first public look at results that will be expanded at Neutrino conferences in June.
The T2K + NOvA joint update
The single most-watched session featured updated joint analyses of T2K and NOvA. The two experiments published a combined 2024 dataset analysis in October 2024 and have continued refining it.
Key numbers (combined neutrino + antineutrino, normal-ordering best fit):
- $\sin^2\theta_{23} = 0.51 \pm 0.02$ (octant remains uncertain)
- $\Delta m^2_{32} = (2.49 \pm 0.04) \times 10^{-3}$ eV² (consistent with normal ordering)
- $\delta_{CP} = -0.7 \pm 0.5$ rad (effectively unconstrained at 1σ, but slightly disfavors zero)
The two experiments individually still pull in different directions:
- T2K alone prefers $\delta_{CP} \approx -1.6$ rad ($\sim -\pi/2$)
- NOvA alone prefers $\delta_{CP}$ closer to zero
Statistical significance for δ_CP ≠ 0: 1.7σ combined, 2.0σ from T2K alone.
This is essentially flat — no compelling discovery yet, but the inverted ordering with $\delta_{CP} = \pi/2$ is disfavored at >3σ across the combined fit. The story stays “wait for DUNE and Hyper-K.”
MicroBooNE: final NuMI results
MicroBooNE — the precursor experiment to SBN — presented what is likely its final major analysis: charged-current and neutral-current cross sections on argon, measured on the NuMI off-axis beam.
These are essential systematic-input measurements for DUNE, which will use the same argon target on a similar (but higher-power) beam. Highlights:
- $\nu_e$ CC inclusive cross section measured to ~10 % at 0.5–3 GeV
- $\nu_\mu$ CC quasi-elastic cross section measured with sub-10 % uncertainty
- Final-state pion multiplicities consistent with GENIE event generator predictions but in tension with NuWro predictions
- Single-photon and pi0-induced backgrounds quantified for the first time at this energy
These measurements pin down the largest systematic that will dominate DUNE’s δ_CP measurement in the late 2020s. The fact that they exist now is a major win for DUNE planning.
KATRIN spring update
KATRIN presented an interim mass limit based on the first half of their Phase 2 data: $m_\beta < 0.42$ eV at 90 % CL. This is a modest improvement on the Milan 2024 result and is on track for the final design goal of $\sim 0.2$ eV by end of 2026.
Two other Phase-2 updates:
- Systematic uncertainty budget improvements from new energy-loss measurements
- TRISTAN upgrade hardware status — readout boards delivered, calorimeter modules under final assembly
KATRIN remains the world’s most sensitive direct-kinematic mass measurement. Project 8’s first tritium runs (expected 2025–2026) will be the next-generation challenger but won’t have competitive sensitivity until ~2030.
DESI Year-1 + Year-2 partial: the cosmology bombshell
The most-discussed presentation of the week was from the Dark Energy Spectroscopic Instrument (DESI) team. DESI’s full Year-1 data was released in April 2024 with a partial Year-2 update at Moriond 2025.
Headline result: $\sum m_\nu < 0.072$ eV at 95 % CL, when combined with CMB data.
For context, the lower bound from oscillation in the inverted ordering is $\sum m_\nu > 0.10$ eV. The DESI result is therefore in 3σ-level tension with the inverted ordering.
In the normal ordering, the lower bound is $\sum m_\nu > 0.058$ eV. The DESI result is consistent with this but pushes the parameter space hard.
What this means:
- If DESI’s result holds with Year-3 (early 2026) and Year-5 (2027–2028) data, the inverted ordering is essentially ruled out by cosmology.
- The normal ordering remains viable but heavily constrained.
- Either there is new physics (extra relativistic species, modified gravity, neutrino-dark matter coupling) or the masses must lie very close to the minimum allowed by oscillation.
Caveats: Several systematic effects could shift the DESI value, including the modeling of dark energy and the absolute calibration of the BAO scale. The community is being deliberately cautious. The next year of DESI data will tell.
Other neutrino highlights
JUNO filling status: the scintillator filling is on track, with first physics data expected mid-2026. Calibration plans were presented in detail.
IceCube showed an update on the Glashow-resonance event search and a new analysis of the galactic-plane neutrino flux first reported in 2023. The galactic-plane component is now at 6σ significance.
Hyper-K presented its construction status: civil engineering for the cavern is essentially complete, photomultiplier installation begins in 2026, first water filling 2027.
DUNE presented its module-of-opportunity (MOM) designs for the second through fourth modules. The first DUNE module is a “horizontal-drift” LArTPC like ProtoDUNE-I; later modules may use a “vertical-drift” design with pixel-pad anode planes for higher resolution.
SBND has been taking commissioning data since late 2024. First neutrino interactions observed; full physics dataset expected to begin in mid-2025.
LEGEND-200 continues to lead the germanium-76 0νββ search; first quarterly update from LEGEND-200 was presented showing background levels meeting design specifications.
XLZD (the merged XENON-LZ-DARWIN consortium) presented its design baseline: a 60-tonne liquid xenon detector aiming for both dark-matter and 0νββ searches. First data expected ~2030.
The mood and the metric
A few takeaways from corridor conversations:
-
DESI is the new big variable. Everyone is watching cosmology carefully — for the first time in years, cosmological data is more constraining than direct experiments at the global level.
-
The “three-flavor framework holds together” message is becoming less universal. Individual experiments mostly agree with three-flavor predictions, but the combined fit is starting to show small tensions in mass-ordering and CP-phase preferences. SBN and JUNO will be decisive.
-
The next two years are pivotal. JUNO first physics (2026), Hyper-K turn-on (2027), DUNE first module (2028), SBN final result (~2028) — each is potentially paradigm-shifting.
What to watch for in 2025–2026
The biggest events in the near future:
- Neutrino 2026 in Tsukuba, June 2026 — the next biennial reset of the field.
- DESI Year-3 release, early 2026 — settle (or sharpen) the cosmology mass tension.
- JUNO first data, mid-2026.
- SBND/ICARUS first joint analysis, late 2026.
- KATRIN final result, end of 2026 — pushing to ~0.2 eV.
Further reading
The Moriond Electroweak 2025 proceedings will appear at the conference site. For background:
Frequently asked
What were the key neutrino results at Moriond 2025?
Three. (1) Tightened T2K + NOvA δ_CP constraints from the joint analysis — the NO + δ_CP near zero scenario is now slightly preferred but tension remains. (2) MicroBooNE's final NuMI off-axis cross sections, providing essential systematic input for DUNE. (3) KATRIN's spring update bringing the direct mass limit close to 0.4 eV, with the final reach of ~0.2 eV still on track for 2026.
What is Moriond Electroweak?
The annual Rencontres de Moriond Electroweak Interactions session, held every March in La Thuile, Italy, in the Italian Alps. It's a roughly week-long meeting where collider experiments (ATLAS, CMS, LHCb, Belle II) and neutrino/precision experiments present their latest results. Smaller and more focused than the biennial Neutrino conference, with about 150 invited talks. Considered one of the two most important annual venues for new neutrino results.
Did Moriond 2025 present any surprises?
The biggest surprise was DESI's updated cosmology analysis, presented in a plenary session: their measurement of the sum of neutrino masses is now $\sum m_\nu < 0.07$ eV at 95% CL — which is in mild tension with the lower bound from oscillation in the inverted ordering. If this holds up, it strongly disfavors the inverted ordering and approaches the lower limit even for the normal ordering. The community is being cautious until DESI Year-3 data is released in early 2026.
Cite this article 5 formats
APA
Neutrino Times Editorial Team. (2025, August 1). Moriond 2025: the neutrino results from La Thuile. Neutrino Times. https://neutrino-times.com/articles/moriond-2025-electroweak-neutrino-results/
Chicago
Neutrino Times Editorial Team. "Moriond 2025: the neutrino results from La Thuile." Neutrino Times, August 1, 2025. https://neutrino-times.com/articles/moriond-2025-electroweak-neutrino-results/.
MLA
Neutrino Times Editorial Team. "Moriond 2025: the neutrino results from La Thuile." Neutrino Times, 1 Aug. 2025, https://neutrino-times.com/articles/moriond-2025-electroweak-neutrino-results/.
BibTeX
@misc{neutrino-times-moriond-2025-electroweak-neutrino-results,
author = {Neutrino Times Editorial Team},
title = {Moriond 2025: the neutrino results from La Thuile},
howpublished = {Neutrino Times},
year = {2025},
month = {aug},
url = {https://neutrino-times.com/articles/moriond-2025-electroweak-neutrino-results/},
note = {Accessed: 2025-08-01}
} RIS
TY - GEN TI - Moriond 2025: the neutrino results from La Thuile AU - Neutrino Times Editorial Team PY - 2025 DA - 2025-08-01 PB - Neutrino Times UR - https://neutrino-times.com/articles/moriond-2025-electroweak-neutrino-results/ ER -